I have a system comprised of a wireless sensor which transmits temperature readings to a main base.
The wireless sensor system is made up of:
- 12F683 pic to take the temperature reading (manchester encoded)
- RF Solutions AM-RT4-433 transmitter to transmit the data
- Currently on a small bread board (proto board) with a 1/4 wavelength wire acting as an antenna
The manchester encoding is: 0 = 10 and 1 = 01 for a total time of 416 micro seconds (each low and high is 208 micro seconds)
The receiver base is made up of (all on bread board again)
- RF Solutions HRR30 receiver with a 1/4 wavelength wire for the antenna
- mbed microcontroller which decodes the data from the receiver and looks for a short sync pattern and then receives the data packet (sync patter is 15 1s followed by a 0 and then the data begins)
This all works fine when transmitting from one side of my desk to the other (1-2m) but once I move the transmitter to another room it becomes very unreliable. The remote system currently takes a sensor reading, then powers up the transmitter to send the data and then powers down the transmitter once transmitted - I can get some transmission at increased distances by increasing the number of times the data packet is transmitted from 1 to 5 with a short delay between them.
This sort of works but it is still not very reliable. Both boards are running from 5V.
Any suggestions on where to look for issues would be great. I assume that using bread board and whip antennas is not great but I would have expected the range to be more than 2 meters - maybe I'm wrong?
I know that other frequencies than 433 MHz might serve me better and I have used the RFM12B transceivers but I would like to stick to these components for now.