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Old 07-10-2017, 11:13 PM
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Default Revisiting OP25

Hi Guys,

So last year I leaned in and got op25 up and running, started on trunk recorder and and then life happened (if your interested ask in a PM and I can fill you in but have a box of tissues ready, just sayin) and I kinda stepped away from all my projects for a while... now I'm back, revisiting op25 kinda went full circle, trying to install it on the latest version of ubuntu and the punting back to 14.04. haven't even attempted trunk recorder again due to my epic failures in the past. pretty sure these cheap dongles are too unstable for trunk recorder.

currently I monitor this system https://www.radioreference.com/apps/db/?sid=6916 specifically the Kansas City Simulcast with marginal success, I know I'm missing a lot of traffic and there are a number of factors. my el cheapo rtl-sdr dongle, my old pc hardware and the minimal antenna (currently the one that came with the dongle) so I'm kinda wondering where the most bang for my buck is at?

I could spring for an airspy mini which would cover the entire system. for close to the same money I could up grade my mobo, processor and memory, or I could spend that same dough on an antenna. now at the end of the day, I plan to do all of that.... but from a bang for my buck perspective what is the top priority?
I
Also I've read a few post about rx.py? which suggest it works on new versions of ubuntu? haven't found anything overly descriptive... In fact most of what I've found revolves around running op25 in a VM with host OS of winblows... [shudder]

So I'd like suggestions, where to start?

TIA
Ralph
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Old 07-10-2017, 11:43 PM
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I haven't dug into OP25, but having used RTL's for quite some time, the best bang for your buck would be a decent antenna. Not sure which RTL you bought, but if it was the one that came with the remote and short whip, that is probably where much of your problem is. Those antennae belong in the trash can.

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Old 07-10-2017, 11:52 PM
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Quote:
Originally Posted by Markb View Post
I haven't dug into OP25, but having used RTL's for quite some time, the best bang for your buck would be a decent antenna. Not sure which RTL you bought, but if it was the one that came with the remote and short whip, that is probably where much of your problem is. Those antennae belong in the trash can.

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Got this guy here,https://www.amazon.com/RTL-SDR-Blog-...ds=Airspy+Mini

it has a prolly 5 ft antenna, I and use it with a usb extension so it's not right on the the CPU... what I do receive is pretty clear (sans the encrypted bits).
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Old 07-11-2017, 6:16 AM
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Cheap $25 RTL dongles work great, but you really need to acquire at least one that has a TCXO because they are so much more stable. I have two, and they both work with 0ppm correction at 773Mhz. (Note: op25 only uses one dongle and will retune itself when outside the sample window.)

As far at op25 versions are concerned, the main line of the repository runs a python app called scope.py which requires Ubuntu 14.04 due to use of specific wx widgets library for the GUI. The 'max' branch has a different python app called 'rx.py' which is curses (text) based and does not require a gui to operate. Optionally you can enable one of several graphical plots which are implemented using gnuplot 5.0 and are thus compatible with Ubuntu 16.04 and later.

rx.py is still evolving and has a few rough edges that are being worked out. One nice feature is the ability to decouple the reception and audio as the stream can be passed across a network via udp if desired. I've heard that Max has a rpi3 successfully running op25 - as soon as mine arrives I plan to try that for myself!

I'd strongly suggest steering clear of virtual machines. I know the main op25 thread was started as a discussion of that topic, but it's really pushing things to run it that way especially if you want nice clean audio.
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