[hpsdr] 10Mhz reference

[Michael Cozzi]

	Glen and Mike,

	I've been through a bit of learning with my Bodnar unit....

	If the GPSDO is accurate you should not need to run the calibration. So 
the correction factor would be 1.0000. If you do run the calibration 
against WWV- the result should be 1.0000.

	At one point I had created an issue with my GPDSO by setting it up for 
other testing, and it was off by a large margin. I could calibrate the 
problem away (about 300hz). But I found my base frequency was 
incorrectly set in the GPSDO. Once that was corrected- the correction 
factor went back to 1.0000.

	So if the GPSDO is "off" but stable, you can correct in software with 
an acceptable result. But the best case is a 1.0000 correction factor.

	Michael- KD8TUT

On 3/3/2017 7:58 AM, Mike Seguin wrote:
> ***** High Performance Software Defined Radio Discussion List *****
>
> Glen,
>
> Step one is to verify that your Jupiter has a valid 3D GPS fix. The
> Jupiter engines output 10 kHz and PPS right after they are powered up.
> Until you get a valid 3D fix, they are not accurate.
>
> To verify you have 3D lock, look at the NMEA GPGGA string. You want to
> see a 3 in that line. This indicates 3D lock.
>
> Mike
>
> On 3/3/2017 7:49 AM, K4KV wrote:
>> ***** High Performance Software Defined Radio Discussion List *****
>>
>> Hello,
>>
>> I have designed my own GPSDO using a Jupiter module with a 10khz
>> output.  My reference
>>
>> TXCO has a feedback input and I divide that down to 10khz as well and
>> compare the Jupiter
>>
>> to the TXCO 10khz output, run them through an exclusive OR gate then
>> filter for the feedback
>>
>> voltage.
>>
>> Using a scope it appears they are perfectly locked.  It also appears the
>> NMEA streams out of the
>>
>> Jupiter show quite a bit of data, I am assuming a lock to the satellites.
>>
>> However, when attached the Hermes, the 10Mhz reference clock shows WWV
>> off by 50-70Hz.
>>
>> My question is: Do you need to also adjust the calibration inside PSDR?
>> I was assuming the cal corr.
>>
>> factor should be the default of zero correction...
>>
>> 73
>>
>> Glen K4KV
>>
>> ps - the 10Mhz output at J20 on the Hermes is 800mv, I hope that is
>> enough!
>>
>>
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