Continue processing data when SDR is unplugged and re-plugged in

[jiangyi1985]

When usb is unplugged and re-plugged in, or if there's a bad usb connection, the program will stop processing data and remain idle. And I have to restart the service.
Is there a way to solve this?

[sam210723]

Hi Ivan,

This is more of a limitation of the way USB works as devices are re-enumerated each time they are plugged in or power cycle.

You could setup some Linux services which have the Restart and RestartSec options set so the application will restart if it crashes when the USB device disconnects. Take a look at the Services section of the setup guide for more detail.

Sam.

[jiangyi1985]

When the USB device disconnects, the service doesn't crash.

Feb 14 20:53:49 kali goesrecv[252377]: 2021-02-14T12:53:49Z [monitor] gain: 34.54, freq:  -124.6, omega: 18.750, vit(avg): 2092, rs(sum):    0, packets:  0, drops:  5
Feb 14 20:53:50 kali goesrecv[252377]: 2021-02-14T12:53:50Z [monitor] gain: 49.34, freq:   -21.5, omega: 18.750, vit(avg): 2081, rs(sum):    0, packets:  0, drops:  5
Feb 14 20:53:51 kali goesrecv[252377]: 2021-02-14T12:53:51Z [monitor] gain: 59.37, freq: -1266.3, omega: 18.750, vit(avg): 2088, rs(sum):    0, packets:  0, drops:  3
Feb 14 20:53:52 kali goesrecv[252377]: 2021-02-14T12:53:52Z [monitor] gain: 66.95, freq: -2333.2, omega: 18.750, vit(avg): 2085, rs(sum):    0, packets:  0, drops:  7
Feb 14 20:53:53 kali goesrecv[252377]: 2021-02-14T12:53:53Z [monitor] gain: 71.38, freq: -2227.2, omega: 18.750, vit(avg): 2083, rs(sum):    0, packets:  0, drops:  5
Feb 14 20:53:54 kali goesrecv[252377]: 2021-02-14T12:53:54Z [monitor] gain: 74.02, freq: -1871.4, omega: 18.750, vit(avg): 2093, rs(sum):    0, packets:  0, drops:  4
Feb 14 20:53:55 kali goesrecv[252377]: 2021-02-14T12:53:55Z [monitor] gain: 76.56, freq: -5412.1, omega: 18.750, vit(avg): 2084, rs(sum):    0, packets:  0, drops:  5
Feb 14 20:53:56 kali goesrecv[252377]: 2021-02-14T12:53:56Z [monitor] gain: 78.93, freq: -6645.5, omega: 18.750, vit(avg): 2095, rs(sum):    0, packets:  0, drops:  5
Feb 14 20:53:57 kali goesrecv[252377]: 2021-02-14T12:53:57Z [monitor] gain: 81.03, freq: -5471.1, omega: 18.750, vit(avg): 2086, rs(sum):    0, packets:  0, drops:  3
Feb 14 20:53:58 kali goesrecv[252377]: 2021-02-14T12:53:58Z [monitor] gain: 81.97, freq: -6902.1, omega: 18.750, vit(avg): 2086, rs(sum):    0, packets:  0, drops:  4
Feb 14 20:53:59 kali goesrecv[252377]: 2021-02-14T12:53:59Z [monitor] gain: 81.98, freq: -6142.0, omega: 18.750, vit(avg): 2091, rs(sum):    0, packets:  0, drops:  5
Feb 14 20:54:00 kali goesrecv[252377]: 2021-02-14T12:54:00Z [monitor] gain: 81.98, freq: -8111.8, omega: 18.750, vit(avg): 2097, rs(sum):    0, packets:  0, drops:  5
Feb 14 20:54:01 kali goesrecv[252377]: 2021-02-14T12:54:01Z [monitor] gain: 81.98, freq: -8817.7, omega: 18.751, vit(avg): 2091, rs(sum):    0, packets:  0, drops:  6
Feb 14 20:54:01 kali goesrecv[252377]: cb transfer status: 5, canceling...
Feb 14 20:54:01 kali goesrecv[252377]: cb transfer status: 5, canceling...
Feb 14 20:54:01 kali goesrecv[252377]: cb transfer status: 5, canceling...
Feb 14 20:54:01 kali goesrecv[252377]: cb transfer status: 5, canceling...
Feb 14 20:54:01 kali goesrecv[252377]: cb transfer status: 5, canceling...
