Performance verification for time counters
In message 409346F4-60E1-4CAE-8602-84FB1C061DB7@n1k.org, Bob kb8tq writes:
The HP3336 with its outstanding level-control is a much
overlooked bargain for this kind of stuff.
I looked for the manual, and it seems to have ROM feeding values to a DAC.
Is that not DDS?
That is for the level control, not for generating the signal.
The level control has a custom HP-chip with two matched thermal
converters, so you can compare the power of two signals with it.
One signal is the RF output, the other comes from a DAC.
The 3336 is as far as I know one of the the most precise instruments
when it comes to amplitude, and it was built specifically for the
last two generations of the Carrier Frequency Coax telephone network
(L4 and L5) where up to 10.800 4kHz telefone channels were stacked
over each other in a single coax cable.
Because the top frequency were near 70 MHz, they needed a repeater
for every mile of cable which is up to 4000 repeaters for a call
across the US.
If every one of those repeaters had a systematic dip of 0.01dB at
the same frequency, That would amount to 40dB attenuation in total,
so the amplitude tolerances were almost insane, in order to keep
the amount of equalizing manageable.
Google: bstj53-10 site:archive.org
It's an amazing story...
The HP3336 and the HP3586 level meter go together to measure these
lines: The 3586 measures the received signal and when it is done
it tells the 3336 to step 4kHz up to the next channel. The crucial
trick is that the 3336 produces the exact same output level for all
10800 channels.
See: HPJ May 1980.
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
Hi
Needless to say demonstrating this 0.001 db sort of gain flatness on a repeater
out to crazy low frequencies is a bit involved. It is a great gig if you happen to be
a consultant …
Bob
On Nov 29, 2017, at 6:36 PM, Poul-Henning Kamp phk@phk.freebsd.dk wrote:
In message 409346F4-60E1-4CAE-8602-84FB1C061DB7@n1k.org, Bob kb8tq writes:
The HP3336 with its outstanding level-control is a much
overlooked bargain for this kind of stuff.
I looked for the manual, and it seems to have ROM feeding values to a DAC.
Is that not DDS?
That is for the level control, not for generating the signal.
The level control has a custom HP-chip with two matched thermal
converters, so you can compare the power of two signals with it.
One signal is the RF output, the other comes from a DAC.
The 3336 is as far as I know one of the the most precise instruments
when it comes to amplitude, and it was built specifically for the
last two generations of the Carrier Frequency Coax telephone network
(L4 and L5) where up to 10.800 4kHz telefone channels were stacked
over each other in a single coax cable.
Because the top frequency were near 70 MHz, they needed a repeater
for every mile of cable which is up to 4000 repeaters for a call
across the US.
If every one of those repeaters had a systematic dip of 0.01dB at
the same frequency, That would amount to 40dB attenuation in total,
so the amplitude tolerances were almost insane, in order to keep
the amount of equalizing manageable.
Google: bstj53-10 site:archive.org
It's an amazing story...
The HP3336 and the HP3586 level meter go together to measure these
lines: The 3586 measures the received signal and when it is done
it tells the 3336 to step 4kHz up to the next channel. The crucial
trick is that the 3336 produces the exact same output level for all
10800 channels.
See: HPJ May 1980.
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
In message 9793F6FA-CB78-4BF1-BC80-6B1A593FC259@n1k.org, Bob kb8tq writes:
Needless to say demonstrating this 0.001 db sort of gain flatness on a repeater
out to crazy low frequencies is a bit involved. It is a great gig if you happen to be
a consultant ...
No consultants were involved, they did it in mass production at WE.
Remember, they needed thousands of repeaters per coax and there were
handfulls of coax'es in each cable.
This is the relevant article about the amplitude:
https://archive.org/details/bstj53-10-1935
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
Hi
The key point here is the term “demonstrating”. When you get to 0.001 Hz it takes
more than just a little time. Not very compatible with a production line. Yes you might
ask “would anybody ever want that demonstrated ? “. The answer is yes, there are people
out the that need it demonstrated. It’s not cheap to do.
Bob
On Nov 29, 2017, at 6:47 PM, Poul-Henning Kamp phk@phk.freebsd.dk wrote:
In message 9793F6FA-CB78-4BF1-BC80-6B1A593FC259@n1k.org, Bob kb8tq writes:
Needless to say demonstrating this 0.001 db sort of gain flatness on a repeater
out to crazy low frequencies is a bit involved. It is a great gig if you happen to be
a consultant ...
No consultants were involved, they did it in mass production at WE.
Remember, they needed thousands of repeaters per coax and there were
handfulls of coax'es in each cable.
