how working a Wireless Microphone Systems?

[macxom]

how working a Wireless Microphone Systems ?

 

[flatulent]

several ways

There are several ways of doing this. The cheapest is to use a one transistor FM transmitter in the FM broadcast band and use a FM broadcast receiver.

A more complex way is to have a quality FM transmitter on one of the television channels and have a custom receiver for it

High end units use the 900 MHz band and digitize the voice and use digital transmission methods with a specialized receiver.

You can also use this method with a blue tooth module for the radio link and use the computer sound card for output.

 

[rfsystem]

If a multiple mic system have to be build a TDMA access sheme should be used. Depending on the level of design you could built up yout own radio and baseband processing.

If you have to reuse some components DECT would be a candidate. It is TDMA with 64kBit/s at one of the 12/12 up/downlink channels. You can combine channels to get n*64kBits/s. DECT was also applied to 2.4GHz ISM by using half of the RF data rate and using half of the time slots. So the FCC emision req. was met and the radio/baseband was preserved.

 

[johnseven]

RFsystem,

Your idea sounds interesting.
Where can I learn more about DECT ?
If your idea works, it would be possible to have a 16 bit 44 Ks/s
wireless mic. (add diversity to minimize multipath conditions).
I worry about real-time performance.
Will there be a delay due to processing ?
Thanks

J7

 

[rfsystem]

National Semiconductor supplies a BB+RF chipset. I think you need some compression method before transmitting data.

DECT uses GFSK at 1.9GHz and there is only antenna selection diversity which is evaluated on a nonstandard prolonged preamble.