This project is about the realisation of an audio link using ZigBee, a standard for low-data wireless communication in the field of sensor networks with focus on economical improvement and reliance while reducing the required amount of power.

Zigbee easily reaches its limit of performance when transferring audio data; hence we examined the maximal data rates of a ZigBee connection on a theoretical basis and verified the results. Half of the available 250kbps bandwidth in ISM-band gets lost when using the ZigBee standard, and due to the inefficient software stack by Microchip the available bandwidth bisects even a second time.

Due to the scarce bandwidth, an audio compression cannot be avoided, hence another part of this project is devoted to evaluate and implement a suitable audio codec on the dsPIC we used. The used adaptive PCM-codec allowes to compress audio data with rates between 16kbps and 64kbps, also there is a hardware MP3-decoder available to transfer music.

In order to use ZigBee for the RF-transmission the following options have been made available: a ZigBee-transceiver by Jennic, an IEEE 802.15.4-transceiver together with the ported stack and a PICDEM Z-board (converted to a modem).

In the end we have developed a circuit, which allows to record speech using a microphone and to send it from a node to the coordinator where it can be reproduced by a headset. At the point of delivery time, the transfer of a 32kbps-ADPCM-encoded datastream using the PICDEM Z modem, is successfully and fully working.