How to configure gain - satnogs not nearly as good as gqrx

SatNOGS
21

Hi Fredy
I’m testing since few hours RSP1A SDR…

journalctl -f -u satnogs-client.service tell me the AGC is enable
How disable AGC managed by SOAPY i believe?
VE2DSK

Jan 07 14:52:34 raspberrypi satnogs-client[1467]: [WARNING] Not updating IFGR gain because AGC is enabled

22

Lets give it a try, I have no experience with the RSP SDR’s and Soapy.

First we need to know if Soapy is able to communicate with the RSP, I know the have a closed source firmware dependency and wonder if you installed that firmware/driver from the RSP supplier.

This should provide some information: Home · pothosware/SoapySDRPlay3 Wiki · GitHub

We need to start with the Soapy probe output to see if there is an option to disable the AGC.

This will be something like: SoapySDRUtil --probe=driver=sdrplay

23

Hi …
Here the ouput of SoapySDRUtil

######################################################

Soapy SDR – the SDR abstraction library

######################################################

Probe device driver=sdrplay
[INFO] devIdx: 0
[INFO] SerNo: 210305C798
[INFO] hwVer: 255
[INFO] rspDuoMode: 0
[INFO] tuner: 1
[INFO] rspDuoSampleFreq: 0.000000

– Device identification

driver=SDRplay
hardware=RSP1A
sdrplay_api_api_version=3.070000
sdrplay_api_hw_version=255

– Peripheral summary

Channels: 1 Rx, 0 Tx
Timestamps: NO
Other Settings:
* RF Gain Select - RF Gain Select
[key=rfgain_sel, default=4, type=string, options=(0, 1, 2, 3, 4, 5, 6, 7, 8, 9)]
* IQ Correction - IQ Correction Control
[key=iqcorr_ctrl, default=true, type=bool]
* AGC Setpoint - AGC Setpoint (dBfs)
[key=agc_setpoint, default=-30, type=int, range=[-60, 0]]
* BiasT Enable - BiasT Control
[key=biasT_ctrl, default=true, type=bool]
* RfNotch Enable - RF Notch Filter Control
[key=rfnotch_ctrl, default=true, type=bool]
* DabNotch Enable - DAB Notch Filter Control
[key=dabnotch_ctrl, default=true, type=bool]

– RX Channel 0

Full-duplex: YES
Supports AGC: YES
Stream formats: CS16, CF32
Native format: CS16 [full-scale=32767]
Antennas: RX
Corrections: DC removal
Full gain range: [0, 48] dB
IFGR gain range: [20, 59] dB
RFGR gain range: [0, 9] dB
Full freq range: [0.001, 2000] MHz
RF freq range: [0.001, 2000] MHz
CORR freq range: MHz
Sample rates: 0.0625, 0.096, 0.125, 0.192, 0.25, …, 6, 7, 8, 9, 10 MSps
Filter bandwidths: 0.2, 0.3, 0.6, 1.536, 5, 6, 7, 8 MHz

24

The only option I see related to AGC is agc_setpoint you can add this option:

Try SATNOGS_SOAPY_RX_DEVICE=driver=sdrplay,agc_setpoint=0

25

VE2DSK -did you ever figure this out? Same issue with AGC on my RSP1A, but this suggestion did not disable for me.

Also, what gain values are you using?

73
K2PI

26

Hi Robert…
adding agc_setpoint=0 work very well for me…
ve2dsk

1 Like
27

Thanks, I tried, but that did not work for me for some reason.

73
K2PI

28

Hi, an old thread, but…
I find it better to use a good coaxial cable to the antenna and place the RPi and SDR as far away from the antenna as possible (inside). This is why:

  • Minimal interference from RPi at the antenna
  • No need to extend power via POE or high current cables
  • No need to build everything in waterproof boxes
  • Full control of the RPi without needing to get out to the antenna site
  • Probably less expensive to use a good coax cable then a good waterproof box, cables for power etc…
4 Likes