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ASK RF interfacing with microcontroller

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learner71

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Hi,
I have tried to connect JMR TX1 ASK RF transmitter with at89c2051. where at89c2051 is sending data to RF transmitter through usart. on receiver side, i have connected JMR RX1. but receiver is not able to receive the data correctly.

Can anyone tell me, what is best ASK RF interfacing protocol.


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bigdogguru

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Are you implementing any sort of encoding/decoding scheme either via hardware or software?

Checkout the new group:

Embedded Wireless Networks

I have many links to RF projects like yours as well as links on Manchester Encoding/Decoding, the most common scheme.
 
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learner71

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Thanks,
How is it possible to send Manchester encoding on JMR TX1. Can you tell me what should be the frequency of RF data i.e 0 to 5. JMR TX1 is operating at 433 MHz. can you explain me the working of ASK RF include the frequency of input data to represent 0/1 bit.
 

bigdogguru

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Data transmission over these simple ASK RF TX/RX pairs is inherently unreliable, too much interference, characteristics of these TX/RX pairs, etc. So you need to implement an encoding scheme for error correction to achieve maximum performance. Manchester Encoding is one of the most popular for these types of TX/RX pairs.

Checkout this appnote concerning implementation:

Manchester encoding using RS232 for Microchip PIC RF applications

It does a fair job of explain the necessity and implementation of Manchester Encoding.

The following is a good tutorial on actual implementation of RF TX/RX with PICs:

PIC Tutorial Twelve - RF remote control

You can uses the downloaded files from the above tutorial as a template for your project.

The above links deal with software implemenation of the encoding scheme. You can however use inexpensive encoder/decoder chipsets:

4 Channel ASK remote with HT12E & HT12D chips

Wireless HC08 Modem

With encoding Baud rates of 19.2K can be regularly obtained as discussed in the above appnote PDF.

Without encoding your actual baud rate will be fairly limited, 1200 BAUD, as in the follow example projects:

Wireless Interface RF Modules

PIC 16F877A BASED DATA MONITORING SYSTEM

I want to welcome you to the Embedded Wireless Network Group, these links and many others are available in the group posting. I believe they should answer many of your questions and give you viable examples which to base your project.

If you have any other questions, feel free to ask me.

I'm constantly looking for reference material on this subject and others, if I come across anything related to your project I'll be sure and post it for you.

---------- Post added at 07:29 ---------- Previous post was at 07:14 ----------

I had forgot your project was Atmel based, so I've included the following Atmel appnote:

Manchester Coding Basics
 
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