Engineering FM – Part 2

This is the second in my series of posts looking at the engineering side of running a community radio station broadcasting on FM. For part one, look here.

This post will be focusing on telemetry, focusing on doing telemetry over IP and integrating bidirectional telemetry for radio metadata.

In our TX system we’ve got a fair few elements – a codec, a silence detector, a redundant playback device (a CF card MP3 player on our budget), a processor, a RDS encoder, a transmitter and a redundant power supply, plus an off-the-shelf (well, out-of-the-skip, actually) 1U rackmount computer. All of this is locked in a rack in a building we have limited physical access to outside working hours (normally – exceptions can be made in emergencies), and it’s not exactly in a convenient place to check by just wandering past it. Additionally, there are periods where the station’s staff are much reduced (over holidays). All in all this means we have to be able to monitor all of the equipment remotely somehow. It’s also convenient for us to be able to control things remotely, and for some things like the RDS encoder we need to be able to control it remotely nearly 24/7. Continue reading Engineering FM – Part 2

Engineering FM – Part 1

This post is the first in a series of posts I’m going to do covering some of the engineering aspects of setting up a Community FM Radio station in the UK, and the lessons I and others learned while setting up the system.

First a bit of background. The station I helped set up, Insanity Radio, will be launching its FM transmissions in the coming weeks, and is a station run and operated entirely by students at Royal Holloway, University of London. The station started back in the 90s broadcasting on FM using a low-power rented transmitter, licensed under Restricted Service Licenses (RSLs) which only allowed for a week or two of broadcasting at a time. The station eventually moved to full-time AM operation, under a Low Power AM license. Back in 2006, a previous manager applied for a license for Community Radio, to permit FM broadcasting on a permanent basis, and in 2009 that license was awarded to Insanity by Ofcom, the UK’s radio regulatory body.

Our license was awarded for a 25 watt EIRP mast to be installed on campus. So in 2009/2010 we got the ball rolling with planning. Continue reading Engineering FM – Part 1

Interfacing Rivendell with the real world on a budget

So, you’ve got this lovely, expensive broadcast console your previous engineers have left for you sitting in your studio. And you’re using all of 3 microphone inputs and a few line inputs.

And, of course, the logic facilities of the console are entirely ignored. It’s a shame, isn’t it? A microphone live light is a wonderful thing to have, and there’s so much you can do with a little bit of GPI. But the cards that provide you with general purpose inputs tend to be expensive, odd and awkward little bits of kit to work with. Let’s fix that! Continue reading Interfacing Rivendell with the real world on a budget