User's Manual

RVP8 User’s Manual
October 2005
TTY Nonvolatile Setups
3–17
3.2.5 Mt<n> — Triggers for Pulsewidth #n
These questions are accessed by typing “Mt”, with an additional argument giving the pulsewidth
number. They configure specific trigger, transmit waveform, and FIR filter properties for the
indicated pulsewidth only.
Trigger #1 – Start: 0.00 usec
#1 – Width: 1.00 usec High:YES
Trigger #2 – Start: 0.00 usec + ( 0.500000 * PRT )
#2 – Width: 10.00 usec High:YES
Trigger #3 – Start: –3.00 usec
#3 – Width: 1.00 usec High:YES
Trigger #4 – Start: –2.00 usec
#4 – Width: 1.00 usec High:YES
Trigger #5 – Start: –1.00 usec
#5 – Width: 1.00 usec High:YES
Trigger #6 – Start: –5.00 usec + (–0.001000 * PRT )
#6 – Width: 2.00 usec High:NO
These parameters list the starting times (in microseconds relative to range zero), the
widths (in microseconds), and the active sense of each of the six triggers generated by
the internal trigger generator. Setting a width to zero inhibits the trigger on that line.
The Start Time can include an additional term consisting of the pulse period times a
fractional multiplier between –1.0 and +1.0. This allows you to produce trigger
patterns that would not otherwise be possible, e.g., a trigger that occurs half way
between every pair of transmitted pulses, and remains correctly positioned regardless
of changes in the PRF Enter this multiplier as “0” if you do not wish to use this term,
and it will be omitted entirely from the printout..
In the above example, Trigger #2 is a 10.0 msec active-high pulse whose leading edge
occurs precisely halfway between the zero-range of every pair of pulses. Likewise,
Trigger #6 is a 2.0 msec active-low pulse whose falling edge is nominally 5.0 msec
prior to range zero, but which is advanced by 1.0 msec for every millisecond of
trigger period. All other triggers behave normally, and have fixed starting times that
do not vary with trigger period.
Some subtleties of these variable start times are:
S The PRT multipliers can only be used in conjunction with the RVP8’s internal
trigger generator. The PRT-relative start times are completely disabled whenever
an external trigger source is chosen from the Mt menu.
S When PRT-relative triggers are plotted by the Pb command, the active portion of
the trigger will be drawn cross-hatched and at a location computed according to
the current PRF. The cross-hatching serves as a reminder that the actual location
of that trigger may vary from it’s presently plotted position.
S The PRT multiplier for a given pulse is applied to the interval of time between
that pulse and the next one. This distinction is important whenever the RVP8 is
generating multiple-PRT triggers, e.g., during DPRT mode, or during Dual-PRF