On Sat, 17 Mar 2012 06:13:28 -0700
gary wrote:
> On 3/17/2012 5:44 AM, Attila Kinali wrote:
> > On Sat, 17 Mar 2012 10:15:17 +
> > "Poul-Henning Kamp" wrote:
> >
> >> Either you need to characterize the exact behaviour of your filter
> >> and build the necessary compensation for its phase/fr
Dear Poul-Henning,
My only argument against your versatile and well-performing solution is
that it is a little bit overkill.
As if running a handfull precision oscillators just for fun isn't
"overkill" also ? :-)
I don't know -- are there any limits for the fun in a time-nut sense? :-)
I hop
I've designed filters for datacom chips. I know filtering. My point is
the original author is making some assumptions in the design which are
not stated.
Yes, my fault, I didn't write it properly, so by a "ferrite rod" in
context of DCF/WWVB reception, I meand a "ferrite antenna in an LC tuned
Any filter's group delay can be equalized by all pass filters.
Delay builds up at the filter corner. Since everything in the real world is
causal, you add delay outside that corner frequency but in the passband to
equalize it. This is to say, you can't remove delay, but just add it to
flatten
Which basically matched my assumption. If the inductor is loaded, you
have a narrowband filter. So again, this does not imply that a ferrite
rod antenna per se has phase distortion. It is the LC filter than
effects the group delay.
On 3/17/2012 6:19 AM, Marek Peca wrote:
Hello, gary,
I los
Yes, in order to equalize group delay, you need to know what to
equalize. But with an educated guess as to the system response, he could
get close.
All this said, in 2012, I would rather the amplifier be simple gain, the
inductor not loaded with capacitance and the filtering done past the
amp
Which basically matched my assumption. If the inductor is loaded, you have a
narrowband filter. So again, this does not imply that a ferrite rod antenna
per se has phase distortion. It is the LC filter than effects the group
delay.
Yes, exactly. Excuse my loose speech before not explicitly men
Hi
The problem with delay compensation in a Time Nut environment is that to do it
you add delay. Your all pass network adds enough delay to the "fast" part of
the passband to make it come out the same as the slow part. In real circuits
you inevitably add some delay everywhere with the all pass,
Yes, in order to equalize group delay, you need to know what to equalize. But
with an educated guess as to the system response, he could get close.
All this said, in 2012, I would rather the amplifier be simple gain, the
inductor not loaded with capacitance and the filtering done past the
ampl
I think the tempco of the ferrite is more significant than drift in the
analog filter. Of course this again implies the better design is to not
load the inductor with a cap, i.e. stay broadband, and then just filter
post the preamp.
The open circuit voltage will be lower without the resonant c
I think the tempco of the ferrite is more significant than drift in the
analog filter.
Perhaps I was unclear in this as well. I do not use nor plan to use any
other filter than the (ferrite-L)-C resonant circuit itself. So, yes, the
tempco of the ferrite makes its coefficients variation.
The
That would be 36ns group delay variation if I did the math correctly.
However, what material are you using for the ferrite? The material can
have a significant tempco.
On 3/17/2012 7:17 AM, Marek Peca wrote:
However, for f0=77.5kHz and B=1kHz, the LC circuit with Q=40 gives phase
error over
That would be 36ns group delay variation if I did the math correctly.
OK
And in article P. Hetzel: Time dissemination via the LF transmitter DCF77
using a pseudo-random phase-shift keying of the carrier, 2nd EFTF
Neuchatel, 1988., they conclude with timing results of about 2..10e-6 s
RMS ove
http://www.fair-rite.com/newfair/materials61.htm
OK, assuming type 61, it is 0.1%/deg C. Let's go with +/- 5 degrees,
which would be for indoor use. I don't have the equation handy for a
damped LC. Certainly undamped would be worst case. f=1/(2*pi*sqrt(LC)).
When the dust settles, the freque
Hi Marek -
I don't know where you are in CZ. I'm on the boarder in DE near PL and
CZ. The distance to DCF77 is about 450km and if I check the amplitude
across 24h I see considerable very deep fading effects! I think it is
useless as a phase-coupled time receiver. At least in specific
position
Dear Henry,
I don't know where you are in CZ. I'm on the boarder in DE near PL and CZ.
my former measurement (the one at YouTube, fairly good reception, winter)
has been done under Erzgebirge, Teplice, CZ. Now I moved near Sumava
(Boehmischer Wald), so tests may follow, if I will return to t
-boun...@febo.com
Date: Sat, 17 Mar 2012 16:10:48
To: Discussion of precise time and frequency measurement
Reply-To: ehy...@arcor.de, Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] WWVB BPSK Receiver Project? (fwd)
Hi Marek -
I don't know where you are in CZ.
gary wrote:
OK, assuming type 61, it is 0.1%/deg C.
IME, Type 78 is the usual choice for resonant antennas below 200 kHz
(tempco of initial permeability = 1.0%/deg C). I have seen Type 33
used for broadband LF/MF antennas (tempco of initial permeability =
0.1%/deg C). Type 61 is generally
Marek Peca schrieb:
This was almost the only reason for ferrite rod -- simplicity and
attenuation of TVs, some LCDs, 50Hz etc.
If you make the antenna about 10x bigger you can omit the whole ferrite.
The only benefit of a ferrite loaded coil is the size of it!
