Issues when transmiting

Projects LimeSDR
1

Hi, I’m trying to use LimeSDR to debug a signal by transmiting an IQ signal from LimeSDR to a HackRF.

The signal seens weird in reception. For example this is the IQ I’m transmiting:

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And this is how I’m receiving with HackRF

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The system are connected through cable. This is my GRC flow:

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Any ideas why it’s not transmitting right?

This is the log:


Generating: '/media/ELTN/Baseband Records/GOES/GRB/top_block.py'

Generating: '/media/ELTN/Baseband Records/GOES/GRB/top_block.py'

Executing: /usr/bin/python -u /media/ELTN/Baseband Records/GOES/GRB/top_block.py

linux; GNU C++ version 5.4.0 20160609; Boost_105800; UHD_003.010.002.000-release

gr-osmosdr v0.1.4-95-g34456aff (0.1.5git) gnuradio 3.7.10
built-in sink types: uhd hackrf bladerf soapy redpitaya file 
[INFO] Make connection: 'LimeSDR-USB [USB 3.0] 9062000C5170C'
[INFO] Estimated reference clock 30,7198 MHz
[INFO] Selected reference clock 30,720 MHz
[INFO] Device name: LimeSDR-USB
[INFO] Reference: 30,72 MHz
[INFO] Init LMS7002M(0)
[INFO] Ver=7, Rev=1, Mask=1
[INFO] LMS7002M calibration values caching Enable
[INFO] LMS7002M cache /home/lucas/.limesuite/LMS7002M_cache_values.db
[INFO] Rx Filter calibrated from cache
[INFO] Tx Filter calibrated from cache
[INFO] Rx Filter calibrated from cache
[INFO] Tx Filter calibrated from cache
SetFrequency using cache values vco:1, csw:213
[INFO] Tx Filter calibrated from cache
############################################################
Tx calibration values found in cache:
   | DC  | GAIN | PHASE
---+-----+------+------
I: | 819 | 1977 | -2
Q: |  10 | 2047 |
############################################################
[+] Selected device: GeForce GTX 980M

Thanks,

2

This is just a guess, but if you are sure that samples sent to device are correct it may be an issue with calibration cache. It is no longer supported and may actually mess things up (as described here), so I would try to add cacheCalibrations=0 to device arguments in osmocom Sink and see what happens.

2 Likes
3

Yep, that did the trick.

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Thanks!

4

Also you dont need a throttle block in your flow graph when there is a hardware sink or source, it may cause underflow in this setup

1 Like