Re: [time-nuts] [FMT-nuts] LightSquared is Toast!!

[Jim Lux]

On 2/15/12 7:16 AM, Peter Vince wrote:

See:<
http://www.nytimes.com/2012/02/15/business/media/fcc-bars-airwave-use-for-broadband-plan.html?_r=1&scp=3&sq=lightsquared&st=cse




Err.. not necessarily.  As one of the commentators in the business press 
said yesterday (paraphrasing).. Harbinger needs to decide whether to 
shut down LightSquared and take their losses now, or arrange their funds 
for the legal battles to come.


When you have billions riding on the bet, a few million in legal fees 
(which is tens of thousands of billable hours: a LOT of work) to go to 
court to get the decision changed isn't always a big problem.


As quoted in the lore of Python.. "I'm not dead yet..."





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Re: [time-nuts] [FMT-nuts] LightSquared is Toast!!

[Rob Kimberley]

Good news for a change!

Rob K

-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Peter Vince
Sent: 15 February 2012 15:16
To: fmt-n...@yahoogroups.com
Cc: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] [FMT-nuts] LightSquared is Toast!!

See: <
http://www.nytimes.com/2012/02/15/business/media/fcc-bars-airwave-use-for-br
oadband-plan.html?_r=1&scp=3&sq=lightsquared&st=cse
>



On 15 February 2012 14:34, David McClain
wrote:

>
>
> Yeaaa! LightSquared GPS-band broadband is gone. Big article on the 
> front page of the NYTimes Business section.
>
>
> Dr. David McClain, de N7AIG
> d...@refined-audiometrics.com
>
>
>
>
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Re: [time-nuts] [FMT-nuts] LightSquared is Toast!!

[Peter Vince]

See: <
http://www.nytimes.com/2012/02/15/business/media/fcc-bars-airwave-use-for-broadband-plan.html?_r=1&scp=3&sq=lightsquared&st=cse
>



On 15 February 2012 14:34, David McClain wrote:

>
>
> Yeaaa! LightSquared GPS-band broadband is gone. Big article on the front
> page of the NYTimes Business section.
>
>
> Dr. David McClain, de N7AIG
> d...@refined-audiometrics.com
>
>
>
>
>
> __._,_.___
>
>
>  Your email settings: Individual Email|Traditional
> Change settings via the 
> Web(Yahoo!
>  ID required)
> Change settings via email: Switch delivery to Daily 
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Re: [time-nuts] FMT on October 13

[Magnus Danielson]

From: "Didier Juges" <[EMAIL PROTECTED]>
Subject: Re: [time-nuts] FMT on October 13
Date: Wed, 26 Sep 2007 05:57:14 -0500
Message-ID: <[EMAIL PROTECTED]>

Didier,

> I just wanted to point out that with reciprocal counters, you can get
> resolution much better than the 1Hz/s you would get with conventional
> frequency counters, even though the actual accuracy of the measurement may
> be way off.

These days conventional counteras are reciprocal counters. It is only the
old-school counters which is not reciprocal. Nothing wrong with old-school,
but a conventional counter of the shelf today is probably a reciprocal jobbie.

> The original question seemed to imply that with a short transmission time,
> you could not guarantee a frequency accuracy of 1e-6 Hz, which you probably
> can't anyhow, but the limit is not the resolution of the instrument or the
> measurement method. 
> 
> I do not know how far off calibration my HP 5370s are, but the 20pS
> resolution is at best only usable under some circumstances that I have not
> isolated yet, due to jitter.
> 
> When measuring a 3.5 MHz signal (@1dBm) from my HP 8657B through 1 meter of
> good coax cable (with counter and generator phase locked to the Thunderbolt
> GPSDO) in Frequency mode with a 1s gate time, the resolution is 1e-5Hz, with
> about 1e-3Hz p-p variation. When measuring over 1 period with 10,000 periods
> sample size, the resolution is only 1e-1Hz with a standard deviation of ~400
> Hz (or about 0.1%). Of course, over the air, it will be much worse due to
> noise, let alone propagation, fading and multipath.

When measuring over a longer period you see a different spot on the ADEV/MDEV
curve. Chances are that you are more unstable there for an OCXO. Both linear
and noise products will make things harder. It can be a challenge to separate
the drift rate due to signal path shifts and that of the OCXO.

Cheers,
Magnus

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Re: [time-nuts] FMT on October 13

[Didier Juges]

); SAEximRunCond expanded to false
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I just wanted to point out that with reciprocal counters, you can get
resolution much better than the 1Hz/s you would get with conventional
frequency counters, even though the actual accuracy of the measurement may
be way off.

The original question seemed to imply that with a short transmission time,
you could not guarantee a frequency accuracy of 1e-6 Hz, which you probably
can't anyhow, but the limit is not the resolution of the instrument or the
measurement method. 

I do not know how far off calibration my HP 5370s are, but the 20pS
resolution is at best only usable under some circumstances that I have not
isolated yet, due to jitter.

When measuring a 3.5 MHz signal (@1dBm) from my HP 8657B through 1 meter of
good coax cable (with counter and generator phase locked to the Thunderbolt
GPSDO) in Frequency mode with a 1s gate time, the resolution is 1e-5Hz, with
about 1e-3Hz p-p variation. When measuring over 1 period with 10,000 periods
sample size, the resolution is only 1e-1Hz with a standard deviation of ~400
Hz (or about 0.1%). Of course, over the air, it will be much worse due to
noise, let alone propagation, fading and multipath.

Didier KO4BB

> -Original Message-
> From: [EMAIL PROTECTED] 
> [mailto:[EMAIL PROTECTED] On Behalf Of Tom Van Baak
> Sent: Wednesday, September 26, 2007 1:45 AM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] FMT on October 13
> 
> > I guess it depends on signal to noise ratio. With 
> reciprocal counters, 
> > you only need one period to measure as acurately as you 
> need, but to 
> > have good acuracy, you need very good S/N, as there is no 
> filtering possible.
> > 
> > For example, the HP 5370 can measure a single period of a 
> signal with 
> > a resolution of 20pS (excluding noise and trigger 
> imperfections), so 
> > excluding these errors, the HP 5370 could measure a single 
> period of a 
> > ~3.5 MHz signal with 7 x10-5 precision (if I have not goofed the 
> > calculations) More periods improve the resolution 
> proportionately 
> > to the quare root. Accuracy is another matter.
> > 
> > Didier KO4BB
> 
> The jitter on a single period is likely very, very high, 
> especially if it comes over the air. That's why one usually 
> measures over a duration of thousands or even millions of 
> periods (effectively called the gate time).
> 
> The HP 53132A makes something like 200,000 measurements per 
> second. As a result, for a certain range of frequencies, it 
> claims 12 digits/sec of resolution (vs. HP 5370 ~11 digits/sec).
> 
> /tvb
> 
> 
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Re: [time-nuts] FMT on October 13

[Magnus Danielson]

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From: "Tom Van Baak" <[EMAIL PROTECTED]>
Subject: Re: [time-nuts] FMT on October 13
Date: Tue, 25 Sep 2007 23:45:12 -0700
Message-ID: <[EMAIL PROTECTED]>

> ); SAEximRunCond expanded to false
> Errors-To: [EMAIL PROTECTED] RETRY
> 
> > I guess it depends on signal to noise ratio. With reciprocal counters, you
> > only need one period to measure as acurately as you need, but to have good
> > acuracy, you need very good S/N, as there is no filtering possible. 
> > 
> > For example, the HP 5370 can measure a single period of a signal with a
> > resolution of 20pS (excluding noise and trigger imperfections), so excluding
> > these errors, the HP 5370 could measure a single period of a ~3.5 MHz signal
> > with 7 x10-5 precision (if I have not goofed the calculations) More
> > periods improve the resolution proportionately to the quare root. Accuracy
> > is another matter.
> > 
> > Didier KO4BB
> 
> The jitter on a single period is likely very, very high, especially
> if it comes over the air. That's why one usually measures over
> a duration of thousands or even millions of periods (effectively
> called the gate time).
> 
> The HP 53132A makes something like 200,000 measurements
> per second. As a result, for a certain range of frequencies, it
> claims 12 digits/sec of resolution (vs. HP 5370 ~11 digits/sec).

As was discussed recently, didn't they do averaging such that they updated
value every second but the raw singel-shot resolution doess not give you the
12 digits/sec. There was a nice explanation in an article on how this was
not improving say ADEV measurements in the end.

Cheers,
Magnus

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Re: [time-nuts] FMT on October 13

[Hal Murray]

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>> Did mounting it on a block of foam help?

> That is a rather bad solution. You want much softer material to react
> to quicker things, such as silicon rubber. Also, that would only be a
> 12 dB/Oct solution. You would really like a few more poles there. The
> trick is to add weight to the calculation. So you want a very soft
> material, holding a thick block (lead) and from this base suspend the
> oscillator through a soft material again. Now you have a 24 dB/Oct
> solution. The trouble you now will have is that the wires will be
> another shock/vibration transport mechanism. They would need to be
> connected to the middle-frame such that outer forces hit the middle
> weigth and not directly on the sensitive part. They would need to be
> soft and arranged is such a way that they do not push or pull the
> inner end, but is allowed to flex alot. 

Yes, but inserting a chunk of foam is a lot easier than finding a block of 
lead.  It's likely to be good enough.  (Make that "good enough for most 
application.  This is time-nuts.  Nothing is good-enough that somebody won't 
suggest something better/nuttier.  :)

Packing bubbles might work too.  I'm thinking of the sheets of bubble wrap 
that are fun to snap rather than the foam peanuts that get all over the place 
and are really nasty if you have a slight static charge.

Does anybody have any data on the sensitivity of a crystal oscillator vs 
frequency of mechanical shock/vibration?  Does it scale with amplitude or 
acceleration or ???





-- 
These are my opinions, not necessarily my employer's.  I hate spam.




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Re: [time-nuts] FMT on October 13

[Tom Van Baak]

); SAEximRunCond expanded to false
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> I guess it depends on signal to noise ratio. With reciprocal counters, you
> only need one period to measure as acurately as you need, but to have good
> acuracy, you need very good S/N, as there is no filtering possible. 
> 
> For example, the HP 5370 can measure a single period of a signal with a
> resolution of 20pS (excluding noise and trigger imperfections), so excluding
> these errors, the HP 5370 could measure a single period of a ~3.5 MHz signal
> with 7 x10-5 precision (if I have not goofed the calculations) More
> periods improve the resolution proportionately to the quare root. Accuracy
> is another matter.
> 
> Didier KO4BB

The jitter on a single period is likely very, very high, especially
if it comes over the air. That's why one usually measures over
a duration of thousands or even millions of periods (effectively
called the gate time).

The HP 53132A makes something like 200,000 measurements
per second. As a result, for a certain range of frequencies, it
claims 12 digits/sec of resolution (vs. HP 5370 ~11 digits/sec).

/tvb


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Re: [time-nuts] FMT on October 13

[Tim Shoppa]

); SAEximRunCond expanded to false
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Hal Murray <[EMAIL PROTECTED]> wrote:
> > Make sure not to get near any of the equipment. Free-running
> > oscillators are sensitive to vibration or shock. You've probably heard
> > the story of my best Sulzer oscillator making small phase or jumps
> > which I eventually correlated to when the kids flushed the toilet down
> > the hall. 
>
> Did mounting it on a block of foam help?

I've had all my toilets mounted on blocks of foam for years now.
They hardly ever make phase jumps any more!

Tim.

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Re: [time-nuts] FMT on October 13

[steve heidmann]

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Did anyone mention sorbothane ?

Magnus Danielson <[EMAIL PROTECTED]> wrote:  From: Hal Murray 
Subject: Re: [time-nuts] FMT on October 13
Date: Tue, 25 Sep 2007 14:23:21 -0700
Message-ID: <[EMAIL PROTECTED]>

> ); SAEximRunCond expanded to false
> Errors-To: [EMAIL PROTECTED] RETRY
> 
> 
> > Make sure not to get near any of the equipment. Free-running
> > oscillators are sensitive to vibration or shock. You've probably heard
> > the story of my best Sulzer oscillator making small phase or jumps
> > which I eventually correlated to when the kids flushed the toilet down
> > the hall. 
> 
> Did mounting it on a block of foam help?

That is a rather bad solution. You want much softer material to react to
quicker things, such as silicon rubber. Also, that would only be a 12 dB/Oct
solution. You would really like a few more poles there. The trick is to add
weight to the calculation. So you want a very soft material, holding a thick
block (lead) and from this base suspend the oscillator through a soft material
again. Now you have a 24 dB/Oct solution. The trouble you now will have is that
the wires will be another shock/vibration transport mechanism. They would need
to be connected to the middle-frame such that outer forces hit the middle
weigth and not directly on the sensitive part. They would need to be soft and
arranged is such a way that they do not push or pull the inner end, but is
allowed to flex alot.

It is all just as normal filtering, but in the acoustical domain.

