This sheet is to estimate of the range that can be expected from an FM or ASK modulated system.
Probability Error Function for coherent 2FSK with fading
A
BLUE curves with average white gaussian noise for ASK (amplitude keying or on/off keying)
FM systems require a receive bandwidth which
The limit of sensitivity for FM systems uses the PEF curve and adds to this the noise floor (-174dBm/Hz) and noise you would get with the bandwidth you specify, as well as the noise-figure of the receiver.
In advanced receivers that use a PLL as the demodulator, this effectivly reduces the noise bandwith.
A similar analysis can be carried out for the fading environment, but of course we cannot measure this directly.
An ASK system requires an IF bandwith that is equal to twice the maximum data rate.
A similar analysis can be carried out for the AWGN environment with ASK
A
A useful plot to test receiver in 2ASK is to use the BLUE curve.
Note, the ASK curve uses a reduced BW
The Friis equation is modified according plots from (RT)
In this sheet I have set n=
2.5
The range is calculated with the TX power in dBm and required BER for
This range is calculated with the TX power in dBm for
Range 1
6dBm TX, 5dB NF, 20kHz dev, 20kHz air data rate, average antenna gain -15dB,
200bits without error, no FEC.
Range 2
TX 6dBm TX, 1:10 FEC, reduce the data rate by quarter, no Manchester.
Improvements.