Experience using rx_power

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RichardG
Posts: 11
Joined: Sat Jun 11, 2016 5:19 pm

Experience using rx_power

Postby RichardG » Thu Aug 18, 2016 1:30 pm

Has anyone had any experience of using rx_power with sdrplay?

http://www.rtl-sdr.com/rx_tools-rtl-sdr-command-line-tools-rtl_power-rtl_fm-rtl_sdr-now-compatible-with-almost-any-sdr/

I have it running but I can't get any sensible output. I think it may may be related to the gain settings but it's really hard to know what to set the values to. I had hoped to use AGC but that doesn't appear to be the enabled and it's unclear how you would turn it on. There was also some changes in the latest API for AGC and I wondered if they had been incorporated into SoapySDR? There also doesn't appear to be anyway of setting sample rate or if bandwidth?

I just wondered if anyone else has this working and could share their settings/work.

Thanks

Richard
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spectrum_says
Posts: 1
Joined: Thu Oct 18, 2018 11:20 pm

Re: Experience using rx_power

Postby spectrum_says » Fri Nov 30, 2018 2:49 pm

Reviving this old thread. I am currently investigating if it is possible to automate Power / SNR measurements with the RSP2. I find SDRuno very useful but lacking in this area.

Did you ever have success with rx_power? I have tried using it a bit, but as far as I can tell the power data it is giving me back is not accurate. I know this because I am injecting a signal of known frequency and power directly to the RSP2 via SMA cable.
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sdrplay
Posts: 915
Joined: Wed Jan 07, 2015 7:58 am

Re: Experience using rx_power

Postby sdrplay » Mon Jan 07, 2019 12:04 pm

rx_power will give you dBfs, not dBm, like SDRuno does.

Have you used the Power/SNR to CSV function in SDRuno?

We'll also be duplicating the CAT command that currently returns dBfs to also return dBm, so automating measurements with a CAT program might suit your need?

Best regards,

Andy

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Raptor30k
Posts: 3
Joined: Wed Dec 26, 2018 7:05 pm

Re: Experience using rx_power

Postby Raptor30k » Thu Jan 10, 2019 6:41 am

sdrplay wrote:rx_power will give you dBfs, not dBm, like SDRuno does.

Have you used the Power/SNR to CSV function in SDRuno?

We'll also be duplicating the CAT command that currently returns dBfs to also return dBm, so automating measurements with a CAT program might suit your need?

Best regards,

Andy


I've tried using Power/SNR to CSV data with my antenna direction data correlated by time. But this requires a lot of manual data manipulation. Doing spreadsheet macros is not my forte.

I would really like to use CAT to get dBm values. I've tried the standard SM0; CAT and get about 5 db per the 0-20 return value. This is not enough resolution for my use. I've already written a signal measurement program in C# that gets dBm from Flex radios. Would like to add SDRuno. Could really use dBm.

What is the CAT command and it's syntax going to be? When? :) I'll beta test. :)

73, BillC
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sdrplay
Posts: 915
Joined: Wed Jan 07, 2015 7:58 am

Re: Experience using rx_power

Postby sdrplay » Thu Jan 10, 2019 9:00 am

Hi Bill,

The change we'll be making is this...

SM0; // Standard S-meter reading
SM1; // SDRuno dBm power reading

result would be (e.g)...

SM00010; // 10 within the range of 0 - 20
SM10943; // -94.3 dBm

It's on the list of features to add, I'll just need to work out when I can get it done. I'll let you know.

Best regards,

Andy

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sdrplay
Posts: 915
Joined: Wed Jan 07, 2015 7:58 am

Re: Experience using rx_power

Postby sdrplay » Thu Jan 10, 2019 9:10 am

Hi,

I've just checked and it will be in the next release (1.3) - if you have a simple piece of code that I can use to check it, please send it to software at sdrplay.com

Best regards,

Andy

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Raptor30k
Posts: 3
Joined: Wed Dec 26, 2018 7:05 pm

Re: Experience using rx_power

Postby Raptor30k » Thu Jan 10, 2019 9:19 pm

Thanks Andy,
I don't have an easy test project available. I could spend a day or two to put something together, if needed, to move this along. :)

But I think the easiest way to test CAT commands is with a serial port Terminal program (I use PuTTY) in conjunction with a virtual serial port cable. I just connected to SDRuno v1.22 and get the expected responses. Right now I tested SM1; thru SM2;, all return SM0004; (or so... my current noise floor on 7 MHz CW 500Hz BW).

Testing with a Terminal program won't tell you everything of course. For instance, my signal plotter program polls the radio as quickly as every 25 ms to allow smoothing out the plot. Not always necessary. Good for smoothing CW or SSB data but not needed for steady carrier signals like AM.

Thanks for the support. Looking forward to v1.3 and hearing from you.
--BillC
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Raptor30k
Posts: 3
Joined: Wed Dec 26, 2018 7:05 pm

Re: Experience using rx_power

Postby Raptor30k » Tue May 07, 2019 11:03 pm

Finally had a real need for this higher resolution data.

It works as advertised in the Version 1.3 (14th March 2019) release notes:
• Extended SM CAT command for power level to return dBm instead of S-Meter
- SM1; return VFO power in dBm as a positive number: SM00084; returned = -84 dBm

Since CAT data comes from each serial port, I can get separate signal strength from each VRX (virtual receiver). Very cool.

Thanks, BillC
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