Re: [time-nuts] Nifty "MINI TIC" for DMTD work detail Info please read

[Bob Camp]

Hi

A pair of common base amps will get you to what ever your layout will permit. A 
single common base at 10 MHz should get you to at least 60 db with a little 
care. If you run a reasonable transistor you can run levels that will fry a 10 
or a 13 dbm mixer. Again, all the discrete circuits work pretty well. It's the 
modular stuff (especially when driven hard) you have to watch out for.

Bob

On Nov 21, 2012, at 1:43 AM, Bruce Griffiths  wrote:

> 
> Reverse isolation at 10MHz is around 43dB.
> This can be improved significantly by using a Sziklai pair instead of a 
> single transistor in each amplifier.
> However one could also do this in a CB amp.
> 
> Since phase detectors require LO and RF input levels of around 10dBm either 
> deign should suffice.
> NIST have shown that high level mixers appear to be somewhat noisier than 
> either the ZRPD1 and 10534A.
> Whilst their custom mixer utilising diode connected 2N222A's has the lowest 
> flicker noise the increased PCB board complexity may not be worthwhile for 
> this application.
> Reducing the isolation amplifier noise contribution should be more effective 
> than any other changes to the DMTD design.
> 
> Bruce
> 
> Bob Camp wrote:
>> Hi
>> 
>> A few more parts and likely not quite as much isolation. None of that means 
>> it won't do a good job though.
>> 
>> Bob
>> 
>> On Nov 20, 2012, at 11:20 PM, Bruce Griffiths  
>> wrote:
>> 
>>   
>>> The attached circuit is somewhat more efficient and a little quieter.
>>> With a little elaboration lower distortion is possible.
>>> 
>>> Bruce
>>> 
>>> Bob Camp wrote:
>>> 
 Hi
 
 Given that common practice is to mis-match the IF port on the mixers, it's 
 probably not realistic to depend on exact match for isolation. Simple / 
 cheap common base buffers likely are a better approach. Lots of isolation 
 and not much flicker noise.
 
 Bob
 
 On Nov 20, 2012, at 9:01 PM, Bruce Griffiths   
 wrote:
 
 
   
> The details about matching (if any) used in the Czech DMTD would be 
> informative.
> 
> To avoid degrading the performance of the DMTD system below that imposed 
> by the mixers any isolation amps used will need a flicker phase noise 
> floor below that of the mixers.
> Even an opamp based isolation amplifier can be at least 10dB quieter (for 
> offsets of 10Hz and below) than a typical minicircuits RF amp.
> This is still about 10dB or so worse than a good mixer.
> A well designed low gain isolation amp built with discrete transistors 
> can have significantly lower additive phase noise than an opamp.
> 
> To reduce the DMTD system noise one can either:
> 
> 1) Carefully match all ports using series resistors, pads etc as 
> necessary to achieve the required isolation together with a high output 
> low flicker phase noise amplifier to drive the splitter
> 
> 2) Use isolation amplifiers with very low flicker phase noise.
> 
> Some isolation between the 2 RF inputs of a DMTD is usually necessary to 
> avoid injection locking of the 2 sources being compared.
> 
> 
> Bruce
> 
> Bob Camp wrote:
> 
> 
>> Hi
>> 
>> Those isolation numbers are *highly* dependent on very good matching at 
>> all ports. That's rarely the case unless you have a bunch of pads 
>> running around the system.
>> 
>> Bob
>> 
>> On Nov 20, 2012, at 5:49 PM, Bruce Griffiths 
>>wrote:
>> 
>> 
>> 
>>   
>>> Typical Minicircuits SMT RF amps have a phase noise at best 20dB worse 
>>> (@10Hz offset) than the mixer/phase detector.
>>> Their reverse isolation is quite low (<<40dB)
>>> 
>>> The principle reason that the Czech DMTD has such low internal noise is 
>>> due to the absence of any isolation amplifiers.
>>> They use the outputs of a 2 way splitter to drive the LO inputs of the 
>>> mixers.
>>> 
>>> A output to output isolation of 40dB or more at 10MHz is possible with 
>>> some minicicuits splitters (e.g. SYPS-2-1).
>>> The ZRPD1 has an RF1 - RF2 isolation of around 70dB at 10MHz.
>>> 
>>> With a channel to channel isolation of around 110dB for a 2x ZRPD1 + 
>>> Splitter combination isolation amplifiers may not be necessary.
>>> 
>>> Bruce
>>> 
>>> Bruce Griffiths wrote:
>>> 
>>> 
>>> 
 Since mixer noise is one of the limiting factors using a mixer with 
 low flicker noise will help.
 NIST found that a custom mixer using diode connected (collector base 
 short) 2N222As had a significantly lower flicker phase noise than 
 either the ZRPD1 or the 10534A.
 They used off the shelf 1:5 impedance ratio transformers (probably 
 from Minicircuits).
 Another issue is the flicker phase noise of any isolation amplifiers 
 used.
>

Re: [time-nuts] Nifty "MINI TIC" for DMTD work detail Info please read

[Bruce Griffiths]

Reverse isolation at 10MHz is around 43dB.
This can be improved significantly by using a Sziklai pair instead of a 
single transistor in each amplifier.

However one could also do this in a CB amp.

Since phase detectors require LO and RF input levels of around 10dBm 
either deign should suffice.
NIST have shown that high level mixers appear to be somewhat noisier 
than either the ZRPD1 and 10534A.
Whilst their custom mixer utilising diode connected 2N222A's has the 
lowest flicker noise the increased PCB board complexity may not be 
worthwhile for this application.
Reducing the isolation amplifier noise contribution should be more 
effective than any other changes to the DMTD design.


Bruce

Bob Camp wrote:

Hi

A few more parts and likely not quite as much isolation. None of that means it 
won't do a good job though.

Bob

On Nov 20, 2012, at 11:20 PM, Bruce Griffiths  
wrote:

   

The attached circuit is somewhat more efficient and a little quieter.
With a little elaboration lower distortion is possible.

Bruce

Bob Camp wrote:
 

Hi

Given that common practice is to mis-match the IF port on the mixers, it's 
probably not realistic to depend on exact match for isolation. Simple / cheap 
common base buffers likely are a better approach. Lots of isolation and not 
much flicker noise.

Bob

On Nov 20, 2012, at 9:01 PM, Bruce Griffiths   
wrote:


   

The details about matching (if any) used in the Czech DMTD would be informative.

To avoid degrading the performance of the DMTD system below that imposed by the 
mixers any isolation amps used will need a flicker phase noise floor below that 
of the mixers.
Even an opamp based isolation amplifier can be at least 10dB quieter (for 
offsets of 10Hz and below) than a typical minicircuits RF amp.
This is still about 10dB or so worse than a good mixer.
A well designed low gain isolation amp built with discrete transistors can have 
significantly lower additive phase noise than an opamp.

To reduce the DMTD system noise one can either:

1) Carefully match all ports using series resistors, pads etc as necessary to 
achieve the required isolation together with a high output low flicker phase 
noise amplifier to drive the splitter

2) Use isolation amplifiers with very low flicker phase noise.

Some isolation between the 2 RF inputs of a DMTD is usually necessary to avoid 
injection locking of the 2 sources being compared.


Bruce

Bob Camp wrote:

 

Hi

Those isolation numbers are *highly* dependent on very good matching at all 
ports. That's rarely the case unless you have a bunch of pads running around 
the system.

Bob

On Nov 20, 2012, at 5:49 PM, Bruce Griffiths
wrote:



   

Typical Minicircuits SMT RF amps have a phase noise at best 20dB worse (@10Hz 
offset) than the mixer/phase detector.
Their reverse isolation is quite low (<<40dB)

The principle reason that the Czech DMTD has such low internal noise is due to 
the absence of any isolation amplifiers.
They use the outputs of a 2 way splitter to drive the LO inputs of the mixers.

A output to output isolation of 40dB or more at 10MHz is possible with some 
minicicuits splitters (e.g. SYPS-2-1).
The ZRPD1 has an RF1 - RF2 isolation of around 70dB at 10MHz.

With a channel to channel isolation of around 110dB for a 2x ZRPD1 + Splitter 
combination isolation amplifiers may not be necessary.

Bruce

Bruce Griffiths wrote:


 

Since mixer noise is one of the limiting factors using a mixer with low flicker 
noise will help.
NIST found that a custom mixer using diode connected (collector base short) 
2N222As had a significantly lower flicker phase noise than either the ZRPD1 or 
the 10534A.
They used off the shelf 1:5 impedance ratio transformers (probably from 
Minicircuits).
Another issue is the flicker phase noise of any isolation amplifiers used.
This is particularly critical if each mixer uses its own isolation amplifiers.

My current amplifier phase noise measurement setup (for measuring the additive 
PN of a pair of well matched amplifiers) has a self noise of around -170dBc/Hz 
@ 1Hz offset for a 10MHz input.
Ideally the additive phase noise of any isolation amplifiers should be well 
below that of the mixers.

Bruce

ewkeh...@aol.com wrote:


   

Yes Bruce I have the paper. I am not suggesting to copy it verbatim but if
there is a way to reach reasonable priced 1 E-14 members of the list should
pipe  in. I am willing to do an other board. the rest of the systems well
on its way.  Einally after three years.
Bert Kehren


In a message dated 11/20/2012 3:28:57 P.M. Eastern Standard Time,
bruce.griffi...@xtra.co.nz writes:

ewkeh...@aol.com wrote:


 

The D/M is being revisited  because  of the counter performance. 1 E-13 is
easily attainable  but the Czech IREE  published a paper and claim 2 E-15.



   

Do you mean the paper ""optimization of dual-mixer time-difference
multiplier" ?
The ZCD developed in this is a b

Re: [time-nuts] Nifty "MINI TIC" for DMTD work detail Info please read

[Bob Camp]

Hi

A few more parts and likely not quite as much isolation. None of that means it 
won't do a good job though. 

Bob

On Nov 20, 2012, at 11:20 PM, Bruce Griffiths  
wrote:

> The attached circuit is somewhat more efficient and a little quieter.
> With a little elaboration lower distortion is possible.
> 
> Bruce
> 
> Bob Camp wrote:
>> Hi
>> 
>> Given that common practice is to mis-match the IF port on the mixers, it's 
>> probably not realistic to depend on exact match for isolation. Simple / 
>> cheap common base buffers likely are a better approach. Lots of isolation 
>> and not much flicker noise.
>> 
>> Bob
>> 
>> On Nov 20, 2012, at 9:01 PM, Bruce Griffiths  
>> wrote:
>> 
>>   
>>> The details about matching (if any) used in the Czech DMTD would be 
>>> informative.
>>> 
>>> To avoid degrading the performance of the DMTD system below that imposed by 
>>> the mixers any isolation amps used will need a flicker phase noise floor 
>>> below that of the mixers.
>>> Even an opamp based isolation amplifier can be at least 10dB quieter (for 
>>> offsets of 10Hz and below) than a typical minicircuits RF amp.
>>> This is still about 10dB or so worse than a good mixer.
>>> A well designed low gain isolation amp built with discrete transistors can 
>>> have significantly lower additive phase noise than an opamp.
>>> 
>>> To reduce the DMTD system noise one can either:
>>> 
>>> 1) Carefully match all ports using series resistors, pads etc as necessary 
>>> to achieve the required isolation together with a high output low flicker 
>>> phase noise amplifier to drive the splitter
>>> 
>>> 2) Use isolation amplifiers with very low flicker phase noise.
>>> 
>>> Some isolation between the 2 RF inputs of a DMTD is usually necessary to 
>>> avoid injection locking of the 2 sources being compared.
>>> 
>>> 
>>> Bruce
>>> 
>>> Bob Camp wrote:
>>> 
 Hi
 
 Those isolation numbers are *highly* dependent on very good matching at 
 all ports. That's rarely the case unless you have a bunch of pads running 
 around the system.
 