Cheers,
Magnus

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-
Don't let your dream ride pass you by.Make it a reality with Yahoo! Autos. 
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Re: [time-nuts] FMT on October 13

[Magnus Danielson]

); SAEximRunCond expanded to false
Errors-To: [EMAIL PROTECTED] RETRY

From: Hal Murray <[EMAIL PROTECTED]>
Subject: Re: [time-nuts] FMT on October 13
Date: Tue, 25 Sep 2007 14:23:21 -0700
Message-ID: <[EMAIL PROTECTED]>

> ); SAEximRunCond expanded to false
> Errors-To: [EMAIL PROTECTED] RETRY
> 
> 
> > Make sure not to get near any of the equipment. Free-running
> > oscillators are sensitive to vibration or shock. You've probably heard
> > the story of my best Sulzer oscillator making small phase or jumps
> > which I eventually correlated to when the kids flushed the toilet down
> > the hall. 
> 
> Did mounting it on a block of foam help?

That is a rather bad solution. You want much softer material to react to
quicker things, such as silicon rubber. Also, that would only be a 12 dB/Oct
solution. You would really like a few more poles there. The trick is to add
weight to the calculation. So you want a very soft material, holding a thick
block (lead) and from this base suspend the oscillator through a soft material
again. Now you have a 24 dB/Oct solution. The trouble you now will have is that
the wires will be another shock/vibration transport mechanism. They would need
to be connected to the middle-frame such that outer forces hit the middle
weigth and not directly on the sensitive part. They would need to be soft and
arranged is such a way that they do not push or pull the inner end, but is
allowed to flex alot.

It is all just as normal filtering, but in the acoustical domain.

Cheers,
Magnus

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Re: [time-nuts] FMT on October 13

[Hal Murray]

); SAEximRunCond expanded to false
Errors-To: [EMAIL PROTECTED] RETRY


> Make sure not to get near any of the equipment. Free-running
> oscillators are sensitive to vibration or shock. You've probably heard
> the story of my best Sulzer oscillator making small phase or jumps
> which I eventually correlated to when the kids flushed the toilet down
> the hall. 

Did mounting it on a block of foam help?


-- 
These are my opinions, not necessarily my employer's.  I hate spam.




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Re: [time-nuts] FMT on October 13

[Tom Van Baak]

); SAEximRunCond expanded to false
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>> While were at it, in the case mentioned above I'm a curious
>> about their FMT frequency standard -- if it's really accurate
>> to parts in 10^12, as they imply, over 10 minutes. I could
>> believe this if it were an Rb or Cs-based GPSDO.
> 
> We're using an Austron 1250A OXCO that's been measured as better than
> 9x10e-13 for averaging times of 1 second out to 1000 seconds; over a
> broader range, it's better than 3x10e-12 from 0.1 seconds to 40,000 seconds.

Ah, if "they" is you, then I have no more worries. Yes, using
that free-running 1250A is the perfect solution; much better
than using the output of a GPSDO.


> Now, an important point -- we're not trying to trim the Austron to be
> precisely on frequency.  We're going to let it run at whatever offset it
> happens to be.  That will help make sure that the signal doesn't have
> lots of zero's at the end, even though the resolution of the
> synthesizers driving the transmitters is limited to 0.1 Hz.

Clever.


> We'll be comparing the Austron against a Z3801a (via my TSC-5120A
> analyzer) and logging the frequency difference for at least several
> hours prior to the test until several hours following.  The TSC gives 16
> digits over 1000 seconds; depending on how much jitter we see, we'll
> probably throw away the last two or three.  Even though the Z3801A may
> be wandering around a bit, with successive 1000 second measurements we
> should have confidence in the actual frequency over 1000 second periods
> to at least parts in the 12s, ultimately limited by the Austron's
> stability.  But since that's known to be in the 13s over the averaging
> period of interest, we think we're safe in claiming accuracy and
> stability of parts in the 12s.

Yes, running the measurement for hours before and after is
the right thing to do. All sounds good.

Make sure not to get near any of the equipment. Free-running
oscillators are sensitive to vibration or shock. You've probably
heard the story of my best Sulzer oscillator making small phase
or jumps which I eventually correlated to when the kids flushed
the toilet down the hall.


> Tom, if I'm missing something in this analysis, I'm seriously open to
> education...

Nothing missing; you nailed it.

/tvb


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Re: [time-nuts] FMT on October 13

[John Ackermann N8UR]

); SAEximRunCond expanded to false
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Didier Juges said the following on 09/24/2007 09:40 PM:
> ); SAEximRunCond expanded to false
> Errors-To: [EMAIL PROTECTED] RETRY
> 
> I guess it depends on signal to noise ratio. With reciprocal counters, you
> only need one period to measure as acurately as you need, but to have good
> acuracy, you need very good S/N, as there is no filtering possible. 
> 
> For example, the HP 5370 can measure a single period of a signal with a
> resolution of 20pS (excluding noise and trigger imperfections), so excluding
> these errors, the HP 5370 could measure a single period of a ~3.5 MHz signal
> with 7 x10-5 precision (if I have not goofed the calculations) More
> periods improve the resolution proportionately to the quare root. Accuracy
> is another matter.

I did some measurements on the frequency counter capability of my 5370B
some time ago, and found that the performance wasn't as good as in time
interval mode.

But it's still not bad -- the internal noise floor was 4x10e-11 for 1
second (using the 1 second gate time).  See
http://www.febo.com/time-freq/hardware/5370B/index.html

John


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Re: [time-nuts] FMT on October 13

[John Ackermann N8UR]

); SAEximRunCond expanded to false
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Tom Van Baak said the following on 09/24/2007 08:57 PM:

> I would think this is especially true for non-local frequencies,
> such as one received over the air. I'll leave it to you FMT
> guys to comment on the magnitude of degradation due to
> transmission and reception noise.

Absolutely.  Probably the best real-world performance you can get with a
skywave signal is on the order of 0.01 Hz.  Propagation effects play
havoc, but the longer the averaging period, the more short-term effects
will average away.  One of the reasons for the fairly long transmission
periods is to both allow longer averaging, but also provide the
opportunity to observe the atmospheric conditions at work.

> While were at it, in the case mentioned above I'm a curious
> about their FMT frequency standard -- if it's really accurate
> to parts in 10^12, as they imply, over 10 minutes. I could
> believe this if it were an Rb or Cs-based GPSDO.

We're using an Austron 1250A OXCO that's been measured as better than
9x10e-13 for averaging times of 1 second out to 1000 seconds; over a
broader range, it's better than 3x10e-12 from 0.1 seconds to 40,000 seconds.

Now, an important point -- we're not trying to trim the Austron to be
precisely on frequency.  We're going to let it run at whatever offset it
happens to be.  That will help make sure that the signal doesn't have
lots of zero's at the end, even though the resolution of the
synthesizers driving the transmitters is limited to 0.1 Hz.

We'll be comparing the Austron against a Z3801a (via my TSC-5120A
analyzer) and logging the frequency difference for at least several
hours prior to the test until several hours following.  The TSC gives 16
digits over 1000 seconds; depending on how much jitter we see, we'll
probably throw away the last two or three.  Even though the Z3801A may
be wandering around a bit, with successive 1000 second measurements we
should have confidence in the actual frequency over 1000 second periods
to at least parts in the 12s, ultimately limited by the Austron's
stability.  But since that's known to be in the 13s over the averaging
period of interest, we think we're safe in claiming accuracy and
stability of parts in the 12s.

Tom, if I'm missing something in this analysis, I'm seriously open to
education...

By the way -- the synthesizers used to drive the transmitter amplifiers
will be PTS 250 SX-51 low noise units, so hopefully the transmitted
signals will have a better-than-the-average-ham-rig phase noise.  The
synthesizers will directly feed the driver and final amplifier stages of
some vintage Kenwood TS-520 ham transceivers with no other mixing --
it'll purely be the synthesizer and a transistor buffer amp driving two
vacuum tube stages to get up to about 75 watts (the rigs can run 100
watts, but we're derating -- and adding fans -- to support the long
key-down times).

John


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Re: [time-nuts] FMT on October 13

[Bruce Griffiths]

Didier Juges wrote:
> I guess it depends on signal to noise ratio. With reciprocal counters, you
> only need one period to measure as acurately as you need, but to have good
> acuracy, you need very good S/N, as there is no filtering possible. 
>
> For example, the HP 5370 can measure a single period of a signal with a
> resolution of 20pS (excluding noise and trigger imperfections), so excluding
> these errors, the HP 5370 could measure a single period of a ~3.5 MHz signal
> with 7 x10-5 precision (if I have not goofed the calculations) More
> periods improve the resolution proportionately to the quare root. Accuracy
> is another matter.
>
> Didier KO4BB
>   
Didier

With band limited gaussian noise and an SNR of 40dB the rms error in
measuring the period of a single cycle is about 0.3%

Bruce

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Re: [time-nuts] FMT on October 13

[Didier Juges]

); SAEximRunCond expanded to false
Errors-To: [EMAIL PROTECTED] RETRY

I guess it depends on signal to noise ratio. With reciprocal counters, you
only need one period to measure as acurately as you need, but to have good
acuracy, you need very good S/N, as there is no filtering possible. 

For example, the HP 5370 can measure a single period of a signal with a
resolution of 20pS (excluding noise and trigger imperfections), so excluding
these errors, the HP 5370 could measure a single period of a ~3.5 MHz signal
with 7 x10-5 precision (if I have not goofed the calculations) More
periods improve the resolution proportionately to the quare root. Accuracy
is another matter.

Didier KO4BB


> -Original Message-
> From: [EMAIL PROTECTED] 
> [mailto:[EMAIL PROTECTED] On Behalf Of Hal Murray
> Sent: Monday, September 24, 2007 5:26 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] FMT on October 13
> 
> 
> > Plans are to transmit two 10 minute test periods, and a 
> third if the 
> > transmitters aren't melting by that point.
> 
> > Our goal is to transmit a signal known in frequency to 
> parts in 10e-12 
> > (i.e., less than 0.0001 Hz error at 10 MHz) and stable to a similar 
> > level during the course of the transmission.  Frequencies will be 
> > measured at the transmitter site with a system capable of 
> microHertz 
> > resolution referenced to a GPS disciplined oscillator, and 
> will also 
> > be monitored by another station in groundwave range that 
> can measure 
> > the frequencies with similar accuracy.
> 
> Suppose I have a pile of good lab gear, and it gets N seconds 
> of signal.
> 
> How accurately can it measure the frequency?
> 
> 
> --
> These are my opinions, not necessarily my employer's.  I hate spam.
> 
> 
> 
> 
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Re: [time-nuts] FMT on October 13

[Tom Van Baak]

>> Plans are to transmit two 10 minute test periods, and a third if the
>> transmitters aren't melting by that point. 
> 
>> Our goal is to transmit a signal known in frequency to parts in 10e-12
>> (i.e., less than 0.0001 Hz error at 10 MHz) and stable to a similar
>> level during the course of the transmission.  Frequencies will be
>> measured at the transmitter site with a system capable of microHertz
>> resolution referenced to a GPS disciplined oscillator, and will also
>> be monitored by another station in groundwave range that can measure
>> the frequencies with similar accuracy. 
> 
> Suppose I have a pile of good lab gear, and it gets N seconds of signal.
> 
> How accurately can it measure the frequency?

Hi Hal,

If you have a low noise CW signal, a cheap, legacy 1 ns
resolution counter will give you 9 digits of resolution per
second. So to measure to parts in 10^12 requires gate
times on the order of a thousand seconds.

A fancier, modern counter like a HP 53132A is almost ten
times better than that so 100 s gate times are all you need
for 12 digits. Further, if it's an oddball frequency (i.e., not
a nice multiple or fraction of 10 MHz) even 10 second gate
times are sufficient with this counter (it does clever CW
oversampling inside).

For extreme counters like HP 5370 or SR 620 with resolution
well under 50 ps you can measure any frequency to 12 digits
in a matter of tens of seconds.

The main problems at this level are often that neither your
frequency reference nor the frequency you are measuring
are stable to parts in 10^12th. So the measurements you
get will contain the sum of noise in both sources and the
counter itself. And this noise is often well above parts in
10^12th. It takes time, statistics, or other tests to determine
the noise contribution of each.

I would think this is especially true for non-local frequencies,
such as one received over the air. I'll leave it to you FMT
guys to comment on the magnitude of degradation due to
transmission and reception noise.

While were at it, in the case mentioned above I'm a curious
about their FMT frequency standard -- if it's really accurate
to parts in 10^12, as they imply, over 10 minutes. I could
believe this if it were an Rb or Cs-based GPSDO.

Usually the accuracy of GPS disciplined oscillators are spec'd
for averaging times over a day. And at one day, parts in 10^12
is very easy (many are down in the low 13's or 14's). But over
a short span like 10 minutes most quartz-based GPSDO wander
in frequency by many parts in 10^11. See, for example, these
two nice quartz GPSDO over 10 minutes and note the scale is
1e-11 per *division*; which is almost 1e-10 full-scale.

http://www.leapsecond.com/pages/fury/#6

/tvb


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Re: [time-nuts] FMT on October 13

[Hal Murray]

> Plans are to transmit two 10 minute test periods, and a third if the
> transmitters aren't melting by that point. 

> Our goal is to transmit a signal known in frequency to parts in 10e-12
> (i.e., less than 0.0001 Hz error at 10 MHz) and stable to a similar
> level during the course of the transmission.  Frequencies will be
> measured at the transmitter site with a system capable of microHertz
> resolution referenced to a GPS disciplined oscillator, and will also
> be monitored by another station in groundwave range that can measure
> the frequencies with similar accuracy. 

Suppose I have a pile of good lab gear, and it gets N seconds of signal.

How accurately can it measure the frequency?


