tomwalters@0: .TH RAMP 1 "1 September 1993"
tomwalters@0: 
tomwalters@0: .SH NAME
tomwalters@0: ramp \-    generate an exponential sawtooth waveform
tomwalters@0: 
tomwalters@0: .SH SYNTAX 
tomwalters@0: ramp [options]
tomwalters@0: 
tomwalters@0: .SH DESCRIPTION
tomwalters@0: Generate samples of an exponential sawtooth waveform at a given sample rate.
tomwalters@0: Samples are written on the stdout in binary shorts or floats according to
tomwalters@0: the `type' option.
tomwalters@0: 
tomwalters@0: .SH OPTIONS
tomwalters@0: 
tomwalters@0: 1. period, amplitude, duration.
tomwalters@0: 
tomwalters@0: The `period' option sets the period of repetition of the waveform in samples.
tomwalters@0: The `duration' option sets the total duration of the output waveform in
tomwalters@0: samples.
tomwalters@0: Both may be given with time units (s or ms) in which case the time is converted to
tomwalters@0: samples using the given `samplerate' option.
tomwalters@0: The `amplitude' option sets the height of the waveform.
tomwalters@0: 
tomwalters@0: 2. polarity
tomwalters@0: 
tomwalters@0: The `polarity' option is used to set the direction of the ramp:
tomwalters@0: 
tomwalters@0: .nf
tomwalters@0:     polarity=ramp   growing exponential:   A.exp(t-T)   0<=t<=T
tomwalters@0:     polarity=damp   decaying exponential:  A.exp(-t)    0<=t<=T
tomwalters@0: .fi
tomwalters@0: 
tomwalters@0: 3. decay
tomwalters@0: 
tomwalters@0: The argument of the exponential is calibrated so that the decay factor is
tomwalters@0: a half-life period.
tomwalters@0: The wave grows/decays to half its given amplitude in the given decay time.
tomwalters@0: 
tomwalters@0: .SH EXAMPLES
tomwalters@0: 
tomwalters@0: 1. Growing exponentials
tomwalters@0: 
tomwalters@0: .nf
tomwalters@0: 	    ramp polarity=ramp dec=1ms
tomwalters@0: .fi
tomwalters@0: 
tomwalters@0: 2. Decaying exponentials
tomwalters@0: 
tomwalters@0: .nf
tomwalters@0: 	    ramp polarity=damp dec=1ms
tomwalters@0: .fi
tomwalters@0: 
tomwalters@0: 3. Half a cycle of an 8ms decaying exponential.
tomwalters@0: 
tomwalters@0: .nf
tomwalters@0: 	    ramp polarity=damp dec=1ms dur=4ms
tomwalters@0: .fi
tomwalters@0: 
tomwalters@0: 4. Modulating a tone with a damped exponential.
tomwalters@0: Note: modulating can be done in floating point using a ramp with unit
tomwalters@0: amplitude, or it can be done in integer arithmetic as below.
tomwalters@0: The scale factor in the `merge' program is used to avoid 16-bit overflow.
tomwalters@0: 
tomwalters@0: .nf
tomwalters@0: 	    tone period=.5ms      > foo1
tomwalters@0: 	    ramp pol=damp dec=1ms > foo2
tomwalters@0: 	    merge op=mult factor=0.01 foo1 foo2 > foo3
tomwalters@0: .fi
tomwalters@0: 
tomwalters@0: 5. Modulating a tone with a ramped exponential.
tomwalters@0: The 800Hz tone is modulated with a unit ramped exponential with a 25ms
tomwalters@0: repetition rate and a 4ms half life.
tomwalters@0: 
tomwalters@0: .nf
tomwalters@0: 	    tone freq=800Hz amp=10000 type=float   > foo1
tomwalters@0: 	    ramp pol=ramp period=25ms dec=4ms amp=1 type=float > foo2
tomwalters@0: 	    merge op=mult type=float foo1 foo2  | ftos > foo3
tomwalters@0: .fi
tomwalters@0: 
tomwalters@0: 6. Modulating a tone with a damped exponential, and half-wave rectifying to
tomwalters@0: generate damped pulses.
tomwalters@0: 
tomwalters@0: .nf
tomwalters@0:     tone period=.5ms amp=500 type=float    > foo1
tomwalters@0:     ramp pol=damp dec=1ms amp=1 type=float > foo2
tomwalters@0:     merge op=mult type=float foo1 foo2 | ftos | gate range=min-0 op=0 > foo3
tomwalters@0: .fi
tomwalters@0: 
tomwalters@0: 7. Modulating white noise with a ramped exponential.
tomwalters@0: 
tomwalters@0: .nf
tomwalters@0: 	    noise type=float  > foo1
tomwalters@0: 	    ramp pol=ramp dec=1ms amp=1 type=float > foo2
tomwalters@0: 	    merge op=mult type=float foo1 foo2 | ftos > foo3
tomwalters@0: .fi
tomwalters@0: 
tomwalters@0: .SH "SEE ALSO"
tomwalters@0: options tone ptrain noise
tomwalters@0: 
tomwalters@0: .SH COPYRIGHT
tomwalters@0: .LP
tomwalters@0: Copyright (c) Applied Psychology Unit, Medical Research Council, 1995
tomwalters@0: .LP
tomwalters@0: Permission to use, copy, modify, and distribute this software without fee 
tomwalters@0: is hereby granted for research purposes, provided that this copyright 
tomwalters@0: notice appears in all copies and in all supporting documentation, and that 
tomwalters@0: the software is not redistributed for any fee (except for a nominal 
tomwalters@0: shipping charge). Anyone wanting to incorporate all or part of this 
tomwalters@0: software in a commercial product must obtain a license from the Medical 
tomwalters@0: Research Council.
tomwalters@0: .LP
tomwalters@0: The MRC makes no representations about the suitability of this 
tomwalters@0: software for any purpose.  It is provided "as is" without express or 
tomwalters@0: implied warranty.
tomwalters@0: .LP
tomwalters@0: THE MRC DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING 
tomwalters@0: ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL 
tomwalters@0: THE A.P.U. BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES 
tomwalters@0: OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, 
tomwalters@0: WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, 
tomwalters@0: ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS 
tomwalters@0: SOFTWARE.
tomwalters@0: