Abacom Transceivers?
Alan S. Timm
Does anyone have any experience with the lower cost transceivers on their site?
RTL-DATA-SAW $16.83
RTF-DATA-SAW $17.39
AM-RTD-315 $24.10
They both claim data rates of 4800bps, but the AM-RTD-315 claims 4800bps using
manchester encoded data, and raw throughput of up to 10Kbps.
Thhe OOPIC board I'm working with can only work up to 1200bps anyways, but if I
don't need the added capabilities of the AM-RTD-315 (whatever those may be) then
I'd like to save the $8.00 per module.
The application is for wireless serial communication with a host PC.
Thanks!
Alan
Gerry Schneider
Alan S. Timm wrote:
I haven't used these specific modules, but have used many others from Abacom, etc.
The RTF/RTL units have 100mSec turn-around time in half-duplex mode - is this fast
enough for you? The RTD claims 5 mSec.
The RTD operates at 315 MHz, the most common frequency for X-10 wireless, remote car
functions and many other wireless functions like doorbells. Will you have an
interference problem?
All of the above units have low-cost, noisy superregen receivers - can you live with
garbage data at the receive end when no data is being transmitted? This is usually
solved with a unique "start of transmission" code or, when allowable, offsetting the
detection bias or increasing the detector hysteresis, which also reduces the
receiver gain and range.
Without Manchester's ability to 'break up" long sequences of 1's or 0's, such data
strings are prone to errors because of the lack of DC response inherent in such
receivers. If not using a coder/decoder, you need to be very careful as to code
sequences, or else implement your own re-coding scheme. This may or may not be a
real problem, and is specific to certain receiver designs.
Not trying to sound negative, and I'm hoping you'll have fun and learn a lot in the
process. IR and RF links are a lot easier to implement than they used to be, but
still not like a piece of wire! :>)
Cheers,
Gerry