-- 
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Re: [time-nuts] FMT

[Didier Juges]

Hi Connie,

My life has been a little complicated lately, but it will settle
eventually :-)

I was surprised to be so close just by ear. 20m was hard because of QSB,
but 40 and 80 were good, with strong and stable signals.

I have Spectrum Lab installed on this "new to me" laptop, so next week
should be better. I will use the HP 8657B instead of the HP 3586 (the
lack of attenuator on the 3586 TG output makes it hard to adjust the
level of the injection signal). Resolution drops to 1 Hz instead of 0.1
Hz, but with Spectrum Lab, that should be fine.

Thanks for running this exercise. That is most interesting. I wish ARRL
had such a good setup...

73,
Didier KO4BB

-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Connie Marshall
Sent: Saturday, May 26, 2007 10:43 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] FMT

Hi Didier,

Good to hear from you. Sounds like you did fine considering how bad
condx
were that night.

I will send out an email on the time and frequency. I think it will be
Thursday night this week, but not sure yet.

Thanks for participating and have a good weekend

73

Connie
K5CM

-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Behalf Of Didier Juges
Sent: Saturday, May 26, 2007 8:11 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] FMT


Well, I was too late sending my results, but I did manage to listen to
the signals this past Wednesday.

I did not have time to prepare anything but listening by ear on the
FT-1000 and using the HP-3586A as a beat generator (free running off
it's internal Ovenair precision OCXO), I managed to get within 0.4 Hz on
40 m and 0.2 Hz on 80m (good signals). I was off by 1.5 Hz on 20m, where
the signal was very weak with QSB, and I did not hear anything on 17m.

Thanks Connie, I will try to be better prepared next week (hooked to GPS
and using Spectrum Lab).

Didier KO4BB


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No virus found in this incoming message.
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12:32 PM



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Re: [time-nuts] FMT

[Connie Marshall]

Hi Didier,

Good to hear from you. Sounds like you did fine considering how bad condx
were that night.

I will send out an email on the time and frequency. I think it will be
Thursday night this week, but not sure yet.

Thanks for participating and have a good weekend

73

Connie
K5CM

-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Behalf Of Didier Juges
Sent: Saturday, May 26, 2007 8:11 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] FMT


Well, I was too late sending my results, but I did manage to listen to
the signals this past Wednesday.

I did not have time to prepare anything but listening by ear on the
FT-1000 and using the HP-3586A as a beat generator (free running off
it's internal Ovenair precision OCXO), I managed to get within 0.4 Hz on
40 m and 0.2 Hz on 80m (good signals). I was off by 1.5 Hz on 20m, where
the signal was very weak with QSB, and I did not hear anything on 17m.

Thanks Connie, I will try to be better prepared next week (hooked to GPS
and using Spectrum Lab).

Didier KO4BB


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Re: [time-nuts] FMT

[Didier Juges]

Well, I was too late sending my results, but I did manage to listen to 
the signals this past Wednesday.

I did not have time to prepare anything but listening by ear on the 
FT-1000 and using the HP-3586A as a beat generator (free running off 
it's internal Ovenair precision OCXO), I managed to get within 0.4 Hz on 
40 m and 0.2 Hz on 80m (good signals). I was off by 1.5 Hz on 20m, where 
the signal was very weak with QSB, and I did not hear anything on 17m.

Thanks Connie, I will try to be better prepared next week (hooked to GPS 
and using Spectrum Lab).

Didier KO4BB


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Re: [time-nuts] FMT Results Published !

[Connie Marshall]

Funny. several people have said they made math mistakes. I wonder if
W1AW would admit to a math mistake... Hmm.. nah, no chance.

-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Behalf Of Bob Raker
Sent: Wednesday, March 07, 2007 8:15 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] FMT Results Published !


One more set: (from PA)

1600
80   -0.1
40   -1.4

WA6ZTY  -1.83  ( I made a stupid 2 Hz math error - my actual measurement was
-0.17)

I agree, it looks like the W1AW 40 M measurement was off.

BR





On 3/7/07, Joe Fitzgerald <[EMAIL PROTECTED]> wrote:
>
> Connie Marshall wrote:
>
> >  In the old FMT days call signs were published with the results.
>
> Here are mine :
>
> 160 0.1
> 80 -0.5
> 40  -1.4
>
> WA6TZY
> 40 No copy
>
> -Joe KM1P
> Boston MA USA
>
>
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Re: [time-nuts] FMT Results Published !

[Bob Raker]

One more set: (from PA)

1600
80   -0.1
40   -1.4

WA6ZTY  -1.83  ( I made a stupid 2 Hz math error - my actual measurement was
-0.17)

I agree, it looks like the W1AW 40 M measurement was off.

BR





On 3/7/07, Joe Fitzgerald <[EMAIL PROTECTED]> wrote:
>
> Connie Marshall wrote:
>
> >  In the old FMT days call signs were published with the results.
>
> Here are mine :
>
> 160 0.1
> 80 -0.5
> 40  -1.4
>
> WA6TZY
> 40 No copy
>
> -Joe KM1P
> Boston MA USA
>
>
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Re: [time-nuts] FMT Results Published !

[Joe Fitzgerald]

Connie Marshall wrote:

 >  In the old FMT days call signs were published with the results.

Here are mine :

160 0.1
80 -0.5
40  -1.4

WA6TZY
40 No copy

-Joe KM1P
Boston MA USA


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Re: [time-nuts] FMT Results Published !

[Connie Marshall]

It was also interesting to note that there were four stations within 1Hz, on
three of the four bands, and all four were over 1Hz high on W1AW 40 meters.

The station that copied both 40 meters signals to less than 1Hz was off by
more than 1Hz on the other two bands.

Here are my results if any one wants to fill in call signs on the spread
sheet. In the old FMT days call signs were published with the results.

160 -0.27
80  -0.45
40  -1.13

WA6ZTY
40  -0.07

Connie
K5CM
Oklahoma


-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Behalf Of Mike Fahmie
Sent: Wednesday, March 07, 2007 11:59 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] FMT Results Published !


At 07:05 AM 3/7/2007, you wrote:
>Mike Fahmie wrote:
> > 2006 FMT results have appeared at:
> >
> > http://www.arrl.org/w1aw/fmt/2006/2006-fmt-results.html
> >
>
>It is curious that none of us managed to be within 1 Hz on 3 bands.  I
>missed out by 1.4 Hz on 40M ... but then there were a lot of us who
>measured on the low side on 40 relative to the umpire.
>
>
>-Joe KM1P
>   Boston MA

There are a number of things that point toward W1AW being about a hertz
high.

1.) Though W1AW received nearly 3 times as many 40M reports as WA6ZTY, each
had nearly the same number of reports in the <1 Hz group, but W1AW had 4
times as many in the 1 to 5 Hz group.

2.) If you look at entries who were in the <1 Hz group on other
measurements, they were all about 1 Hz low on W1AW's 40 M signal.

3.) Only one person who copied WA6ZTY <1 Hz copied W1AW <1 Hz.

-Mike-


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Re: [time-nuts] FMT Results Published !

[Mike Fahmie]

At 07:05 AM 3/7/2007, you wrote:
>Mike Fahmie wrote:
> > 2006 FMT results have appeared at:
> >
> > http://www.arrl.org/w1aw/fmt/2006/2006-fmt-results.html
> >
>
>It is curious that none of us managed to be within 1 Hz on 3 bands.  I
>missed out by 1.4 Hz on 40M ... but then there were a lot of us who
>measured on the low side on 40 relative to the umpire.
>
>
>-Joe KM1P
>   Boston MA

There are a number of things that point toward W1AW being about a hertz high.

1.) Though W1AW received nearly 3 times as many 40M reports as WA6ZTY, each 
had nearly the same number of reports in the <1 Hz group, but W1AW had 4 
times as many in the 1 to 5 Hz group.

2.) If you look at entries who were in the <1 Hz group on other 
measurements, they were all about 1 Hz low on W1AW's 40 M signal.

3.) Only one person who copied WA6ZTY <1 Hz copied W1AW <1 Hz.

-Mike-


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Re: [time-nuts] FMT Results Published !

[Joe Fitzgerald]

Mike Fahmie wrote:
> 2006 FMT results have appeared at:
> 
> http://www.arrl.org/w1aw/fmt/2006/2006-fmt-results.html
> 

It is curious that none of us managed to be within 1 Hz on 3 bands.  I 
missed out by 1.4 Hz on 40M ... but then there were a lot of us who 
measured on the low side on 40 relative to the umpire.


-Joe KM1P
  Boston MA


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Re: [time-nuts] FMT 2006 results

[John Ackermann N8UR]

if it turns out that there really is an anomaly on 40M, we'll let ARRL 
know; last year they were off by about 0.4Hz on 160M so something like 
this isn't a first.

One problem is that they really don't aim the test at the time-nuts 
crowd, and frankly their measurement system isn't at the level some of 
us would like to see.  And the change of transmitter hardware this year 
didn't help.

I don't want to go into details on the list, but there is some activity 
going on to try to improve the situation next year.

John
-

Rex wrote:
> John and others,
> 
> I didn't play in this game so I haven't been paying close attention to
> the contest or results. In my skimming of the messages I think I am
> hearing that several knowledgeable people came out with results close to
> each other but offset from the "winning" results.
> 
> If I am correct in my assessment, seems like the ARRL should be made
> aware that the process or the specification of the contest signal may be
> lacking in some details.
> 
> What do you think was the issue? Was it a modulated carrier on SSB with
> some residual rather than pure CW?
> 
> If there is some consensus of close mis-measured results in this group,
> seems like the ARRL needs to be informed about it so exactly what the
> signal is  is described or the contest is modified with a better pure CW
> carrier in the future.
> 
> Am I right, or am I completely missing the point in some way?
> 
> -Rex
> 
> On Thu, 4 Jan 2007 00:54:34 -0600, "Connie Marshall"
> <[EMAIL PROTECTED]> wrote:
> 
>> Looks good John Our readdings are within .03Hz on 160, .1Hz on 80, and
>> .06Hz on 40 of each other.
>>
>> Connie
>>
>> -Original Message-
>> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
>> Behalf Of John Ackermann N8UR
>> Sent: Wednesday, January 03, 2007 9:33 AM
>> To: Discussion of precise time and frequency measurement
>> Subject: [time-nuts] FMT 2006 results
>>
>>
>> I've put my FMT results at http://www.febo.com/time-freq/fmt/fmt2006/
>> based on the preliminary numbers from ARRL that Connie posted here.
>>
>> As I noted earlier, I screwed up the math and ended up being off on all
>> three bands by 75 to 110 Hz -- double the delta between W1AW and my
>> marker, because I did USB math when the receivers were set to LSB.
>>
>> After correcting that error, I was -0.295 Hz on 160, -0.343 Hz on 40,
>> and -1.066 Hz on 40.  That's a bit more like it, though the error on 40
>> is interesting, and I see that a few other folks saw that problem, too.
>> We'll have to wait for the final results from W1AW to see if their 40M
>> frequency had a typo.
>>
>> I think a couple of other folks noted, as did I, that on 40M there
>> appeared to be two signals close to each other (I measured about 0.5
>> Hz).  An FFT with enough resolution to separate them lost any ability to
>> look for CW in the waterfall, so I had to guess which was the correct
>> signal.  I chose the sharper one, which was the higher frequency of the
>> two; had I picked the one that was more smeared out, I would have been
>> more like -0.5 Hz off.
>>
>> I've learned my lesson -- from now on, all measurements will be taken in
>> USB mode!
>>
>> John
>>
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Re: [time-nuts] FMT 2006 results

[Rex]

John and others,

I didn't play in this game so I haven't been paying close attention to
the contest or results. In my skimming of the messages I think I am
hearing that several knowledgeable people came out with results close to
each other but offset from the "winning" results.

If I am correct in my assessment, seems like the ARRL should be made
aware that the process or the specification of the contest signal may be
lacking in some details.

What do you think was the issue? Was it a modulated carrier on SSB with
some residual rather than pure CW?

If there is some consensus of close mis-measured results in this group,
seems like the ARRL needs to be informed about it so exactly what the
signal is  is described or the contest is modified with a better pure CW
carrier in the future.

Am I right, or am I completely missing the point in some way?

-Rex

On Thu, 4 Jan 2007 00:54:34 -0600, "Connie Marshall"
<[EMAIL PROTECTED]> wrote:

>Looks good John Our readdings are within .03Hz on 160, .1Hz on 80, and
>.06Hz on 40 of each other.
>
>Connie
>
>-Original Message-
>From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
>Behalf Of John Ackermann N8UR
>Sent: Wednesday, January 03, 2007 9:33 AM
>To: Discussion of precise time and frequency measurement
>Subject: [time-nuts] FMT 2006 results
>
>
>I've put my FMT results at http://www.febo.com/time-freq/fmt/fmt2006/
>based on the preliminary numbers from ARRL that Connie posted here.
>
>As I noted earlier, I screwed up the math and ended up being off on all
>three bands by 75 to 110 Hz -- double the delta between W1AW and my
>marker, because I did USB math when the receivers were set to LSB.
>
>After correcting that error, I was -0.295 Hz on 160, -0.343 Hz on 40,
>and -1.066 Hz on 40.  That's a bit more like it, though the error on 40
>is interesting, and I see that a few other folks saw that problem, too.
> We'll have to wait for the final results from W1AW to see if their 40M
>frequency had a typo.
>
>I think a couple of other folks noted, as did I, that on 40M there
>appeared to be two signals close to each other (I measured about 0.5
>Hz).  An FFT with enough resolution to separate them lost any ability to
>look for CW in the waterfall, so I had to guess which was the correct
>signal.  I chose the sharper one, which was the higher frequency of the
>two; had I picked the one that was more smeared out, I would have been
>more like -0.5 Hz off.
>
>I've learned my lesson -- from now on, all measurements will be taken in
>USB mode!
>
>John
>
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Re: [time-nuts] FMT 2006 results

[Connie Marshall]

Looks good John Our readdings are within .03Hz on 160, .1Hz on 80, and
.06Hz on 40 of each other.

