Wireless digital audio transmission

As communication modules NRF24L01 were used (Semiconductor). They work on 2.4GHz band. The sound is compressed to MPEG1 layer3 format.
Transmitter:
It was built on AT91SAM7S64 microcontroller.
Because of the transmission speed of NRF24L01 (400kbps) as a sound encoder, the LAME MP3 Encoder was used. The bitrate was set to 320kbps. The compression is made on the computer.
A output module to PulseAurio was written, therefore all the sounds can be sent to wireless speakers. The delay associated with buffering can be adjusted. The transmitter is seen in the system as a serial port /dev/ttyUSBx



Receiver:
The processor is AT91SAM7S512 (this decoder requires many RAM), Helix decoder, as a DAC TDA1543 was used:



Schema:



Range:
It works through a wall, through floors, etc. (sometimes, the antenna must be set to right angle):

An Logitech Unifying receiver was programmed, but it has lower bitrate (128kbps) and lower range. Why LAME not A2DP? A2DP is not stable, and LAME has better sound quality.

Updated version:
With DAC CS4344



Comparison with the old edition (with external DAC):



The transmitter is a reprogrammed Logitech Unifying with an additional antenna



Screen from PulseAudio:



The new version can measure the input voltage.
Current consumption:

• about 60mA while playing
• about 14mA while waiting for transmission

Available connectors: I/O, PWMs, RS, I2C, LEDs, USB
Instead of audio socket, 4 goldpins can be mounted.

Receiver schema:




Link to original thread – Bezprzewodowa cyfrowa transmisja audio.