All ZERO RecvStream samples, completely underrun

Projects LimeSDR
1

I’m new to SDRs and i’m trying my best to learn to code it.
I am currently attempting to receive 2.4GHz signals (assuming to read WiFi router waves). But i’m reading all Zeros. Could someone mentor me in this setup?

receiving snippet:

lms_stream_t receiveStream;
receiveStream.channel = 0;
receiveStream.isTx = false;
receiveStream.fifoSize = 256 * 64;
receiveStream.throughputVsLatency = 1;
receiveStream.dataFmt = lms_stream_t::LMS_FMT_I16;
receiveStream.linkFmt = lms_stream_t::LMS_LINK_FMT_I16;
int sampleSize = 32;
std::vector<int> samples(sampleSize,0);
lms_stream_meta_t meta;
lms_stream_status_t status;

if (LMS_SetupStream(....
if (LMS_StartStream(....
for (int i = 0; i<5; i++) {
    int samples_received = LMS_RecvStream(&receiveStream, samples.data(), sampleSize, &meta, 1000);
    if (samples_received < 0) {
        std::cerr << i << ": Failed to receive samples: " << LMS_GetLastErrorMessage() << std::endl;
        continue;
    }
    std::cout << i << ": ";
    for (int j = 0; j < sampleSize; j++) {
        std::cout << samples[j] << "; ";
    }
}

Here are my output

$ ./Receiver
Found 1 device(s)
[device Sl No: 0] LimeSDR Mini, media=USB 3.0, module=FT601, addr=24607:1027, serial=1DA168E6FF2FF2
Reference clock 40.00 MHz
Device opened successfully
Device initialized successfully
RX channel 0 enabled successfully
RX sample rate set to 3 MHz
RX center frequency set to 2.4 GHz
RX antenna set to 1
RX gain was set to 30 dB
Rx LPF min bandwidth is 4MHz when TIA gain is set to -12 dB
RX LPF configured
RX LPF bandwidth set to 1.8 MHz
Calibrating Rx for 2.5 MHz (requested 1.8 MHz [out of range])
Rx calibration finished
RX channel calibrated successfully.
RX stream setup successfully.
RX stream started successfully.
RX Stream Status: FIFO 0/16320, Underrun: 0, Overrun: 0, Dropped: 0
0: 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; TimeStamp :0
1: 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; TimeStamp :0
2: 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; TimeStamp :0
3: 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; TimeStamp :0
4: 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; TimeStamp :0
RX Stream Status: FIFO 0/16320, Underrun: 5, Overrun: 0, Dropped: 0
RX stream stopped successfully.
RX stream destroyed successfully.

some additional notes:

i have tried sample rates from 3MHz to 30MHz, RX gains 20dB & 30dB
and few other parameters too… but nothing seems to help…

2

Hi, can’t really help without seeing all your code. What is the library version you are using? Does the LimeSuite/src/examples/basicRX.cpp at master · myriadrf/LimeSuite · GitHub produce non zero values for you?

1 Like
3

Hi Ricardas, Thanks for sharing the basicRX.cpp. I just became aware of the “Fix for v2” to enable TX channel between Init & RX channel enabling. This helped me fix my code, and I’m seeing some data being streamed.

Thanks a lot again; my frustration is down now.