Feb 14 20:54:01 kali goesrecv[252377]: cb transfer status: 5, canceling...
Feb 14 20:54:02 kali goesrecv[252377]: 2021-02-14T12:54:02Z [monitor] gain: 81.98, freq: -9166.3, omega: 18.751, vit(avg): 2096, rs(sum):    0, packets:  0, drops:  3
Feb 14 20:54:03 kali goesrecv[252377]: 2021-02-14T12:54:03Z [monitor] gain:  0.00, freq:     0.0, omega: 0.000, vit(avg):    0, rs(sum):    0, packets:  0, drops:  0
Feb 14 20:54:04 kali goesrecv[252377]: 2021-02-14T12:54:04Z [monitor] gain:  0.00, freq:     0.0, omega: 0.000, vit(avg):    0, rs(sum):    0, packets:  0, drops:  0
Feb 14 20:54:05 kali goesrecv[252377]: 2021-02-14T12:54:05Z [monitor] gain:  0.00, freq:     0.0, omega: 0.000, vit(avg):    0, rs(sum):    0, packets:  0, drops:  0
Feb 14 20:54:06 kali goesrecv[252377]: 2021-02-14T12:54:06Z [monitor] gain:  0.00, freq:     0.0, omega: 0.000, vit(avg):    0, rs(sum):    0, packets:  0, drops:  0
Feb 14 20:54:07 kali goesrecv[252377]: 2021-02-14T12:54:07Z [monitor] gain:  0.00, freq:     0.0, omega: 0.000, vit(avg):    0, rs(sum):    0, packets:  0, drops:  0
//
//USB device re-connected at this point
//
Feb 14 20:54:08 kali goesrecv[252377]: 2021-02-14T12:54:08Z [monitor] gain:  0.00, freq:     0.0, omega: 0.000, vit(avg):    0, rs(sum):    0, packets:  0, drops:  0
Feb 14 20:54:09 kali goesrecv[252377]: 2021-02-14T12:54:09Z [monitor] gain:  0.00, freq:     0.0, omega: 0.000, vit(avg):    0, rs(sum):    0, packets:  0, drops:  0
Feb 14 20:54:10 kali goesrecv[252377]: 2021-02-14T12:54:10Z [monitor] gain:  0.00, freq:     0.0, omega: 0.000, vit(avg):    0, rs(sum):    0, packets:  0, drops:  0
Feb 14 20:54:11 kali goesrecv[252377]: 2021-02-14T12:54:11Z [monitor] gain:  0.00, freq:     0.0, omega: 0.000, vit(avg):    0, rs(sum):    0, packets:  0, drops:  0
Feb 14 20:54:12 kali goesrecv[252377]: 2021-02-14T12:54:12Z [monitor] gain:  0.00, freq:     0.0, omega: 0.000, vit(avg):    0, rs(sum):    0, packets:  0, drops:  0
Feb 14 20:54:13 kali goesrecv[252377]: 2021-02-14T12:54:13Z [monitor] gain:  0.00, freq:     0.0, omega: 0.000, vit(avg):    0, rs(sum):    0, packets:  0, drops:  0
Feb 14 20:54:14 kali goesrecv[252377]: 2021-02-14T12:54:14Z [monitor] gain:  0.00, freq:     0.0, omega: 0.000, vit(avg):    0, rs(sum):    0, packets:  0, drops:  0
Feb 14 20:54:15 kali goesrecv[252377]: 2021-02-14T12:54:15Z [monitor] gain:  0.00, freq:     0.0, omega: 0.000, vit(avg):    0, rs(sum):    0, packets:  0, drops:  0
Feb 14 20:54:16 kali goesrecv[252377]: 2021-02-14T12:54:16Z [monitor] gain:  0.00, freq:     0.0, omega: 0.000, vit(avg):    0, rs(sum):    0, packets:  0, drops:  0

And when the USB device reconnects, it doesn't do anything. There will be no data.

I guess what I need to do is to change the code and make the program crash whenever the USB device disconnects, so that systemctl can then restart it?

Which lines of code should I change?

[sam210723]

Hi Ivan,

It seems the source queue used in the main loop of demodulator.cc is not closing correctly when the device is unplugged. I'll do some testing of this so it cleanly exits with an error code when no more samples are being received from the device.

Are you using an Airspy or RTL-SDR?

[jiangyi1985]

Hi Sam,

I’m using RTL-SDR