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Function: freq_inject_chirp()

0 void freq_inject_chirp(float c0, float c90, int offset, float invMpc, float* ch0tilde, float* ch90tilde, float* htilde, int n)
The bottom-line test of any optimal filtering code or searching routines is: can you inject ``fake" signals into the data stream, and properly detecting them, while properly rejecting all other signatures of instrumental effects, etc. This routine injects artificial signals into the frequency-domain strain $\tilde h(f)$. The plane of the binary system is assumed to be normal to the line to the detector.

The arguments are:

c0: Input. The coefficient of the 0-phase template to inject.
c90: Input. The coefficient of the $90^\circ$-phase to inject. Note that $c_0^2 + c_{90}^2$ should be 1.
offset: Input. The offset number of samples at which the injected chirp starts, in the time domain.
invMpc: Input. The inverse of the distance to the system (measured in Mpc).
ch0tilde: Input. The FFT of the phase-0 chirp (strain units) at a distance of 1 Mpc.
ch90tilde: Input. The FFT of the phase-90 chirp (strain units) at a distance of 1 Mpc.
htilde: Output. The FFT of the gravity-wave strain. Note that this routine adds into and increments this array, so that if it contains another ``signal" like IFO noise, the chirp is simply super-posed onto it.
n: Input. Defines the lengths of the various arrays ch0tilde[0..n-1], ch90tilde[0..n-1], and htilde[0..n-1].

Note that in making use of this injection routine, you must determine the level of the quantization noise of the ADC, and be careful to inject a properly dithered version of this signal when its amplitude is small compared to the ADC quantization step size.

Author: Bruce Allen, ballen@dirac.phys.uwm.edu
Comments: See the comments for time_inject_chirp, particularly with respect to the digital quantization noise.


next up previous contents
Next: Function: time_inject_chirp() Up: GRASP Routines: Gravitational Radiation Previous: Function: find_chirp()   Contents
Bruce Allen 2000-11-19