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Offset in Frequency for Airspy Discovery on PI server

f1jek
 
Edited

Hi Simon,


I am trying (not so easy) to get SDR console work with the Airspy Discovery on a PI3 spyserver.

1) Finally the Airspy is seen by the PI3. This is cool. Configured as 0 to 260 000 000Hz coverage in the Pi.

2) SDR-console sees the Airspy on the PI3 (thus thinking it's a HF+), this is good.

3) But SDR-console displays an offset of about 150kHZ on low frequencies, but it's OK above (!!!). The station you see here is the BBC.

73(s de J-Luc F1JEK

f1jek
 

Answering to myself for more informations :

- Coming from the upper frequencies (with the mouse), I get BBC at 198kHz. OK

- Once I have passed 100kHz, instead of going lower, SDR console steps up to above 100k, STILL DISPLAYING a frequency lower of 100kHz. NOK

In other words, it does not do what it says as soon as a "low frequency" has been tuned one time.

J-Luc

Jim Smith G0OFE
 

Hello,

Please generate a screenshot of the software when it shows the problem, using the camera icon top left.

Then post the screenshot to this group as an attachment.

Someone will hopefully be able to help further.

================================
Jim, Bournemouth, Dorset. IO90BR.
Elad FDM-S2, Airspy HF+, SDRPlay and Funcube Dongle SDR Recievers
8-element OP-DES for Band 2, 8-element LFA for 2m, 3-element LFA for 6m, 20m Windom for HF,. Wellbrook 1530 Loop for LF


On 29/09/2019 16:36, f1jek wrote:
Answering to myself for more informations :

- Coming from the upper frequencies (with the mouse), I get BBC at 198kHz. OK

- Once I have passed 100kHz, instead of going lower, SDR console steps up to above 100k, STILL DISPLAYING a frequency lower of 100kHz. NOK

In other words, it does not do what it says as soon as a "low frequency" has been tuned one time.

J-Luc

f1jek
 
Edited

This is a screen copy of BBC on 32kHz (!) when the problem has occured. Note that the scale zero under the main WF is not zero at all .

Coming from the upper frequency with the VFO, all is correct (2nd picture).

Note that SDR# does not have this issue -> not a server problem.

J-Luc

f1jek
 

@simon, any idea ?

f1jek
 

Hi.

To reproduce :

- Tune 77kHz (DCF-77) with BW 48kHz -> it works
- Change BW to 96 or more -> no more reception, all freq shifted
- Turn back to 48kHz or less -> it works.

F1JEK - Airspy HF+ can often be reach from the internet.

J-Luc

jdow
 

If the bandwidth/samplerate chosen results in a negative frequency - it ain't gonna work.
{^_^}

On 20191005 02:52:55, f1jek wrote:
Hi.
To reproduce :
- Tune 77kHz (DCF-77) with BW 48kHz -> it works
- Change BW to 96 or more -> no more reception, all freq shifted
- Turn back to 48kHz or less -> it works.
/F1JEK - Airspy HF+/ can often be reach from the internet.
J-Luc

f1jek
 

Ah ah except that you can say that in this case (approaching the zero F), the sampling F is kept fixed at half the passband and it works.

This is quite common and probably the solution used by SDR# which is working in this case.

73's

J-Luc