 Bob
 
 On Nov 20, 2012, at 5:49 PM, Bruce Griffiths   
 wrote:
 
 
   
> Typical Minicircuits SMT RF amps have a phase noise at best 20dB worse 
> (@10Hz offset) than the mixer/phase detector.
> Their reverse isolation is quite low (<<40dB)
> 
> The principle reason that the Czech DMTD has such low internal noise is 
> due to the absence of any isolation amplifiers.
> They use the outputs of a 2 way splitter to drive the LO inputs of the 
> mixers.
> 
> A output to output isolation of 40dB or more at 10MHz is possible with 
> some minicicuits splitters (e.g. SYPS-2-1).
> The ZRPD1 has an RF1 - RF2 isolation of around 70dB at 10MHz.
> 
> With a channel to channel isolation of around 110dB for a 2x ZRPD1 + 
> Splitter combination isolation amplifiers may not be necessary.
> 
> Bruce
> 
> Bruce Griffiths wrote:
> 
> 
>> Since mixer noise is one of the limiting factors using a mixer with low 
>> flicker noise will help.
>> NIST found that a custom mixer using diode connected (collector base 
>> short) 2N222As had a significantly lower flicker phase noise than either 
>> the ZRPD1 or the 10534A.
>> They used off the shelf 1:5 impedance ratio transformers (probably from 
>> Minicircuits).
>> Another issue is the flicker phase noise of any isolation amplifiers 
>> used.
>> This is particularly critical if each mixer uses its own isolation 
>> amplifiers.
>> 
>> My current amplifier phase noise measurement setup (for measuring the 
>> additive PN of a pair of well matched amplifiers) has a self noise of 
>> around -170dBc/Hz @ 1Hz offset for a 10MHz input.
>> Ideally the additive phase noise of any isolation amplifiers should be 
>> well below that of the mixers.
>> 
>> Bruce
>> 
>> ewkeh...@aol.com wrote:
>> 
>>   
>>> Yes Bruce I have the paper. I am not suggesting to copy it verbatim but 
>>> if
>>> there is a way to reach reasonable priced 1 E-14 members of the list 
>>> should
>>> pipe  in. I am willing to do an other board. the rest of the systems 
>>> well
>>> on its way.  Einally after three years.
>>> Bert Kehren
>>> 
>>> 
>>> In a message dated 11/20/2012 3:28:57 P.M. Eastern Standard Time,
>>> bruce.griffi...@xtra.co.nz writes:
>>> 
>>> ewkeh...@aol.com wrote:
>>> 
>>> 
 The D/M is being revisited  because  of the counter performance. 1 
 E-13 is
 easily attainable  but the Czech IREE  published a paper and claim 2 
 E-15.
 
 
   
>>> Do you mean the paper ""optimization of dual-mixer time-difference
>>> multiplier" ?
>>> The ZCD developed in this is a bit of a kludge and is far  from optimum.

Re: [time-nuts] Nifty "MINI TIC" for DMTD work

[heathkid]

Yet another... please add me to the list... I'm very interested.  Thanks!


On 11/19/2012 2:04 PM, cdel...@juno.com wrote:
> "MINI-TIC" for DMTD work
>
>
> Hi Everyone!
>
> I've been testing a Miniature 2 channel TIC that Bert Kehren and Juerg
> Koegel
> and Richard Mc Corkle have designed.
>
> It has 9 digits/Sec. and with a 1HZ offset in the DMTD unit gives a
> resolution of 1X10-15th  at 10 MHz, 2X10-15 with a 5 MHz input, when
> measuring 
> Allan deviation. The 200 MHz version doubles the resolution.
>
> Of course the baseline performance of the DMTD unit and the stability of
> the DMTD reference determines the actual accuracy you can obtain. 
>
> (My dual mixer has a baseline of approx. 8X10-14th at 1 second and my
> best reference is  4X10-13th at 1 second.)
>
> The "MINI" takes a 5 or 10 MHz reference that only has to be stable to
> parts in 10-8th/sec.
> I used a neat 14PIN ovenized DIP clock chip I got on eBay and recently 
> discussed on the list.
>
> The reference is multiplied to 100Mhz for use as the counters clock.
>
> The "MINI" is about 2.5 by 2 inches and has only 5 chips. Two opto
> couplers an 
> op amp for two analog channels are also on the board. If run on 5 volt a
> 3.3 V 
> regulator is also on the board. Power required is +5VDC 0.05 A  and +- 12
>
> (for the RS232 interface)
>
> It also has two pins you can individually ground to measure the period of
> the beat
> note from either channel.
>
> This allows you to adjust the offset frequency quickly and accurately.
>
> I installed the "MINI" into a 1U chassis with the power supply and also
> added "heartbeat" LEDS for each channel to show the presence of the 1PPS 
> inputs.
>
> I have plotted several Rubidium and many Quartz using the "MINI"
> simultaneously with a SR620 counter/timer. The plots are "identical"! So
> much 
> so that I am going to "retire" and sell my SR620!
>
> I understand work is complete on a 4 channel counters and Bluetooth
> interface, 
> and work is ongoing on a LCD.
>
> The "MINI" material cost is less than $25.00 depending on how many 
> boards are ordered!
>
> Resoution based on clock frequency and beat frequency:
>
> Carrier[MHz]  Beat [Hz] HeterodyneTIC [ns]   Resolution
> 10101.00E+06101.00E-14
> 1011.00E+07101.00E-15
> 1011.00E+0755.00E-16
> 10101.00E+0655.00E-15
> 5105.00E+05102.00E-14
> 515.00E+06102.00E-15
> 515.00E+0651.00E-15
> 5105.00E+0551.00E-14
> 
> Woman is 53 But Looks 25
> Mom reveals 1 simple wrinkle trick that has angered doctors...
> http://thirdpartyoffers.juno.com/TGL3141/50aa82cb1214a2ca03f8st04duc
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.


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and follow the instructions there.

Re: [time-nuts] Year 2000?

[John Allen]

Yes, Two of my PC's asked if I wanted to change the data and time to -8xxx
days, 0 hours, 0 minutes, 0 seconds.  A real head scratcher until I saw the
link below.  I believe the time server was tick.usno.navy.mil
The Time Sync software that I use is D4 - see:

http://www.thinkman.com/dimension4/


Regards to all,

John, K1AE

-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Bob Smither
Sent: Tuesday, November 20, 2012 9:50 PM
To: Discussion of precise time and frequency measurement
Subject: [time-nuts] Year 2000?

Anyone notice this?:

  https://isc.sans.edu/diary.html?n&storyid=14548


Seems a Navy NTP server claimed it was year 2000 for a while.




___
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To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

[time-nuts] Year 2000?

[Bob Smither]

Anyone notice this?:

  https://isc.sans.edu/diary.html?n&storyid=14548

Seems a Navy NTP server claimed it was year 2000 for a while.


<>___
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To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Nifty "MINI TIC" for DMTD work detail Info please read

[Bob Camp]

Hi

Given that common practice is to mis-match the IF port on the mixers, it's 
probably not realistic to depend on exact match for isolation. Simple / cheap 
common base buffers likely are a better approach. Lots of isolation and not 
much flicker noise. 

Bob

On Nov 20, 2012, at 9:01 PM, Bruce Griffiths  wrote:

> The details about matching (if any) used in the Czech DMTD would be 
> informative.
> 
> To avoid degrading the performance of the DMTD system below that imposed by 
> the mixers any isolation amps used will need a flicker phase noise floor 
> below that of the mixers.
> Even an opamp based isolation amplifier can be at least 10dB quieter (for 
> offsets of 10Hz and below) than a typical minicircuits RF amp.
> This is still about 10dB or so worse than a good mixer.
> A well designed low gain isolation amp built with discrete transistors can 
> have significantly lower additive phase noise than an opamp.
> 
> To reduce the DMTD system noise one can either:
> 
> 1) Carefully match all ports using series resistors, pads etc as necessary to 
> achieve the required isolation together with a high output low flicker phase 
> noise amplifier to drive the splitter
> 
> 2) Use isolation amplifiers with very low flicker phase noise.
> 
> Some isolation between the 2 RF inputs of a DMTD is usually necessary to 
> avoid injection locking of the 2 sources being compared.
> 
> 
> Bruce
> 
> Bob Camp wrote:
>> Hi
>> 
>> Those isolation numbers are *highly* dependent on very good matching at all 
>> ports. That's rarely the case unless you have a bunch of pads running around 
>> the system.
>> 
>> Bob
>> 
>> On Nov 20, 2012, at 5:49 PM, Bruce Griffiths  
>> wrote:
>> 
>>   
>>> Typical Minicircuits SMT RF amps have a phase noise at best 20dB worse 
>>> (@10Hz offset) than the mixer/phase detector.
>>> Their reverse isolation is quite low (<<40dB)
>>> 
>>> The principle reason that the Czech DMTD has such low internal noise is due 
>>> to the absence of any isolation amplifiers.
>>> They use the outputs of a 2 way splitter to drive the LO inputs of the 
>>> mixers.
>>> 
>>> A output to output isolation of 40dB or more at 10MHz is possible with some 
>>> minicicuits splitters (e.g. SYPS-2-1).
>>> The ZRPD1 has an RF1 - RF2 isolation of around 70dB at 10MHz.
>>> 
>>> With a channel to channel isolation of around 110dB for a 2x ZRPD1 + 
>>> Splitter combination isolation amplifiers may not be necessary.
>>> 
>>> Bruce
>>> 
>>> Bruce Griffiths wrote:
>>> 
 Since mixer noise is one of the limiting factors using a mixer with low 
 flicker noise will help.
 NIST found that a custom mixer using diode connected (collector base 
 short) 2N222As had a significantly lower flicker phase noise than either 
 the ZRPD1 or the 10534A.
 They used off the shelf 1:5 impedance ratio transformers (probably from 
 Minicircuits).
 Another issue is the flicker phase noise of any isolation amplifiers used.
 This is particularly critical if each mixer uses its own isolation 
 amplifiers.
 
 My current amplifier phase noise measurement setup (for measuring the 
 additive PN of a pair of well matched amplifiers) has a self noise of 
 around -170dBc/Hz @ 1Hz offset for a 10MHz input.
 Ideally the additive phase noise of any isolation amplifiers should be 
 well below that of the mixers.
 
 Bruce
 
 ewkeh...@aol.com wrote:
   
> Yes Bruce I have the paper. I am not suggesting to copy it verbatim but if
> there is a way to reach reasonable priced 1 E-14 members of the list 
> should
> pipe  in. I am willing to do an other board. the rest of the systems well
> on its way.  Einally after three years.
> Bert Kehren
> 
> 
> In a message dated 11/20/2012 3:28:57 P.M. Eastern Standard Time,
> bruce.griffi...@xtra.co.nz writes:
> 
> ewkeh...@aol.com wrote:
> 
>> The D/M is being revisited  because  of the counter performance. 1 E-13 
>> is
>> easily attainable  but the Czech IREE  published a paper and claim 2 
>> E-15.
>> 
>>   
> Do you mean the paper ""optimization of dual-mixer time-difference
> multiplier" ?
> The ZCD developed in this is a bit of a kludge and is far  from optimum.
> Reverse engineering the circuit from the description given in  the paper
> isn't too difficult.
> They claim an instrument limited ADEV of  ~7E-15 @ 1s.
> Do you have a copy of this paper?
> 
>> Bert  Kehren   Miami
>>  ___
>> 
>>   
> Bruce
> 
> 
>>> 
>>> ___
>>> time-nuts mailing list -- time-nuts@febo.com
>>> To unsubscribe, go to 
>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>> and follow the instructions there.
>>> 
>> 
>> ___
>> time-nuts mailing 

Re: [time-nuts] Nifty "MINI TIC" for DMTD work detail Info please read

[Bruce Griffiths]

The details about matching (if any) used in the Czech DMTD would be 
informative.


To avoid degrading the performance of the DMTD system below that imposed 
by the mixers any isolation amps used will need a flicker phase noise 
floor below that of the mixers.
Even an opamp based isolation amplifier can be at least 10dB quieter 
(for offsets of 10Hz and below) than a typical minicircuits RF amp.

This is still about 10dB or so worse than a good mixer.
A well designed low gain isolation amp built with discrete transistors 
can have significantly lower additive phase noise than an opamp.


To reduce the DMTD system noise one can either:

1) Carefully match all ports using series resistors, pads etc as 
necessary to achieve the required isolation together with a high output 
low flicker phase noise amplifier to drive the splitter


2) Use isolation amplifiers with very low flicker phase noise.

Some isolation between the 2 RF inputs of a DMTD is usually necessary to 
avoid injection locking of the 2 sources being compared.



Bruce

Bob Camp wrote:

Hi

Those isolation numbers are *highly* dependent on very good matching at all 
ports. That's rarely the case unless you have a bunch of pads running around 
the system.

Bob

On Nov 20, 2012, at 5:49 PM, Bruce Griffiths  wrote:

   

Typical Minicircuits SMT RF amps have a phase noise at best 20dB worse (@10Hz 
offset) than the mixer/phase detector.
Their reverse isolation is quite low (<<40dB)

The principle reason that the Czech DMTD has such low internal noise is due to 
the absence of any isolation amplifiers.
They use the outputs of a 2 way splitter to drive the LO inputs of the mixers.

A output to output isolation of 40dB or more at 10MHz is possible with some 
minicicuits splitters (e.g. SYPS-2-1).
The ZRPD1 has an RF1 - RF2 isolation of around 70dB at 10MHz.

With a channel to channel isolation of around 110dB for a 2x ZRPD1 + Splitter 
combination isolation amplifiers may not be necessary.

