Connecting to SDRs using serial numbers in python

[Bill Voss]

Hello,

I'm working on an application where I need to connect multiple SDRs of the same type (AirSpy R2). Each one has a different antenna so I need to be able to distinguish between them.

We can display connected devices with:

device_list = SoapySDR.Device.enumerate()

for device in device_list:

    print(device)

With two AirSpys connected this gives:

{device_id=0, driver=airspy, label=AIRSPY [260868c8:2673939b], serial=260868c8:2673939b}

{device_id=1, driver=airspy, label=AIRSPY [260868c8:266b479b], serial=260868c8:266b479b}

I've tried many approaches for then using this info to a specific SDR. Two of these are:

1) 

args = dict(driver='airspy', serial='260868c8:266b479b')

sdr = SoapySDR.Device(args)

args = dict(driver='airspy', serial='260868c8:2673939b')

sdr2 = SoapySDR.Device(args)

print(sdr.getHardwareInfo())

print(sdr2.getHardwareInfo())

This prints:

{device_id=0, origin=https://github.com/pothosware/SoapyAirspy}

{device_id=0, origin=https://github.com/pothosware/SoapyAirspy}

It's connected to the same device twice?

2) Instead trying to reference via device_id:

args = {'driver':'airspy', 'device_id':'0'}

sdr = SoapySDR.Device(args)

args = {'driver':'airspy', 'device_id':'1'}

sdr2 = SoapySDR.Device(args)  # Crashes here!

print(sdr.getHardwareInfo())

print(sdr2.getHardwareInfo())

However, this crashes at the seconds at the marked line, traceback:

Traceback (most recent call last):

  File "./multi_connect_test.py", line 36, in <module>

    sdr2 = SoapySDR.Device(args)

  File "/home/bill/miniforge3/envs/cusignal-dev/lib/python3.6/site-packages/SoapySDR.py", line 1926, in __new__

    return cls.make(*args, **kwargs)

RuntimeError: Airspy device_id out of range [0 .. 1].

Any advice would be great!

Thanks,

Bill

[righthal...@gmail.com]

In C++ , I do what amounts to -

sdr = SoapySDR.Device(device_list[0])

sdr2 = SoapySDR.Device(device_list[1])

perhaps that will work in python

[Bill Voss]

Thank you for the idea - unfortunately this gives the same error as my attempt 2), with the device_id being out of range.

I'm wondering if it is a bug in the python bindings.

[righthal...@gmail.com]

I could be that the driver can only handle one device at a time. Sdrplay can handle only one at a time. Rtlsdr can handle several sticks. You could test it with SdrGlut. SdrGlut can handle several devices if the driver is up to it.. 

https://github.com/righthalfplane/SdrGlut/releases/tag/v1.21

[Bill Voss]

Thanks for the input. I've got CubicSDR installed already, so I used that - I was able to open two windows, each reading from a separate AirSpy.

I think that this shows that the driver can handle multiple devices?

[righthal...@gmail.com]

CubicSDR uses the C++ interface  - there must be a problem with the python routines.

[righthal...@gmail.com]

What version of CubicSDR were you using and How did you get it to open two windows ? It always opens the second device into the same window as the first device for me with Cubic 2.3 and 2.5.

I have heard that you can open one device directly and a second device through soapyremote - perhaps that will work.

[Bill Voss]

I'm using CubicSDR v0.2.3 on Ubuntu 18.04. Just opening the app twice creates two separate windows for me.

Ideally, I would be able to reference device i with SoapySDR.Device.enumerate()[i] in Python, just like you do in C++.

I'll open an issue in github.

[righthal...@gmail.com]

I tried what you are trying to do with rtlsdr sticks - it opens both sticks without a problem. 

[Josh Blum]

FYI I moved the issue here: https://github.com/pothosware/SoapyAirspy/issues/26

This is undoubtedly the device index changing after the first open.

Ive been on a quest to make sure device drivers support open by serial and don't expose internal things like enumeration indexes.

I'm sure the original SoapyAirspy was only tested against a single device. And it definitely needs the "treatment" :-)

-josh

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[Bill Voss]

Thanks Josh!

I'll reply on the issue page.