RF tx/rx module using computer serial communication encoding

[david90]

RF module question

Can RF tx/rx module use computer serial communication encoding scheme to encode and decode?

I want to connect the tx module to directly to my computer serial port and have it send out ascii data to the rx module.

 

[vale]

RF module question

who knows what module you are using?

 

[david90]

RF module question

the one that have data in and data out. bit by bit transmission.

 

[nikhilele]

RF module question

regular rf tx/rx modules doesnot allows you to do this, they need special encoders/decoders for data transmition operation, if they are incorporated with modem then only u can connect them to the serial port directly, beware serial port ouput swings between +/-12 so u may need rs232 to ttl convertor or soo.

 

[david90]

RF module question

The tx/rx that I have this one
**broken link removed**

I'm not sure if it is a correct way to test them but I powered the rx and tx with 5V. On the receiver, the data out is connected to an LED and the tx dataIn is connected to 5V. The output of the dataout on the rx is around 0.8V and max out at 1.8V when I connect dataIn of the tx to VCC. On the ebay page, the output is suppose to be TTL meaning between 0 and 5V but i'm not getting it. Maybe the way i'm testing the modules is wrong.

Also the DataOut voltages jumps alot.

 

[philba]

RF module question

there are lots of noise related problems with sending a serial stream using those devices. I think a DC "signal" is going to be especially susceptable to noise. If you have a scope you will see a mess on the data output pin.

For data comm, you should look up manchester encoding for techniques on how to encode for (more) reliable data transmission.

For things like encoding a small muber of buttons, you could use the holtek encoder/decoder chips for a very simple implementation.

 

[david90]

RF module question

Why is DC more susceptable to noise? I did test out the rx and tx by just sending a DC 5 volt signal without any decoder/encoder IC and the output of the rx is not very stable. Maybe because there are other 315mhz signal in the air??

 

[david90]

RF module question

Does manchester encoding help to lower errors in noisy transmission?