Bruce

Bruce Griffiths wrote:
 

Since mixer noise is one of the limiting factors using a mixer with low flicker 
noise will help.
NIST found that a custom mixer using diode connected (collector base short) 
2N222As had a significantly lower flicker phase noise than either the ZRPD1 or 
the 10534A.
They used off the shelf 1:5 impedance ratio transformers (probably from 
Minicircuits).
Another issue is the flicker phase noise of any isolation amplifiers used.
This is particularly critical if each mixer uses its own isolation amplifiers.

My current amplifier phase noise measurement setup (for measuring the additive 
PN of a pair of well matched amplifiers) has a self noise of around -170dBc/Hz 
@ 1Hz offset for a 10MHz input.
Ideally the additive phase noise of any isolation amplifiers should be well 
below that of the mixers.

Bruce

ewkeh...@aol.com wrote:
   

Yes Bruce I have the paper. I am not suggesting to copy it verbatim but if
there is a way to reach reasonable priced 1 E-14 members of the list should
pipe  in. I am willing to do an other board. the rest of the systems well
on its way.  Einally after three years.
Bert Kehren


In a message dated 11/20/2012 3:28:57 P.M. Eastern Standard Time,
bruce.griffi...@xtra.co.nz writes:

ewkeh...@aol.com wrote:
 

The D/M is being revisited  because  of the counter performance. 1 E-13 is
easily attainable  but the Czech IREE  published a paper and claim 2 E-15.

   

Do you mean the paper ""optimization of dual-mixer time-difference
multiplier" ?
The ZCD developed in this is a bit of a kludge and is far  from optimum.
Reverse engineering the circuit from the description given in  the paper
isn't too difficult.
They claim an instrument limited ADEV of  ~7E-15 @ 1s.
Do you have a copy of this paper?
 

Bert  Kehren   Miami
  ___

   

Bruce

 


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Re: [time-nuts] WWVB PSK demodulation; simple carrier regeneration?

[paul swed]

Dave
A couple of comments numbers of folks on Time-nuts have suggested the same
types of approaches. Though outside of an armchair discussion not much
happens. So I believe that what you say is reasonable. Jut remember lots of
the country has poor reception so that really makes life hard.
It was absolutely not apparent to me early on exactly when the phase would
change.
I was looking at all the wrong places as they say. I did find it and since
then its been confirmed. So it makes it even harder.
But lots of tinkering actually has gone on with more traditional methods
and they all worked poorly.
Back to what you are thinking.
The problem may actually be easier. So sure downconvert etc. But all you
want to know is the phase flipped and then flip an inverting amp in or out
of line. That creates a corrected non psk shifted signal or as a I say
"d-psk-d". It doesn't even have to happen instantly. I check for 3 60 KHz
cycles to make sure it was not some noise faking me out. The way the phase
tracking rcvrs work it could be 1/4 second and don't believe it would be an
issue. They are pretty tolerant.
This simple reality is what makes this pretty interesting. I don't believe
you need a lot of processing at all. I am looking directly at the 60 Khz
and writing the program in basic and have plenty of cycles left over.
So I think its a lot more about trying then the ole arm chair. I have a
pile of should have worked boards. Sure have learned allot and thanks to
numbers of time-nuts for thoughts and support.
Regards
Paul
WB8TSL

On Tue, Nov 20, 2012 at 6:39 PM, David Armstrong
wrote:

> Hi,
> I am have thinking / tinkering / planning a wwvb receiver for
> longer
> than I am willing to admit!!  It seems to me that one could take a
> ferrite loop, JFET buffer, ADC and a small microprocessor to get down to
> baseband - say 20 Hz complex sampling rate - and then output on a serial
> port for more processing - initially on a PC - but after the  algorithms
> are developed -  on the same micro or another one.  My current tinkering
> plan is an ADC operating at 80 KHz sampling rate into an AVR.
> Alternately one could easily use an ARM with the built in ADC like
> Poul-Henning Kamp and his last Loran receiver.  (but I have the AVR and
> the experience with it)
>
> I don't think the signal processing to get down to 20 Hz complex is
> that hard.  It would allow the use as a amplitude based receiver -  take
> the absolute value of the complex signal or one could do both the
> amplitude and phase receiver.  Did anyone notice that the phase changes
> are delayed 1/10 of a second from the beginning of the 'bit' so that the
> phase change is always in a 17 dB down RF state?
>
> Dave Armstrong
>
>
>
> On Tue, 2012-11-20 at 08:50 -0500, paul swed wrote:
> > Great thread.
> > Bob in the d-psk-r thats exactly what I am doing is flipping a switch on
> > the incoming signal.
> > That normalizes it. However in its current approach it is random as
> either
> > 0 or 180 out always. No attempt has been made to determine 0. But it does
> > run the phase tracking rcvrs fine. That said for Pete. The time tracking
> > rcvrs like the spectracom 8170 does require a non PSK carrier to work. So
> > thats why  I preserve the AM for those types of rcvrs.
> > But on to what you have written. I tinkered with a soundcard and spectrum
> > lab and it showed some promise. If you are willing to have a big power
> > sucking pc/laptop running 24 X 7 thats going to be a great solution as
> you
> > have shown. Just take the output of the 1s and 0s and when you see a 1
> flip
> > a inverting amplifier. Thatthen feeds the old rcvrs. Done.
> > I do not have matlab so would love to see what you did to do the
> decoding.
> > I strongly believe your approach is completely as valid as mine. Like you
> > say there are some very interesting thoughts on how to do this.
> > By the way big issue much of the US actually has very poor wwvb
> reception.
> > Thats what I have had to struggle with.
> > Regards
> > Paul.
> >
> > On Tue, Nov 20, 2012 at 7:56 AM, Bob Camp  wrote:
> >
> > > Hi
> > >
> > > I believe the "lowest cost" approach is to take the RF and run it
> through
> > > an simple switch. The switch either has a 0 degree or a 180 degree
> phase
> > > shift. Drive the control of the switch with a computer generated track
> of
> > > the known modulation format. Let the computer get time via NTP and just
> > > generate the (really slow) switch drive waveform. A diode ring and a
> pair
> > > of transformers will do for the switch.
> > >
> > > Is it a bit noisy? - yes. Should it bother a receiver that already
> deals
> > > with a lot of noise? - probably not if your NTP is within <10ms.
> > >
> > > Bob
> > >
> > > On Nov 20, 2012, at 2:52 AM, Peter Monta  wrote:
> > >
> > > > Here are a few demodulated frames of WWVB's new BPSK bits:
> > > >
> > > > 0011101101000 01101 0(0)001100111(0)011011011(0)1010110 00 0 000
> 00 0
> > > > 0011101101000 00100 0(1)0011

Re: [time-nuts] Nifty "MINI TIC" for DMTD work detail Info please read

[Bob Camp]

Hi

Those isolation numbers are *highly* dependent on very good matching at all 
ports. That's rarely the case unless you have a bunch of pads running around 
the system.

Bob

On Nov 20, 2012, at 5:49 PM, Bruce Griffiths  wrote:

> Typical Minicircuits SMT RF amps have a phase noise at best 20dB worse (@10Hz 
> offset) than the mixer/phase detector.
> Their reverse isolation is quite low (<<40dB)
> 
> The principle reason that the Czech DMTD has such low internal noise is due 
> to the absence of any isolation amplifiers.
> They use the outputs of a 2 way splitter to drive the LO inputs of the mixers.
> 
> A output to output isolation of 40dB or more at 10MHz is possible with some 
> minicicuits splitters (e.g. SYPS-2-1).
> The ZRPD1 has an RF1 - RF2 isolation of around 70dB at 10MHz.
> 
> With a channel to channel isolation of around 110dB for a 2x ZRPD1 + Splitter 
> combination isolation amplifiers may not be necessary.
> 
> Bruce
> 
> Bruce Griffiths wrote:
>> Since mixer noise is one of the limiting factors using a mixer with low 
>> flicker noise will help.
>> NIST found that a custom mixer using diode connected (collector base short) 
>> 2N222As had a significantly lower flicker phase noise than either the ZRPD1 
>> or the 10534A.
>> They used off the shelf 1:5 impedance ratio transformers (probably from 
>> Minicircuits).
>> Another issue is the flicker phase noise of any isolation amplifiers used.
>> This is particularly critical if each mixer uses its own isolation 
>> amplifiers.
>> 
>> My current amplifier phase noise measurement setup (for measuring the 
>> additive PN of a pair of well matched amplifiers) has a self noise of around 
>> -170dBc/Hz @ 1Hz offset for a 10MHz input.
>> Ideally the additive phase noise of any isolation amplifiers should be well 
>> below that of the mixers.
>> 
>> Bruce
>> 
>> ewkeh...@aol.com wrote:
>>> Yes Bruce I have the paper. I am not suggesting to copy it verbatim but if
>>> there is a way to reach reasonable priced 1 E-14 members of the list should
>>> pipe  in. I am willing to do an other board. the rest of the systems well
>>> on its way.  Einally after three years.
>>> Bert Kehren
>>> 
>>> 
>>> In a message dated 11/20/2012 3:28:57 P.M. Eastern Standard Time,
>>> bruce.griffi...@xtra.co.nz writes:
>>> 
>>> ewkeh...@aol.com wrote:
 The D/M is being revisited  because  of the counter performance. 1 E-13 is
 easily attainable  but the Czech IREE  published a paper and claim 2 E-15.
 
>>> Do you mean the paper ""optimization of dual-mixer time-difference
>>> multiplier" ?
>>> The ZCD developed in this is a bit of a kludge and is far  from optimum.
>>> Reverse engineering the circuit from the description given in  the paper
>>> isn't too difficult.
>>> They claim an instrument limited ADEV of  ~7E-15 @ 1s.
>>> Do you have a copy of this paper?
 Bert  Kehren   Miami
  ___
 
>>> Bruce
>>> 
> 
> 
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Re: [time-nuts] time-nuts Digest, Vol 100, Issue 82 Nifty "MINI TIC" for DMTD

[Geoffrey Smith]

Bert,

Thanks for this update.  I appreciate your effort.

Regards
Geoffrey 

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   1. Nifty "MINI TIC" for DMTD update please read (ewkeh...@aol.com)


--

Message: 1
Date: Tue, 20 Nov 2012 08:27:35 -0500 (EST)
From: ewkeh...@aol.com
To: time-nuts@febo.com
Subject: [time-nuts] Nifty "MINI TIC" for DMTD update please read
Message-ID: <1258.27fbb907.3ddcd...@aol.com>
Content-Type: text/plain; charset="us-ascii"

Thank all of you for the response
It is clear that because of the volume an organized response is necessary.  
Didier has offered his site and that is how it will be organized and a
complete set of documentation and pictures will be available. Maybe start
with the 1 pps  MAX 3000 version of the TADD-2 Mini on steroids. Solderable
and below 20 $ total parts cost.
At this time I am not taking down any names. 
 
Step one
documentation will be completed, Brian has offered to complete what he
started a year ago, things have changed.
Step two
Juerg will complete his display board, the attached picture is the prototype
development board, display will be larger
 
In the meantime I think dialog and focus would be helpful  in deciding what
would make the best affordable Dual Mixer. 
Counter and display is under control. The noise  floor of the D/M is key,
counter exceeds requirements.
 
During the next couple of weeks I will do a more detailed explanation of the
features of the 4 channel counter and its application. 
 
Bert Kehren Miami
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[time-nuts] MIni TIC for DMTD work

[Geoffrey Smith]

I am an interested party.

 

Who is coordinating the board orders?

 

Is there any wiki or a web site details for the project?

 

Regards

Geoffrey 

 

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Re: [time-nuts] WWVB PSK demodulation; simple carrier regeneration?

[David Armstrong]

Hi,
I am have thinking / tinkering / planning a wwvb receiver for longer
than I am willing to admit!!  It seems to me that one could take a
ferrite loop, JFET buffer, ADC and a small microprocessor to get down to
baseband - say 20 Hz complex sampling rate - and then output on a serial
port for more processing - initially on a PC - but after the  algorithms
are developed -  on the same micro or another one.  My current tinkering
plan is an ADC operating at 80 KHz sampling rate into an AVR.
Alternately one could easily use an ARM with the built in ADC like
Poul-Henning Kamp and his last Loran receiver.  (but I have the AVR and
the experience with it) 

I don't think the signal processing to get down to 20 Hz complex is
that hard.  It would allow the use as a amplitude based receiver -  take
the absolute value of the complex signal or one could do both the
amplitude and phase receiver.  Did anyone notice that the phase changes
are delayed 1/10 of a second from the beginning of the 'bit' so that the
phase change is always in a 17 dB down RF state?  