Connie

-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Behalf Of John Ackermann N8UR
Sent: Wednesday, January 03, 2007 9:33 AM
To: Discussion of precise time and frequency measurement
Subject: [time-nuts] FMT 2006 results


I've put my FMT results at http://www.febo.com/time-freq/fmt/fmt2006/
based on the preliminary numbers from ARRL that Connie posted here.

As I noted earlier, I screwed up the math and ended up being off on all
three bands by 75 to 110 Hz -- double the delta between W1AW and my
marker, because I did USB math when the receivers were set to LSB.

After correcting that error, I was -0.295 Hz on 160, -0.343 Hz on 40,
and -1.066 Hz on 40.  That's a bit more like it, though the error on 40
is interesting, and I see that a few other folks saw that problem, too.
 We'll have to wait for the final results from W1AW to see if their 40M
frequency had a typo.

I think a couple of other folks noted, as did I, that on 40M there
appeared to be two signals close to each other (I measured about 0.5
Hz).  An FFT with enough resolution to separate them lost any ability to
look for CW in the waterfall, so I had to guess which was the correct
signal.  I chose the sharper one, which was the higher frequency of the
two; had I picked the one that was more smeared out, I would have been
more like -0.5 Hz off.

I've learned my lesson -- from now on, all measurements will be taken in
USB mode!

John

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Re: [time-nuts] FMT

[John Ackermann N8UR]

John Miles said the following on 12/29/2006 03:24 PM:

> Does the 3586C have an AGC-controlled IF output?  A BFO synthesizer would be
> a good idea, but it might not be necessary if you can filter and measure the
> IF directly.

It has an IF output as well as a built in counter with 0.1 Hz
resolution.  However, there is no AGC as such.  You can put it into a
100dB dynamic range mode, which reduces sensitivity, or in an
autoranging mode where the gain is stepped in 10dB increments.  Or you
can turn the ranging off and manually set the gain.  The autoranging
results in transients that are annoying in a waterfall, so I usually set
the range manually and live with a bit of distortion if it overloads
from time to time.

John

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Re: [time-nuts] FMT

[John Miles]

I didn't enter the FMT due to the lack of an HF antenna, but my original
plan was to downconvert the signal with a GPS-locked LO, then run it through
a logamp and a very narrow CW filter and straight into my 5370B without any
demodulation at all.  As long as there were no interferers within the CW
filter's bandwidth -- which it sounds like there may have been -- that
should have worked about as well as any other technique.

Does the 3586C have an AGC-controlled IF output?  A BFO synthesizer would be
a good idea, but it might not be necessary if you can filter and measure the
IF directly.

-- john, KE5FX


>
> One of my plans is to build a BFO synthesizer to replace the crystals
> and thereby eliminate any frequency offset.  Having done that I should
> be able to directly determine frequency by measuring the output tone.
>
> John
>


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Re: [time-nuts] FMT

[John Ackermann N8UR]

Mike Suhar said the following on 12/29/2006 02:32 PM:

> I used an HP 3586C Frequency Selective Voltmeter with the tracking generator
> looped back to the RF input via a step attenuator.  The audio output went to
> the PC.  An ICOM IC-745 was tuned to the 160M signal to hear the test
> announcements throughout the test period.  The antenna on the HP was a SWL
> slopper antenna that favors the lower frequencies.  The ICOM was on a
> 40-meter dipole. 

I too use the 3586C but there is one thing to be aware of: while the
main frequency synthesis system can be locked to an external reference,
the BFO signal comes from an independent oscillator that is not
disciplined.

The last IF is at 15.625 kHz and the BFO frequency (generated on board
A22) is (for the "C" version) is either 17.475 kHz (USB) or 13.775 kHz
(LSB).  The BFO is derived from a crystal -- 1.7475 MHz for USB and
1.3775 MHz for LSB; the crystal frequency is divided by 100.
Interestingly, it appears that the BFO signal is injected into the
product detector as a square wave; unless I missed it, there's no filter
following the divider.

After a bit of warm-up, the BFO is very stable (dividing by 100
certainly helps reduce any drift) but the nominal 1850 Hz tone generated
by a signal on the tuned frequency is likely to be off by a fraction of
a Hertz.

One of my plans is to build a BFO synthesizer to replace the crystals
and thereby eliminate any frequency offset.  Having done that I should
be able to directly determine frequency by measuring the output tone.

John

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Re: [time-nuts] FMT

[Mike Suhar]

I also sent the Spectrum Lab data to a spreadsheet.  Once I got the carrier
at the frequency I wanted I did not touch the receiver.  I made two mistakes
this time: 1. I did not record a wav file, 2. my FFT settings were such that
it made tuning difficult.  The settings were fine once I found the carrier
but getting there was another matter. Because of this I was unable to tune
in the 40-meter signal.  I found it just as the test ended but it was too
late to get any data.  

I used an HP 3586C Frequency Selective Voltmeter with the tracking generator
looped back to the RF input via a step attenuator.  The audio output went to
the PC.  An ICOM IC-745 was tuned to the 160M signal to hear the test
announcements throughout the test period.  The antenna on the HP was a SWL
slopper antenna that favors the lower frequencies.  The ICOM was on a
40-meter dipole. 

My numbers:

160M:  1 854 317.77   [ARRL: 1 854 317.5 Hz]
80M:   3 587 117.82   [ARRL: 3 587 117.5 Hz]

I did not attempt to receive the west coast signal. 

Mike


-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of James Maynard
Sent: Friday, December 29, 2006 2:14 PM
To: [EMAIL PROTECTED]
Cc: tim-nuts mailing list
Subject: Re: [time-nuts] FMT

Yes. I regret now that I rounded off the WA6ZTY frequency to the nearest 
0.1 Hz.  I might have been exactly in agreement if only I had rounded to 
the nearest 10 millihertz.

I used a Ten-Ted RX340 receiver, which has the advantage that it accepts 
an external 10 MHz frequency reference at its rear panel and phase-locks 
all its oscillators to the 10 MHz reference. That made the measurement 
comparatively easy. I would set the receiver for CW reception with its 
BFO offset 800 Hz from the center of the passband, and feed the output 
to SpectrumLab, running on my laptop with an external USB sound card. I 
calibrated the sound card against WWV audio before the test.

I captured the Spectrum lab measurements to a text file, which I 
imported into Microsoft Excel to compute the mean and standard deviation 
of the peak frequency within a passband centered on 800 Hz. This worked 
well for the W1AW measurements: once having tuned the receiver, I left 
its dial alone for the duration of the test. As I recall, the one-sigma 
jitter on the received W1AW frequency was 1 or 2 Hz -- so I certainly 
did NOT consider my measurement more accurate than about 0.1 Hz.

Unfortunately, when it came to the WA6ZTY part of the test, I 
kepttweaking the receiver frequency by a Hz or so (it tunes in one-hertz 
steps) and that made the spreadsheet file captured from SpectrumLab less 
useful.  I didn't fell confident that I had made a good estimate of the 
standard deviation of the measured frequency. because of my mistake of 
tweaking the receiver frequency. So I rounded that measurement, too, to 
the nearest 100 millihertz.

If I had only NOT disturbed the receiver tuning during the WA6ZTY 
frequency measurement, I could have made a better estimate of the 
one-sigma frequency jitter. Then I would have had a better estimate of 
the accuracy of the measurement, and might have rounded it to the 
nearest 10 millihertz rather than to the nearest 100 millihertz.

-- 
James Maynard
Salem, Oregon, USA


Connie Marshall wrote:
> Hi James,
> 
> Looks like your W1AW 40m reading is inline with the rest of the readings.
I
> still think Joe (W1AW station manager) may have just made a typo mistake
> when he copied the readings to the email he sent me. My W1AW 40m signal
was
> good, about 55 db out of the noise on Spectran. My WA6ZTY signal was fair
to
> good. My reading for WA6ZTY would be the same as yours if I rounded to the
> nearest tenth.
> 
> Would be nice to find someone capable of doing 2 or 3 runs per year. I'm
> wondering if WA6ZTY would be interested in doing some unofficial FMT runs
> several times a year. Sure would help get the math errors out, if we all
got
> more than one shot per year. I would be glad to do it but I wouldn't be
> anymore accurate than W1AW on TX as I currently have no way of locking my
TX
> signal to a stable standard. But then again, maybe high accuracy is not as
> important as just the experience of getting it all together to make a
> measurement under the time pressure of 3 minutes. Were you active in the
old
> days when W1AW made 3 or 4 FMT's per year and reading to the nearest Hz
was
> considered good hi hi.
> 
> Hope your having a good Holiday Season
> 
> Connie
> K5CM
> 
> PS: by the way my Daughter's call is N5KK
> 
> 
> -Original Message-
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
> Behalf Of James Maynard
> Sent: Friday, December 29, 2006 4:22 AM
> To: tim-nuts mailing list
> Subject: Re: [time-nuts] FMT
> 
> 
> My numbers were:
> W1AW (40 m band):   7038806.3 Hz
>  (1.4 Hz higher than the official reading)

Re: [time-nuts] FMT

[James Maynard]

Yes. I regret now that I rounded off the WA6ZTY frequency to the nearest 
0.1 Hz.  I might have been exactly in agreement if only I had rounded to 
the nearest 10 millihertz.

I used a Ten-Ted RX340 receiver, which has the advantage that it accepts 
an external 10 MHz frequency reference at its rear panel and phase-locks 
all its oscillators to the 10 MHz reference. That made the measurement 
comparatively easy. I would set the receiver for CW reception with its 
BFO offset 800 Hz from the center of the passband, and feed the output 
to SpectrumLab, running on my laptop with an external USB sound card. I 
calibrated the sound card against WWV audio before the test.

I captured the Spectrum lab measurements to a text file, which I 
imported into Microsoft Excel to compute the mean and standard deviation 
of the peak frequency within a passband centered on 800 Hz. This worked 
well for the W1AW measurements: once having tuned the receiver, I left 
its dial alone for the duration of the test. As I recall, the one-sigma 
jitter on the received W1AW frequency was 1 or 2 Hz -- so I certainly 
did NOT consider my measurement more accurate than about 0.1 Hz.

Unfortunately, when it came to the WA6ZTY part of the test, I 
kepttweaking the receiver frequency by a Hz or so (it tunes in one-hertz 
steps) and that made the spreadsheet file captured from SpectrumLab less 
useful.  I didn't fell confident that I had made a good estimate of the 
standard deviation of the measured frequency. because of my mistake of 
tweaking the receiver frequency. So I rounded that measurement, too, to 
the nearest 100 millihertz.

If I had only NOT disturbed the receiver tuning during the WA6ZTY 
frequency measurement, I could have made a better estimate of the 
one-sigma frequency jitter. Then I would have had a better estimate of 
the accuracy of the measurement, and might have rounded it to the 
nearest 10 millihertz rather than to the nearest 100 millihertz.

-- 
James Maynard
Salem, Oregon, USA


Connie Marshall wrote:
> Hi James,
> 
> Looks like your W1AW 40m reading is inline with the rest of the readings. I
> still think Joe (W1AW station manager) may have just made a typo mistake
> when he copied the readings to the email he sent me. My W1AW 40m signal was
> good, about 55 db out of the noise on Spectran. My WA6ZTY signal was fair to
> good. My reading for WA6ZTY would be the same as yours if I rounded to the
> nearest tenth.
> 
> Would be nice to find someone capable of doing 2 or 3 runs per year. I'm
> wondering if WA6ZTY would be interested in doing some unofficial FMT runs
> several times a year. Sure would help get the math errors out, if we all got
> more than one shot per year. I would be glad to do it but I wouldn't be
> anymore accurate than W1AW on TX as I currently have no way of locking my TX
> signal to a stable standard. But then again, maybe high accuracy is not as
> important as just the experience of getting it all together to make a
> measurement under the time pressure of 3 minutes. Were you active in the old
> days when W1AW made 3 or 4 FMT's per year and reading to the nearest Hz was
> considered good hi hi.
> 
> Hope your having a good Holiday Season
> 
> Connie
> K5CM
> 
> PS: by the way my Daughter's call is N5KK
> 
> 
> -Original Message-
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
> Behalf Of James Maynard
> Sent: Friday, December 29, 2006 4:22 AM
> To: tim-nuts mailing list
> Subject: Re: [time-nuts] FMT
> 
> 
> My numbers were:
> W1AW (40 m band):   7038806.3 Hz
>  (1.4 Hz higher than the official reading)
> 
> WA6ZTY: 7028351.5 Hz
>  (0.03 Hz higher than the official reading)
> 
> I only submitted readings to the nearest 100 mHz (that is, 0.1 Hz),
> as I didn't think my measurements supported more digits of precision
> than that.
> 
> I could not copy W1AW by ear, although I did pick out the call sign
> once during the test. I could not copy the announcements of when they
> were measuring the 160 m, or the 80 m, or the 40 m signal. I only saw a
> faint waterfall trace, and only on 40 m.
> 
> --
> James Maynard, K7KK
> Salem, Oregon, USA
> 
> 
> 
> 
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> 
> .
> 




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Re: [time-nuts] FMT

[James Maynard]

My numbers were:
W1AW (40 m band):   7038806.3 Hz
 (1.4 Hz higher than the official reading)

WA6ZTY: 7028351.5 Hz
 (0.03 Hz higher than the official reading)

I only submitted readings to the nearest 100 mHz (that is, 0.1 Hz),
as I didn't think my measurements supported more digits of precision
than that.

