Weird behaviour simply changing the SR

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Patrick73
Posts: 76
Joined: Thu May 31, 2018 9:39 am

Weird behaviour simply changing the SR

Post by Patrick73 » Thu Jul 12, 2018 2:44 pm

Hi !

I noticed something 'strange' by simply increasing the SR, from 2 to 6, in ZIF mode, dec set to 1.
See the attached captures, all centred on the same frequency.

What happens ?
Attachments
SR 2MHz ZIF.JPG
SR set to 2 : normal situation
SR 2MHz ZIF.JPG (135.57 KiB) Viewed 13970 times
SR 3MHz ZIF.JPG
Increasing SR to 3 MHz ...
SR 3MHz ZIF.JPG (166.8 KiB) Viewed 13970 times
SR 4 MHz ZIF.JPG
Now SR set to 4 MHz
SR 4 MHz ZIF.JPG (173.27 KiB) Viewed 13970 times

Reason: No reason

Patrick73
Posts: 76
Joined: Thu May 31, 2018 9:39 am

Re: Weird behaviour simply changing the SR

Post by Patrick73 » Thu Jul 12, 2018 2:47 pm

Part 2 :
Attachments
SR 5 MHz ZIF.JPG
Back to normal now with SR set to 5 MHz
SR 5 MHz ZIF.JPG (137.9 KiB) Viewed 13968 times
SR 6 MHz ZIF.JPG
It also looks good when set to 6 MHz
SR 6 MHz ZIF.JPG (137.41 KiB) Viewed 13968 times

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sdrplay
Posts: 978
Joined: Wed Jan 07, 2015 7:58 am

Re: Weird behaviour simply changing the SR

Post by sdrplay » Thu Jul 12, 2018 2:51 pm

The IF bandwidth can be either 200, 300, 600, 1536, 5000, 6000, 7000 or 8000 kHz

So for sample rates of 2, 3 and 4 MHz, the 1536 kHz IF bandwidth is used, so you will see attenuation of the signal outside of the IF bandwidth. At 5 MHz, the 5 MHz IF bandwidth is used, so that's why it looks "normal" again.

Best regards,

SDRplay Support

Reason: No reason

Patrick73
Posts: 76
Joined: Thu May 31, 2018 9:39 am

Re: Weird behaviour simply changing the SR

Post by Patrick73 » Thu Jul 12, 2018 3:11 pm

Thanks for the explanation.

Best regards.

Reason: No reason

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