Hi Gents,
I am a noobie, but am currently fiddling around with the RF Links and have noticed some things that are quite illuminating (to me at least). Maybe it might helpful to you.
I am using 434Mhz RF Links, and 17cm antennae where applicable. For data being sent over RF, I am sending about 10 lines of text of about 9 letters in each line:
EFFECT OF RF TRANSMISSION RATE
at 5cm separation between transmitter and receiver, no antennae for both transmitter and receiver.
2000 BPS: 30 % (the 10 lines of code totally correct)
4000 BPS: 40 %
5000 BPS: 60 %
6000 BPS: 40 %
6000 BPS: 20 %
EFFECT OF ANTENNAE
5000 bps rate selected as above.
Separation: 5cm
Receiver: No Antenna
Transmitter: No Antenna
Reliablity: 60 % (the 10 lines of code totally correct)
Separation: 50cm
Receiver: No Antenna
Transmitter: No Antenna
Reliablity: 30 %
Separation: 300cm (3m)
Receiver: No Antenna
Transmitter: No Antenna
Reliablity: not tested, but probably very low
Separation: 50cm
Receiver: With Antenna
Transmitter: No Antenna
Reliablity: 95 % (the 10 lines of code totally correct)
Separation: 50cm
Receiver: With Antenna
Transmitter: With Antenna
Reliablity: 0 % (the transmitter probably overwhelms the receiver)
Separation: 300cm
Receiver: With Antenna
Transmitter: No Antenna
Reliablity: 80 %
Separation: 300cm
Receiver: With Antenna
Transmitter: With Antenna
Reliablity: 95 %
Sorry I am not an engineer, so I can only make some rough guesses on what I am seeing:
- Looks like the RF Bit Rate has to be chosen with the kind of code in the sketch? By this I mean that if the code is heavy the loop will take longer to run, so the loop cycle is longer. Whether a higher or lower bit rate is beneficial to my code I can't tell. I had to use trial and error.
- The antenna has a BIG effect on the reliability of the communication. Unfortunately I again can't pin point specifics. It looks like a case by case basis for each transmitter / receiver pair?
Maybe a more RF savvy guy can shed more insight into this?
K in Sg