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##

Function: `time_inject_chirp()`

0
`void time_inject_chirp(float c0, float c90, int offset, float
invMpc, float* chirp0, float* chirp90, float* data, float *response, float *work, int n) `

This is a time-domain version of the previous function `freq_inject_chirp()` which injects chirps in the time-domain (after
deconvolving them with the detector's response function). This routine
injects artificial signals into the time-domain strain . 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 -phase to
inject. Note that
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).
`chirp0:` Input. The time-domain phase-0 chirp (strain units) at a distance of 1 Mpc.
`chirp90:` Input. The time-domain phase-90 chirp (strain units) at a distance of 1 Mpc.
`data:` Output. The detector response in time that would be produced by the
specified binary inspiral. 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.
`response:` Input. The function that specifies the response function of the
IFO. This is produced by the routine `normalize_gw()`.
`work:` Output. A working array.
`n:` Input. Defines the lengths of the various arrays `chirp0[0..n-1]`,
`chirp90[0..n-1]`, `data[0..n-1]`, `work[0..n-1]`, and `response[0..n+1]` (note that
this "+" sign is *not* a typo!).

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:
A short look at the time-domain signal which is injected shows that it
has a low-amplitude spike at the very start. This may be an
un-avoidable Gibbs phenomenon associated with the turn-on of the
waveform. A second interesting point is that for many interesting
signals, the amplitude of the injected signal in the time domain is
*below* the level of the quantization noise. Thus, a sensible
injection scheme would be to add it into an appropriately dithered
(float) version of the integer signal stream, then cast that back into
an integer. This should be tried.

** Next:** Vetoing techniques (time domain
** Up:** GRASP Routines: Gravitational Radiation
** Previous:** Function: freq_inject_chirp()
** Contents**
Bruce Allen
2000-11-19