Dave Armstrong



On Tue, 2012-11-20 at 08:50 -0500, paul swed wrote:
> Great thread.
> Bob in the d-psk-r thats exactly what I am doing is flipping a switch on
> the incoming signal.
> That normalizes it. However in its current approach it is random as either
> 0 or 180 out always. No attempt has been made to determine 0. But it does
> run the phase tracking rcvrs fine. That said for Pete. The time tracking
> rcvrs like the spectracom 8170 does require a non PSK carrier to work. So
> thats why  I preserve the AM for those types of rcvrs.
> But on to what you have written. I tinkered with a soundcard and spectrum
> lab and it showed some promise. If you are willing to have a big power
> sucking pc/laptop running 24 X 7 thats going to be a great solution as you
> have shown. Just take the output of the 1s and 0s and when you see a 1 flip
> a inverting amplifier. Thatthen feeds the old rcvrs. Done.
> I do not have matlab so would love to see what you did to do the decoding.
> I strongly believe your approach is completely as valid as mine. Like you
> say there are some very interesting thoughts on how to do this.
> By the way big issue much of the US actually has very poor wwvb reception.
> Thats what I have had to struggle with.
> Regards
> Paul.
> 
> On Tue, Nov 20, 2012 at 7:56 AM, Bob Camp  wrote:
> 
> > Hi
> >
> > I believe the "lowest cost" approach is to take the RF and run it through
> > an simple switch. The switch either has a 0 degree or a 180 degree phase
> > shift. Drive the control of the switch with a computer generated track of
> > the known modulation format. Let the computer get time via NTP and just
> > generate the (really slow) switch drive waveform. A diode ring and a pair
> > of transformers will do for the switch.
> >
> > Is it a bit noisy? - yes. Should it bother a receiver that already deals
> > with a lot of noise? - probably not if your NTP is within <10ms.
> >
> > Bob
> >
> > On Nov 20, 2012, at 2:52 AM, Peter Monta  wrote:
> >
> > > Here are a few demodulated frames of WWVB's new BPSK bits:
> > >
> > > 0011101101000 01101 0(0)001100111(0)011011011(0)1010110 00 0 000 00 0
> > > 0011101101000 00100 0(1)001100111(1)011011011(1)1010111 00 0 000 00 0
> > > 0011101101000 01000 0(0)001100111(0)011011011(0)1011000 00 0 000 00 0
> > >
> > > The fields are described in the NIST document [1]:  sync word, parity
> > word,
> > > time in binary minutes, and various metadata.  The bits in parentheses
> > are
> > > the "marker" bits which have less power; it appears they're using all
> > three
> > > as duplicates of time[0], the LSB of the time word.
> > >
> > > Strong signal here in California, even during daytime.  My receiver is
> > just
> > > a hacked-up ferrite loop, JFET buffer, sound card, and Matlab.  About 300
> > > Hz single-sided bandwidth.
> > >
> > > So it's an interesting question:  what is the simplest device that can
> > > change this signal into something the legacy WWVB receivers can track,
> > > without any modification at all to the legacy receiver?  By "simplest" I
> > > mean avoiding any intelligence like carrier acquisition, timing recovery,
> > > or bit demodulation; but it should still have good noise performance to
> > the
> > > largest extent possible.
> > >
> > > One candidate might be this:  multiply the signal by an estimate of its
> > > phase one minute ago.  The frames are very similar minute-to-minute, as
> > can
> > > be seen above.  The exceptions are the parity word, changes in the
> > > metadata, and rollovers in the time word involving large numbers of bits.
> > > (I wish they had Gray-coded the time word, or, better, scrambled it in
> > some
> > > way so that the time word can't nearly emulate the sync word for many
> > > minutes running, which looks like a risk with the current format.)  But
> > > aside from this, the legacy receiver would be seeing carrier *
> > > xor(minute_i, minute

Re: [time-nuts] Nifty "MINI TIC" for DMTD work detail Info please read

[Bruce Griffiths]

Typical Minicircuits SMT RF amps have a phase noise at best 20dB worse 
(@10Hz offset) than the mixer/phase detector.

Their reverse isolation is quite low (<<40dB)

The principle reason that the Czech DMTD has such low internal noise is 
due to the absence of any isolation amplifiers.
They use the outputs of a 2 way splitter to drive the LO inputs of the 
mixers.


A output to output isolation of 40dB or more at 10MHz is possible with 
some minicicuits splitters (e.g. SYPS-2-1).

The ZRPD1 has an RF1 - RF2 isolation of around 70dB at 10MHz.

With a channel to channel isolation of around 110dB for a 2x ZRPD1 + 
Splitter combination isolation amplifiers may not be necessary.


Bruce

Bruce Griffiths wrote:
Since mixer noise is one of the limiting factors using a mixer with 
low flicker noise will help.
NIST found that a custom mixer using diode connected (collector base 
short) 2N222As had a significantly lower flicker phase noise than 
either the ZRPD1 or the 10534A.
They used off the shelf 1:5 impedance ratio transformers (probably 
from Minicircuits).
Another issue is the flicker phase noise of any isolation amplifiers 
used.
This is particularly critical if each mixer uses its own isolation 
amplifiers.


My current amplifier phase noise measurement setup (for measuring the 
additive PN of a pair of well matched amplifiers) has a self noise of 
around -170dBc/Hz @ 1Hz offset for a 10MHz input.
Ideally the additive phase noise of any isolation amplifiers should be 
well below that of the mixers.


Bruce

ewkeh...@aol.com wrote:
Yes Bruce I have the paper. I am not suggesting to copy it verbatim 
but if
there is a way to reach reasonable priced 1 E-14 members of the list 
should
pipe  in. I am willing to do an other board. the rest of the systems 
well

on its way.  Einally after three years.
Bert Kehren


In a message dated 11/20/2012 3:28:57 P.M. Eastern Standard Time,
bruce.griffi...@xtra.co.nz writes:

ewkeh...@aol.com wrote:
The D/M is being revisited  because  of the counter performance. 1 
E-13 is
easily attainable  but the Czech IREE  published a paper and claim 2 
E-15.



Do you mean the paper ""optimization of dual-mixer time-difference
multiplier" ?
The ZCD developed in this is a bit of a kludge and is far  from optimum.
Reverse engineering the circuit from the description given in  the paper
isn't too difficult.
They claim an instrument limited ADEV of  ~7E-15 @ 1s.
Do you have a copy of this paper?

Bert  Kehren   Miami
  ___


Bruce




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Re: [time-nuts] An other project

[EWKehren]

There is no schematic, it is beside the Wenzel all in the MAX 3000 a string 
 of dividers and depending on what we want selected outputs and all outputs 
have  synchronizers to the input to reduce jitter.
Bert
 
In a message dated 11/20/2012 5:22:50 P.M. Eastern Standard Time,  
dlewis6...@austin.rr.com writes:

Bert:  could you post the schematic,  please?









--
From:  
Sent: Tuesday, November 20, 2012 3:13 PM
To:  
Subject: [time-nuts] An other  project

> I did mention a MAX 3000 implementation of a 1 pps  generator. The 
attached
> picture shows the prototype. This came about  to generate timing signals 
to
> test the counters. It is a TADD-2 Mini  on steroids. Besides the Wenzel
> input and  4 outputs parraleled  with resistors it has presently 6 inputs 
> for
> output   selecting  or synchronizing and 6 additional outputs. Example  
duty
> cycle,  frequency out of the 50 ohm.This is a good example  of the 
> flexibility of
> the use  of this IC. If there is  interest maybe we can agree on a couple 
> of
> versions and   find some one in the US and some one in Europe to sell a 
> kit.
>  Juerg and I are  not getting in the kit business but it may be a  
precursor
> when D/M systems will  roll out. At 25 $ in the US and  20 Euro in the EU 
> who
> ever does it will make a  little  money for their trouble. That price 
would
> include shipping!
>  Members can also use the unit to knit their own version, IC's can be
>  reprogrammed. This is also the board that was used to do the jitter 
test.  
> Passed
> with flying colors. Let me know what you think but I  will not take 
orders,
> but  find a way to make it available if  there is interest
> Bert Kehren.  


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Re: [time-nuts] An other project

[dlewis6767]

Bert:  could you post the schematic, please?









--
From: 
Sent: Tuesday, November 20, 2012 3:13 PM
To: 
Subject: [time-nuts] An other project


I did mention a MAX 3000 implementation of a 1 pps generator. The attached
picture shows the prototype. This came about to generate timing signals to
test the counters. It is a TADD-2 Mini on steroids. Besides the Wenzel
input and  4 outputs parraleled with resistors it has presently 6 inputs 
for

output  selecting  or synchronizing and 6 additional outputs. Example duty
cycle,  frequency out of the 50 ohm.This is a good example of the 
flexibility of
the use  of this IC. If there is interest maybe we can agree on a couple 
of
versions and  find some one in the US and some one in Europe to sell a 
kit.

Juerg and I are  not getting in the kit business but it may be a precursor
when D/M systems will  roll out. At 25 $ in the US and 20 Euro in the EU 
who

ever does it will make a  little money for their trouble. That price would
include shipping!
Members can also use the unit to knit their own version, IC's can be
reprogrammed. This is also the board that was used to do the jitter test. 
Passed

with flying colors. Let me know what you think but I will not take orders,
but  find a way to make it available if there is interest
Bert Kehren. 



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Re: [time-nuts] Nifty "MINI TIC" for DMTD work

[Steve]

I'm interested in two...

Thanks,

Steve


On Nov 19, 2012, at 8:04 PM, cdel...@juno.com wrote:

> 
> "MINI-TIC" for DMTD work
> 
> 
> Hi Everyone!
> 
> I've been testing a Miniature 2 channel TIC that Bert Kehren and Juerg
> Koegel
> and Richard Mc Corkle have designed.
> 
> It has 9 digits/Sec. and with a 1HZ offset in the DMTD unit gives a
> resolution of 1X10-15th  at 10 MHz, 2X10-15 with a 5 MHz input, when
> measuring 
> Allan deviation. The 200 MHz version doubles the resolution.
> 
> Of course the baseline performance of the DMTD unit and the stability of
> the DMTD reference determines the actual accuracy you can obtain. 
> 
> (My dual mixer has a baseline of approx. 8X10-14th at 1 second and my
> best reference is  4X10-13th at 1 second.)
> 
> The "MINI" takes a 5 or 10 MHz reference that only has to be stable to
> parts in 10-8th/sec.
> I used a neat 14PIN ovenized DIP clock chip I got on eBay and recently 
> discussed on the list.
> 
> The reference is multiplied to 100Mhz for use as the counters clock.
> 
> The "MINI" is about 2.5 by 2 inches and has only 5 chips. Two opto
> couplers an 
> op amp for two analog channels are also on the board. If run on 5 volt a
> 3.3 V 
> regulator is also on the board. Power required is +5VDC 0.05 A  and +- 12
> 
> (for the RS232 interface)
> 
> It also has two pins you can individually ground to measure the period of
> the beat
> note from either channel.
> 
> This allows you to adjust the offset frequency quickly and accurately.
> 
> I installed the "MINI" into a 1U chassis with the power supply and also
> added "heartbeat" LEDS for each channel to show the presence of the 1PPS 
> inputs.
> 
> I have plotted several Rubidium and many Quartz using the "MINI"
> simultaneously with a SR620 counter/timer. The plots are "identical"! So
> much 
> so that I am going to "retire" and sell my SR620!
> 
> I understand work is complete on a 4 channel counters and Bluetooth
> interface, 
> and work is ongoing on a LCD.
> 
> The "MINI" material cost is less than $25.00 depending on how many 
> boards are ordered!
> 
> Resoution based on clock frequency and beat frequency:
> 
> Carrier[MHz]  Beat [Hz] HeterodyneTIC [ns]   Resolution
> 10101.00E+06101.00E-14
> 1011.00E+07101.00E-15
> 1011.00E+0755.00E-16
> 10101.00E+0655.00E-15
> 5105.00E+05102.00E-14
> 515.00E+06102.00E-15
> 515.00E+0651.00E-15
> 5105.00E+0551.00E-14
> 
> Woman is 53 But Looks 25
> Mom reveals 1 simple wrinkle trick that has angered doctors...
> http://thirdpartyoffers.juno.com/TGL3141/50aa82cb1214a2ca03f8st04duc
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Re: [time-nuts] An other project

[Edgardo Molina]

Dear Bert,

Good afternoon. Nice to hear from you and your current project.

Please count me in when the time comes. Do you have the spec sheet for this 
project? I am about to buy the TADD-2 Mini to get a 1PPS  signal from my 
HP-5065A that does not provide such an output. Whenever you are ready, I will 
raise my hand.

Thank you.


