[Lowfer] Sampling Rate and Frequency Calibration

[John Andrews]

Pat,

Great! Have fun...

JA

On 1/25/2014 5:21 PM, Pat Bunn wrote:
> John
>
> I also tested the circuit this morning and it worked first time as expected. I used a 16F628A as I had some and had no problems programming the hex file.
>
> The pcb worked fine with no changes required and the 74HCT4046 worked fine as a signal conditioner for my 10 MHz GPS signal.
>
> Pat
> N4LTA
>
> Sent from my iPhone
>
> On Jan 25, 2014, at 2:56 PM, <jrusgrove at comcast.net> wrote:
>
>> JA
>>
>> Just wanted to offer feedback on how well your preprogrammed pic works. The setup here is GPS disciplined 10 MHz > 74HC4046 > your programmed PIC16F84A. It's sure handy having calibrated outputs all the way down to 1000 seconds ... didn't have the patience to check that particular output but all others are working ;~) . This simplified circuit replaces a number of divider chips that were required to give me just 10 kHz.
>>
>> FWIW, in the system here, the 10 kHz output from the pic feeds the right channel of SpecLab (in stereo mode) which is then used by the Frequency Error Compensation utility to discipline the soundcard sampling rate to 10 kHz. With the RF-590 receiver already disciplined at 10 MHz and now the soundcard at 10 kHz I'm seeing frequency accuracies in the uHz.
>>
>> Curious if you 'tested' the input frequency range for the programmed pic? It would make an excellent general purpose divider 'test instrument' where frequencies other than 1 Mhz, 100 kHz, 10 kHz, 1 kHz etc are needed ... if the input can be adjusted over a wide frequency range.
>>
>> Jay W1VD  WD2XNS  WE2XGR/2  WG2XRS/2
>>
>>
>>
>>
>> ----- Original Message ----- From: <w1tag at charter.net>
>> To: <lowfer at mailman.qth.net>
>> Sent: Tuesday, January 21, 2014 8:52 AM
>> Subject: [Lowfer] Sampling Rate and Frequency Calibration
>>
>>
>>> In response to the recurring question about how to calibrate sound card sampling rates and check receiver audio output frequency "on the cheap," I have put up an article on a simple calibrator circuit that provides 1 kHz and 100 kHz outputs. See:
>>> http://www.w1tag.com/Calibrator/Freq_Cal.htm
>>>
>>> As the article notes, I can provide small quantities of  programmed divider chips. Anyone interested should contact me directly, not through the mail list.
>>>
>>> John, W1TAG
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