Wednesday, April 9, 2025

LimeSDR Mini 2.4, Rx degradation with GR

I have a LimeSDR Mini 2.4.  When I test Rx performance using the LimeSuiteGUI, I see performance in line with the device specifications.  With GNU Radio 3.10.1.1 under Ubuntu 22.04.5, the performance is severely degraded.  The GR test is a simple flowgraph of a Soapy LimeSDR Sink into a QT GUI Sink.

The relevant snippet from the generated Python code ls:
********************************************

        self.soapy_limesdr_source_0 = None
        dev = 'driver=lime'
        stream_args = ''
        tune_args = ['']
        settings = ['']

        self.soapy_limesdr_source_0 = soapy.source(dev, "fc32", 1, 'soapy=0,driver=lime',
                                  stream_args, tune_args, settings)
        self.soapy_limesdr_source_0.set_sample_rate(0, samp_rate)
        self.soapy_limesdr_source_0.set_bandwidth(0, 5000000)
        self.soapy_limesdr_source_0.set_frequency(0, freq)
        self.soapy_limesdr_source_0.set_frequency_correction(0, 0)
        self.soapy_limesdr_source_0.set_gain(0, min(max(gain, -12.0), 61.0))
***************************************************



The GR console log suggests that something is being lost in transit.

 

**********************************************************************

Warning: Ignoring XDG_SESSION_TYPE=wayland on Gnome. Use QT_QPA_PLATFORM=wayland to run on Wayland anyway.

[INFO] Make connection: 'LimeSDR Mini [USB 3.0] 1DA13CDBCB3B1C'

[INFO] Reference clock 40.00 MHz

[INFO] Device name: UNKNOWN

[INFO] Reference: 40 MHz

[INFO] LMS7002M register cache: Disabled

[INFO] RX LPF configured

[INFO] RX LPF configured

[INFO] Rx calibration finished

******************************************************************

 

Soapy recognises the device.

*****************************************************

dave@dave-Inspiron-3020:~$ SoapySDRUtil --info

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

##     Soapy SDR -- the SDR abstraction library     ##

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

 

Lib Version: v0.8.1-g6e99da18

API Version: v0.8.200

ABI Version: v0.8-3

Install root: /usr/local

Search path:  /usr/local/lib/SoapySDR/modules0.8-3

Module found: /usr/local/lib/SoapySDR/modules0.8-3/libLMS7Support.so (23.11.0-b39cb61e)

Available factories... lime

Available converters...

 -  CF32 -> [CF32, CS16, CS8, CU16, CU8]

 -  CS16 -> [CF32, CS16, CS8, CU16, CU8]

 -  CS32 -> [CS32]

 -   CS8 -> [CF32, CS16, CS8, CU16, CU8]

 -  CU16 -> [CF32, CS16, CS8]

 -   CU8 -> [CF32, CS16, CS8]

 -   F32 -> [F32, S16, S8, U16, U8]

 -   S16 -> [F32, S16, S8, U16, U8]

 -   S32 -> [S32]

 -    S8 -> [F32, S16, S8, U16, U8]

 -   U16 -> [F32, S16, S8]

 -    U8 -> [F32, S16, S8]

***********************************************

 

dave@dave-Inspiron-3020:~$ SoapySDRUtil --find

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

##     Soapy SDR -- the SDR abstraction library     ##

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

 

Found device 0

  addr = 24607:1027

  driver = lime

  label = LimeSDR Mini [USB 3.0] 1DA13CDBCB3B1C

  media = USB 3.0

  module = FT601

  name = LimeSDR Mini

  serial = 1DA13CDBCB3B1C

***************************************************

 

Any advice on how to proceed, please?

 

Thanks

 

Dave




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