Cheap radio monitoring equipment part 1

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Cheap radio monitoring equipment part 1

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January 25, 2016 at 2:59 pm

#703065
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General Lighting

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This lot would have set you back about €10 000 just a few years ago!

Below are two links for where to get it from Amazon + some useful advice from the radioamateurs in Essex (I may even get my license from one of their clubs as our local one only does it once every year in October and I missed last years weekend, ironically because I was working long hours getting some WLAN equipment to work correctly!)

I actually have a Ofcom suppliers license for UHF/VHF communications radios but that doesn’t allow me to transmit on amateur frequencies; although everyone is permitted to monitor them. It is also now legal to monitor aircraft and maritime comms (as we are in the EU/CEPT).

As the radioamateurs are usually middle class folk who stay on the right side of the law the essexham links don’t explain some of the other stuff like decoding pagers (although its legal for me to decode my own messages) and/or your neighbours remote controls/alarms; as well as model aircraft and drones and other such things but once you’ve installed the software its easy to work out where these signals are and get software to process them. I have included a link from the main RTL SDR site which some other decoder apps 😉

Realtek Software Defined Radio for £10

More on how to configure the software – you will need a fairly powerful computer, Win7/10 are best unless you are a Linux boffin. In some cases you will need the free virtual audio cable so you can “pipe” the output of the radio receiver into software that expects a soundcard input.

Realtek RTL SDR Dongle Explored by Essex Ham

The BIG List of RTL-SDR Supported Software – rtl-sdr.com

VB-Audio Virtual Apps=[

I suggest also buying the MCX to PAL TV antenna adapter as the small antenna supplied with the device isn’t much good. You can build your own antenna using a TV antenna plug, coax cable and bits of wire; its size will depend on what frequencies you plan to monitor.
February 16, 2016 at 9:11 pm

#979490
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@general-lighting

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This is the RTL-SDR in action (monitoring a cheap Chinese mini transmitter of the sort sold in supermarkets for listening to MP3 players in older cars that only have VHF/FM receivers). These transmitters are always slightly off frequency – apparently because a cheaper quartz (also widely used in other computer equipment) can be used in the PLL circuit instead of one cut for a specialised frequency.

There since appears to be someone else using 87,5 Mhz in the area with a stronger signal (and hopefully better equipment!) – in case Ofcom happen to be watching that is nothing to do with me!

That said if I’d known they were planning to be on air tonight (when I checked earlier the frequency was clear) I’d have picked another test frequency rather than cut across the pirate as I used to do the same stuff back in the day (many years ago!) so have some respect for them – they have at least picked a frequency which is less likely to cause problems to other VHF transmissions (there is a lot of maritime and aviation comms round here) or make things awkward for the community broadcasters at the other end of Band II (105-108 MHz)

I was only making this video to show how the RTL-USB SDR setup works – pager transmissions don’t sound quite as pleasant and are too short in duration to show the pretty colours on the display…
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