Single board cpu

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wildbillx

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I am wondering if anyone has set up a raspberry pi type single board cpu to run things like op25 (for phase 2 monitoring), unitrunker (to see systems), and a sdr# type program for analyzing. My idea is to have a small single board cpu with sdr dongle and a touch screen to do all the above for under $125. If anyone has tried this or something like this please let me know. Thanks
 

boatbod

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I think the general consensus is that a Raspberry Pi 3 doesn't have enough cpu horsepower to run OP25. You probably could make it work with a single board intel x64.
 

princessthelus

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OP25 isn't as optimized as DSD+. It would take some coders to simplify the code and make it not eat as much processor power as it does right now. I think though op25 is more just a project of seeing what they could do with P25 decoding as DSD+ is more of how much can we do with general decoding. I don't know how active the op25 team is but i think the code is GPL and open source so if you wanted to read a book on coding and make an android app with a dongle driver.
 

Dygear

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Max, who's an active OP25 dev, monitors this thread.

And I'd say that Raspberry Pi 3 is a hard choice to target for SDR just because you need some specialized code, namely ARM assembly, to make it fast to a level we would need. This is a pretty good overview on why embedded platforms are not great right now for SDR work.. I see that talk as more of a Call To Arms, than anything else. They admit up front that they need a better solution.

It should also be noted that as far as I am aware, none of the Raspberry Pi OSes give you access to the 64 bit registers. Right now PIXEL is running in 32bit mode, meaning you don't have access to the faster part of the CPU within that OS. You'd have to compile your own version of that OS to give you access to those registers. This is explained pretty well in the GRCon16 - GNU Radio and VOLK on ARMv8, Doug Geiger talk.

[Edit] So yeah, you should probably use a NUC.
 

WPXS472

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Has anyone considered thin clients? They have 1.8 Ghz Atom processors and a couple of Gigs of RAM. They are cheap on eBay. I have a couple of HP units and a couple of Dells. They run a stripped down version of XP. I seem to remember sticking a USB stick in one and booting to Linux without hassle. When I get the time, I am going to try one with an SDR dongle and SDR#.
 

kb5udf

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My efforts

This type of project was a fascination of mine some time back. I looked into many options including
various mini-pc boxes that could be trunk mounted on radio rack etc, like intel NUC.

I originally tried a refurb toshiba windows tablet I got for not much more than 100 bucks. It had sufficient horsepower to run unitrunker and decode p25 with dsd. Problem was Toshiba kept limiting the functionality of the one USB port to stop you from sending/receiving data and charging. After alot of work and research, best I could do was almost maintain battery (with a special cable) then get data out by having to use a powered usb hub, to which I connected
the rtl dongles. The result is functional, and I run it on my desk sometimes, but resulted in a rats nest of wires.

Next, I found a cheap windows netbook on ebay for 100 bucks. Much easier solution. I got two 5 dollar LTE antennas which do great on 700/800 and they stick up off the screen like rabbit ears. The netbook has full sized usb ports, so I attatch the dongles with short cable extenders so as not to stress the usb ports on the netbook. This setup has worked reasonably well, and I use it mobile on trips if wife is driving. If you wanted less clutter I suppose you could do something like sticking the dongles and cables to the lid of the netbook with epoxy, or having some type of remote hub and antennas in your trunk, with just a usb exentension cable to the netbook.

FYI forgot to mention both of these setups have been used to run, I believe what is called rtl-scanner, that does spectrum sweeping.

I would close with this. I think ultimately a windtel tablet offers a pretty simple and elegant solution, given the built in touch screen, provided you
find one that can send/receive usb data and maintain a charge/keep powered up indefinately.

Good Luck and let us know what you decide; happy experimenting!

KB5UDF->W5JAB
 
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cg

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I use Thin Clients for remote monitoring (ProScan & 996P2's) and have tried to get them to do DSDPlus with poor results. I think the processors are not quite robust enough for DSDPlus w/ FMP24 and the audio hardware may be an issue as well. Some of the real new ones have dual core x86 processors so may be able to handle the needs of DSDPlus & FMP24. The newer Thin Clients also run newer versions of Windows Embedded. You do need to learn some basics of working with TCs but they are fun once you get them up and running.

They also use very little electricity, I think my scanner/TC setups each use around $0.25 worth of electricity a month. Another benefit is that you can set up the TC to restart if there is a power failure.

I would think Unitrunker using RTL-SDR type dongle would be no problem as would TRUNK88 with a RTL-SDR dongle.

chris
 
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