418Mhz Link Works why doesnt 434Mhz RF Link work?

Wireless & IoT
1

http://www.rentron.com/Files/CIP8_TWS8BIT.pdf

Please refer to the schematic on the link above. My setup is almost like this except that when i initially set everything up using the 418Mhz Link, I had to put the baud rates to 2400bps for anything to transmit (Anyone know why?), further i had to include additional 10uF capacitors one on each side close to the receiver and transmitter for anything to transmit and or receive.

Also instead of the “example relay drive circuit” I have two TIL311 hexadecimal displays, which includes the BCD converts, drivers, latches. Altogether its a relatively simple circuit.

After getting the 418Mhz Link to work I made a PCB and get that working. Still having the protoboard setup i just basically unplugged the 418MHz RF link and installed the 434Mhz, and there is nothing on the displays. I’m thinking that it is a capacitance problem, and i just got lucky with the 418Mhz Link and placed the correct cap levels, enough to clean up the signal and not too much to interfere with the carrier frequency. The waveform coming from the data out line of the receiver looks like valid data but when put into the decoder there is nothing. There has to be some flaw in the transmission cause the decoder will not display anything until the check-sum bits and sync bits are correct, telling me that it may be a capacitance problem.

I was hoping that someone may know the correct capacitance levels to use that will work and not interfere with the carrier, or maybe have another idea that may work?

Any help would be greatly appreciated.

Thanks

2

The TWS/RWS 434 modules only support upto 3K baud, and 2400 is a the recommended speed

3

also keep in mind that you will get alot of noise from breadboards, as the tracks act like capacitors in the circuit. This my not be whats happening, just prolblems i’ve had in the past…

mounting the modules on the far side of breadboards and even ditching the antennas and just keeping the units close (<1ft apart) helped me get rid of alot of the noise as just the smallest movment of a wire antenna was generating plenty of noise for me.

not sure if this is of any use, but gl man.

4

There are 4800bps RF Links available and here are the links:

For the 418Mhz 4800bps RF Link

http://www.sparkfun.com/commerce/produc … ts_id=7817

For the 434Mhz 4800bps RF Link

http://www.sparkfun.com/commerce/produc … ts_id=7815

And the above links are what I bought, so unless sparkfun is yanking me around shouldnt the Links still work at 4800bps since that is what they say they are rated at?

And second was that using the protoboard with no antennas and doing what you descriped was exactly what i was doing and by doing so enabled the 418Mhz RF Link to work.

Maybe Ill just make a PCB and use the 434MHz RF Link and see what happens.

Nevertheless thanks for your opinion, if you have any other ideas ill be glad to listen to them