TM 11-6625-3081-23
1-24.
TEST CONSOLE TEST BENCH 2A2 (cont)
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(b) Digitized output from the EBS tubes is continuously sampled by two inde-
pendent time bases (one per channel) and stored in memory. The time bases are pro-
grammed to partition their memory (2K by eight-bit block) into one to eight records of
equal length.
Since each record requires a separate trigger to initiate acquisition,
several occurrences of a signal may be acquired before data must be read from memory.
Valid record lengths are 256, 512, 1024, and 2048 bytes. Records can be further
divided into 1 to 14 segments.
(2) Analog Signals.
The analog input signals from the plug-in programmable
amplifiers are coupled
to the digitizer through the plug-in interface. The differ-
ential outputs of the plug-in interface drive the deflection amplifiers, which in turn
drive the vertical deflection plates of the EBS tubes.
Since the electron beam covers
the entire target horizontally, no horizontal deflection is necessary.
(a) The plug-in interface also carries the analog trigger signals for the
trigger generators which accept the signals from the plug-ins (or the rear panel TRIG
IN connectors) and generate digital trigger signals for the time base.
(b) Trigger parameters such as level, slope, coupling, and source are set by
the 6800 microprocessor (MPU) on the basis of front panel inputs or commands received
on the IEEE 488 bus.
(c) Circuits are included to position the beam and control its rotation with
respect to the vertical diode stripes on the target.
The high-voltage supply
generates the 10-kilovolt accelerating potential and the focus potentials for the
tubes.
(3) Data Flow.
The eight-bit, gray-code outputs from the EBS tubes are contin-
uously sampled at 5 nanosecond intervals by the strobed, hybrid comparators.
The time
bases control data storage by providing the memory addresses, clock signals, and
select signals for the data memory.
Data is stored in the memory in gray-code format.
On output, the data is converted to binary by a gray code-to-binary converter on the
translator board.
It is then sent over an internal, high-speed, data bus to the IEEE
488 bus interface.
(4) Digitizer Control.
The 6800 microprocessor system is the digitizer master
controller.
It accepts and decodes commands from the front panel or the IEEE 488 bus
and sets the digitizer operating parameters in response to these commands.
It also
controls the IEEE 488 bus and the plug-in interface.
c. VHF CABLE ENTRY PANEL 2A2A2
(1) General.
The VHF cable entry panel 2A2A2 contains 15 BNC connectors, only
three are used.
One (J1) is connected to the radiometer assembly 2A1A2A3, and two
(J2,J3) are connected to the video signal generator in the electronics drawer assembly
2A2A7.
These connectors are used during testing to connect TPS or test instrument
cables.
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