10781A Pulse Converter Block Diagram - HP 5501A Operating And Service Manual

struction is interpreted by the multiplier card a s an input operation. The VOL data is loaded
into the buffer and then multiplied by the preselected units constant from the constants ROM.
The product i s stored in the shift register for future use. This result represents a compensated
units-conversion number for converting fringe displacement data from the counter cards to
the preselected unit of measure. For additional information and schematics, refer to the
10761A Multiplier Operating and Service Manual.
3.20 10781A Pulse Converter
The 10781A Pulse Converter (Figure 3-77) i s a quarter-rack size electronic module for 5501A
Laser Transducer systems which accepts the R E F (reference) and MEAS (measurement sig-
nals and outputs displacement information in pulse or A-Quad-B format. The A-Quad-B out-
put i s designed to interface to some hardwired controllers and other closed-loop systems
which contain reversible counters.
-
Ref
-
12.6 MHz
OIclllator
Signal
Replication
Ref A
RefA
-
Error
Detect
Circuitt
Figure 3-77. 10787A Pulse Converter Block Diagram
Resolution of 10781A Pulse Converter output i s one-quarter wavelength (approximately
6.23 x 10-6 inches). If desired, pulse pairs may be generated to create an apparent resolution
of 1/8 wavelength. A pair of jumper wires allows selection of either up and down pulses or
A-Quad-B format output; another jumper wire allows the pulse output to be disabled in the
event of an error detection on the axis being monitored (error trip). The pulse converter is
designed to provide a simple method of converting the reference and measurement signals to
pulses that can be counted by a user's counting electronics.
The reference and measurement signals are applied to signal reception and isolation circuits.
These circuits contain photo-isolation devices which convert the differential input signal
pairs to single-ended signals with TTL logic levels. Additional immunity to external noise is
obtained by applying these signals to Schmitt trigger circuits.