[op25-dev] RTL-SDR and OP25 on Linux Mint 64-bit

iain macdonnell - N6ML n6ml@dseven.org [op25-dev] op25-dev at yahoogroups.com
Tue May 15 16:47:18 UTC 2018


On Tue, May 15, 2018 at 9:31 AM, mpuppet at yahoo.com [op25-dev]
<op25-dev at yahoogroups.com> wrote:
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> Hello everyone,
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> First of all: Thank you to the admins for granting me access to this group! :)
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> I am a musician and IT professional living in southern California, but I have little experience with radio. I recently bought an RTL-SDR dongle (the silver one) and I successfully got it working on Win10 with HDSDR and DSDplus, so I can decode DSD and P25 phase I, mainly. I also have an installation of Linux Mint, 64-bit. I'm running everything on a gaming PC that I built, so it's got a lot of speed and RAM.
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> Before I gained access to this group, I followed this PDF to setup the dongle on Linux Mint:
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> https://ranous.files.wordpress.com/2018/02/rtl-sdr4linux_quickstartv2-18.pdf
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> I then managed to get OP25 installed. Once I gained access to this group and started to skim over the various tips and tutorials, I took a few days to decide what options I wanted to try: Raspi+OP25? Ubuntu 14.04 32-bit in a VM? Or stick with Linux Mint?
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> I decided to try the Ubuntu 14.04 32-bit tutorial yesterday. I spent the entire day trying to get Ubuntu 32-bit installed in a VM before I realized it didn't like that I was trying to give it 16GB of RAM. 8GB did the trick. But after following the tutorial found here from 2017, OP25 generated a lot of errors and decided to put it down and go back to Mint for a while.

I've had success with boadbot's fork on both Ubuntu 18.04 and Mint
18.3 (both 64-bit) within the last few days - see the last couple of
pages of https://forums.radioreference.com/software-defined-radio/301459-virtualbox-project-run-op25-windows-7-a-101.html

14.04 is pretty old at this point - I wouldn't use it as a starting point.


> Through the tutorials and RadioReference.com, I managed to find a local p25 control channel for the police. So I setup a trunk.tsv file and trunkk.tsv with the groups I wanted to listen to.
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> As of this morning, I was able to run OP25 in a terminal window in Mint, tuned to 470.025, using rx.py.
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> The command I am running is:
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> python rx.py --args 'rtl' -g 65 -f 470.025e6 -N 'LNA:49' -2 -V -v 0 -S 1000000 -q 2 -T trunk.tsv
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> The problem is, I'm not sure if it is working because:
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> 1. I hear no audio (using an external sound module, alsamixer is working properly to route audio to this device)
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> 2. When I run the script with the above command, my terminal window fills up with the error "tuning error +1200".  The frequency displays in the lower left corner as 470.025000.

You should redirect stderr to a file to avoid interfering with the
curses interface - append "2>stderr.log" to your command line.

"tuning error" generally means that you need to do some fine-tuning.
If you have gnuplot-x11 installed, you should be able to bring up
spectrum or mixer plots, and use that to see if your control channel
is centered. If not, adjust your PPM (-q) and fine tune (-d) to fix
it. When you get the control channel, you should see the "tsbks" count
continually increase in the top bar of the UI.

    ~iain
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