Going Digital

Forum for DMR, dPMR, NEXEDGE, Mototrbo, MARC, Tetra & all other DIGITAL modes

Going Digital

Postby LewisW296 » Sat Apr 21, 2018 12:58 am

Good Evening all,

I've been doing a bit of "google-jitsu" regarding scanning digital frequencies. It is at this point, I should warn you that I'm an utter noob to digital scanning. There are 2 things that keep repeating themselves and that is a discriminator tap modification (which is not an option) and some sort of dongle which doesn't require any modification. Can someone please explain to me what I would need to do (or link me to some easy reading literature regarding it) if I wanted to pursue the dongle path. And a few questions:

1. Is this tech still "valid" in the current scanning community?
2. Some sources have said the dongle acts as a scanner to itself. Does this mean I won't require the scanner?
3. Can someone cite me a reliable dongle?
4. Is there any other software required for the dongle to work?

Sorry for the noobish questions but we all start somewhere. And weighing in on a 4 year old thread... well that's just rude :wink:
LewisW296
 
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Re: Going Digital

Postby G4RMT » Sat Apr 21, 2018 10:42 am

You need to google sdr-plus and ssd-plus. There plenty of youtube hits - some good some confusing. Essentially though the basics are these.


All dongles are not equal - the receivers all have far more spurious responses and odd noise floor increases than 'real' radios, but they are of course dirt cheap. The killer for success is how good you are with computers. One of our members here spent three frustrating months struggling to get going because with computers, they're all slightly different, so help is tricky - different menus, different windows, different ways to access things. Once you get the things working in analogue, you discover they are NOT a scanner. They listen to one frequency. They can have lots of hits stored but they did not scan between them, or click through memories and stop. They display what they are hearing visually which is brilliant and you can see nearby hits pop up, click on them and hear them. The DSD software allows your computer to decode unencrypted digital transmissions. Again, it's notoriously tricky to get set up on some computers and needs some understanding of how your computer routes the data - so what comes out of the SDR gets routed to the digital software, then what comes out of that goes to the speakers. Once you get them going they are great for giving you the info to put in a digital radio system - the software tells you it's slot two, and perhaps a certain colour code - and of course what kind of digital signal it is. If you have a handheld digital radio, SDR and DSD can make programming much easier as you know what to enter.

I have a few dongles I've picked up on the net - some are good for HF and not so hot above, others don't do HF and are OK on UHF and VHF. They all indicate signals exist where they don't. You see a spike on the screen that isn't a valid signal but a birdie generated internally. They have very little filtering, being tiny so often get swamped by very strong signals. They need you to adjust gain and other parameters to suit your location and antennas, and they all tend to be a bit unreliable on their accuracy - so you find a signal on a known frequency and then adjust the display so the line is on the right frequency. Mine also drifts - meaning I do this fairly regularly.
They're great things - just don't expect miracles - and I have two of one dongle type, and they are quite different in performance, but for twenty quid.......?
G4RMT
 
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