Hackrf One signal loss randomly

[Alexander Benfatto]

Hello,

I’ve installed an Ubuntu virtual machine (VMware) with the latest DAB tools. I’ve managed to get the DAB+ transmission to work with two radio stations. So far, the transmission works fine for an hour or two but there are times where the signal drops out completely out for a few seconds randomly.

I’ve read somewhere it might be the clocking of the hackrf one device. I’m not sure.

Can anyone point me in the right direction in how I can solve this problem?

Thanks,

Alexander

[Alexander Benfatto]

Hello again,

This is just an update.

I would like to also add there is no errors / warnings or info’s on any of the console windows where the transmission end is running. This is quite amazing / strange. Therefore, is making it harder to find the problem. Any help world be appreciated.

Cheers,

Alexander

[Rashid Mustapha]

Hi Alexander,

You should probably try your modulator implementation on with an OS running on bare metal, not a hypervisor. Although the other tools (ODR-audioenc, ODR-DabMux) are generally ok when virtualised  The abstraction from the hardware adds a lot of unknowns. If you absolutely must...use a container (docker) as at least that uses the kernel directly rather than a via a 3rd party.

That said, it may well be clocking. Does your SDR have a TCXO fitted? Also, have you proritised/niced odr-dabmod and the HackRF transfer tool appropriately? There are errors in you screenshot suggesting not.

R.

  

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[Alexander Benfatto]

Hello Rash,

Thanks for your answer. In the past I have tried running the whole thing (the modulator) in bare metal). In other words, there hasn’t been a difference between running it between a hypervisor and bare metal. The signal still drops out randomly. I could try it on a different machine and see the results. The different machine is older maybe it might give me some better results.

Quote: “Does your SDR have a TCXO fitted?” I believe not. I think it is the stock version. Does this really matter? Since it is perfect for any high-accuracy experimentation such as GPS-related projects. Does this include DAB / DAB+?

Quote: “Also, have you prioritised/niced odr-dabmod and the HackRF transfer tool appropriately?” I’m not sure what you mean by the question (to be exact), however I am having problems with prioritisation with the modulator but I’m not sure how to fix it. Any help / ideas would be nice.

Alexander

[Rashid Mustapha]

Hello again, 

Take a look at the man pages for 'nice'.

If that doesn't make the problem go away, you could look into HackRF clocking...

R.

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[Alexander Benfatto]

Hello Rash,

Thanks for your answer. I have used the nice command for odr-dabmod with good results. The transmission went fine for over 6 hours (only one time).

I’ve decided to return to the “hackrf_transfer” command for further exploration. My transmission sample rate is 6144k and in the mux my “zmq-buffer” is :40 and also my “zmq-prebuffering” is :20.

In the attachment you can see the “hackrf_transfer” console. The constant transmission to the hackrf is always about 12.3 or sometimes 12.1. You can see highlighted that the transmission to the hackrf drops to 10.7 then spikes to 13.1 then goes back to 12.1 then 12.3. during that time is where the signal drops. It now seems to be apparent that this is not a clocking issue but a buffering issue.

Is there a way I can solve this issue?

I’ve noticed when the transmission ran for more that 6 hours the physical machine (where the VM is running) was idling the whole time.

I know that sometimes Windows 10 does other hidden tasks that might break the transmission / buffer.

Cheers,

Alexander

[Rashid Mustapha]

Hi,

You could try adding a buffer into the pipeline. The below might need checking though. One can also specify the block transfer size etc..

|mbuffer -m 2M -P 80 -q |

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[Alexander Benfatto]

Hello,

I’ve installed Ubuntu 20.04 on my computer (bare metal) and also the packages required for the DAB modules to be compiled. All went successful. I’ve then started transmitting in DAB+ and found out that the signal keeps on dropping out every half an hour to an hour. This is a bit worse than when I was running it in a virtual machine (in VMware). I’m posting the full commands and the files that I using if anyone can point me in the right direction or if I’m missing something.

Any help would be appreciated.

Computer Specs:

CPU: Intel Core i5-8400

RAM: 32GB

Network: Gigabit Lan

Cheers,

Alexander