VirtualWire Speed

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markvr

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I'm interested in using Virtual Wire but was wondering if anyone knew what the likely data rates are - there is a section on that page about it, but doesn't specify any actual numbers.

I'm not expecting great things, but is 500bps over 20 feet clear space likely to be possible?

Also, that page says:
When separated by about 20 feet with ordinary office furniture, and a 13 cm wire attached to each (in the middle of the 10 to 15 cm suggested), they were able to communicate, but approximately 20% of messages were corrupted.
Click to expand...

I'm guessing that means the messages coming out the library are corrupted? i.e. I need to do my own error checking - the library doesn't do any? If this is the case, does anyone know any suitable algorithms/libraries for the Teensy? I'll be sending sequences of blocks of 3 bytes (for RGB LEDs) , so I guess a quick and dirty method would be for every 4th byte to add the previous 3 bytes "mod 256"...but then what if the checksum byte gets lost, would need to maintain the sequence somehow...hmmm!
 
When I tested, I didn't have proper antennas. I just cut some chunks of wire that were, honestly, just random length. They probably work much better with properly matched antennas. Those very cheap modules I got didn't have antennas, or any good info about what to use for the antenna.
 
Can you give me an idea of what speeds you were getting, even with unmatched antennas? I don't even know what order of magnitude we are talking, 10bps, 100bps, 1kbps, 10kbps....1Gbps :) ?!
 
Hi, I've used lots of 433MHz radios & the virtualwire software. The devices I've used have been the cheapest I could find on ebay.
The issue I've had isn't with virtualwire but with the hardware. Some will work at 30+ feet without antenna - some struggle at 12 inches.
I can usually get 100 feet range in open air (in a noisey environment) with an antenna. I've never tried to optimise this - I use them in a student lab.
I've always used the default rate.
 
Some calculated wire lenghts for different frequencies. I use them with RFM12B and RFM69W modules quite successful:

433 MHz: 16.5cm
868 MHz: 8.2cm
915 MHz: 7.8cm

Just cut a wire this length and attach it so it goes straight up like an ....hmm... antenna ;-)
 
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