Transverter Calibration Error - SDRPlay RSP2

All bug reports here please
g4ogi
Posts: 20
Joined: Tue Jun 22, 2021 7:54 am

Transverter Calibration Error - SDRPlay RSP2

#1

Unread post by g4ogi »

Problem description
Using the calibration option in SDR-Console when using an RSP2Pro as the IF results in incorrect frequency adjustment
This is compounded when changing band (or "Favourite") as the calibration seems to get reset to zero.
The same issue is NOT experienced using Perseus as the IF

Scenario
I use an SDRPlay RSP2Pro as an IF for 13cm and 9cm with 144Mhz and 432MHz respectively.
I found that locking the RSP2 to a frequency reference caused SDR-Console to crash or lock up so abandoned that idea to continue with the free running LO.
From time to time this LO needs to be adjusted slightly and to achieve this I use the Calibration facility in SDR-Console.
Unfortunately on clicking one of the frequency steps to make the adjustment the frquency DOES NOT change.

I find that by either stopping console (Home/Stop) then restarting (Home/Start), or by selecting a different band/frequency the correction is then applied.
Unfortunately selecting and new frequency or favourite, or stopping and restarting, or a new session, this frequency adjustment is lost.

The actual frequency adjustment applied seems to be 0ppm even though the calibration window reports that a certain correction (other than 0) has been appllied.
The issue is further compounded by an observationthat after a few minutes of changing calibration and not aletring frquency etc, the correction automatically is reset resulting in a frequency jump.
Whilst not adding much to the description a screenshot has been added to illustrate the effect (Calibration-error-SDRPlay-2022-08-03-154456.jpeg)

This behaviour has not been observered when using the Perseus as my 28MHz IF for 23cm. Normal operation has been observed at all times.

Environment
Windows 10 ++
SDR-Console v3.2 build 2665, although this effect has been notice from v3.1 (and possibly earlier)

********** Addition NDS 20220804 0900utc **********
A better ilustration of the issue can be seen in the second attachment
I calibrated SDR-Console to show GB3MHZ on 2320.830MHz. This involved setting the calibration value to 0.016ppm to adjust the 37Hz error.
This was fine as can be seen in the lower half of the screen.
As soon as I pressed --><-- button to re-centre the display (although it was already centred) the 37Hz frequency error re-appeared as seen in the top part of the screen.
Ignore the other blips on the screen as these are the first order PI4 tones (that are also moved 37Hz)

This implies that the 0,.016ppm correction is not used in updating the display.
********************

Nick - g4ogi
Attachments
GB3MHZ 13cm PI4 signal being shifted 37Hz on screen re-centre
GB3MHZ 13cm PI4 signal being shifted 37Hz on screen re-centre
Calibration-error-SDRPlay-2022-08-03-154456.jpeg

jdow
Posts: 800
Joined: Mon Aug 10, 2020 8:17 pm

Re: Transverter Calibration Error - SDRPlay RSP2

#2

Unread post by jdow »

What makes you even begin to think the signal you are tuning in is as accurate as 16 parts per billion? Is it known to be locked to GPS? If the ppm error is fed as a correction to the RSP2, does it accept that small a correction or is it only integer ppm?

{o.o} Just wondering? If your RSP2 is not GPS locked it could drift 16 ppb due to local temperature changes within minutes. (And if it IS GPS locked why are you trying to adjust the ppm setting?)

Post Reply