fb = range2beat(r,slope) converts
the range of a dechirped linear FMCW signal to the corresponding beat frequency. slope is
the slope of the FMCW sweep.

fb = range2beat(r,slope,c) specifies
the signal propagation speed.

Calculate the maximum beat frequency in the
received signal of an upsweep FMCW waveform. Assume that the waveform
can detect a target as far as 18 km and sweeps a 300 MHz band in 1
ms. Also assume that the target is stationary.

slope = 300e6/1e-3;
r = 18e3;
fb = range2beat(r,slope);

Beat frequency of dechirped signal, returned as an array of
nonnegative numbers in hertz. Each entry in fb is
the beat frequency corresponding to the corresponding range in r.
The dimensions of fb match the dimensions of r.

For an up-sweep or down-sweep FMCW signal,
the beat frequency is F_{t} – F_{r}.
In this expression, F_{t} is
the transmitted signal's carrier frequency, and F_{r} is
the received signal's carrier frequency.

For an FMCW signal with triangular sweep, the upsweep and downsweep
have separate beat frequencies.