Handheld Radio data transmission

[Devryd]

Hi guys, 
I am trying to send 2 bytes of data over handheld radios. I use 2 raspberry pi picos an the data is encoded with 5 different frequencies. The software so far works if I connect the picos together, but if I add the radios in between, they introduce too much noise, so that the recieving pico cant decode the message anymore. Do you have an idea, how I could clean up the output?

[akio123008]

Few tips that may help:

 

- 2 bytes of data isn't a whole lot to transmit. You might want to consider reducing the number of levels, e.g. use 2 audio frequencies instead of 5.

 

- Make sure to space the audio frequencies as far apart as you can.

 

- Not all audio frequencies are transmitted well by handheld radios. These devices are made for speech, and for that you only need 0.5 - 5kHz or even less, so they have very aggressive low and high pass filters in them, cutting out all low and high frequencies. It's possible some of the sound frequencies you picked are out the range of the radios.

 

- You can try adding a low pass filter to the output to filter out HF noise/harmonics.

 

 

[Devryd]

I am using 700Hz to 1200Hz so that should be fine
Yeah I might need a low pass filter, 

3 minutes ago, akio123008 said:

Few tips that may help:

 

- 2 bytes of data isn't a whole lot to transmit. You might want to consider reducing the number of levels, e.g. use 2 audio frequencies instead of 5.

 

- Make sure to space the audio frequencies as far apart as you can.

 

- Not all audio frequencies are transmitted well by handheld radios. These devices are made for speech, and for that you only need 0.5 - 5kHz or even less, so they have very aggressive low and high pass filters in them, cutting out all low and high frequencies. It's possible some of the sound frequencies you picked are out the range of the radios.

 

- You can try adding a low pass filter to the output to filter out HF noise/harmonics.