Regards,



Edgardo Molina
Dirección IPTEL

www.iptel.net.mx

T : 55 55 55202444
M : 04455 10045822

Piensa en Bits SA de CV



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On Nov 20, 2012, at 3:13 PM, ewkeh...@aol.com wrote:

> I did mention a MAX 3000 implementation of a 1 pps generator. The attached  
> picture shows the prototype. This came about to generate timing signals to  
> test the counters. It is a TADD-2 Mini on steroids. Besides the Wenzel 
> input and  4 outputs parraleled with resistors it has presently 6 inputs for 
> output  selecting  or synchronizing and 6 additional outputs. Example duty 
> cycle,  frequency out of the 50 ohm.This is a good example of the flexibility 
> of 
> the use  of this IC. If there is interest maybe we can agree on a couple of 
> versions and  find some one in the US and some one in Europe to sell a kit. 
> Juerg and I are  not getting in the kit business but it may be a precursor 
> when D/M systems will  roll out. At 25 $ in the US and 20 Euro in the EU who 
> ever does it will make a  little money for their trouble. That price would 
> include shipping!
> Members can also use the unit to knit their own version, IC's can be  
> reprogrammed. This is also the board that was used to do the jitter test. 
> Passed  
> with flying colors. Let me know what you think but I will not take orders, 
> but  find a way to make it available if there is interest
> Bert Kehren.<1PPS.jpg>___
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Re: [time-nuts] Wavecrest DTS 2077 Service Manual?

[Henk ten Pierick]

Hi Said,

Look at Dieder's site.

Groet,

Henk

Op 20 nov. 2012 om 02:36 heeft saidj...@aol.com het volgende geschreven:

> There is one calibration that can only be started by a GPIB command. I ran  
> into that, my unit constantly said something like "xxx calibration 
> required" or  similar during power on. No way to do it with the front panel 
> buttons.
> 
> It is easy to start that cal using Visi, or via sending a GPIB command  if 
> I remember correctly. Unfortunately I lost my Visi CD..
> 
> bye,
> Said
> 
> 
> In a message dated 11/19/2012 01:47:55 Pacific Standard Time,  
> h...@deriesp.demon.nl writes:
> 
> Hi,
> 
> The Wavecrest DTS 207X has a number of proms and also  battery back-up
> devices. I think it will be wise to check these  first.
> Or are you sure that it is hardware? How old is your  DTS?
> 
> Henk
> 
> 
> 
>> In the meantime I heard that Wavecrest is  not distributing service
>> manuals. All repair is  depot.repair.
>> 
>> This makes me considering if I should take the  chance on a second unit,
>> hoping to get one working out of two, or  simply to give up and accept
>> that these boxes are only intended to be  used as door stops of land fill
>> once defective... I've never been  confronted with such a poor customer
>> sevice attitude  before.
>> 
>> Nevertheless... is there anyone who has acquired some  experience with
>> the DTS-series innards who would be willing to share  his knowledge?
>> 
>> Adrian
>> 
>> 
>> Adrian  schrieb:
>>> Anyone have a Wavecrest DTS 2075/77/79 service  manual?
>>> 
>>> I've recently got a DTS 2077 that however  turned out to be defective.
>>> There was a power supply failure that  I could fix, but there is still
>>> a power-up selftest error message  and calibratin fails.
>>> 
>>> Adrian
>>> 
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>> 
>> 
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Re: [time-nuts] eBay Ublox

[paul swed]

any luck on the ntp server?

On Sat, Nov 10, 2012 at 1:31 AM, David J Taylor <
david-tay...@blueyonder.co.uk> wrote:

> oh thats my kind of basement wall wart. Place it on the wall and forget it.
> I have nas drives that way. They spin down and power consumption is I want
> to say 5-8 watts been a long time. May be lower. You access them they spin
> up and get your data stay up for a while and back down.
> A quite basement no heat and little power.
> Regards
> Paul.
> ==**==
>
> .. and no noisy fans either, Paul!  The unit takes micro-USB power, so you
> could perhaps power it from those junked mobile phone chargers!
>
>
> Cheers,
> David
> --
> SatSignal Software - Quality software written to your requirements
> Web: http://www.satsignal.eu
> Email: david-tay...@blueyonder.co.uk
>
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Re: [time-nuts] Nifty "MINI TIC" for DMTD work detail Info please read

[Bruce Griffiths]

Since mixer noise is one of the limiting factors using a mixer with low 
flicker noise will help.
NIST found that a custom mixer using diode connected (collector base 
short) 2N222As had a significantly lower flicker phase noise than either 
the ZRPD1 or the 10534A.
They used off the shelf 1:5 impedance ratio transformers (probably from 
Minicircuits).

Another issue is the flicker phase noise of any isolation amplifiers used.
This is particularly critical if each mixer uses its own isolation 
amplifiers.


My current amplifier phase noise measurement setup (for measuring the 
additive PN of a pair of well matched amplifiers) has a self noise of 
around -170dBc/Hz @ 1Hz offset for a 10MHz input.
Ideally the additive phase noise of any isolation amplifiers should be 
well below that of the mixers.


Bruce

ewkeh...@aol.com wrote:

Yes Bruce I have the paper. I am not suggesting to copy it verbatim but if
there is a way to reach reasonable priced 1 E-14 members of the list should
pipe  in. I am willing to do an other board. the rest of the systems well
on its way.  Einally after three years.
Bert Kehren


In a message dated 11/20/2012 3:28:57 P.M. Eastern Standard Time,
bruce.griffi...@xtra.co.nz writes:

ewkeh...@aol.com wrote:
   

The D/M is being revisited  because  of the counter performance. 1 E-13 is
easily attainable  but the Czech IREE  published a paper and claim 2 E-15.

 

Do you mean the paper ""optimization of dual-mixer time-difference
multiplier" ?
The ZCD developed in this is a bit of a kludge and is far  from optimum.
Reverse engineering the circuit from the description given in  the paper
isn't too difficult.
They claim an instrument limited ADEV of  ~7E-15 @ 1s.
Do you have a copy of this paper?
   

Bert  Kehren   Miami
  ___

 

Bruce

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Re: [time-nuts] Nifty "MINI TIC" for DMTD work detail Info please read

[EWKehren]

Yes Bruce I have the paper. I am not suggesting to copy it verbatim but if  
there is a way to reach reasonable priced 1 E-14 members of the list should 
pipe  in. I am willing to do an other board. the rest of the systems well 
on its way.  Einally after three years.
Bert Kehren
 
 
In a message dated 11/20/2012 3:28:57 P.M. Eastern Standard Time,  
bruce.griffi...@xtra.co.nz writes:

ewkeh...@aol.com wrote:
>
> The D/M is being revisited  because  of the counter performance. 1 E-13 is
> easily attainable  but the Czech IREE  published a paper and claim 2 E-15.
>   
Do you mean the paper ""optimization of dual-mixer time-difference  
multiplier" ?
The ZCD developed in this is a bit of a kludge and is far  from optimum.
Reverse engineering the circuit from the description given in  the paper 
isn't too difficult.
They claim an instrument limited ADEV of  ~7E-15 @ 1s.
Do you have a copy of this paper?
> Bert  Kehren   Miami
>  ___
> 
Bruce

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Re: [time-nuts] GPS Modules Indoors

[Bob Camp]

Hi

If "indoors" always includes a view through unshielded windows to towards the 
equator, then you might be ok. If it includes pole only facing offices in a 
conventional steel structure - not so much. The issue isn't so much time, as 
ability to get a good enough signal to lock to. If you add a "unknown" location 
(you don't have a survey) and an "unknown" almanac (you have been off for a 
while), that just makes things harder. 

Consider that while I can get cell phone coverage anywhere in my home, there 
are buildings in the area that I can't get coverage in. Around here, (as in 
most urban areas), if I can't get a cell phone signal, there's no chance at all 
of getting GPS. 

Provided you have a valid almanac, a rational location fix (as in a survey), 
and are tracking multiple satellites, I can't think of a case where you would 
have a significant time error. That may just be my lack of imagination. 

For one second accuracy, a time tick over a cell phone should be fine. That 
would be far more robust than a GPS setup.

Bob

On Nov 20, 2012, at 6:33 AM, Tom Harris  wrote:

> Greetings
> 
> I know that the accuracy of GPS degrades indoors. However, suppose
> that I just want to turn a GPS module on, acquire the current time
> accurate to a second, and then turn it off. I can get a good deal on
> the U-Blox LEA-5H modules (same as used on Arduino shields I think),
> which have a high sensitivity, and I can use an active antenna if
> needed.
> 
> Am I wasting my time. Sorry for not requiring the time more accurate
> than a second, but that's all the clients require.
> 
> -- 
> 
> Tom Harris 
> 
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Re: [time-nuts] Nifty "MINI TIC" for DMTD work detail Info please read

[Bruce Griffiths]

ewkeh...@aol.com wrote:


The D/M is being revisited because  of the counter performance. 1 E-13 is
easily attainable but the Czech IREE  published a paper and claim 2 E-15.
   
Do you mean the paper ""optimization of dual-mixer time-difference 
multiplier" ?

The ZCD developed in this is a bit of a kludge and is far from optimum.
Reverse engineering the circuit from the description given in the paper 
isn't too difficult.

They claim an instrument limited ADEV of ~7E-15 @ 1s.
Do you have a copy of this paper?

Bert Kehren   Miami
___
   

Bruce

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Re: [time-nuts] GPS Modules Indoors

[Bob Camp]

Hi

Ten seconds a month is "wrist watch" accuracy at constant temperature. For $3 
Maxim will sell you a +/- 2 ppm real time clock.  That will hold your 1 second 
for 500,000 sec (5.787 days).  A cheap cell phone style TCXO at $1 or so should 
hold < 1 ppm over a modest range. That will get you out to > 10 days. 

A lot depends on how stable and repeatable your environment is. Most indoor 
areas cycle up and down, but they repeat the cycle. What happens this week is a 
lot like what happened a week ago. If you can take a time reading every few 
days, you likely can do some smarts to extend the holdover quite a bit. With a 
modern low power CPU, the smarts will pull a lot less current than your real 
time clock or your TCXO. 

Yup, this is all basement engineering. If somebody's life depends on it, maybe 
not such a good idea.

Bob

On Nov 20, 2012, at 10:46 AM, Chris Albertson  wrote:

> I don't think GPS is ever so in accurate as to have a 1 second error.  If
> it has a solution at all it is going to be at least within a millisecond.
> 
> The way "everyone" handles "holdover" (Holdover is timekeeping with GPS is
> not available) is to keep a local clock driven off a stable oscillator.
> Then when you do have GPS you adjust the clock.  Then when GPS goes away
> you "free wheel".
> 
> With your very loose one second requirements you can use a rather
> inexpensive clock, perhaps just a TCXO.   The question is how long of a
> hold over period must you be able to handle.   If GPS will is unavailable
> for a month then you will need a VERY good clock but if you will only loose
> GPS for a few hours at most it can be cheaper.
> 
> Active antenna are not a perfect solution.  What the GPS needs is good
> signal to noise and the amplifier amplifies noise as well as signal.  It
> can help in some cases and is worth doing if you have the space and power
> budget.
> 
> So to design this step one is to select an oscillator that has the required
> stability for "one second error durring the worst case holdover period" thn
> build a clock based on that.   Next design a way to re-set the clock based
> on GPS.
> 
> 
> On Tue, Nov 20, 2012 at 3:33 AM, Tom Harris  wrote:
> 
>> Greetings
>> 
>> I know that the accuracy of GPS degrades indoors. However, suppose
>> that I just want to turn a GPS module on, acquire the current time
>> accurate to a second, and then turn it off. I can get a good deal on
>> the U-Blox LEA-5H modules (same as used on Arduino shields I think),
>> which have a high sensitivity, and I can use an active antenna if
>> needed.
>> 
>> Am I wasting my time. Sorry for not requiring the time more accurate
>> than a second, but that's all the clients require.
>> 
>> --
>> 
>> Tom Harris 
>> 
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>> 
> 
> 
> 
> -- 
> 
> Chris Albertson
> Redondo Beach, California
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Re: [time-nuts] GPS Modules Indoors

[Hal Murray]

celephi...@gmail.com said:
> I know that the accuracy of GPS degrades indoors. However, suppose that I
> just want to turn a GPS module on, acquire the current time accurate to a
> second, and then turn it off. I can get a good deal on the U-Blox LEA-5H
> modules (same as used on Arduino shields I think), which have a high
> sensitivity, and I can use an active antenna if needed.

You haven't defined "indoors".  I think you will have to try it in your 
location(s).

It won't work deep inside a machine room.  We tried it once in a typical 
two-story silicon valley office building.  It didn't work there.  We also 
tried it in the 5th floor of a modern office building with a great view.  It 
didn't work, probably because of some anti-heat coating on the windows.

Inside my single floor house, they work most of the time.


albertson.ch...@gmail.com said:
> I don't think GPS is ever so in accurate as to have a 1 second error.  If it
> has a solution at all it is going to be at least within a millisecond. 

I've seen occasional way-off "solutions" from GPS modules.  I don't have 
examples handy but I wouldn't depend on a single/quick answer in any critical 
application.


-- 
These are my opinions.  I hate spam.




