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Very short range bidirectional RF link.

I need to be able to transmit analog data (1..100khz) over a very short range (max 2 metres) reliably and without wires. IR is not a possibility as there are times when the stations will not be able to "see" each other. Latency must be much less than 1ms, hence digitising and bluetooth (with its 40..50ms latency) is out. Several pairs of units may be being used in close proximity hence single frequency "garage door opener" style devices are out. Of course it has to run on 3 volts, almost no current and be no bigger than a quarter. Any chips or modules suitable ?. cheers M

Reply to
moby
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A method:

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Achieving it within the other constraints (no current, size of quarter, etc) will depend on your abilities.

Cheers, John

Reply to
John - KD5YI

Check out the laipac tech RF ASK modules. You can either encode the data yourself, or use them in conjunction with the Holtek HT12E and HT12D encoder and decoder chips, which will do it for you, and also allow

8 bit addressing of devices.

They are not tranceivers, so you'll need both a transmitter and a receiver for each station, and some kind of simple protocol for preventing garbled data (eg, checksums, packet headers, sequence numbers, retransmission, etc, etc.)

They have pretty good range, and don't require anything fancy for antennas (1/4 wavelength wire works well. 1/2 wavelength dipole would probably work better, although I suspect they are impedance matched for the wire antenna. They are 433MHz).

If you are looking for chip level solutions, try Chipcon. They have various tranceivers on a chip that would work for you. Their Zigbee chips may be what you want. They will do more of the high-level work for you.

Microchip also has a transmitter on a PIC + external receiver chip solution (see rfPIC on the microchip site).

--
Regards,
  Bob Monsen

What good your beautiful proof on (the transcendence of) PI.  Why 
investigate such problems, given that irrational numbers do not even exist?
- Leopold Kronecker
Reply to
Bob Monsen

"moby" I need to be able to transmit analog data (1..100khz) over a very short

** You will have to place your future order with the Intergalactic IC Warehouse on Mars.

Minimum quantity = 10 billion units.

The folk from Alpha Centuari have them all on back order at the moment.

........ Phil

Reply to
Phil Allison

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