Communications Blockset

Structure of the Demo

The demo contains the following elements:

• Master transmitter,
• Radio channel
• IEEE 802.11b interferer
• Slave receiver,
• Bit error rate (BER) display
• Instrumentation.

The transmitter subsystem performs speech coding, buffering, framing, header error control (HEC), forward error correction (FEC), GFSK modulation, and frequency hopping. Channel effects modeled include thermal noise, path loss and interference. The Free Space Path Loss block, from the RF Impairments library, models path loss. The IEEE 802.11b interferer is a masked subsystem that opens up a mask dialog for user input on double-clicks. Mean packet rate, packet length, power and frequency location in the ISM band can be specified in the mask dialog. The Slave Receiver recovers speech from the transmitted signal, performing all the complementary operations that the transmitter does, but in reverse order..

The demo makes extensive use of frame-based processing, which can propagate large frames of samples at each execution step, allowing for much faster simulation of digital systems. The double connector lines between the blocks indicate frame-based signals.

The demo also uses subsystems to organize groups of blocks, and it uses Goto/From block pairs and colored regions to make the block diagram visually neater.

Bluetooth Voice Transmission Demo

Mask Variables