I could not copy W1AW by ear, although I did pick out the call sign 
once during the test. I could not copy the announcements of when they 
were measuring the 160 m, or the 80 m, or the 40 m signal. I only saw a 
faint waterfall trace, and only on 40 m.

-- 
James Maynard, K7KK
Salem, Oregon, USA




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Re: [time-nuts] FMT

[Connie Marshall]

Hey Henry Looks like your W1AW 40m numbers are in line with the others.
I just checked my audio wave file with spectran, and the 40 meter signal was
strong and stable. Joe (W1AW station manager)said he would post the results
to the W1AW/FMT website soon, so we will wait and see if it is the same
numbers as he gave me today in his email.

Connie
K5CM

-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Behalf Of Henry Knoepfle
Sent: Thursday, December 28, 2006 9:47 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] FMT


Interesting!
My numbers:

160:  1854317.9
80: 3587117.6
40: 7308806.0

Henry
KB7NIE

On 12/28/06, Connie Marshall <[EMAIL PROTECTED]> wrote:

> Hi Bill,
>
> Several others have now said they were off by 1 Hz on 40m. Possibly Joe (
> W1AW Station manager) typed the frequency wrong to my email, or W1AW
> measured the freq incorrectly that night or as John mentioned there was a
> artifact from the transmitter, or the Doppler was indeed that bad. I still
> need to go back and look and my audio file with Spectran again.
>
> As I mentioned in an earlier email I was only off by .07 Hz on the WA6ZTY
> run so I tend to think my system was working properly on 40m hmm.
>
> Connie
> K5CM
>
> -Original Message-
> From: Bill Tracey [mailto:[EMAIL PROTECTED]
> Sent: Thursday, December 28, 2006 5:41 PM
> To: [EMAIL PROTECTED]; Discussion of precise time and frequency
> measurement; Time-Nuts
> Subject: Re: [time-nuts] FMT
>
>
> Very interesting - the measurements I submitted were:
>
> 160: 1854317.63
> 80: 3857117.47
> 40: 7038806.11
>
> 40 (west coast): 7028351.61
>
> I too got a  >1hz high error on W1AW on 40.  As I recall, the data had a
> double peak in it - think I picked the stronger peak which apparently was
> the wrong one.  Apparently the propagation on 40 was interesting when the
> test was run.
>
> Cheers,
>
> Bill (kd5tfd)
>
> At 02:25 PM 12/28/2006, Connie Marshall wrote:
>
> >Here are the W1AW FMT Numbers I just received from Joe, NJ1Q (W1AW
> Station
> >Manager)
> >160m - 1854317.5 Hz
> >80m   - 3587117.5
> >40m  -  7038804.9 Hz
> >
> >My copy of W1AW:
> >160M  1854317.77 Hz
> >   80M  3587117.95 Hz
> >   40M  7038806.03 Hz
> >I missed the 40m W1AW frequency by 1 Hz for some reason Hmm.. I
> will
> >go back and replay my audio file and see if I made a math mistake some
> >where.
> >
> >My copy of WA6ZTY
> >40M - 7028351.545 Hz
> >
> >Connie
> >K5CM
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>
>
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Re: [time-nuts] FMT

[Henry Knoepfle]

Interesting!
My numbers:

160:  1854317.9
80: 3587117.6
40: 7308806.0

Henry
KB7NIE

On 12/28/06, Connie Marshall <[EMAIL PROTECTED]> wrote:

> Hi Bill,
>
> Several others have now said they were off by 1 Hz on 40m. Possibly Joe (
> W1AW Station manager) typed the frequency wrong to my email, or W1AW
> measured the freq incorrectly that night or as John mentioned there was a
> artifact from the transmitter, or the Doppler was indeed that bad. I still
> need to go back and look and my audio file with Spectran again.
>
> As I mentioned in an earlier email I was only off by .07 Hz on the WA6ZTY
> run so I tend to think my system was working properly on 40m hmm.
>
> Connie
> K5CM
>
> -Original Message-
> From: Bill Tracey [mailto:[EMAIL PROTECTED]
> Sent: Thursday, December 28, 2006 5:41 PM
> To: [EMAIL PROTECTED]; Discussion of precise time and frequency
> measurement; Time-Nuts
> Subject: Re: [time-nuts] FMT
>
>
> Very interesting - the measurements I submitted were:
>
> 160: 1854317.63
> 80: 3857117.47
> 40: 7038806.11
>
> 40 (west coast): 7028351.61
>
> I too got a  >1hz high error on W1AW on 40.  As I recall, the data had a
> double peak in it - think I picked the stronger peak which apparently was
> the wrong one.  Apparently the propagation on 40 was interesting when the
> test was run.
>
> Cheers,
>
> Bill (kd5tfd)
>
> At 02:25 PM 12/28/2006, Connie Marshall wrote:
>
> >Here are the W1AW FMT Numbers I just received from Joe, NJ1Q (W1AW
> Station
> >Manager)
> >160m - 1854317.5 Hz
> >80m   - 3587117.5
> >40m  -  7038804.9 Hz
> >
> >My copy of W1AW:
> >160M  1854317.77 Hz
> >   80M  3587117.95 Hz
> >   40M  7038806.03 Hz
> >I missed the 40m W1AW frequency by 1 Hz for some reason Hmm.. I
> will
> >go back and replay my audio file and see if I made a math mistake some
> >where.
> >
> >My copy of WA6ZTY
> >40M - 7028351.545 Hz
> >
> >Connie
> >K5CM
> >___
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> >time-nuts@febo.com
> >https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>
>
>
>
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Re: [time-nuts] FMT

[Connie Marshall]

Hi Bill,

Several others have now said they were off by 1 Hz on 40m. Possibly Joe (
W1AW Station manager) typed the frequency wrong to my email, or W1AW
measured the freq incorrectly that night or as John mentioned there was a
artifact from the transmitter, or the Doppler was indeed that bad. I still
need to go back and look and my audio file with Spectran again.

As I mentioned in an earlier email I was only off by .07 Hz on the WA6ZTY
run so I tend to think my system was working properly on 40m hmm.

Connie
K5CM

-Original Message-
From: Bill Tracey [mailto:[EMAIL PROTECTED]
Sent: Thursday, December 28, 2006 5:41 PM
To: [EMAIL PROTECTED]; Discussion of precise time and frequency
measurement; Time-Nuts
Subject: Re: [time-nuts] FMT


Very interesting - the measurements I submitted were:

160: 1854317.63
80: 3857117.47
40: 7038806.11

40 (west coast): 7028351.61

I too got a  >1hz high error on W1AW on 40.  As I recall, the data had a
double peak in it - think I picked the stronger peak which apparently was
the wrong one.  Apparently the propagation on 40 was interesting when the
test was run.

Cheers,

Bill (kd5tfd)

At 02:25 PM 12/28/2006, Connie Marshall wrote:

>Here are the W1AW FMT Numbers I just received from Joe, NJ1Q (W1AW Station
>Manager)
>160m - 1854317.5 Hz
>80m   - 3587117.5
>40m  -  7038804.9 Hz
>
>My copy of W1AW:
>160M  1854317.77 Hz
>   80M  3587117.95 Hz
>   40M  7038806.03 Hz
>I missed the 40m W1AW frequency by 1 Hz for some reason Hmm.. I
will
>go back and replay my audio file and see if I made a math mistake some
>where.
>
>My copy of WA6ZTY
>40M - 7028351.545 Hz
>
>Connie
>K5CM
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Re: [time-nuts] FMT

[John Ackermann N8UR]

Bill Tracey said the following on 12/28/2006 06:41 PM:

> I too got a  >1hz high error on W1AW on 40.  As I recall, the data had a 
> double peak in it - think I picked the stronger peak which apparently was 
> the wrong one.  Apparently the propagation on 40 was interesting when the 
> test was run.

I have to admit that I screwed up royally this year and had a math error
that threw all my results off by 70 to 100 Hz (stupid error -- getting
my sideband math backwards).  I'll get my results up on the web site
soon, both "as submitted" and what they would have been with the correct
math.

But I wanted to mention that I also saw a double hump on 40M, with about
0.5 Hz separation.  I wonder if it was an artifact of the transmitter,
or one of propagation.  As I understand it, the League this year used
regular ham transceivers instead of the old Harris rigs.  On 160 and 80
they had Ten-Tecs, and on 40 I think an Icom.

John

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Re: [time-nuts] FMT

[Bill Tracey]

Very interesting - the measurements I submitted were:

160: 1854317.63
80: 3857117.47
40: 7038806.11

40 (west coast): 7028351.61

I too got a  >1hz high error on W1AW on 40.  As I recall, the data had a 
double peak in it - think I picked the stronger peak which apparently was 
the wrong one.  Apparently the propagation on 40 was interesting when the 
test was run.

Cheers,

Bill (kd5tfd)

At 02:25 PM 12/28/2006, Connie Marshall wrote:

>Here are the W1AW FMT Numbers I just received from Joe, NJ1Q (W1AW Station
>Manager)
>160m - 1854317.5 Hz
>80m   - 3587117.5
>40m  -  7038804.9 Hz
>
>My copy of W1AW:
>160M  1854317.77 Hz
>   80M  3587117.95 Hz
>   40M  7038806.03 Hz
>I missed the 40m W1AW frequency by 1 Hz for some reason Hmm.. I will
>go back and replay my audio file and see if I made a math mistake some
>where.
>
>My copy of WA6ZTY
>40M - 7028351.545 Hz
>
>Connie
>K5CM
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Re: [time-nuts] FMT -- 40M strangeness?

[James Maynard]

You might also look over your data, and, if you captured a screen image, 
that image.  I assume that the ionoshpere was rising at the time of the 
FMT.  If that is the case, then f1 should be lower in frequency than f0, 
and f2 lower in frequency than f1.

If, however, the fainter trace is *higher* in frequency than the 
stronger trace, and especially if the fainter trace is *narrower* than 
the stronger trace, then the fainter trace may be groundwave reception 
at the transmitted frequency, f0.

-- 
James Maynard, K7KK
Salem, Oregon, USA


John Ackermann N8UR wrote:
> Really interesting analysis, James.  I'll need to do some checking to
> determine my distance from W1AW, and where that puts me in the skip zone.
> 
> John
> 
> 
> James Maynard said the following on 11/19/2006 02:08 PM:
> 
>>John Ackermann N8UR wrote:
>>
>>>Without giving away any actual numbers, did anyone else notice either a
>>>fuzzy signal, or some interference within about 1 Hz of W1AW on 40M?
>>>
>>>I recorded the entire test run and have been unable to prove to myself
>>>exactly where W1AW is; almost any sample of data I select shows two
>>>signals within about 1 Hz -- depending on just what segment of the data
>>>I analyze, I can sometimes get one peak that is sharper and another that
>>>is smeared out over about 0.5Hz, but I'm not confident about which one
>>>is the real thing.  An FFT with enough bins to separate the two signals
>>>loses the CW keying, so I can't use that to see which one is real.
>>>
>>>Again, nobody post actual frequencies, but if you've looked at the 40M
>>>signal very closely, I'd appreciate finding out whether this is local to
>>>me, or something others saw.
>>>
>>>Thanks,
>>>
>>>John
>>>
>>>___
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>>>
>>>
>>>.
>>>
>>
>>For me, the W1AW signal was quite faint. It was visible on Specturm 
>>Lab's waterfall display as a rather broad, fuzzy trace, but I could not 
>>copy it by ear. (I did, once, hear the call sign, W1AW.) So my 
>>measurement of its frequency was by averaging the Sprectrum Lab text 
>>output (File | Text file export... | Export of calculated data) after I 
>>had imported into a Microsoft Excel file.  I computed a mean of the data 
>>in one of the spreadsheet columns to get the frequency that I used in my 
>>FMT submission.  I also computed the standard deviation of that column, 
>>and saw that it was spread over several hertz.
>>
>>You were closer to W1AW, and had a stronger signal to work with than I. 
>>But I surmise that were seeing the same phenonemon: ionospheric doppler 
>>-- and especially the effect of multipath on the doppler-shifted signal.
>>
>>Suppose that, at the time of the FMT, the ionosphere was rising. (It 
>>usually does at and after sunset.)  I assume that you were beyond the 
>>ground-wave coverage zone of W1AW, but were getting it on sky-wave. 
>>Let's denote the frequencies of the W1AW signal as transmitted (or 
>>received on ground wave), and after one-hop, two-hop, etc. skywave 
>>reflections as follows:
>>
>>f0 = transmitted frequency = frequency as received on groundwave
>>f1 = frequency as received after one reflection from the ionoshphere
>>f2 = frequency after two reflections
>>f3 = frequency after three reflections
>>etc,
>>
>>If the ionosphere is moving, f1 will differ from f0 by some amount that 
>>depends at the rate at which the ionosphere is moving. For two-hop 
>>reception, f2 will differ from f1 by a similar amount -- but not exactly 
>>the same, because of differences in the angles of incidence to the 
>>reflecting surface.
>>
>>I surmise that the strongest signal you received was proably W1AW as 
>>received at frequency f1 (after one hop) and the second, fainter trace 
>>was W1AW as received at frequency f2 (after two hops). You are probably 
>>beyond the zone of ground-wave reception, so you did not receive W1AW at 
>>its actual transmitted frequency, f0.
>>
>>Which leads to an interesting possibility.  If you assume that the 
>>difference, f1-f0, is almost the same as the difference, f2-f1, you may 
>>be able to use this information to infer the true transmitted frequency, f0.
>>
>>I, on the other hand, had such faint and blurred reception that I was 
>>unable to discrimate between f1, f2, f3, etc., and so could not try to 
>>compute f0.
>>
> 
> 
> 
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Re: [time-nuts] FMT -- 40M strangeness?