In ancient time radios had flat a
iscussion of precise time and frequency measurement
Reply-To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] WWVB BPSK Receiver Project? (fwd)
gary wrote:
>OK, assuming type 61, it is 0.1%/deg C.
IME, Type 78 is the usual choice for resonant antennas be
Peca; Discussion of precise time and frequency
measurement
Reply-To: ehy...@arcor.de, Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] WWVB BPSK Receiver Project? (fwd)
Marek Peca schrieb:
> This was almost the only reason for ferrite rod -- simplicity and
>
In the end every antenna receives the EM wave! The EM-wave is the far
field. The antenna works in the near field where a dominant component
can be the E or M. That depends on the antenna. Between the near and the
far field the field is "converted" and local Z0 highly complicated.
As far as I know
e: [time-nuts] WWVB BPSK Receiver Project? (fwd)
Marek Peca schrieb:
This was almost the only reason for ferrite rod -- simplicity and
attenuation of TVs, some LCDs, 50Hz etc.
If you make the antenna about 10x bigger you can omit the whole ferrite.
The only benefit of a ferrite loaded coil is the
No, there is a geometric saturation. You can't use the better
permeability in reality.
The optimum length to width relation is about 6 to 10 for ferrite rods.
Here is a diagram:
http://ehydra.dyndns.info/NG/time-nuts/Pettengill%20002.jpg
This is one of the classics in my link list:
http://www.b
In message <4f64f279.4040...@arcor.de>, ehydra writes:
>Marek Peca schrieb:
>> This was almost the only reason for ferrite rod -- simplicity and
>> attenuation of TVs, some LCDs, 50Hz etc.
>
>If you make the antenna about 10x bigger you can omit the whole ferrite.
I have used two antennas, an u
Poul-Henning Kamp schrieb:
> In message <4f64f279.4040...@arcor.de>, ehydra writes:
>> Marek Peca schrieb:
>
>>> This was almost the only reason for ferrite rod -- simplicity and
>>> attenuation of TVs, some LCDs, 50Hz etc.
>> If you make the antenna about 10x bigger you can omit the whole
ferr
In message <4f65d971.8070...@arcor.de>, ehydra writes:
>http://home.earthlink.net/~christrask/Complementary%20Push-Pull%20Amplifiers.pdf
> > In my implementation, it covered DC to 200MHz until I low-pass'ed it.
>
>His designs are always a good source but this one is AC-coupled ;-)
Not in my imple
I wonder because ALL of the shown circuits in his pdf are AC-coupled.
It is maybe possible to servo-loop with OpAmps but surely not worth the
effort.
Useful too as a Scope FET-probe.
- Henry
Poul-Henning Kamp schrieb:
> In message <4f65d971.8070...@arcor.de>, ehydra writes:
>
>>
http://hom
On Sun, 18 Mar 2012 13:25:54 +
"Poul-Henning Kamp" wrote:
> In message <4f65d971.8070...@arcor.de>, ehydra writes:
>
> >http://home.earthlink.net/~christrask/Complementary%20Push-Pull%20Amplifiers.pdf
> > > In my implementation, it covered DC to 200MHz until I low-pass'ed it.
> >
> >His desi
The circuit in question doesn't appear to be in the PDF. You need to use
a lot of caution with Lankford's theories. I don't want to get into a
pissing contest, so I will leave it at that.
Push pull with transformers goes back to the tube days. It is a
convenient scheme to kill 2nd harmonic dis
I'd not use a vertical antenna at all. Far too prone to EMI.
My choice would be a center tapped, shielded, air core loop, running into
a low noise instrumentation amp. Center tap of loop to twinax shield,
grounded at preamp.
The instrumentation amp has fixed gain, and very high CMRR and PSRR. It
My choice would be a center tapped, shielded, air core loop, running into
a low noise instrumentation amp. Center tap of loop to twinax shield,
grounded at preamp.
The instrumentation amp has fixed gain, and very high CMRR and PSRR. It
also does the differential to single ended conversion properl
ehydra wrote:
I wonder because ALL of the shown circuits in his pdf are AC-coupled.
It is maybe possible to servo-loop with OpAmps but surely not worth
the effort.
Useful too as a Scope FET-probe.
Not really the gain inaccuracy is somewhat excessive.
One can do much better with the right ci
In message <20120318182440.7cb729c2b018b0b2ca5f9...@kinali.ch>, Attila Kinali w
rites:
>On Sun, 18 Mar 2012 13:25:54 +
>> Not in my implementation, I have eliminated the input capacitor because
>> the active element is 3cm from the PCB,
>
>Could you explain how the distance of the antenna to t
DC in a transformer raises the low frequency corner a bit. Obviously not
a problem in your case.
I should point out that every active device Lankford puts in the signal
chain adds noise since the amp is really just a buffer, not an
amplifier. You really want front end gain so that devices afte
In message <4f669a4d.3010...@lazygranch.com>, gary writes:
>DC in a transformer raises the low frequency corner a bit. Obviously not
>a problem in your case.
I just double-checked, because that rang a bell. I did reinstate
the capacitors as 2.2uF films in the final article for exactly that
reas
gary schrieb:
Just meditating out loud, if you were to go push pull with a ferrite
antenna AND you are winding it yourself, you could avoid the biasing
resistors by putting a center tap in the antenna itself, then tie that
center tap to an appropriate bias voltage. I haven't seen this done, so
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