dop2speed

Convert Doppler shift to speed

Syntax

radvel = dop2speed(dps,lambda)

Description

radvel = dop2speed(dps,lambda) returns the radial velocity in meters per second. This value corresponds to the one-way Doppler shift dps for the wavelength lambda.

Examples

Calculate Speed of Car

Calculate the radial velocity of an automobile based on the Doppler shift of a continuous-wave radar. The radar carrier frequency is 24.15 GHz. Assume a doppler shift of 2.880 kHz.

f0 = 24.15e9;
lambda = physconst('LightSpeed')/f0;
dopshift = 2.880e3;
radvel = dop2speed(dopshift,lambda)

radvel = 
35.7516

The radial velocity is 35.75 meters per second or 80 miles/hour.

Input Arguments

dps — One-way Doppler shift

scalar | vector | matrix

One-way Doppler shift in hertz, specified as a scalar, vector, or matrix.

Data Types: single | double

lambda — Wavelength

positive scalar

Wavelength in meters, specified as a positive scalar.

Data Types: single | double

Output Arguments

radvel — Radial velocity

scalar | vector | matrix

Radial velocity in meters per second, returned as a scalar, vector, or matrix.

More About

Doppler-Radial Velocity Relation

The radial velocity of a source relative to a receiver can be computed from the one-way Doppler shift:

$$V_{s,r}=\Delta f\lambda$$

where V_s,r denotes the radial velocity of the source relative to the receiver, Δf is the Doppler shift in hertz, and λ is the carrier frequency wavelength in meters.

Extended Capabilities

C/C++ Code Generation

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

Usage notes and limitations:

Does not support variable-size inputs.

This function supports single and double precision for input data and arguments.

References

[1] Rappaport, T. Wireless Communications: Principles & Practices. Upper Saddle River, NJ: Prentice Hall, 1996.

[2] Skolnik, M. Introduction to Radar Systems, 3rd Ed. New York: McGraw-Hill, 2001.

Version History

Introduced in R2011a