This is the relevant article about the amplitude:
https://archive.org/details/bstj53-10-1935
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
On 11/29/17 3:41 PM, Bob kb8tq wrote:
Hi
Needless to say demonstrating this 0.001 db sort of gain flatness on a repeater
out to crazy low frequencies is a bit involved. It is a great gig if you happen to be
a consultant …
Bob
demonstrating 0.001 dB (or would that really be 0.1 mB or 100 microBels)
precision in any application is a bit involved. That's 0.03%
HI
On Nov 29, 2017, at 8:41 PM, jimlux jimlux@earthlink.net wrote:
On 11/29/17 3:41 PM, Bob kb8tq wrote:
Hi
Needless to say demonstrating this 0.001 db sort of gain flatness on a repeater
out to crazy low frequencies is a bit involved. It is a great gig if you happen to be
a consultant …
Bob
demonstrating 0.001 dB (or would that really be 0.1 mB or 100 microBels) precision in any application is a bit involved. That's 0.03%
Yup, now do it at some silly low frequency ( 0.(some number of zeros)1 Hz …. great way to waste a lot of time.
Bob
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On 11/29/17 5:53 PM, Bob kb8tq wrote:
HI
On Nov 29, 2017, at 8:41 PM, jimlux jimlux@earthlink.net wrote:
On 11/29/17 3:41 PM, Bob kb8tq wrote:
Hi
Needless to say demonstrating this 0.001 db sort of gain flatness on a repeater
out to crazy low frequencies is a bit involved. It is a great gig if you happen to be
a consultant …
Bob
demonstrating 0.001 dB (or would that really be 0.1 mB or 100 microBels) precision in any application is a bit involved. That's 0.03%
Yup, now do it at some silly low frequency ( 0.(some number of zeros)1 Hz …. great way to waste a lot of time.
That's a volt meter....
It's the "do it at 1 Hz and 10 MHz and every 1 Hz in between" that is
the challenge.
At that low a frequency aren’t you actually testing the temperature and time stability of the gain controlling components?
Tim N3QE
On Nov 29, 2017, at 9:04 PM, jimlux jimlux@earthlink.net wrote:
On 11/29/17 5:53 PM, Bob kb8tq wrote:
HI
On Nov 29, 2017, at 8:41 PM, jimlux jimlux@earthlink.net wrote:
On 11/29/17 3:41 PM, Bob kb8tq wrote:
Hi
Needless to say demonstrating this 0.001 db sort of gain flatness on a repeater
out to crazy low frequencies is a bit involved. It is a great gig if you happen to be
a consultant …
Bob
demonstrating 0.001 dB (or would that really be 0.1 mB or 100 microBels) precision in any application is a bit involved. That's 0.03%
Yup, now do it at some silly low frequency ( 0.(some number of zeros)1 Hz …. great way to waste a lot of time.
That's a volt meter....
It's the "do it at 1 Hz and 10 MHz and every 1 Hz in between" that is the challenge.
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.
Hi
That’s certainly part of the issue. The fact that you are measuring a transfer function
in the phase domain is another issue.
Before this gets to nutty, there is indeed a “peaking” spec on things like a stratum 1
through 4 device. That also gets carried into the OCx domains as well. Since (as was
pointed out at the start) you are worried about large groups of (possibly identical) units, the
peaking numbers need to be mighty small. It only takes one question of the form “that’s
a nice paper analysis … can you demonstrate it?” to head you off to (do me) silly testing
programs.
Bob
On Nov 29, 2017, at 9:08 PM, Tim Shoppa tshoppa@gmail.com wrote:
At that low a frequency aren’t you actually testing the temperature and time stability of the gain controlling components?
Tim N3QE
On Nov 29, 2017, at 9:04 PM, jimlux jimlux@earthlink.net wrote:
On 11/29/17 5:53 PM, Bob kb8tq wrote:
HI
On Nov 29, 2017, at 8:41 PM, jimlux jimlux@earthlink.net wrote:
On 11/29/17 3:41 PM, Bob kb8tq wrote:
Hi
Needless to say demonstrating this 0.001 db sort of gain flatness on a repeater
out to crazy low frequencies is a bit involved. It is a great gig if you happen to be
a consultant …
Bob
demonstrating 0.001 dB (or would that really be 0.1 mB or 100 microBels) precision in any application is a bit involved. That's 0.03%
Yup, now do it at some silly low frequency ( 0.(some number of zeros)1 Hz …. great way to waste a lot of time.
That's a volt meter....
It's the "do it at 1 Hz and 10 MHz and every 1 Hz in between" that is the challenge.
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 list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
In message 42A2F881-1631-402C-8ED6-2C863F6FEE71@n1k.org, Bob kb8tq writes:
Needless to say demonstrating this 0.001 db sort of gain flatness on a repeater
out to crazy low frequencies is a bit involved. It is a great gig if you happen to be
a consultant …
demonstrating 0.001 dB (or would that really be 0.1 mB or 100 microBels) precision in any application is a bit involved. That's 0.03%
Yup, now do it at some silly low frequency ( 0.(some number of zeros)1 Hz …. great way to waste a lot of time.
Sorry, I don't see the challenge: HP3458A in sampling mode, careful cabling, done.
At RF frequencies where you have to think about impedance however...
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.