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Re: [time-nuts] Nifty "MINI TIC" for DMTD update

[EWKehren]

be able to handle 56 K RS232 and use AV software, to me that is not  
trivial, and Juerg is to busy to hold hands beside me.
Bert
 
 
In a message dated 11/20/2012 11:33:44 A.M. Eastern Standard Time,  croma6
4...@yahoo.it writes:


Hi,  Bert,

no problem for the OCXO's (10811, Morion, ALtra CPLD) or other  material 
or soldering skills. But, to be precise, what is the  "

Software know
how" ?


C-ProteusBasic-MicroC, ecc  ?



thanks

Andrea IW2FDH






Il  20/11/2012 17.00, ewkeh...@aol.com ha scritto:
> Bert  Kehren


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Re: [time-nuts] Nifty "MINI TIC" for DMTD update

[Croma641]

Hi, Bert,

no problem for the OCXO's (10811, Morion, ALtra CPLD) or other material 
or soldering skills. But, to be precise, what is the "


Software know
how" ?


C-ProteusBasic-MicroC, ecc ?



thanks

Andrea IW2FDH






Il 20/11/2012 17.00, ewkeh...@aol.com ha scritto:

Bert Kehren



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[time-nuts] Nifty "MINI TIC" for DMTD update

[EWKehren]

I have checked my inventory and I have boards and parts for a couple of  
dual mixers and counters. I will work with some ones that are willing to build 
 and test them right away and have a good quality OCXO for offset like a 
10811 or  Morion and a second high performance OCXO for measuring noise floor. 
A third  OCXO would even be better to perform an actual AV. Software know 
how is also  mandatory so you will not repeat what I did. Have to have 
experience in board  assembly but there are only 9 SMD parts involved and they 
are 
of the solderable  kind.
Contact me off list and we will work out the details. Please only ones that 
 are very interested and serious to move this project forward. All parts 
and  boards will be strictly actual cost.
 
Bert Kehren Miami.
 
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Re: [time-nuts] GPS Modules Indoors

[Chris Albertson]

I don't think GPS is ever so in accurate as to have a 1 second error.  If
it has a solution at all it is going to be at least within a millisecond.

The way "everyone" handles "holdover" (Holdover is timekeeping with GPS is
not available) is to keep a local clock driven off a stable oscillator.
Then when you do have GPS you adjust the clock.  Then when GPS goes away
you "free wheel".

With your very loose one second requirements you can use a rather
inexpensive clock, perhaps just a TCXO.   The question is how long of a
hold over period must you be able to handle.   If GPS will is unavailable
for a month then you will need a VERY good clock but if you will only loose
GPS for a few hours at most it can be cheaper.

Active antenna are not a perfect solution.  What the GPS needs is good
signal to noise and the amplifier amplifies noise as well as signal.  It
can help in some cases and is worth doing if you have the space and power
budget.

So to design this step one is to select an oscillator that has the required
stability for "one second error durring the worst case holdover period" thn
build a clock based on that.   Next design a way to re-set the clock based
on GPS.


On Tue, Nov 20, 2012 at 3:33 AM, Tom Harris  wrote:

> Greetings
>
> I know that the accuracy of GPS degrades indoors. However, suppose
> that I just want to turn a GPS module on, acquire the current time
> accurate to a second, and then turn it off. I can get a good deal on
> the U-Blox LEA-5H modules (same as used on Arduino shields I think),
> which have a high sensitivity, and I can use an active antenna if
> needed.
>
> Am I wasting my time. Sorry for not requiring the time more accurate
> than a second, but that's all the clients require.
>
> --
>
> Tom Harris 
>
> ___
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> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>



-- 

Chris Albertson
Redondo Beach, California
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Re: [time-nuts] WWVB PSK demodulation; simple carrier regeneration?

[paul swed]

Great thread.
Bob in the d-psk-r thats exactly what I am doing is flipping a switch on
the incoming signal.
That normalizes it. However in its current approach it is random as either
0 or 180 out always. No attempt has been made to determine 0. But it does
run the phase tracking rcvrs fine. That said for Pete. The time tracking
rcvrs like the spectracom 8170 does require a non PSK carrier to work. So
thats why  I preserve the AM for those types of rcvrs.
But on to what you have written. I tinkered with a soundcard and spectrum
lab and it showed some promise. If you are willing to have a big power
sucking pc/laptop running 24 X 7 thats going to be a great solution as you
have shown. Just take the output of the 1s and 0s and when you see a 1 flip
a inverting amplifier. Thatthen feeds the old rcvrs. Done.
I do not have matlab so would love to see what you did to do the decoding.
I strongly believe your approach is completely as valid as mine. Like you
say there are some very interesting thoughts on how to do this.
By the way big issue much of the US actually has very poor wwvb reception.
Thats what I have had to struggle with.
Regards
Paul.

On Tue, Nov 20, 2012 at 7:56 AM, Bob Camp  wrote:

> Hi
>
> I believe the "lowest cost" approach is to take the RF and run it through
> an simple switch. The switch either has a 0 degree or a 180 degree phase
> shift. Drive the control of the switch with a computer generated track of
> the known modulation format. Let the computer get time via NTP and just
> generate the (really slow) switch drive waveform. A diode ring and a pair
> of transformers will do for the switch.
>
> Is it a bit noisy? - yes. Should it bother a receiver that already deals
> with a lot of noise? - probably not if your NTP is within <10ms.
>
> Bob
>
> On Nov 20, 2012, at 2:52 AM, Peter Monta  wrote:
>
> > Here are a few demodulated frames of WWVB's new BPSK bits:
> >
> > 0011101101000 01101 0(0)001100111(0)011011011(0)1010110 00 0 000 00 0
> > 0011101101000 00100 0(1)001100111(1)011011011(1)1010111 00 0 000 00 0
> > 0011101101000 01000 0(0)001100111(0)011011011(0)1011000 00 0 000 00 0
> >
> > The fields are described in the NIST document [1]:  sync word, parity
> word,
> > time in binary minutes, and various metadata.  The bits in parentheses
> are
> > the "marker" bits which have less power; it appears they're using all
> three
> > as duplicates of time[0], the LSB of the time word.
> >
> > Strong signal here in California, even during daytime.  My receiver is
> just
> > a hacked-up ferrite loop, JFET buffer, sound card, and Matlab.  About 300
> > Hz single-sided bandwidth.
> >
> > So it's an interesting question:  what is the simplest device that can
> > change this signal into something the legacy WWVB receivers can track,
> > without any modification at all to the legacy receiver?  By "simplest" I
> > mean avoiding any intelligence like carrier acquisition, timing recovery,
> > or bit demodulation; but it should still have good noise performance to
> the
> > largest extent possible.
> >
> > One candidate might be this:  multiply the signal by an estimate of its
> > phase one minute ago.  The frames are very similar minute-to-minute, as
> can
> > be seen above.  The exceptions are the parity word, changes in the
> > metadata, and rollovers in the time word involving large numbers of bits.
> > (I wish they had Gray-coded the time word, or, better, scrambled it in
> some
> > way so that the time word can't nearly emulate the sync word for many
> > minutes running, which looks like a risk with the current format.)  But
> > aside from this, the legacy receiver would be seeing carrier *
> > xor(minute_i, minute_(i-1)), which is mostly carrier, and should result
> in
> > good tracking.  It's like a differentially-coherent receiver in reverse.
> >
> > The local oscillator would have to be accurate to a fraction of an RF
> cycle
> > over one minute, which works out to ~30 ppb, OCXO territory.  Is there
> some
> > way to do this with just a TCXO?  Maybe stability is all that's needed
> > rather than accuracy.
> >
> > As for timing receivers, it's not clear to me that the BPSK helps at all.
> > The timing marker is the amplitude modulation, and, assuming no cycle
> slips
> > in the carrier loop, this can be averaged for as long as one likes to
> > refine the position of the falling edge (something like the "Hatch
> filter"
> > for GPS, carrier-aided code tracking).  The BPSK just helps the bit
> > demodulation; but the bits are so predictable---was help really needed
> > here, assuming a minimally-DSP-capable receiver?
> >
> > Cheers,
> > Peter
> >
> > [1] NIST-Enhanced-WWVB-Broadcast-Format-sept-2012-Radio-Station-staff.pdf
> > ___
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> > To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> > and follow the instructions there.
>
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Re: [time-nuts] WWVB PSK demodulation; simple carrier regeneration?

[Bob Camp]

Hi

I believe the "lowest cost" approach is to take the RF and run it through an 
simple switch. The switch either has a 0 degree or a 180 degree phase shift. 
Drive the control of the switch with a computer generated track of the known 
modulation format. Let the computer get time via NTP and just generate the 
(really slow) switch drive waveform. A diode ring and a pair of transformers 
will do for the switch.

Is it a bit noisy? - yes. Should it bother a receiver that already deals with a 
lot of noise? - probably not if your NTP is within <10ms.

Bob

On Nov 20, 2012, at 2:52 AM, Peter Monta  wrote:

> Here are a few demodulated frames of WWVB's new BPSK bits:
> 
> 0011101101000 01101 0(0)001100111(0)011011011(0)1010110 00 0 000 00 0
> 0011101101000 00100 0(1)001100111(1)011011011(1)1010111 00 0 000 00 0
> 0011101101000 01000 0(0)001100111(0)011011011(0)1011000 00 0 000 00 0
> 
> The fields are described in the NIST document [1]:  sync word, parity word,
> time in binary minutes, and various metadata.  The bits in parentheses are
> the "marker" bits which have less power; it appears they're using all three
> as duplicates of time[0], the LSB of the time word.
> 
> Strong signal here in California, even during daytime.  My receiver is just
> a hacked-up ferrite loop, JFET buffer, sound card, and Matlab.  About 300
> Hz single-sided bandwidth.
> 
> So it's an interesting question:  what is the simplest device that can
> change this signal into something the legacy WWVB receivers can track,
> without any modification at all to the legacy receiver?  By "simplest" I
> mean avoiding any intelligence like carrier acquisition, timing recovery,
> or bit demodulation; but it should still have good noise performance to the
> largest extent possible.
> 
> One candidate might be this:  multiply the signal by an estimate of its
> phase one minute ago.  The frames are very similar minute-to-minute, as can
> be seen above.  The exceptions are the parity word, changes in the
> metadata, and rollovers in the time word involving large numbers of bits.
> (I wish they had Gray-coded the time word, or, better, scrambled it in some
> way so that the time word can't nearly emulate the sync word for many
> minutes running, which looks like a risk with the current format.)  But
> aside from this, the legacy receiver would be seeing carrier *
> xor(minute_i, minute_(i-1)), which is mostly carrier, and should result in
> good tracking.  It's like a differentially-coherent receiver in reverse.
> 
> The local oscillator would have to be accurate to a fraction of an RF cycle
> over one minute, which works out to ~30 ppb, OCXO territory.  Is there some
> way to do this with just a TCXO?  Maybe stability is all that's needed
> rather than accuracy.
> 
> As for timing receivers, it's not clear to me that the BPSK helps at all.
> The timing marker is the amplitude modulation, and, assuming no cycle slips
> in the carrier loop, this can be averaged for as long as one likes to
> refine the position of the falling edge (something like the "Hatch filter"
> for GPS, carrier-aided code tracking).  The BPSK just helps the bit
> demodulation; but the bits are so predictable---was help really needed
> here, assuming a minimally-DSP-capable receiver?
> 
> Cheers,
> Peter
> 
> [1] NIST-Enhanced-WWVB-Broadcast-Format-sept-2012-Radio-Station-staff.pdf
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Re: [time-nuts] Recommended parameters for Timelab ADEV analysis

[John Ackermann N8UR]

Hi Edgardo --

Sorry, I should have explained.  Tau0 is shorthand for the "base" tau -- the 
actual interval between each measurement.  You can measure longer tau by simply 
using every nth measurement.  So tau0 = 1 second simply means you're taking a 
reading once per second.

