Very short range bidirectional RF link.

[moby]

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

 

[Phil Allison]

"moby" <[email protected]


** Beware - Sheep Shagging, Google Groupie

Baaaaaaaahhhhhhhhhhhh ..............

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

** 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

 

[John - KD5YI]

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

A method:

http://www.imagineeringezine.com/journal/bpulse.html

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

Cheers,
John

 

[Bob Monsen]

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

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