Post by thread:C-Code for RF communications using PWM (Encoding &

I like to thank you in advance for any information. I am trying to use a RF Transmitter and a Receiver for data communications. I was told I should encode data to PWM then Xmitt via RF then decode the PWM on the receiver side. Does any one have any experience with PWM encoding and decoding. I could use either a software based PWM or hardware based Pics. I have been doing tests with out any encoding, and I keep getting stray data from RF. Thanks again for any help on this. Jerry Iacobucci spam_OUTjerryTakeThisOuTcanlinks.com

Jerry Iacobucci wrote: > > I like to thank you in advance for any information. > > I am trying to use a RF Transmitter and a Receiver for data communications. > I was told I should encode data to PWM then Xmitt via RF then decode the > PWM on the receiver side. Does any one have any experience with PWM > encoding and decoding. I could use either a software based PWM or hardware > based Pics. You should try to do two things righ from the start : 1) Ensure that your PIC RX code can adjust itself to slight variations in bit length. Depending on your TX side, you may find the bit lengths to vary slightly. 2) Try to make your codes DC-less so your rf discrimination is better. Manchester encoding is great for this, and quite do-able on a PIC. > I have been doing tests with out any encoding, and I keep getting stray > data from RF. Welcome to RF! If you find a way to solve that problem, you'd become very, very rich! -- Friendly Regards /"\ \ / Tjaart van der Walt X ASCII RIBBON CAMPAIGN .....tjaartKILLspam@spam@wasp.co.za / \ AGAINST HTML MAIL |--------------------------------------------------| | WASP International | |R&D Engineer : GSM peripheral services development| |--------------------------------------------------| | Mobile : tjaartKILLspamsms.wasp.co.za (160 text chars) | | http://www.wasp.co.za/~tjaart/index.html | |Voice: +27-(0)11-622-8686 Fax: +27-(0)11-622-8973| | WGS-84 : 26¡10.52'S 28¡06.19'E | |--------------------------------------------------|

> I am trying to use a RF Transmitter and a Receiver for data communications. > I was told I should encode data to PWM then Xmitt via RF then decode the > PWM on the receiver side. Does any one have any experience with PWM > encoding and decoding. I could use either a software based PWM or hardware > based Pics. There are a whole bunch of ways to transmit PWM, including gating the RF carrier on and off according to a timer output.. That, and the methods to receive it are a huge subject. > I have been doing tests with out any encoding, and I keep getting stray > data from RF. You will. That's the nature of an RF link. Error correction codes fix some errors, and error checking mechanisms let you know when an error occurred, but don't fix it. Error-free RF links do not exist.

At 12:52 AM 22/04/99 -0400, you wrote: Hi Jerry, We were talking about the Indigo radios and on these there is no need for the PWm. Also stray Rf is eliminated as it is all handled by the onboard PIC. If this is not the radio you intend using please excuse the post. Peter {Quote hidden}> I like to thank you in advance for any information. > >I am trying to use a RF Transmitter and a Receiver for data communications. > I was told I should encode data to PWM then Xmitt via RF then decode the >PWM on the receiver side. Does any one have any experience with PWM >encoding and decoding. I could use either a software based PWM or hardware >based Pics. > >I have been doing tests with out any encoding, and I keep getting stray >data from RF. > >Thanks again for any help on this. > > >Jerry Iacobucci >.....jerryKILLspam.....canlinks.com > Peter Grey Noesystems

>You will. That's the nature of an RF link. Error correction codes fix some >errors, and error checking mechanisms let you know when an error occurred, >but don't fix it. > >Error-free RF links do not exist. > ********* And you better believe it. ************ ************* Julian Fine *********** ********** EraseMEjulianspam_OUTTakeThisOuTfine.co.za ******** ******* http://www.fine.co.za ******* ** http://www.eagle-wireless.co.za **