John

On Nov 20, 2012, at 2:29 AM, Edgardo Molina  wrote:

> Dear John Ackermann,
> 
> I find your reply to my request to be very interesting. Without fear of 
> asking. May I know how do I achieve a Tau 0 measurement in a 1 second 
> interval with my setup? (HP-53132A + TimeLab). 
> 
> Please tell me if I am wrong.  I assume I would take the 10 MHz output from 
> the 53132A and plug it into the Channel 1 input, while the external reference 
> of 10 MHz is disconnected. 
> 
> As far as I am concerned, TimeLab does not allow a value of 0 for Tau. If I 
> enter zero as the measurement time duration I get an error and actual 
> acceptable Tau range. The smaller value is in the order of 1E-6s. Am I 
> getting it right? I am sorry for my confusion.
> 
> Regards,
> 
> 
> 
> Edgardo Molina
> Dirección IPTEL
> 
> www.iptel.net.mx
> 
> T : 55 55 55202444
> M : 04455 10045822
> 
> Piensa en Bits SA de CV
> 
> 
> 
> Información anexa:
> 
> 
> 
> 
> CONFIDENCIALIDAD DE INFORMACION
> 
> Este mensaje tiene carácter confidencial. Si usted no es el destinarario de 
> este mensaje, le suplicamos se lo notifique al remitente mediante un correo 
> electrónico y que borre el presente mensaje y sus anexos de su computadora 
> sin retener una copia de los mismos. Queda estrictamente prohibido copiar 
> este mensaje o hacer usode el para cualquier propósito o divulgar su en forma 
> parcial o total su contenido. Gracias.
> 
> 
> NON-DISCLOSURE OF INFORMATION
> 
> This email is strictly confidential and may also be privileged. If you are 
> not the intended recipient please immediately advise the sender by replying 
> to this e-mail and then deleting the message and its attachments from your 
> computer without keeping a copy. It is strictly forbidden to copy it or use 
> it for any purpose or disclose its contents to any third party. Thank you.
> 
> 
> 
> 
> 
> 
> On Nov 14, 2012, at 8:13 PM, John Ackermann N8UR  wrote:
> 
>> Edgardo, the minimum sample rate in practice is determined by the noise 
>> floor of the measurement system.  I would suggest that you do a baseline 
>> test by measuring the counter reference against itself with a tau0 (sample 
>> rate) of 1 second.  You'll see a best-case result and from it you can 
>> determine at which sample rate your noise floor is better than the predicted 
>> performance of the oscillator under test.  You'll probably find that you are 
>> measurement-noise limited below several hundred seconds.
>> 
>> Also, you'll generally get a lower noise floor doing time interval rather 
>> than frequency measurements, so you might experiment with that, which 
>> normally involves using a low-rate signal such as PPS for "start" and "stop" 
>> channels.
>> 
>> John
>> 
>> On Nov 14, 2012, at 8:43 PM, Edgardo Molina  wrote:
>> 
>>> Dear Group,
>>> 
>>> Now that I have setup TimeLab along with the Prologix GPIB to USB adapter 
>>> and the HP-53132A frecuency counter, I am starting to get some data from my 
>>> frequency standards. Still I think I have a long way to go in front of me.
>>> 
>>> One of the main concerns that cross my mind at this point are:
>>> 
>>> a. What is the recommended sampling duration to consider for Quartz, 
>>> Rubidium  and other types of oscillators?
>>> b. What are the recommended sampling intervals for the above mentioned 
>>> oscillator types?
>>> c. I am using a 10 MHz Rb FE-5806A frequency standard as an external 
>>> reference for the HP-53132A. 
>>> d. I am connecting my DUT at the frequency counter channel 1
>>> e. I am setting Timelab for Data Type = Frequency
>>> f. My graphs somehow have the same geometry of classical ADEV examples, I 
>>> can differentiate the ADEV noise types quite easily.
>>> g. Should I use sub-second sampling intervals for my graphs to start closer 
>>> to the vertical axis of the graph? Or should I use a conservative 1s 
>>> sampling rate?
>>> 
>>> With the previous questions I am looking for consistency in my ADEV 
>>> studies. Are there any typical ADEV conditions to be considered when 
>>> analysing this way?
>>> Am I missing something? My apologies to everybody if I am missing something 
>>> or doing it the wrong way. In the end I want to learn more than anything 
>>> else.
>>> 
>>> Your kind comments are welcome. Thank you.
>>> 
>>> Best regards,
>>> 
>>> 
>>> 
>>> Edgardo Molina
>>> Dirección IPTEL
>>> 
>>> www.iptel.net.mx
>>> 
>>> T : 55 55 55202444
>>> M : 04455 10045822
>>> 
>>> Piensa en Bits SA de CV
>>> 
>>> 
>>> 
>>> Información anexa:
>>> 
>>> 
>>> 
>>> 
>>> CONFIDENCIALIDAD DE INFORMACION
>>> 
>>> Este mensaje tiene carácter confidencial. Si usted no es el destinarario de 
>>> este mensaje, le suplicamos se lo notifique al remitente mediante un corr

Re: [time-nuts] Nifty "MINI TIC" for DMTD work

[Pascual Arbona]

I am interested in one.


- Original Message - 
From: 

To: 
Sent: Monday, November 19, 2012 8:04 PM
Subject: [time-nuts] Nifty "MINI TIC" for DMTD work




"MINI-TIC" for DMTD work


Hi Everyone!

I've been testing a Miniature 2 channel TIC that Bert Kehren and Juerg
Koegel
and Richard Mc Corkle have designed.

It has 9 digits/Sec. and with a 1HZ offset in the DMTD unit gives a
resolution of 1X10-15th  at 10 MHz, 2X10-15 with a 5 MHz input, when
measuring
Allan deviation. The 200 MHz version doubles the resolution.

Of course the baseline performance of the DMTD unit and the stability of
the DMTD reference determines the actual accuracy you can obtain.

(My dual mixer has a baseline of approx. 8X10-14th at 1 second and my
best reference is  4X10-13th at 1 second.)

The "MINI" takes a 5 or 10 MHz reference that only has to be stable to
parts in 10-8th/sec.
I used a neat 14PIN ovenized DIP clock chip I got on eBay and recently
discussed on the list.

The reference is multiplied to 100Mhz for use as the counters clock.

The "MINI" is about 2.5 by 2 inches and has only 5 chips. Two opto
couplers an
op amp for two analog channels are also on the board. If run on 5 volt a
3.3 V
regulator is also on the board. Power required is +5VDC 0.05 A  and +- 12

(for the RS232 interface)

It also has two pins you can individually ground to measure the period of
the beat
note from either channel.

This allows you to adjust the offset frequency quickly and accurately.

I installed the "MINI" into a 1U chassis with the power supply and also
added "heartbeat" LEDS for each channel to show the presence of the 1PPS
inputs.

I have plotted several Rubidium and many Quartz using the "MINI"
simultaneously with a SR620 counter/timer. The plots are "identical"! So
much
so that I am going to "retire" and sell my SR620!

I understand work is complete on a 4 channel counters and Bluetooth
interface,
and work is ongoing on a LCD.

The "MINI" material cost is less than $25.00 depending on how many
boards are ordered!

Resoution based on clock frequency and beat frequency:

Carrier[MHz]  Beat [Hz] HeterodyneTIC [ns]   Resolution
10101.00E+06101.00E-14
1011.00E+07101.00E-15
1011.00E+0755.00E-16
10101.00E+0655.00E-15
5105.00E+05102.00E-14
515.00E+06102.00E-15
515.00E+0651.00E-15
5105.00E+0551.00E-14

Woman is 53 But Looks 25
Mom reveals 1 simple wrinkle trick that has angered doctors...
http://thirdpartyoffers.juno.com/TGL3141/50aa82cb1214a2ca03f8st04duc
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Re: [time-nuts] Nifty "MINI TIC" for DMTD work detail Info please read

[EWKehren]

Dave
Thank you for your offer. I think I have the documentation solved. Brian,  
who helped in the past has offered to help and has some of the previous work 
to  build on.
As to PIC programming I will ask Juerg to get with you off list.
Bert
 
 
In a message dated 11/19/2012 8:47:25 P.M. Eastern Standard Time,  
mcqu...@sonic.net writes:

Hi  Bert,

What kind or sort of documentation is  needed?

schematics?
PC layout?
software / firmware  documentation?

I've been programming PICs intermittently for 10+ years.  Some of my 
projects use 2 or 4 line LCD displays. I have given other  
microcontrollers a short test spin.

I've also done some Verilog  with the Altera DE0 nano board (Cyclone IV 
EP4CE22F17), a period counter  that used an internal PLL to boost the 
hardware 50 MHz to 300 MHz for  better resolution. Also FPGA for software 
defined radio signal processing  (Cyclone III).


Dave  McQuate
WA8YWQ
mcqu...@sonic.net


On 11/19/2012 2:28 PM,  ewkeh...@aol.com wrote:
>
> Allow me to put all this in   perspective. Three years ago having just
> joined time-nuts I started to  be  interested in Dual Mixers. Having CS 
and Rb my
> main interest  was and still is  low noise signal generators and I have 
all
> the  HP equipment for those  measurements. Did my first Shera Rb about  
2000
> and a few more since. Time was  not and still is not much of  an interest 
my
> best time instrument is a modified  PICTIC  II.
> Starting with the original NBS paper  I came to the  conclusion that the
> major cost would be the counter, something I   would have very little use 
for,
> for other projects since I am well  equipped up  to 40 GHz. That is when I
> came up with the idea of  what I call a ping pong  counter a counter that 
counts
> every  period, sort of pseudo time stamping. Back  of an envelop  
calculation
> and I went on the list stating that I think a $   200  D/M system not
> counting OCXO’s  was doable. What was  needed was help with the PIC 
codes. First
> response was  “that is  why we call our self Time-nuts”. However Richard 
Mc
> Cokle did offer  his  help and he has been key to the success. The goal 
of $
> 200  for all material for  a 4 channel counter and D/M is attainable if  
10
> boards are ordered.
> The first set of boards where  done  in about 5 month. Several people 
tested
> the D/M but kept on  using their counter  and my thanks go out to Corby 
who
> tested the  very first  D/M.
> I was left testing the counter and  logic  is my strong suit as Juerg will
> attest my weakness is software even  though  at one time I set up and was 
in
> charge of a software  group. Had problems with  the counter PC interface. 
Now
> thanks to  Corby I now know that the problem was  the 56K RS 232 versus 
9.6
>  K. Tells you how brilliant I am on that subject. Till  recently I 
thought  RS
> 232 is RS232.
> I did reach out to the list and   connected with Fred Tijddingen who 
offered
> to help. I send him a  counter and he  asked me to get him some parts that
> where not  time related after he agreed to  pay for them. After I shipped
>  them, never heard from him again. Be careful, I do  not know if any one  
else had
> that experience. Many of you know I used to ship  and  only asked to be 
paid
> after you got the parts. Well now I am a lot  more  selective.
> A year ago I connected with list  member  Juerg Koegel. We share the same
> priorities and complement each other  with  our skill sets. On top of that
> Juerg has the equipment that  I lack and the know  how to make it talk to 
PC’s.
> On top  of  that Juerg had used a MAX 3000 G/A for a PICTIC counter. 
Perfect
>  match. Juerg  can also write PIC code, not like Richard but what we   
need.
> First out the 2 channel and 4  channel counters now with  G/A’s and 
Richards
> PIC;s. The two channel measures  phase and  period in the ping pong mode
> allowing you to do the basics of a  single  D/M. The 4 channel was 
intended for
> two D/M’s or with an  additional 2 channel  for three corner hat. Can 
also be
> used for  cross correlation.
> How ever the 4 channel in  combination with  one D/M allows also very high
> resolution frequency comparison   only limited by the noise floor of the 
D/M.
> Since the A/V measurements  are most  likely not a daily activity using 
this
> instrument for  frequency measurements or  aging tests over long term 
makes
> it a  very useful tool. Juerg does not want me  to talk to much about it, 
 but
> he is right now busy writing PIC code for a 4 line  LCD  display that also
> includes a Vinculum VDRIVE2 that allows recording  data on  a USB flash 
drive,
> interfaces with a PC using RS 232,  USB and Bluetooth. I call  it the 
Swiss
> Army Knife, because of  all the things the combination D/M, Counter  and 
Juerg
> LCD can  do.
> The D/M is being revisited because  of the counter  performance. 1 E-13 is
> easily attainable but the Czech IREE   published a paper and claim 2 E-15.
> Would be nice to get 1 E-14. Tried  to get  

Re: [time-nuts] GPS Modules Indoors

[David J Taylor]

Greetings

I know that the accuracy of GPS degrades indoors. However, suppose
that I just want to turn a GPS module on, acquire the current time
accurate to a second, and then turn it off. I can get a good deal on
the U-Blox LEA-5H modules (same as used on Arduino shields I think),
which have a high sensitivity, and I can use an active antenna if
needed.

Am I wasting my time. Sorry for not requiring the time more accurate
than a second, but that's all the clients require.

Tom Harris
=

Tom,

If the GPS has a battery backup, then you might get re-acquisition within 
less than 30 seconds of powering up.  That's approximate with a u-blox 
NEO-6M on the top floor of a two-storey building, about 1/3 the way into the 
room, so most of the signal is through the roof.


Without battery backup, the acquisition time might be a lot longer (15-20 
minutes), or even worse (hours) with a different GPS module which needs a 
much stronger signal to acquire than to track.  The one which took hours had 
a 15 mm square patch antenna (AdaFruit), versus the 25 mm square antenna on 
the u-blox board I had.


The two units I am comparing are shown on my Web page here:

 http://www.satsignal.eu/ntp/Raspberry-Pi-NTP.html

although it's down right now.  I quite accpet that other folks may have 
different results (or if "indoors" is next to a window!).


