Simple FPGA FM transmitter
May 7 - Radio Day!
I hope this note will be just in time.
Recently, an article about a project based on the Raspberry Pi board was on the hub - just a piece of wire was connected to it and ... that's all. The program running on the Raspberry Pi managed to broadcast in the FM band simply through this piece of wire.
Here is a link to that article on the hub
Now a similar project has appeared for Altera Cyclone III FPGAs. Again, a short piece of wire is connected directly to the output of the chip, in this case, the FPGA chip.
Audio file in WAV format 22050Hz, 8 bits, MONO is simply transmitted to the board via the serial port. The board accepts bytes and broadcasts this stream in the FM band at a frequency of 90 MHz.
There is a demonstration video broadcast on youtube, though the music is somewhat sleepy.
It can be seen that the melody is received not only by the household radio next to the board, but also in the car in the yard, about fifteen meters.
The original project for the Mars rover2 board with a detailed description appeared here .
The frequency modulator itself is written in Verilog HDL and is very simple. The project uses an initial frequency of 450 MHz and is almost always divided by 5 with a resulting frequency of 90 MHz. Since for frequency modulation it is necessary to change the frequency within small limits, sometimes after many divisions by 5 the insert “division by 4” is done. The more such inserts, the higher the average frequency of the digital sequence. This is sufficient for the receiver to detect the signal.
It’s good that there are quite detailed explanations for the project and testbenches and timing diagrams of signals. Now, dealing with the transfer method has become quite simple.
I hope this project will be interesting to everyone who is interested in radio, as well as digital FPGA circuitry.
I hope this note will be just in time.
Recently, an article about a project based on the Raspberry Pi board was on the hub - just a piece of wire was connected to it and ... that's all. The program running on the Raspberry Pi managed to broadcast in the FM band simply through this piece of wire.
Here is a link to that article on the hub
Now a similar project has appeared for Altera Cyclone III FPGAs. Again, a short piece of wire is connected directly to the output of the chip, in this case, the FPGA chip.
Audio file in WAV format 22050Hz, 8 bits, MONO is simply transmitted to the board via the serial port. The board accepts bytes and broadcasts this stream in the FM band at a frequency of 90 MHz.
There is a demonstration video broadcast on youtube, though the music is somewhat sleepy.
It can be seen that the melody is received not only by the household radio next to the board, but also in the car in the yard, about fifteen meters.
The original project for the Mars rover2 board with a detailed description appeared here .
The frequency modulator itself is written in Verilog HDL and is very simple. The project uses an initial frequency of 450 MHz and is almost always divided by 5 with a resulting frequency of 90 MHz. Since for frequency modulation it is necessary to change the frequency within small limits, sometimes after many divisions by 5 the insert “division by 4” is done. The more such inserts, the higher the average frequency of the digital sequence. This is sufficient for the receiver to detect the signal.
It’s good that there are quite detailed explanations for the project and testbenches and timing diagrams of signals. Now, dealing with the transfer method has become quite simple.
I hope this project will be interesting to everyone who is interested in radio, as well as digital FPGA circuitry.