The purpose of FMCW range estimation is to estimate the range of a target. For example, a radar for collision avoidance in an automobile needs to estimate the distance to the nearest obstacle. FMCW range estimation algorithms can vary in the details, but the typical high-level procedure is as follows:
Dechirp — Dechirp the received signal
by mixing it with the transmitted signal. If you use the
dechirp
function, the transmitted signal is the
reference signal.
Find beat frequency — From the dechirped signal, extract the beat frequency or pair of beat frequencies. If the FMCW signal has a sawtooth shape (up-sweep or down-sweep sawtooth shape), you extract one beat frequency. If the FMCW signal has a triangular sweep, you extract up-sweep and down-sweep beat frequencies.
Extracting beat frequencies can use a variety of algorithms. For example, you can use the following features to help you perform this step:
pwelch
or periodogram
psd
findpeaks
rootmusic
phased.CFARDetector
Compute range — Use the beat frequency
or frequencies to compute the corresponding range value. The
beat2range
function can perform this
computation.
While developing your algorithm, you might also perform these auxiliary tasks:
Visualize targets in the range-Doppler domain, using the
phased.RangeDopplerResponse
System object™.
Determine whether you need to compensate for range-Doppler coupling. Such
coupling can occur if the target is moving relative to the radar. You can use
the rdcoupling
function to compute the range offset due to
range-Doppler coupling. If the range offset is not negligible, common
compensation techniques include:
Subtracting the range offset from your initial range estimate
Having the FMCW signal use a triangle sweep instead of an up sweep or down sweep
Explore the relationships among your system’s range requirements and parameters of the FMCW waveform. You can use these functions:
range2time
time2range
range2bw
beat2range
| dechirp
| findpeaks
| periodogram
| phased.FMCWWaveform
| phased.RangeDopplerResponse
| pwelch
| range2beat
| range2bw
| range2time
| rdcoupling
| rootmusic
| time2range