[time-nuts] Interesting frequency standard project
Max Robinson
max at maxsmusicplace.com
Sat Jul 5 03:45:22 UTC 2014
The best way to measure the frequency of an AM station is to first pass it
through a Crystal filter to strip off the modulation sidebands. After that
limiting is usually not necessary. You can do that in either TRF mode, or
in the IF of a superhet with a synthesized local oscillator.
Regards.
Max. K 4 O DS.
Email: max at maxsmusicplace.com
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----- Original Message -----
From: "Alexander Pummer" <alexpcs at ieee.org>
To: "Discussion of precise time and frequency measurement"
<time-nuts at febo.com>
Sent: Friday, July 04, 2014 5:59 PM
Subject: Re: [time-nuts] Interesting frequency standard project
> for an AM station is strait forward at first use a narrow filter to make
> sure that you have just one station and feed the filter out put into a
> limiter the output of the limiter will be the carrier.
> 73
> KJ6UHN Alex
>
> On 7/4/2014 3:27 PM, Hal Murray wrote:
>> paulswedb at gmail.com said:
>>> The key to these systems is that the transmitters have very good
>>> references.
>>> In the US at least we have no requirement for that level of stability on
>>> the
>>> MW broadcasts. Though evidently some stations are quite good. I think I
>>> have
>>> a list some place have to re-look.
>> How stable are they? Could they provide a good regional reference if
>> somebody with a good setup would measure several stations and publish the
>> results? How often would you have to measure?
>>
>> How do you measure the frequency of an AM or FM station? Wait for
>> silence
>> and process it like CW?
>>
>> Any suggestions for a receiver (or whatever) that would be appropriate
>> for
>> that sort of project? I assume the main requirements are an external
>> freq in
>> and a serial/USB port to adjust the knobs.
>>
>> ----------
>>
>> Ages ago, I remember seeing a small booklet (20 pages?) from NBS
>> describing
>> their setup with HP that was using NBC's atomic clock for time
>> distribution.
>> HP's part was to run the west coast calibration to get the delay over
>> phone
>> lines from the east coast to the west coast. Has anybody seen a copy of
>> that
>> booklet online?
>>
>>
>
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