[John Ackermann N8UR]

Really interesting analysis, James.  I'll need to do some checking to
determine my distance from W1AW, and where that puts me in the skip zone.

John


James Maynard said the following on 11/19/2006 02:08 PM:
> John Ackermann N8UR wrote:
>> Without giving away any actual numbers, did anyone else notice either a
>> fuzzy signal, or some interference within about 1 Hz of W1AW on 40M?
>>
>> I recorded the entire test run and have been unable to prove to myself
>> exactly where W1AW is; almost any sample of data I select shows two
>> signals within about 1 Hz -- depending on just what segment of the data
>> I analyze, I can sometimes get one peak that is sharper and another that
>> is smeared out over about 0.5Hz, but I'm not confident about which one
>> is the real thing.  An FFT with enough bins to separate the two signals
>> loses the CW keying, so I can't use that to see which one is real.
>>
>> Again, nobody post actual frequencies, but if you've looked at the 40M
>> signal very closely, I'd appreciate finding out whether this is local to
>> me, or something others saw.
>>
>> Thanks,
>>
>> John
>>
>> ___
>> time-nuts mailing list
>> time-nuts@febo.com
>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>
>>
>> .
>>
> For me, the W1AW signal was quite faint. It was visible on Specturm 
> Lab's waterfall display as a rather broad, fuzzy trace, but I could not 
> copy it by ear. (I did, once, hear the call sign, W1AW.) So my 
> measurement of its frequency was by averaging the Sprectrum Lab text 
> output (File | Text file export... | Export of calculated data) after I 
> had imported into a Microsoft Excel file.  I computed a mean of the data 
> in one of the spreadsheet columns to get the frequency that I used in my 
> FMT submission.  I also computed the standard deviation of that column, 
> and saw that it was spread over several hertz.
> 
> You were closer to W1AW, and had a stronger signal to work with than I. 
> But I surmise that were seeing the same phenonemon: ionospheric doppler 
> -- and especially the effect of multipath on the doppler-shifted signal.
> 
> Suppose that, at the time of the FMT, the ionosphere was rising. (It 
> usually does at and after sunset.)  I assume that you were beyond the 
> ground-wave coverage zone of W1AW, but were getting it on sky-wave. 
> Let's denote the frequencies of the W1AW signal as transmitted (or 
> received on ground wave), and after one-hop, two-hop, etc. skywave 
> reflections as follows:
> 
> f0 = transmitted frequency = frequency as received on groundwave
> f1 = frequency as received after one reflection from the ionoshphere
> f2 = frequency after two reflections
> f3 = frequency after three reflections
> etc,
> 
> If the ionosphere is moving, f1 will differ from f0 by some amount that 
> depends at the rate at which the ionosphere is moving. For two-hop 
> reception, f2 will differ from f1 by a similar amount -- but not exactly 
> the same, because of differences in the angles of incidence to the 
> reflecting surface.
> 
> I surmise that the strongest signal you received was proably W1AW as 
> received at frequency f1 (after one hop) and the second, fainter trace 
> was W1AW as received at frequency f2 (after two hops). You are probably 
> beyond the zone of ground-wave reception, so you did not receive W1AW at 
> its actual transmitted frequency, f0.
> 
> Which leads to an interesting possibility.  If you assume that the 
> difference, f1-f0, is almost the same as the difference, f2-f1, you may 
> be able to use this information to infer the true transmitted frequency, f0.
> 
> I, on the other hand, had such faint and blurred reception that I was 
> unable to discrimate between f1, f2, f3, etc., and so could not try to 
> compute f0.
> 


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Re: [time-nuts] FMT -- 40M strangeness?

[James Maynard]

John Ackermann N8UR wrote:
> Without giving away any actual numbers, did anyone else notice either a
> fuzzy signal, or some interference within about 1 Hz of W1AW on 40M?
> 
> I recorded the entire test run and have been unable to prove to myself
> exactly where W1AW is; almost any sample of data I select shows two
> signals within about 1 Hz -- depending on just what segment of the data
> I analyze, I can sometimes get one peak that is sharper and another that
> is smeared out over about 0.5Hz, but I'm not confident about which one
> is the real thing.  An FFT with enough bins to separate the two signals
> loses the CW keying, so I can't use that to see which one is real.
> 
> Again, nobody post actual frequencies, but if you've looked at the 40M
> signal very closely, I'd appreciate finding out whether this is local to
> me, or something others saw.
> 
> Thanks,
> 
> John
> 
> ___
> time-nuts mailing list
> time-nuts@febo.com
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> 
> 
> .
> 
For me, the W1AW signal was quite faint. It was visible on Specturm 
Lab's waterfall display as a rather broad, fuzzy trace, but I could not 
copy it by ear. (I did, once, hear the call sign, W1AW.) So my 
measurement of its frequency was by averaging the Sprectrum Lab text 
output (File | Text file export... | Export of calculated data) after I 
had imported into a Microsoft Excel file.  I computed a mean of the data 
in one of the spreadsheet columns to get the frequency that I used in my 
FMT submission.  I also computed the standard deviation of that column, 
and saw that it was spread over several hertz.

You were closer to W1AW, and had a stronger signal to work with than I. 
But I surmise that were seeing the same phenonemon: ionospheric doppler 
-- and especially the effect of multipath on the doppler-shifted signal.

Suppose that, at the time of the FMT, the ionosphere was rising. (It 
usually does at and after sunset.)  I assume that you were beyond the 
ground-wave coverage zone of W1AW, but were getting it on sky-wave. 
Let's denote the frequencies of the W1AW signal as transmitted (or 
received on ground wave), and after one-hop, two-hop, etc. skywave 
reflections as follows:

f0 = transmitted frequency = frequency as received on groundwave
f1 = frequency as received after one reflection from the ionoshphere
f2 = frequency after two reflections
f3 = frequency after three reflections
etc,

If the ionosphere is moving, f1 will differ from f0 by some amount that 
depends at the rate at which the ionosphere is moving. For two-hop 
reception, f2 will differ from f1 by a similar amount -- but not exactly 
the same, because of differences in the angles of incidence to the 
reflecting surface.

I surmise that the strongest signal you received was proably W1AW as 
received at frequency f1 (after one hop) and the second, fainter trace 
was W1AW as received at frequency f2 (after two hops). You are probably 
beyond the zone of ground-wave reception, so you did not receive W1AW at 
its actual transmitted frequency, f0.

Which leads to an interesting possibility.  If you assume that the 
difference, f1-f0, is almost the same as the difference, f2-f1, you may 
be able to use this information to infer the true transmitted frequency, f0.

I, on the other hand, had such faint and blurred reception that I was 
unable to discrimate between f1, f2, f3, etc., and so could not try to 
compute f0.

-- 
James Maynard, K7KK
Salem, Oregon, USA



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Re: [time-nuts] FMT

[John Ackermann N8UR]

I debated whether to stay up and try, but with my lousy antennas I 
thought the odds of hearing it here in Ohio were fairly small, so I went 
to bed instead...

John


Henry Knoepfle wrote:
> Did anyone hear the west coast station?  I and another station here in
> Tucson did not.
> 
> Henry
> 
> 
> On 11/16/06, John Ackermann N8UR <[EMAIL PROTECTED]> wrote:
>> Hi Bert --
>>
>> We tend to talk about FMT techniques before the test, and a little bit
>> about propagation, etc., afterwards.  But I don't share, and I don't
>> think anyone else should share, results until after the submission
>> deadline on the 15th.  After that, it's fair game.
>>
>> 73,
>> John
>> 
>>
>> Bert wrote:
>>> Hi everyone,
>>>
>>> Is it common practice to share your FMT results on the time-nuts
>> mailaing list? Or is there pride in trying to be the best of the best (who
>> knows...)?
>>> Should we all wait after December 15th...?
>>>
>>> Cheers.
>>>
>>> Bert, VE2ZAZ
>>>
>>>
>>>
>>> __
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>>> Tired of spam?  Yahoo! Mail has the best spam protection around
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>>>
>>
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Re: [time-nuts] FMT

[Bill Tracey]

Heard it in Round Rock, TX (EM10) - was considerably weaker than W1AW.

Bill (kd5tfd)

At 11:47 PM 11/16/2006, you wrote:
>Did anyone hear the west coast station?  I and another station here in
>Tucson did not.
>
>Henry



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Re: [time-nuts] FMT

[Henry Knoepfle]

Did anyone hear the west coast station?  I and another station here in
Tucson did not.

Henry


On 11/16/06, John Ackermann N8UR <[EMAIL PROTECTED]> wrote:
>
> Hi Bert --
>
> We tend to talk about FMT techniques before the test, and a little bit
> about propagation, etc., afterwards.  But I don't share, and I don't
> think anyone else should share, results until after the submission
> deadline on the 15th.  After that, it's fair game.
>
> 73,
> John
> 
>
> Bert wrote:
> > Hi everyone,
> >
> > Is it common practice to share your FMT results on the time-nuts
> mailaing list? Or is there pride in trying to be the best of the best (who
> knows...)?
> >
> > Should we all wait after December 15th...?
> >
> > Cheers.
> >
> > Bert, VE2ZAZ
> >
> >
> >
> > __
> > Do You Yahoo!?
> > Tired of spam?  Yahoo! Mail has the best spam protection around
> > http://mail.yahoo.com
> >
> > ___
> > time-nuts mailing list
> > time-nuts@febo.com
> > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> >
> >
>
>
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Re: [time-nuts] FMT

[John Ackermann N8UR]

Hi Bert --

We tend to talk about FMT techniques before the test, and a little bit 
about propagation, etc., afterwards.  But I don't share, and I don't 
think anyone else should share, results until after the submission 
deadline on the 15th.  After that, it's fair game.

73,
John


Bert wrote:
> Hi everyone,
> 
> Is it common practice to share your FMT results on the time-nuts mailaing 
> list? Or is there pride in trying to be the best of the best (who knows...)? 
> 
> Should we all wait after December 15th...?
> 
> Cheers.
> 
> Bert, VE2ZAZ
> 
> 
> 
> __
> Do You Yahoo!?
> Tired of spam?  Yahoo! Mail has the best spam protection around 
> http://mail.yahoo.com 
> 
> ___
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Re: [time-nuts] FMT

[Mike Suhar]

Wait until after the deadline filing date to post any results.  You can talk
about your experiences but leave out the numbers.

Mike


-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Bert
Sent: Thursday, November 16, 2006 7:28 AM
To: time-nuts@febo.com
Subject: [time-nuts] FMT

Hi everyone,

Is it common practice to share your FMT results on the time-nuts mailaing
list? Or is there pride in trying to be the best of the best (who knows...)?


Should we all wait after December 15th...?

Cheers.

Bert, VE2ZAZ



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Re: [time-nuts] FMT

[Didier Juges]

Recent radios of that grade all have TCXOs, and that level of 
performance is really not that hard to achieve today at constant 
temperature.

My Yaesu FT-1000 Mk5 Field (with TCXO) drifts much less than 0.5 Hz at 
14 MHz between 30 minutes and one hour after being turned on (in 
receive), but a couple of Hz during the 1st 1/2 hour (from memory, I did 
not record the data). I have not tried after continuous, prolonged 
transmission. I need to retake this data now that I have much better 
equipment. With regard to accuracy, the rig is about 0.82 Hz low at 14 
MHz after warm-up (original factory adjustment, the rig is about 2.5 
years old), measured in AM transmit mode, using a 40dB power attenuator 
on the output driving an HP 5370A counter with 1 sec gate time, with a 
Thunderbolt GPSDO as external reference.

My older Kenwood TS-440S/AT radio (no TCXO, bought new in 1991), drifts 
about 100 Hz (at 14 MHz) during the 1st 30 minutes of operation 
(receive) but is quite stable after that ( I did not measure how much, 
but absolutely no noticeable drift in normal operation, for instance 
using WWV's zero beat as a reference), regardless of Tx or Rx operation.

