Changing gears for a while and building an ISM (2.54GHz) Radar for
automotive and industrial purposes. experimentation. The prototype will serve as a testbed for Doppler, Gated CW, and LFMCW applications.
Not going into too much detail tonight, just finished bringing up the transmitter subsystem prototype. +14dBm output power which is about 3dB off of the mark. However the measurement was taken with a detection diode, not very accurate.
In the link budget calculation in the block diagram above, +14dBm is more than enough to sense vehicles over 100 feet away. Frankly the detection distance if far greater, however even 100 feet may be pushing the limit of practicality on the highway. Without high antenna directivity, multipath will be more of an issue.
I do intend to investigate whether FMCW is a more robust detection method in multipath environments, specifically when an FFT is applied to the back end. For example, in an environment where a known path interferer will always be present, ie the road, then an interference zone (IZ) can be designated.
More details to come, the project is very much a work in progress. FPGA tutorials are still in the works, stay tuned for the second NCO lab!