transmitting RF

Jayguy5000

I am interested in transmitting RF signals between basic stamps. I know parallax has an already set up transmitter and receiver but I·need to use different frequencies. has any one done this before? or can I get pointed in the direction of some one who has? Really all I will be doing is replacing what parallax has provided with my own parts and a different freq. cb radios will work if I can connect a bs2 to each radio. any help is apprectiated. THANKS

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Actually I think Im going to add the whiskers to my tank and let it roam, just need to figure out where.

Mike Green

For CB radios, amateur radios, and other units made for audio, you need some kind of modem (modulator-demodulator) so that what the radio sees is audio. The Stamps can generate a simple tone which, with filtering, could be used for transmitting, but you'll need some kind of tone decoder to reliably detect the tone or tones. You could use a DTMF generator/decoder which is used for touch-tone dialing and is commonly used with radios for this purpose. It can be used to send/receive 4 bits at a time. Alternatively, you could use a 202 type modem chip which uses one of two tones for half-duplex serial signalling. You can buy ready made such modems designed for amateur radio, but they will work with CB units as well. Check the CB rules to see if this is allowed. Some channels are specifically for radio control use and this may be permitted on those channels only. There have been all kinds of construction articles over the years on this subject for amateur radio. Check the ARRL's website for some suggestions.

Mike Green

If you don't need to use a specific radio or specific frequencies, the xBee devices that Martin Hebel sells with Stamp adapters work very well for digital (serial) data at 2.4GHz. The devices he carries are only 1mw with limited range, but the manufacturer (MaxStream) does sell 100mw units with correspondingly higher range that can be used with Martin's adapters.

Newzed

I have three of Martin's XBEEs -· 2 of the 100mw and 1 of the 1mw.· They work very well.·

Sid

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Sid Weaver
Don't have VGA?

Newzed@aol.com
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Martin Hebel

Thanks for the promo Mike and Sid (Mike, are you the Mike in Mn?), here's a link if you need it.

http://www.selmaware.com/appbee/

JayGuy, the XBee's mentioned can use up to 13 different frequencies, or they can be given unique ID's on the same frequency, much like WiFi/TCP-IP in the way networks and devices are uniquely addressed.

Also, as a side note, due to the need to make up some Propeller proto-boards of my own for some university reseach while waiting for Parallax to release theirs, I added some extra sq in's to produce an XBee adapter board for the up-coming propeller proto-board to fit in their 20-pin headers (pick one of the 4!)·and made for the 3.3V Vdd (which simplifies the design extremely).·Should be ready in a couple weeks.

-Martin



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Martin Hebel
StampPlot - Graphical Data Acquisition and Control
AppBee -·2.4GHz Wireless Adapters & transceivers·for the BASIC Stamp & Other controllers·