Documentation

This is machine translation

Translated by Microsoft
Mouse over text to see original. Click the button below to return to the English verison of the page.

Bluetooth Frequency Hopping

This model shows a simple Bluetooth® wireless data link. Bluetooth is a short-range radio link technology that operates in the 2.4 GHz Industrial, Scientific, and Medical (ISM) band. The example modulates signals using Gaussian frequency shift keying (GFSK) over a radio channel with maximum capacity of 1 Mbps.

The example uses frequency hopping over a 79 MHz frequency range to avoid interference with other devices transmitting in the band. In this scheme, the sender divides the transmission time into 625-microsecond slots, and uses a new hop frequency for each slot. Although the data rate is only 1 Mbps, a much larger bandwidth of 79 MHz is required to simulate the frequency hopping effects.

Structure of the Example

The example contains a master transmitter, a slave receiver, and an AWGN channel in between.

  • A Binary Cyclic Encoder block is used for the error correction encoder.

  • The frequency hopping GFSK modulation is constructed with a CPM Modulator block and an MFSK Modulator block.

  • An MFSK Demodulator block is used to construct the frequency hopping demodulator.

  • Receive Delay calculation: The 'Assemble Packets of 625 bits at 1Mbps' buffer causes a delay of 625 samples. The 'Disassemble packet' subsystem contains a buffer with the output size of 15 which cases a delay of 15. Further, the signals have to be aligned before they are passed through the decoder as each 10 bit message corresponds to a particular 15 bit sequence. For this a 5 sample delay is used in 'Disassemble packet'. Thus the total delay is 625 + 15 + 5 = 645. As the processing is done to the samples that have been cyclic encoded with a rate of 3/2, the effective sample delay in the system is 645*2/3 = 430.

The received signal spectrum is shown by the Spectrum Analyzer

Results and Displays

To examine the performance of this example, double-click the icons to open the error rate display and scopes.

References

The Bluetooth standards can be found at: http://www.bluetooth.com/

Was this topic helpful?