range2beat

Convert range to beat frequency

Syntax

fb = range2beat(r,slope)

fb = range2beat(r,slope,c)

Description

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.

Examples

Maximum Beat Frequency in FMCW Radar System

Calculate the maximum beat frequency in MHz for an upsweep FMCW waveform. The waveform sweeps a 300 MHz band in 1 ms. Assume that the waveform can detect a stationary target as far as 18 km.

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

fb = 36.0249

Input Arguments

r — Range

array of nonnegative numbers

Range, specified as an array of nonnegative numbers in meters.

Data Types: double

slope — Sweep slope

nonzero scalar

Slope of FMCW sweep, specified as a nonzero scalar in hertz per second.

Data Types: double

c — Signal propagation speed

speed of light (default) | positive scalar

Signal propagation speed, specified as a positive scalar in meters per second.

Data Types: double

Output Arguments

fb — Beat frequency of dechirped signal

array of nonnegative numbers

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.

Data Types: double

More About

Beat Frequency

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.

Algorithms

The function computes 2*r*slope/c.

References

[1] Pace, Phillip. Detecting and Classifying Low Probability of Intercept Radar. Artech House, Boston, 2009.

[2] Skolnik, M.I. Introduction to Radar Systems. New York: McGraw-Hill, 1980.

Extended Capabilities

C/C++ Code Generation

Generate C and C++ code using MATLAB® Coder™.

Usage notes and limitations:

Does not support variable-size inputs.