FM interpreting system for 10 bucks?

I was recently at a conference where they used FM radio frequencies for interpreting. The attendants could either use their smartphones to receive the signals or borrow a pocket FM radio.

I thought: “What an easy alternative to the bulky, expensive systems you usually see.” So I did some research. There are some legal restrictions on broadcasting over FM, so it’s hard to purchase a cheap, strong transmitter, although it’s apparently easy to DIY.

However, there are tiny car radio transmitters on the web for 10 EUR or less that will do the job for most smaller settings. They easily broadcast 10 m and can be modded to extend the range. (The simplest way is to tape some copper wire to the casing, but there are more techy options on YouTube.) You can set them to send on any FM frequency, from 87.5 to 108.0 MHz. The sound quality is just like radio and there’s no delay, as in VoIP.

As interpreter you can use it with your laptop (speaking through a microphone and sticking the transmitter in your line out socket). In this case you have to do a few clicks de-mute your microphone (Windows).

Or you can plug it to your smartphone. There are apps that let you send your phone microphone to your headphone jack (where your FM transmitter is plugged in).

In the end, you should be able to simultaneously interpret for larger audiences using only your phone/computer, the transmitter and your listeners’ smartphones (or a couple of cheap pocket FM radios). Of course you need one transmitter per language pair.

You should be able to cover up to 20 m without major modifications. Let’s say you want 5 languages + 10 pocket radios. The whole set should cost you less than 100 EUR and fit in a handbag. I tested a single-transmitter setup; it works best using my laptop. Let me know in the comments if you find any improvements!


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