SegFault by using 2 RF channels and Glonass L1/L2

[nifx]

gnss_sdr_glonass_l1_l2.txt

Hi all,

first of all, thanks a lot for this amazing tool. I really enjoy using it. Currently, I do some tests with Glonass samples. It is my first multi-frequency configuration. It uses Glonass L1 / L2. Please find the configuration attached.

If I start gnss_sdr 0.0.17 (Docker) with the attached configuration, I get a segfault:

Initializing GNSS-SDR v0.0.17 ... Please wait. Logging will be written at . RF Channels: 2 Processing file ./IqStream, which contains 175383063552 samples (350766127104 bytes) GNSS signal recorded time to be processed: 158.69 [s] Segmentation fault (core dumped)

If I downstrip the configuration to separate L1 and L2 into separate configuration files, both are working. But if I use 2 RF channels, I cannot get it running.

Note: I minimized the number of channels in the attached configuration to get a feeling if I did something wrong here. I also tested with more channels without success.

From the logfiles, I cannot find anything suspicious. Only .INFO is generated, unfortunately without any error messages.

Thanks a lot for any ideas.

BR Nico

[jwmelto]

A File_Signal_Source does not provide two channels of output.

The most likely situation is that you have recorded G1 in one file and G2 in another. Simply specify two File_Signal_Sources as SignalSource0 and SignalSource1

(I should point out that the File_Signal_Source does not support the sampling_frequency attribute, so that does nothing (except perhaps serve as documentation).

You can also use the Multichannel_File_Signal_Source which is similar to two file sources (It allows you to specify any number of files/channels).

[nifx]

Thanks @jwmelto for your feedback. Indeed, I have a high-bandwidth sample file (~550MHz sample rate, complex samples) which contains L1 and L2. But nevertheless, I was able to define 2 signal sources pointing to the same file which is working better, thanks to your hint. Thus, I do not get a segmentation fault with this solution.

But what I don't understand now is the following:

• if I configure channels for 1G (Glonass L1 C/A) and 2G (Glonass L2 C/A), I see only console output for Glonass L1 (tracking started, NAV decoded)
• if I set the number of channels for Glonass L1 C/A to 0, I see the console output for Glonass L2
• but why does it not work for both L1 / L2 simultaneously?

Please find the configuration attached. gnss_sdr_glonass_l1_l2.txt

I played a lot of different combinations of:

• GNSS-SDR.num_sources
• Receiver.sources_count
• RF_channel_ID (I think this not the correct one for multiple signal sources)
• Signal_Source_ID (I think this is the one to use)

I would expect to see tracking and NAV messages in the console output for Glonass L1 and L2. Do you have any insights why this does not seem to work?

[nifx]

I also tried SignalSource_ID vs. Signal_Source_ID The first one is described in the table at https://gnss-sdr.org/docs/sp-blocks/channels/ The last one is used in the example at the bottom of the page. But it makes no difference

[nifx]

I also tried it with Multichannel_File_Signal_Source also in combination with RF_channel_ID in channel assignments. Still no luck

[nifx]

Funny thing is that I get GPS L1 C/A + Glonass L2 C/A running. But when I replace GPS L1 C/A with Glonass L1 C/A, Glonass L2 C/A seems dead.