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I'm using the RSP1A SDR and I want to understand how to choose the best configuration for receiving a signal of 125 khz bandwidth.

I would like to know if when choosing the option 200 KHz IF bandwidth with 2MSamples/s sample rate:

  • we actually receive 2 Mhz of bandwidth and the remaining 900 Khz from both sides of the spectrum are attenuated

OR

  • we only receive 200 khz of bandwidth sampled at 2 MSamples/s rate.

Since i want to reduce the sample rate of the captured signal, i also would like to know if

  • I only have to downsample (reduce the sample rate by a factor of N) since it is already filtered to a 200 Khz bandwidth

OR

  • filter and then downsample as it is usually recommended to avoid aliasing.

Links to the RSP1A technical information : https://www.sdrplay.com/wp-content/uploads/2018/01/RSP1A-Technical-Information-R1P1.pdf and the RSP1A datasheet https://www.sdrplay.com/docs/171113RSP1AdatasheetV1.6.pdf

EDIT for clarification : As shown in the screenshot, for each sample rate (in this case I'm using the minimal allowed value : 2 MSamples/s), we can choose an IF bandwidth equal or less than the chosen sample rate value (so here i can choose between 1536, 600, 300 or 200 KHz).

enter image description here

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  • $\begingroup$ When you refer to an option you can choose, what do you mean? Are you using software that has pre-selected configurations you need to choose from? $\endgroup$ – MBaz Oct 10 at 13:15
  • $\begingroup$ I'm referring to the options available when using the RSP1A API (which are also available when using the gnuradio block RSP1A source from the OOT module : gr-sdrplay gitlab.com/HB9FXQ/gr-sdrplay ). I'll edit the post and add a screenshot to show the available options . $\endgroup$ – Hayfa Oct 10 at 15:35
  • $\begingroup$ So the option is not actually "IF Bandwidth" but just "Bandwidth". This could refer to the BPF in the front end, or in baseband. Are you sure which is it? $\endgroup$ – MBaz Oct 10 at 15:57
  • $\begingroup$ Well, I used "IF bandwidth" instead of just "bandwidth" because that's the term used by the SDRplay support in this forum discussion sdrplay.com/community/… $\endgroup$ – Hayfa Oct 10 at 16:20

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