Reported RX Frequncies in WSJT-X?

[MaverickNH]

Looking at WSJT-X 1.7rc2 ALL_WSPR log and seeing RX frequencies such as 14.0971282. Seems like too many digits unless reporting 10th of a Hertz as in 14,097,128.2 Hz. Perhaps this is calculated as an average over the RX window?

Looking at the log for RX over 500+ RXs, I find the RX frequency range is 206Hz. Actual TX 14,097,037 and average RX at 14,097,110, or +73Hz.

I have a GPSDO managed PC clock as well as a GPSDO managed frequency oscillator in my K3S transceiver, so my regulation is pretty tight.

What are the major components of the deviation in reported RX frequency? I posted on WSPRnet also, but one seldom gets replies there on any posts.

Bret/N4SRN

[Richard Lamont]

On 23/11/16 11:16, MaverickNH wrote:

> Looking at WSJT-X 1.7rc2 ALL_WSPR log and seeing RX frequencies such as
> 14.0971282. Seems like too many digits unless reporting 10th of a Hertz as
> in 14,097,128.2 Hz. Perhaps this is calculated as an average over the RX
> window?
>
> Looking at the log for RX over 500+ RXs, I find the RX frequency range is
> 206Hz. Actual TX 14,097,037 and average RX at 14,097,110, or +73Hz.
>
> I have a GPSDO managed PC clock as well as a GPSDO managed frequency
> oscillator in my K3S transceiver, so my regulation is pretty tight.
>
> What are the major components of the deviation in reported RX frequency? I
> posted on WSPRnet also, but one seldom gets replies there on any posts.

There are errors at the TX end, errors at the RX end and errors in the
middle: ionospheric doppler shift.

With a K3S + GPSDO, the biggest source of RX error might be the
tolerance of the sampling frequency of the sound card. The built-in USB
sound card has a 100ppm clock crystal, corresponding to ±0.15 Hz @ 1500 Hz.

--
Richard G4DYA

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[Joe Subich, W4TV-4]

On 11/23/2016 6:16 AM, MaverickNH wrote:
> Looking at WSJT-X 1.7rc2 ALL_WSPR log and seeing RX frequencies such as
> 14.0971282. Seems like too many digits unless reporting 10th of a Hertz as
> in 14,097,128.2 Hz. Perhaps this is calculated as an average over the RX
> window?

Yes it is calculated:  Dial (carrier) frequency + tone (audio
frequency) of the sync bits.

> Looking at the log for RX over 500+ RXs, I find the RX frequency range is
> 206Hz. Actual TX 14,097,037 and average RX at 14,097,110, or +73Hz.

This would appear to indicate a "dial" frequency of 14,096.000 KHz with
a transmit audio frequency (sync bits) of 1,037 Hz while signals you
receive have somewhat dial or audio frequencies.

73,

    ... Joe, W4TV


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[briancom]

On 11/23/2016 12:51 PM, Richard Lamont wrote:
>
>
> There are errors at the TX end, errors at the RX end and errors in the
> middle: ionospheric doppler shift.

Doppler shifts are 1 Hz or less at these frequencies.

Look to rig calibration as the major source.  Many guys don't calibrate
their rigs.  Being 100 Hz off is quite reasonable.

73 de Brian/K3KO

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[MaverickNH]

I might take a measure of variability at different frequencies to see if the range size is correlated to frequency.

Bret/N4SRN