Cheers,
David
--
SatSignal Software - Quality software written to your requirements
Web: http://www.satsignal.eu
Email: david-tay...@blueyonder.co.uk 



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[time-nuts] GPS Modules Indoors

[Tom Harris]

Greetings

I know that the accuracy of GPS degrades indoors. However, suppose
that I just want to turn a GPS module on, acquire the current time
accurate to a second, and then turn it off. I can get a good deal on
the U-Blox LEA-5H modules (same as used on Arduino shields I think),
which have a high sensitivity, and I can use an active antenna if
needed.

Am I wasting my time. Sorry for not requiring the time more accurate
than a second, but that's all the clients require.

-- 

Tom Harris 

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Re: [time-nuts] Efratom PRFS202 Portable Rb Freq. Std. Manual

[GandalfG8]

Hi Edgardo
 
The original PRFS standard used an FRS module so I suspect yours will too,  
but a quick check when it arrives should confirm for sure.
The VRFS standard, which is a VXIbus unit, also uses the FRS, although  the 
FRT standard used the FRK module.
 
A quick Google search on Efratom manuals will provide plenty of information 
 on the modules themselves and the manual for the original PRFS is here
_https://rapidshare.com/files/2358203472/Efratom_PRFS.pdf_ 
(https://rapidshare.com/files/2358203472/Efratom_PRFS.pdf) 
 
The FRT manual and calibration instructions are here
_https://rapidshare.com/files/717321523/Efratom_FRT.zip_ 
(https://rapidshare.com/files/717321523/Efratom_FRT.zip) 
 
The VRFS is obviously very different mechanically but it's possible  there 
may be some circuit similarities, although no promises:-), so if  you'd like 
a copy of that manual it's at...
_https://rapidshare.com/files/450749387/Efratom_VRFS.pdf_ (https://
rapidshare.com/files/450749387/Efratom_VRFS.pdf) 
 
Regards
 
Nigel
GM8PZR
 
 
In a message dated 20/11/2012 06:48:02 GMT Standard Time, xe1...@amsat.org  
writes:

Dear  Group,

Good morning. I recently got an Efratom PRFS202 Portable  Rubidium 
Frequency Standard. Mint condition. Locking in 3 minutes or so.  Outputs OK, 
both 
sine and TTL. 

It seems a simple straightforward  instrument. Still I would like to know 
if anybody has a manual available for  it. I tried looking for it online and 
no luck so far. This unit was marketed  also using the Datum brand. Same 
model.

Anybody has at least a brochure  or general specs for this particular unit? 
Any experience or comments for this  unit? Got it at a decent price 
considering the lack of information.

As  always, your kind comments are surely welcome.  

Thanks!


Regards,



Edgardo Molina
Dirección  IPTEL

www.iptel.net.mx

T : 55 55 55202444
M : 04455  10045822

Piensa en Bits SA de CV



Información  anexa:




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NON-DISCLOSURE OF INFORMATION

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not the  intended recipient please immediately advise the sender by 
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Re: [time-nuts] Recommended parameters for Timelab ADEV analysis

[Bruce Griffiths]

Its actually Tau with a subscript 0.
This is the the time interval between successive measurements.
e.g. if a measurement is taken every second then Tau0 is 1 sec.

Bruce

Edgardo Molina wrote:

Dear John Ackermann,

I find your reply to my request to be very interesting. Without fear of asking. 
May I know how do I achieve a Tau 0 measurement in a 1 second interval with my 
setup? (HP-53132A + TimeLab).

Please tell me if I am wrong.  I assume I would take the 10 MHz output from the 
53132A and plug it into the Channel 1 input, while the external reference of 10 
MHz is disconnected.

As far as I am concerned, TimeLab does not allow a value of 0 for Tau. If I 
enter zero as the measurement time duration I get an error and actual 
acceptable Tau range. The smaller value is in the order of 1E-6s. Am I getting 
it right? I am sorry for my confusion.

Regards,



Edgardo Molina
Dirección IPTEL

www.iptel.net.mx

T : 55 55 55202444
M : 04455 10045822

Piensa en Bits SA de CV



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On Nov 14, 2012, at 8:13 PM, John Ackermann N8UR  wrote:

   

Edgardo, the minimum sample rate in practice is determined by the noise floor 
of the measurement system.  I would suggest that you do a baseline test by 
measuring the counter reference against itself with a tau0 (sample rate) of 1 
second.  You'll see a best-case result and from it you can determine at which 
sample rate your noise floor is better than the predicted performance of the 
oscillator under test.  You'll probably find that you are measurement-noise 
limited below several hundred seconds.

Also, you'll generally get a lower noise floor doing time interval rather than frequency 
measurements, so you might experiment with that, which normally involves using a low-rate signal 
such as PPS for "start" and "stop" channels.

John

On Nov 14, 2012, at 8:43 PM, Edgardo Molina  wrote:

 

Dear Group,

Now that I have setup TimeLab along with the Prologix GPIB to USB adapter and 
the HP-53132A frecuency counter, I am starting to get some data from my 
frequency standards. Still I think I have a long way to go in front of me.

One of the main concerns that cross my mind at this point are:

a. What is the recommended sampling duration to consider for Quartz, Rubidium  
and other types of oscillators?
b. What are the recommended sampling intervals for the above mentioned 
oscillator types?
c. I am using a 10 MHz Rb FE-5806A frequency standard as an external reference 
for the HP-53132A.
d. I am connecting my DUT at the frequency counter channel 1
e. I am setting Timelab for Data Type = Frequency
f. My graphs somehow have the same geometry of classical ADEV examples, I can 
differentiate the ADEV noise types quite easily.
g. Should I use sub-second sampling intervals for my graphs to start closer to 
the vertical axis of the graph? Or should I use a conservative 1s sampling rate?

With the previous questions I am looking for consistency in my ADEV studies. 
Are there any typical ADEV conditions to be considered when analysing this way?
Am I missing something? My apologies to everybody if I am missing something or 
doing it the wrong way. In the end I want to learn more than anything else.

Your kind comments are welcome. Thank you.

Best regards,



Edgardo Molina
Dirección IPTEL

www.iptel.net.mx

T : 55 55 55202444
M : 04455 10045822

Piensa en Bits SA de CV



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Re: [time-nuts] Efratom PRFS202 Portable Rb Freq. Std. Manual

[Edgardo Molina]

Thanks to Ed, I now have a general brochure and spec sheet. There it mentions 
an internal setting resolution (for frequency adjustment). It should be 
described in detail the manual. 

I kindly inquire again if someone has experience with the adjustment of this 
unit or has access to it's manual. I will be grateful for that. 

Thanks again.


Regards,



Edgardo Molina
Dirección IPTEL

www.iptel.net.mx

T : 55 55 55202444
M : 04455 10045822

Piensa en Bits SA de CV



Información anexa:




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mensaje o hacer usode el para cualquier propósito o divulgar su en forma 
parcial o total su contenido. Gracias.


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On Nov 20, 2012, at 12:47 AM, Edgardo Molina  wrote:

> Dear Group,
> 
> Good morning. I recently got an Efratom PRFS202 Portable Rubidium Frequency 
> Standard. Mint condition. Locking in 3 minutes or so. Outputs OK, both sine 
> and TTL. 
> 
> It seems a simple straightforward instrument. Still I would like to know if 
> anybody has a manual available for it. I tried looking for it online and no 
> luck so far. This unit was marketed also using the Datum brand. Same model.
> 
> Anybody has at least a brochure or general specs for this particular unit? 
> Any experience or comments for this unit? Got it at a decent price 
> considering the lack of information.
> 
> As always, your kind comments are surely welcome. 
> 
> Thanks!
> 
> 
> Regards,
> 
> 
> 
> Edgardo Molina
> Dirección IPTEL
> 
> www.iptel.net.mx
> 
> T : 55 55 55202444
> M : 04455 10045822
> 
> Piensa en Bits SA de CV
> 
> 
> 
> Información anexa:
> 
> 
> 
> 
> CONFIDENCIALIDAD DE INFORMACION
> 
> Este mensaje tiene carácter confidencial. Si usted no es el destinarario de 
> este mensaje, le suplicamos se lo notifique al remitente mediante un correo 
> electrónico y que borre el presente mensaje y sus anexos de su computadora 
> sin retener una copia de los mismos. Queda estrictamente prohibido copiar 
> este mensaje o hacer usode el para cualquier propósito o divulgar su en forma 
> parcial o total su contenido. Gracias.
> 
> 
> NON-DISCLOSURE OF INFORMATION
> 
> This email is strictly confidential and may also be privileged. If you are 
> not the intended recipient please immediately advise the sender by replying 
> to this e-mail and then deleting the message and its attachments from your 
> computer without keeping a copy. It is strictly forbidden to copy it or use 
> it for any purpose or disclose its contents to any third party. Thank you.
> 
> 
> 
> 
> 
> 
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Re: [time-nuts] Nifty "MINI TIC" for DMTD work

[REEVES Paul]

and one more for the list!

regards,
Paul

-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf 
Of ewkeh...@aol.com
Sent: 19 November 2012 19:53
To: time-nuts@febo.com
Subject: Re: [time-nuts] Nifty "MINI TIC" for DMTD work

Don
lets see how much interest and which counter and in the 2 channel it is 3
PIC's and 1 G/A and the 4 channel 5 PIC's and 2 G/A. Easy to solder Juerg
and I  are 70+ so soldering is a key consideration
Bert Kehren.



In a message dated 11/19/2012 2:48:39 P.M. Eastern Standard Time,
d...@montana.com writes:

uh, ok,  how do we order the boards?
Don L

cdel...@juno.com
>
>  "MINI-TIC" for DMTD work
>
>
> Hi Everyone!
>
>  I've been testing a Miniature 2 channel TIC that Bert Kehren and Juerg
>  Koegel
> and Richard Mc Corkle have designed.
>
> It has 9  digits/Sec. and with a 1HZ offset in the DMTD unit gives a
> resolution  of 1X10-15th  at 10 MHz, 2X10-15 with a 5 MHz input, when
>  measuring
> Allan deviation. The 200 MHz version doubles the  resolution.
>
> Of course the baseline performance of the DMTD  unit and the stability of
> the DMTD reference determines the actual  accuracy you can obtain.
>
> (My dual mixer has a baseline of  approx. 8X10-14th at 1 second and my
> best reference is  4X10-13th  at 1 second.)
>
> The "MINI" takes a 5 or 10 MHz reference that  only has to be stable to
> parts in 10-8th/sec.
> I used a neat  14PIN ovenized DIP clock chip I got on eBay and recently
> discussed on  the list.
>
> The reference is multiplied to 100Mhz for use as the  counters clock.
>
> The "MINI" is about 2.5 by 2 inches and has  only 5 chips. Two opto
> couplers an
> op amp for two analog  channels are also on the board. If run on 5 volt a
> 3.3 V
>  regulator is also on the board. Power required is +5VDC 0.05 A  and  +-
> 12
>
> (for the RS232 interface)
>
> It  also has two pins you can individually ground to measure the period
>  of
> the beat
> note from either channel.
>
> This  allows you to adjust the offset frequency quickly and  accurately.
>
> I installed the "MINI" into a 1U chassis with the  power supply and also
> added "heartbeat" LEDS for each channel to show  the presence of the 1PPS
> inputs.
>
> I have plotted  several Rubidium and many Quartz using the "MINI"
> simultaneously with  a SR620 counter/timer. The plots are "identical"! So
> much
> so  that I am going to "retire" and sell my SR620!
>
> I understand  work is complete on a 4 channel counters and Bluetooth
>  interface,
> and work is ongoing on a LCD.
>
> The "MINI"  material cost is less than $25.00 depending on how many
> boards are  ordered!
>
> Resoution based on clock frequency and beat  frequency:
>
> Carrier[MHz]  Beat [Hz]  HeterodyneTIC [ns]   Resolution
>  10101.00E+06101.00E-14
> 1011.00E+07101.00E-15
>  1011.00E+0755.00E-16
> 10101.00E+0655.00E-15
>  5105.00E+05102.00E-14
> 515.00E+06102.00E-15
>  515.00E+0651.00E-15
> 5105.00E+0551.00E-14
>  
> Woman is  53 But Looks 25
> Mom reveals 1 simple wrinkle trick that has angered  doctors...
>  http://thirdpartyoffers.juno.com/TGL3141/50aa82cb1214a2ca03f8st04duc
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>


--
"Neither the voice of authority  nor the weight of reason and argument
are as significant as experiment, for  thence comes quiet to the mind."
De Erroribus Medicorum, R. Bacon, 13th  century.
"If you don't know what it is, don't poke it."
Ghost in the  Shell


Dr. Don Latham AJ7LL
Six Mile Systems LLP
17850 Six  Mile Road
POB 134
Huson, MT, 59846
VOX  406-626-4304
www.lightningforensics.com
www.sixmilesystems.com



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