How to get better sound from your FM transmitter

By Ulf Ligander

Radio 88

Gothenburg

Sweden

Many FM transmitters have built-in stereo audio inputs, and RDS encoders as accessories (RDS = Radio Data System) If you look around on the Internet you will find much of this hardware. Most people who buy transmitters or builds its own FM station, whether it is such a legal or a pirate, purchasing a complete stereo transmitters and RDS units.

Don’t!!

My advice is, buy a mono transmitter and make sure that it has a flat frequency response down to 10 Hz. Okay 50 Hz, but not higher! Why? If you like to have perfect modulation control, this is the best way to start.
You have a computer. Get a software like Breakaway Broadcast.
Replace your sound card in your computer with a good professional card. Jul@ works great.
Do you have a laptop, buy EMU 0202 USB card. The soundcard must have 192 kHz sampling rate.

Out from your soundcard you only use one of the stereo channels, connected to your FM transmitter audio in

Now you have a stereo transmitter with perfect control of your broadcast signal. Adjust it properly, you have 100% modulation, and one of the best sounding radio stations in your surroundings. Sound pressure is the cleanest and best you can get. RDS is not built into Breakaway Broadcast, but you can buy this software from Airomate. This small cheep program is prepared for use with Breakway Broadcast, and is stable to 100%.
Result is a stereo signal with RDS and 100% verification that you are not over modulate, and you have one of the best sound pressure on the FM band!

On your computer you have all the MP3 files you need. Use Zara Radio or some thing else, as your player, and make sure you use 320 kb/s Mp3 or FLAC files. Why? No listeners want to hear the bad sound from MP3 files less then 320 kB/s.. Trust me.. I hear it, and the hard disk is so big today so you don’t need lower bitrates.

Breakaway Broadcast.

http://www.claessonedwards.com/index.php?option=com_content&view=article&id=47&Itemid=55

Airomate RDS

http://www.diffusionsoftware.com/airomate.php

Juli@ soundcard

http://ixbtlabs.com/articles2/esi-julia/

FM Transmitter

http://www.progressive-concepts.com/info/item.html?id=45

Power Amp. and antenna systems

http://www.pcs-electronics.com/fm-amplifiers-c-41.html

This is what I recommend. Another transmitter maybe make a good result.