Radio - without the radio - SDR software defined radio

Channel Hopper

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Whilst I have a number of valve sets on bookshelves, the aerials outside are in serious need of maintenance owing to some rodents and rot setting into the clamps holding the poles and the nylon isolators. I'll get round to it at some point

In the meantime howeverI have been dabbling with a virtual online system called Hamsphere for the past couple of months and was quite impressed on how friendly it was to use.

That was until I saw this one earlier this week

http://websdr.ewi.utwente.nl:8901/

Unlike Hamsphere there is no logging on required Additionally the 'waterfall' facility gives a very easy guide as to which frequencies are being used, from longwave up to the 20metre band (14MHz or so), and there are buttons for changing the bandwidth and side band facilities.

A very nice piece of SDR (software defined radio.)
 

PaulR

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I went to talk at our local radio club last month about SDR and very interesting it was. You can turn a £5 FM dongle into a very powerful device with a very wide frequency span with suitable software - most of which are open source and free.

Then we went on the Internet and logged into a site (it may have been the same) and used the equipment at a distance.

Marvellous stuff and I want to play with a dongle (oo-err missus) myself.
 

Archived-1

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yes we have moved a long way over the last few years airplay speakers are great c/h for sending sounds around the house but do come at a price atm :-(.
 

2cvbloke

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I'm guessing that this is the radio equivalent of C*Net (see https://www.ckts.info/ ), allowing you to interface older equipment with services streamed over the web (In the case of C*Net, it's connecting everything from a simple software phone on a computer to real telephones, and simple PBXs to whole Strowger exchanges, all via VOIP), though when it comes to radio, it has me at a loss as I never realy got into radio communication, the most I ever did was dabbled in CB radio... :lol:
 

Hixxy1

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The possibilities are endless with SDR. There's the drm receivers about. There's some people that's made DAB transmitters and multiplexes using some sdr software and I've even heard talk of people hacking the police tetra radio systems using sdr devices.
 
A

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image.jpg Got my dongle today and everything seems to be working well. Just needs an arieal from outside. Well worth £4.98 inc postage.
 

Fisty McB

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I've been on that University of Twente SDR receiver a few times, and a very good job it is too.

Also have one of those RTL2832 dongles for cheap SDR. It's OK but I wouldn't rely on it for very serious DX work simply due to the nature of the dongle only being a few quid not hiding its sensitivity and selectivity - it overloads easily and there are notable spurs of interference. But for its price there's not really any room to complain, plus you can use it on a few Android tables and phones where it supports USB on-the-go for a very portable solution.
 
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The possibilities are endless with SDR. There's the drm receivers about. There's some people that's made DAB transmitters and multiplexes using some sdr software and I've even heard talk of people hacking the police tetra radio systems using sdr devices.
Is there any way of recive tetra?
 

Channel Hopper

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Of course, the frequencies (380 - 464 MHz) are within the range of most UHF dongles, but there would be an issue with the decryption. The official transceivers are not that expensive in the first place.

http://ukradioscanning.com/viewtopic.php?f=5&t=53
 
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aceb

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No, you won't be able to listen in to the old bill or any other airwave user, either with an SDR or hardware. True the RTL dongles do suffer with their low dynamic range but much of the noise is generated from the USB port and PC in general. I've mounted mine is a copper clad container and used decent connectors and cable through out, the PC is already as quiet as I can get it for radio work and the end results are excellent. The dongle definitely does not lack sensitivity in the urban environment, waterfall traces and recovered audio easily match my Icom 8500. To get the best out of these dongles a big antenna and appropriate filtering are recommended.
 

Hixxy1

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Is there any way of recive tetra?
Yes you can recieve and decode Tetra using a dongle/SDR and Linux software.

However, if you're trying to eavesdrop on the UK police, they use an extra layer of encryption. Which results in a load of muddy noise, similar to a weak DAB signal.

There's a few videos on youtube of people demonstrating their rig in action.
 

smoggy07

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Would that be the same as the ambulance & Fire service?
yup, the ambulance and fire brigade should all be on the airwave net now, the only exception being the uhf fireground freqs up in the 400`s (around 457.xx I think) but you'd need to be really close to hear them

you've got no chance of listening to airwave unless you can acquire a "lost" handset that hasn't been stunned, airwave uses secure TEA2 encryption and unless you have the keys you cant decode it
 
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