Didier KO4BB


Colin Bradley wrote:
> I received the following email from the station manager of W1AW.
>
> Hi Colin,
>  
> I didn't want to answer your question too soon.
>  
> On the days prior to the FMT, I conduct measurements at 1 hour, 3 and 6 hours 
> after initial warm-up.  (And of course, this time frame includes the normal 
> broadcast schedule.)
>  
> >From what I can see, the drift on the Orion and Pro IIs is minimal.  For 
> >example, from the 3 to 6 hour time period (today), the "40-meter" Orion 
> >drifted 0.12 Hz.  The "80-meter" Pro II drifted about 0.11 Hz and the 
> >"160-meter" Pro II drifted about 0.04 Hz.  (You have to understand that 
> >these three radios are here for evaluation only, and went through their 
> >respective Service Departments before we received them.)
>  
> And just now, I conducted a quick test to see what the "real short-term" 
> drift would be (given the time frame of the FMT).  I didn't notice any 
> significant difference.
>  
> I'm a little surprised at these numbers.  But I have to go on what my counter 
> is telling me.  Oddly enough, when we used to run the Harris exciters (during 
> past FMTs), it was not uncommon for me to see at least a 2-4 Hz difference in 
> the 3 to 6 hour time period.
>  
> So we'll see...
>  
> Good luck!
>  
> 73,
>  
> Joseph Carcia, NJ1Q
> W1AW Station Manager
>
> Interesting...I would not have thought these transceivers were that stable. 
> Colin
>
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Re: [time-nuts] FMT

[John Ackermann N8UR]

That's interesting -- from your earlier message, I thought they were
still running the Harris exciters for the test itself.  It'll be
interesting to monitor the drift during the test.

My plan is to record audio (W1AW plus my known-frequency marker) of all
three bands simultaneously for the whole test period, so if the
propagation gods are smiling upon us, I'll be able to look at the
beginning-to-end drift.

Two of the bands will use HP 3586C selective voltmeters driven from an
HP 5065A (using the internal tracking generator as the marker), while
40M will be on an Icom 746 with a PTS synthesizer hooked to the same
5065A providing the marker.  The audio from all three receivers is fed
into a 4-input Delta44 sound card and recorded as separate .wav files.

It's a shame the test wasn't a week or two later -- I just acquired two
more 3586Cs on eBay today so I would have been able to use the same
hardware for all three bands.  That'll have to wait until next year...
(I really love the 3586C as an HF measurement machine.)  I also hope
that by next year I'll have the crystal in the Delta44 slaved to the
external reference, and that will remove my last significant source of
measurement uncertainty -- though the Delta44 sample rate seems to be
very stable even on its own.

John


Colin Bradley said the following on 11/15/2006 04:37 PM:
> I received the following email from the station manager of W1AW.
> 
> Hi Colin,
>  
> I didn't want to answer your question too soon.
>  
> On the days prior to the FMT, I conduct measurements at 1 hour, 3 and 6 hours 
> after initial warm-up.  (And of course, this time frame includes the normal 
> broadcast schedule.)
>  
> From what I can see, the drift on the Orion and Pro IIs is minimal.  For 
> example, from the 3 to 6 hour time period (today), the "40-meter" Orion 
> drifted 0.12 Hz.  The "80-meter" Pro II drifted about 0.11 Hz and the 
> "160-meter" Pro II drifted about 0.04 Hz.  (You have to understand that these 
> three radios are here for evaluation only, and went through their respective 
> Service Departments before we received them.)
>  
> And just now, I conducted a quick test to see what the "real short-term" 
> drift would be (given the time frame of the FMT).  I didn't notice any 
> significant difference.
>  
> I'm a little surprised at these numbers.  But I have to go on what my counter 
> is telling me.  Oddly enough, when we used to run the Harris exciters (during 
> past FMTs), it was not uncommon for me to see at least a 2-4 Hz difference in 
> the 3 to 6 hour time period.
>  
> So we'll see...
>  
> Good luck!
>  
> 73,
>  
> Joseph Carcia, NJ1Q
> W1AW Station Manager
> 
> Interesting...I would not have thought these transceivers were that stable. 
> Colin
> 
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Re: [time-nuts] FMT

[Normand Martel]

--- John Ackermann N8UR <[EMAIL PROTECTED]> wrote:

> Hi Normand --
> 
> Your method is similar to mine, except that I use a
> much closer beat 
> note (usually less than 100 Hz) and use spectrum
> analyzer software and a 
> sound card to measure the beat note (in the form of
> the delta between 
> two traces on the waterfall display).

Well, you use long term DIGITAL techniques to track
probably to the µHz.. i simply use an ANALOG technique
to get down to a +/- 10 mHz resolution, and using a
higher beat frequency is simply more comfortable to
the eye (X-Y scope display). Also, my generator has a
100 Hz resolution, so i can only use 100 Hz multiple
beat notes.

> 
> I think one of the reasons this method works so well
> is that the FFT 
> effectively averages the signal over some time, and
> I use a tool in the 
> software to derive an average across all the FFT
> results.  That smooths 
> out the instantaneous variations that make real-time
> measurement such a 
> challenge.
> 
> John
> 

Maybe some day!!

73 de Normand VE2UM



 

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Re: [time-nuts] FMT

[John Ackermann N8UR]

Didier Juges said the following on 11/10/2006 10:05 PM:
> Hi Mike,
> 
> Interesting, I was just doing pretty much that, except that I did not 
> think of using the tracking generator of the 3586A as a reference, I 
> used an 8657B synthesizer phase locked to the Thunderbolt GPSDO to 
> inject a reference signal 20Hz above the test signal (I used WWV at 5 
> MHz for test), so that I could display both signals at the same time in 
> the FFT using Spectrum Lab. Setting the two very close eliminates the 
> risk of selecting the wrong sideband and reduces the error caused by the 
> sound card sample rate being off.

I've used the 3586 tracking generator trick for the last couple of
years.  It makes the tuning process much, much simpler because there's
only one knob to twiddle.

I usually use the 400Hz bandwidth in the receiver, and a window running
a shallow FFT for quick response.  The tracking generator signal will
always show up at nominally 1850 Hz in the receiver passband (it may be
a Hz or more off because the BFO is generated from a separate crystal
and isn't locked to the reference).  It stays put as the unknown signal
moves with the tuning knob.  So, look around 1850 Hz on the display, and
tune so the unknown is maybe 50 Hz away from the tracking generator
signal.  Then take your measurement.  It's important to have a good
variable attenuator on the tracking generator line as you need to match
its level pretty closely to the unknown signal level in order to get
comparable amplitudes on the display.

John


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Re: [time-nuts] FMT

[Didier Juges]

Hi Mike,

Interesting, I was just doing pretty much that, except that I did not 
think of using the tracking generator of the 3586A as a reference, I 
used an 8657B synthesizer phase locked to the Thunderbolt GPSDO to 
inject a reference signal 20Hz above the test signal (I used WWV at 5 
MHz for test), so that I could display both signals at the same time in 
the FFT using Spectrum Lab. Setting the two very close eliminates the 
risk of selecting the wrong sideband and reduces the error caused by the 
sound card sample rate being off.

I found out using the slowest sampling rate (5 kHz or so) and the 
largest FFT size seems to give the best resolution (10 mHz?) and good 
filtering (several seconds of time constant). I also set the software to 
display one bin per pixel.

There is a screen plot of Spectrum Lab with the 2 signals on my web site 
http://www.ko4bb.com/Test_Equipment/SpectrumLab.png

Exporting the data to a file and using a spreadsheet to do the post 
processing is a good idea, thanks.

To display the generator frequency using the peak function, I simply 
disconnect the antenna, which causes the generator to be the largest 
signal. I intend to do that a few times during the test to make sure 
everything is stable.

I have not found out how to export data to a file so that it includes 
the peak, but I'll be looking (I started using Spectrum Lab a couple of 
weeks ago and there are a lot of settings I am not familiar with yet)... 
If I don't find soon, I may send you a message :-) I am interested also 
in finding how you can output two peaks (signal under test and 
generator) to the log file.

It's interesting to look at the peak on WWV and see it wobble at the 
rate of the fading (or close). During a few minutes of observations, the 
frequency was about 0.5 Hz low and it fluctuated by about 0.4 Hz peak to 
peak with a period of a few seconds.

I only have an 80m antenna at the moment (quarter wave slopper hanging 
from the 50 feet tower), so that will be the band where I will have my 
best shot. I may try 40m as east coast signals tend to be good on the 
80m slopper, in spite of the severe mismatch.

Didier KO4BB


Mike Suhar wrote:
> John and I use a similar technique.  I am running Windows so I use DL4YHF's
> Spectrum Lab FFT software.  Spectrum Lab will output each line of the
> waterfall display to a tab delimited text file.  Using the function
> peak_f(f1,f2) I output the frequency of the peak within F1 and F2 to the
> file.  I also output the peak of the signal generator's carrier in a band
> above or below the band of the desired carrier. The difference between the
> two is used to calculate the final carrier frequency.  You just have to
> remember to be in the same sideband USB or LSB and on the same side of the
> signal generator carrier for each measurement in order not to confuse adding
> or subtracting the delta.  At the end of the test the output file contains
> several lines of data. I import the file into a spreadsheet.  The
> spreadsheet calculates the delta and averages all the readings.  I may have
> several hundred lines of output.  
>
> As for the audio sample rate and FFT size I have used several the past
> couple of years.  I am sure they are optimal but they work.  I am currently
> running the audio sample rate at 11025 with the FFT size of 32768 with a
> decimate factor of 2.  Bin size is around 168 millihertz.  This helps cut
> down on any CW that may be near the desired carrier as I won't see those
> signals as they are too fast to fill the bin. 
>
> For this year's FMT I will use my HP 3586C with its internal tracking
> generator looped back into its own antenna port (via a step attenuator).
> This will serve as the signal generator used in the past.  A  Z3801 feeds
> the external timebase of the 3586C.  
>
> It has been interesting to measure the carriers of local AM broadcast and
> shortwave stations.  Our local stations are a few hertz off but WLW (700
> KHz) is dead on. I wonder what they are using for frequency control?
>
> Mike
>   


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Re: [time-nuts] FMT

[Mike Suhar]

John and I use a similar technique.  I am running Windows so I use DL4YHF's
Spectrum Lab FFT software.  Spectrum Lab will output each line of the
waterfall display to a tab delimited text file.  Using the function
peak_f(f1,f2) I output the frequency of the peak within F1 and F2 to the
file.  I also output the peak of the signal generator's carrier in a band
above or below the band of the desired carrier. The difference between the
two is used to calculate the final carrier frequency.  You just have to
remember to be in the same sideband USB or LSB and on the same side of the
signal generator carrier for each measurement in order not to confuse adding
or subtracting the delta.  At the end of the test the output file contains
several lines of data. I import the file into a spreadsheet.  The
spreadsheet calculates the delta and averages all the readings.  I may have
several hundred lines of output.  

As for the audio sample rate and FFT size I have used several the past
couple of years.  I am sure they are optimal but they work.  I am currently
running the audio sample rate at 11025 with the FFT size of 32768 with a
decimate factor of 2.  Bin size is around 168 millihertz.  This helps cut
down on any CW that may be near the desired carrier as I won't see those
signals as they are too fast to fill the bin. 

For this year's FMT I will use my HP 3586C with its internal tracking
generator looped back into its own antenna port (via a step attenuator).
This will serve as the signal generator used in the past.  A  Z3801 feeds
the external timebase of the 3586C.  

It has been interesting to measure the carriers of local AM broadcast and
shortwave stations.  Our local stations are a few hertz off but WLW (700
KHz) is dead on. I wonder what they are using for frequency control?

Mike

  

-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of John Ackermann N8UR
Sent: Friday, November 10, 2006 6:34 PM
To: Hal Murray
Cc: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] FMT

Hal Murray said the following on 11/10/2006 04:52 PM:
>> I think one of the reasons this method works so well is that the FFT
>> effectively averages the signal over some time, and I use a tool in
>> the  software to derive an average across all the FFT results.  That
>> smooths  out the instantaneous variations that make real-time
>> measurement such a  challenge. 
> 
> What size FFT are you using?  What sort of averaging are you doing?
> 
> What is the bandwidth of the signal you are looking at?  How does that 
> compare to the bin size of your FFT?
> 
> If you are recording the raw data and then post processing the signal, I'd

> expect you could FFT the whole thing.  It has to fit in memory, but that 
> doesn't look like a problem.  I think that would get the bin size down to
1/N 
> Hz if you had N seconds of data.  (But I'm not a DSP wizard.)
> 
> If you do that, there is only one sample so there is nothing to average in

> the time dimension.  If the signal is wide enough to end up in several
bins, 
> you could average in the frequency dimension.

The signal is a CW wave.

I use a Linux spectrum analysis program called Baudline.  It allows me
to do a couple of neat things.  First is that it can downconvert to
improve resolution by decimating and frequency shifting, so I can work
with a spectrum maybe 100 Hz wide.  Then I run a fairly deep FFT -- I
think I used 8192 bins last year.  You end up with resolution in the
milliHertz, but of course after decimating a bunch and using the deep
FFt, it takes 10 or more seconds to fill the bins.

I end up with a waterfall display showing the reference and unknown
signals over the length of the test.  Baudline has another neat tool,
which allows you to do an average over length of the waterfall.  So, I
end up with a single trace that represents the average over the length
of the test.  Baudline also has a "delta" feature that will calculate
the delta frequency between two signals, so that give me the final
output number that I work against the frequency of the known signal to
get the result.

