Beating Pirates at Their Own Game

Driving around the local area with my car radio tuned to 87.5 FM, I was really surprised at what I was able to pick up. After repeated tests, I've been able to work out that there's a small pirate radio station in my neighbouring town. They play a variety of music, it's a real (sometimes rather odd) mix with no commentary between tracks and every now and gain there is the sound of someone typing out a text message, so the audio source is an iPhone. It's been a really nice surprise to find and I've been listening to it lots as I pass through the town.

After further investigation, I was able to track one of the signals down to an area hotel on the edge of the town and I wondered if they were broadcasting music on their own in-house station, or it could be emanating from one of the nearby factories. When I was a student working in the factories during the summer months, you would have to wear ear defenders but these had radios in them that we tuned to an internal frequency that played albums on repeat. It's possible that this is what I'm picking up.

I have also started listening on 87.5FM close to the main A road that runs close to me. Those in-car transmitters are still very popular these days and I'm picked up many of them as they pass by. I guess people prefer 87.5FM as it's at the start of the dial and so easier to tune their cars' radios into them. These transmissions regularly get interupted by satnav announcements.

The following ideas and builds detailed in this post are purely for education purposes and I take no responsibility for how they are used by others. Please check your local laws surround FM transmissions.

I struck upon an idea. What if you could set up a small transmitter, ride out to said locations and broadcast my own content for those hotel residents and communters to listen to.  I have previously experimented with hacking those small in-car FM transmitters to boost their range (video below) and something like this could easily be utilised for what is now being called Project Warehouse Takeover.

The first prototype worked well and it was small enough to be clipped to a bike to become a truly mobile pirate station. I was even able to use a mobile phone as both a power and audio source, which was a really good last minute addition. As with most of my prototypes when they start out, they always start big in size and this first version was a little cumbersome to have clipped to a bike's handlebars.

To ensure no interference would be caused, a range check was conducted away from built up areas and a range of approximately 300 metres was achieved.

Taking the points from this test, improvements were made and a second, more compact transmitter box was built, complete with a detachable aerial wire. It still utilises the same idea as before of using a phone as a power and audio source.

Repeating the test and having a correctly matched vertical aerial wire, was able to just about achieve a distance of 500 metres before the signal complete disappeared into the static. That's 500 metres in all directions! That's a massive area for something as low powered as this.


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