Has anyone out there had any experience using radio modems for serial communication? If so, what brand equipment, what did you think of it, what kind of application, and lastly, over what kind of distance were you sending & receiving?

Thanks

Allan Coppock

www.racetiming.com

Not sure what you are trying to send, but we use the Alge TED/TX-RX to send serial data all the time with great success up to about 4-5 miles line of sight(later very important!).

Serial data we send includes the timer to pc via wireless to time from the ski lodge in place of the timing shack(better view of course). We use primarily S4's for timebase which has a baud rate of 4800.

We also send the serial display data back up the hill to the GAZ displays from the timing computer in the lodge.

Things to know....
1. What software you will be using and test, test,test before hand with the wireless in place!
2. The Alge TED's are limited to baud rates of up to 4800, so make sure your timing device does not excede this rate.
3. Alge protocol must be strictly followed to allow the Xon and Xoff commands to allow you to not burn up batteries as fast as with "direct, always ON (Xmit) mode" which we use for the Timer to PC. The PC to Display uses what is called "program 1" and has the Xon/Xoff commands to the display boards using any Broder applications. If using SST software you will need to keep your display system in the "direct, always On or Program 6".

Fred can make you cables with power supplied that will ease the use of batteries if you have power at both ends of your timing area.

Good luck,
Jim

Allan,

I have been using a radio modem made by Max Stream ( 9XSTREAM-PKD-R ) it is a 900 MHz stand alone modem that can be used with RS 232/422/485. The range is rated up to 7 miles. I have used it only up to 1 mile but they have worked well. There is a high gain antenna that that is an add on which will increase your range quite a bit. These units sell for around $300 each.

http://www.maxstream.net/products/xstream/pkg/9xsteam.php

Hope this helps,

Todd Rebhan

Todd - Thanks for the reply. Where did you buy yours, and do you recall the cost. Also, have you had any occassions where they did not function as expected.

Thanks,

Allan

www.racetiming.com

I have also used MaxStreams and Proxims, which I think have become the same product line in a buyout (one bought the other).

Pretty decent gadgets for low-volume, non-mission-critical RF serial comms, such as driving a GAZ display down at the warming hut.

Not much throughput, though.

And of course the ALGE TED telesignals are versatile, and they look cool as well.

James Broder
Broder's Skunkware Scoring & Timing Software
http://www.skunkware.tv

Aerocomm ConnexLink also work very well. They run on a 2.4ghz spread spectrum frequency which doesn't interfere with 802.11b. about $400 per set and can use one server with many clients.
www.aerocomm.com