John

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Re: [time-nuts] FMT

[John Ackermann N8UR]

Hal Murray said the following on 11/10/2006 04:52 PM:
>> I think one of the reasons this method works so well is that the FFT
>> effectively averages the signal over some time, and I use a tool in
>> the  software to derive an average across all the FFT results.  That
>> smooths  out the instantaneous variations that make real-time
>> measurement such a  challenge. 
> 
> What size FFT are you using?  What sort of averaging are you doing?
> 
> What is the bandwidth of the signal you are looking at?  How does that 
> compare to the bin size of your FFT?
> 
> If you are recording the raw data and then post processing the signal, I'd 
> expect you could FFT the whole thing.  It has to fit in memory, but that 
> doesn't look like a problem.  I think that would get the bin size down to 1/N 
> Hz if you had N seconds of data.  (But I'm not a DSP wizard.)
> 
> If you do that, there is only one sample so there is nothing to average in 
> the time dimension.  If the signal is wide enough to end up in several bins, 
> you could average in the frequency dimension.

The signal is a CW wave.

I use a Linux spectrum analysis program called Baudline.  It allows me
to do a couple of neat things.  First is that it can downconvert to
improve resolution by decimating and frequency shifting, so I can work
with a spectrum maybe 100 Hz wide.  Then I run a fairly deep FFT -- I
think I used 8192 bins last year.  You end up with resolution in the
milliHertz, but of course after decimating a bunch and using the deep
FFt, it takes 10 or more seconds to fill the bins.

I end up with a waterfall display showing the reference and unknown
signals over the length of the test.  Baudline has another neat tool,
which allows you to do an average over length of the waterfall.  So, I
end up with a single trace that represents the average over the length
of the test.  Baudline also has a "delta" feature that will calculate
the delta frequency between two signals, so that give me the final
output number that I work against the frequency of the known signal to
get the result.

John

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Re: [time-nuts] FMT

[Hal Murray]

> I think one of the reasons this method works so well is that the FFT
> effectively averages the signal over some time, and I use a tool in
> the  software to derive an average across all the FFT results.  That
> smooths  out the instantaneous variations that make real-time
> measurement such a  challenge. 

What size FFT are you using?  What sort of averaging are you doing?

What is the bandwidth of the signal you are looking at?  How does that 
compare to the bin size of your FFT?

If you are recording the raw data and then post processing the signal, I'd 
expect you could FFT the whole thing.  It has to fit in memory, but that 
doesn't look like a problem.  I think that would get the bin size down to 1/N 
Hz if you had N seconds of data.  (But I'm not a DSP wizard.)

If you do that, there is only one sample so there is nothing to average in 
the time dimension.  If the signal is wide enough to end up in several bins, 
you could average in the frequency dimension.

-- 
The suespammers.org mail server is located in California.  So are all my
other mailboxes.  Please do not send unsolicited bulk e-mail or unsolicited
commercial e-mail to my suespammers.org address or any of my other addresses.
These are my opinions, not necessarily my employer's.  I hate spam.




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Re: [time-nuts] FMT

[John Ackermann N8UR]

Hi Normand --

Your method is similar to mine, except that I use a much closer beat 
note (usually less than 100 Hz) and use spectrum analyzer software and a 
sound card to measure the beat note (in the form of the delta between 
two traces on the waterfall display).

I think one of the reasons this method works so well is that the FFT 
effectively averages the signal over some time, and I use a tool in the 
software to derive an average across all the FFT results.  That smooths 
out the instantaneous variations that make real-time measurement such a 
challenge.

John


Normand Martel wrote:
> Personnaly, i use a self-developed technique to
> remotely measure a station's frequency:
> 
> I use a precision OXCO controlled RF signal generator
> to inject an unmodulated (CW) signal (via a
> directional coupler) signal 1000 Hz below the actual
> station's frequency (example, to monitor CHU at 7335
> kHz, i inject a 7334 kHz signal into the coupler). I
> then adjust the generator's level to obtain a
> comfortable 1000 Hz from my receiver (in AM mode
> preferably, but it even works in FM... do not use SSB
> or CW modes, since the receiver's BFO will interfere).
> Finally, i measure the  1 kHz beat's frequency with
> precision (for that, i use an synthesized audio
> generator with a ramp (sawtooth) output on an o'scope
> in a X-Y function (X = ramp, Y = beat).
> 
> I prefer to use a ramp rather than a sine signal,
> since the ramp closely resembles a classic temporal
> sweep in a scope. This way, it becomes very easy to
> see if the generator's frequency is above or below the
> beat's frequency, which is much harder with a sine X
> input.
> 
> One other way is to use the scope in classic mode with
> the audio synthetizer (preferably in square wave, but
> sine would also do the job) feeding the scope's
> external trigger.
> 
> However, on distant HF signals, it becomes very hard
> to precisely measure the station's frequency due to
> the signal's fading which has important effects on the
> signal's phase. This phase unstability originates from
> the constantly changing RF signal's path due to the
> naturally unstable ionosphere's condition.
> 
> The receiver does NOT need to be a precision unit (you
> could even use a VFO controlled radio), since the beat
> comes from the heterodyning between the station's and
> the generator's signals.
> 
> 73 de Normand Martel VE2UM
> Montreal, Qc. Canada.
> 
> --- John Ackermann N8UR <[EMAIL PROTECTED]> wrote:
> 
>> Hi Colin --
>>
>> Actually, the transmitters used for the FMT seem to
>> be very stable and 
>> as far as I've been able to observe (during each of
>> the 4 FMTs since 
>> they restarted the event) don't drift by a
>> noticeable amount during the 
>> test.
>>
>> I'm actually more concerned about the ARRL's
>> measurement setup than I am 
>> about the transmitter stability.  At least through
>> last year, they 
>> measured the frequency off-air by hooking the
>> counter to an outside 
>> antenna through a bandpass filter, rather than
>> tapping off the output of 
>> the transmitters.  With multiple KW signals floating
>> around the 
>> vicinity, there's lots of opportunity for counter
>> confusion.  Some of us 
>> believe that ARRL's frequency measurement of the
>> 160M signal last year 
>> was about 0.4 Hz off, and I suspect the measurement
>> setup caused that.
>>
>> John
>> 
>>
>> Colin Bradley wrote:
>>> I just finished several email exchanges with Joe
>> Carcia, station manager for W1AW, about the
>> operation of the station. I had hoped that the
>> regular daily bulletins broadcast by W1AW would be
>> tightly controlled in frequency, which would allow
>> me to get some practice measuring them. He informed
>> me that they use two IC-756Pro II¢s and one Orion I
>> for the transmissions. These radios do not permit
>> the use of external standards for frequency control.
>> Neither do the Harris 3200¢s. All of these radios
>> use TCXO¢s for frequency control. This setup will be
>> the same used for the FMT on the 15th.  They will
>> monitor frequency with a counter hooked to their
>> Z3801. 
>>>  
>>> It¢s hard to believe, with a 100-watt amplifier in
>> the same case, that these radios don¢t drift several
>> cycles during a long transmission. For that reason I
>> would encourage persons making measurements to do so
>> during the specified time for each frequency in
>> question. I think it would be very hard to measure
>> the frequency to 1 cycle or less with the frequency
>> control they use. The West Coast station that will
>> broadcast a 40-meter test signal which will, most
>> likely, be more accurate. That station will be using
>> a Heathkit DX-60 into a 400-watt amp. Frequency
>> control is from a HP-107BR into a HP-5100
>> synthesizer. While old, this equipment will probably
>> be up to the job. The oscillator is set against GPS
>> and the whole setup will be independently monitored
>> by another station a mile away with a Cesium
>> standard. 
>>> Coli

Re: [time-nuts] FMT

[Normand Martel]

Personnaly, i use a self-developed technique to
remotely measure a station's frequency:

I use a precision OXCO controlled RF signal generator
to inject an unmodulated (CW) signal (via a
directional coupler) signal 1000 Hz below the actual
station's frequency (example, to monitor CHU at 7335
kHz, i inject a 7334 kHz signal into the coupler). I
then adjust the generator's level to obtain a
comfortable 1000 Hz from my receiver (in AM mode
preferably, but it even works in FM... do not use SSB
or CW modes, since the receiver's BFO will interfere).
Finally, i measure the  1 kHz beat's frequency with
precision (for that, i use an synthesized audio
generator with a ramp (sawtooth) output on an o'scope
in a X-Y function (X = ramp, Y = beat).

I prefer to use a ramp rather than a sine signal,
since the ramp closely resembles a classic temporal
sweep in a scope. This way, it becomes very easy to
see if the generator's frequency is above or below the
beat's frequency, which is much harder with a sine X
input.

One other way is to use the scope in classic mode with
the audio synthetizer (preferably in square wave, but
sine would also do the job) feeding the scope's
external trigger.

However, on distant HF signals, it becomes very hard
to precisely measure the station's frequency due to
the signal's fading which has important effects on the
signal's phase. This phase unstability originates from
the constantly changing RF signal's path due to the
naturally unstable ionosphere's condition.

The receiver does NOT need to be a precision unit (you
could even use a VFO controlled radio), since the beat
comes from the heterodyning between the station's and
the generator's signals.

73 de Normand Martel VE2UM
Montreal, Qc. Canada.

--- John Ackermann N8UR <[EMAIL PROTECTED]> wrote:

> Hi Colin --
> 
> Actually, the transmitters used for the FMT seem to
> be very stable and 
> as far as I've been able to observe (during each of
> the 4 FMTs since 
> they restarted the event) don't drift by a
> noticeable amount during the 
> test.
> 
> I'm actually more concerned about the ARRL's
> measurement setup than I am 
> about the transmitter stability.  At least through
> last year, they 
> measured the frequency off-air by hooking the
> counter to an outside 
> antenna through a bandpass filter, rather than
> tapping off the output of 
> the transmitters.  With multiple KW signals floating
> around the 
> vicinity, there's lots of opportunity for counter
> confusion.  Some of us 
> believe that ARRL's frequency measurement of the
> 160M signal last year 
> was about 0.4 Hz off, and I suspect the measurement
> setup caused that.
> 
> John
> 
> 
> Colin Bradley wrote:
> > I just finished several email exchanges with Joe
> Carcia, station manager for W1AW, about the
> operation of the station. I had hoped that the
> regular daily bulletins broadcast by W1AW would be
> tightly controlled in frequency, which would allow
> me to get some practice measuring them. He informed
> me that they use two IC-756Pro II¢s and one Orion I
> for the transmissions. These radios do not permit
> the use of external standards for frequency control.
> Neither do the Harris 3200¢s. All of these radios
> use TCXO¢s for frequency control. This setup will be
> the same used for the FMT on the 15th.  They will
> monitor frequency with a counter hooked to their
> Z3801. 
> >  
> > It¢s hard to believe, with a 100-watt amplifier in
> the same case, that these radios don¢t drift several
> cycles during a long transmission. For that reason I
> would encourage persons making measurements to do so
> during the specified time for each frequency in
> question. I think it would be very hard to measure
> the frequency to 1 cycle or less with the frequency
> control they use. The West Coast station that will
> broadcast a 40-meter test signal which will, most
> likely, be more accurate. That station will be using
> a Heathkit DX-60 into a 400-watt amp. Frequency
> control is from a HP-107BR into a HP-5100
> synthesizer. While old, this equipment will probably
> be up to the job. The oscillator is set against GPS
> and the whole setup will be independently monitored
> by another station a mile away with a Cesium
> standard. 
> > Colin Bradley
> > 
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>
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Re: [time-nuts] FMT

[John Ackermann N8UR]

Hi Colin --

Actually, the transmitters used for the FMT seem to be very stable and 
as far as I've been able to observe (during each of the 4 FMTs since 
they restarted the event) don't drift by a noticeable amount during the 
test.

I'm actually more concerned about the ARRL's measurement setup than I am 
about the transmitter stability.  At least through last year, they 
measured the frequency off-air by hooking the counter to an outside 
antenna through a bandpass filter, rather than tapping off the output of 
the transmitters.  With multiple KW signals floating around the 
vicinity, there's lots of opportunity for counter confusion.  Some of us 
believe that ARRL's frequency measurement of the 160M signal last year 
was about 0.4 Hz off, and I suspect the measurement setup caused that.

John


Colin Bradley wrote:
> I just finished several email exchanges with Joe Carcia, station manager for 
> W1AW, about the operation of the station. I had hoped that the regular daily 
> bulletins broadcast by W1AW would be tightly controlled in frequency, which 
> would allow me to get some practice measuring them. He informed me that they 
> use two IC-756Pro II’s and one Orion I for the transmissions. These radios do 
> not permit the use of external standards for frequency control. Neither do 
> the Harris 3200’s. All of these radios use TCXO’s for frequency control. This 
> setup will be the same used for the FMT on the 15th.  They will monitor 
> frequency with a counter hooked to their Z3801. 
>  
> It’s hard to believe, with a 100-watt amplifier in the same case, that these 
> radios don’t drift several cycles during a long transmission. For that reason 
> I would encourage persons making measurements to do so during the specified 
> time for each frequency in question. I think it would be very hard to measure 
> the frequency to 1 cycle or less with the frequency control they use. The 
> West Coast station that will broadcast a 40-meter test signal which will, 
> most likely, be more accurate. That station will be using a Heathkit DX-60 
> into a 400-watt amp. Frequency control is from a HP-107BR into a HP-5100 
> synthesizer. While old, this equipment will probably be up to the job. The 
> oscillator is set against GPS and the whole setup will be independently 
> monitored by another station a mile away with a Cesium standard. 
> Colin Bradley
> 
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