<< dopnoise Choice of Particular Signals griffitc >>

stftb >> stftb > Choice of Particular Signals > doppler

doppler

Generate complex Doppler signal

Calling Sequence

[FM,AM,IFLAW] = doppler(N, FS, F0, D, V)
[FM,AM,IFLAW] = doppler(N, FS, F0, D, V, T0)
[FM,AM,IFLAW] = doppler(N, FS, F0, D, V, T0, C)

Parameters

N :

a positive integer: the number of points.

FS :

a positive scalar : the sampling frequency (in Hertz).

F0 :

a scalar in ]0 FS/2]: the target frequency (in Hertz).

D :

a positive scalar: the distance from the line to the observer (in meters).

V :

a positive scalar: the target velocity (in m/s).

T0 :

a positive integer in [1 N]: the time center index (default : round(N/2)).

C :

a positive scalar: the wave velocity (in m/s) (default : 340).

FM :

a real column vector of size N: the output frequency modulation.

AM :

a real column vector of size N: the output amplitude modulation.

IFLAW :

a real column vector of size N: the output instantaneous frequency law.

Description

Returns the frequency modulation (FM), the amplitude modulation (AM) and the instantaneous frequency law (IFLAW) of the signal received by a fixed observer from a moving target emitting a pure frequency f0.

Examples

rand("seed",0)
N = 512; 
[fm,am,iflaw] = doppler(N,200,65,10,50);
clf
subplot(211); plot(real(am.*fm));xtitle(_("Signal "))
subplot(212); plot(iflaw);
[ifhat,t] = instfreq(sigmerge(am.*fm,noisecg(N),15),11:502,10);
plot(t,ifhat,'g');
xtitle(_("Instantaneous frequency"))
legend([_("Requested"),_("Observed")]);

See also

Authors


Report an issue
<< dopnoise Choice of Particular Signals griffitc >>