Tektronix ECO422D, Инструкция по эксплуатации

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Theory of Operation
4- 2
ECO422D SD/HD Changeover Unit Instruction Manual
ECO422D Block Level Description
Primary
check
Reference
Voltage
Generator
Voltage
Selector
Backup
check
other channels
other channels
Primary
Backup
One of
eleven channels
Relay
Output
Sync source
Auto
Decision
logic
Source
switch
Alarm
driver
Primary
Latch
Flag
Backup
Latch
Flag
Reset
(front panel)
Primary Fault Indicator
Backup Fault Indicator
Alarm (to Remote)
Figure 4- 1: ECO422D Block diagram
The Primary and Backup signals for each channel enter through the BNCs and
are applied directly to a Relay, where one signal is switched through to the
rear-panel Output and the other terminates in 75
Ω
. The rest of the circuitry
determines which signal goes to the Output.
The Primary and Backup signals are also applied to the Primary and Backup
Check circuitry. This block consists of a peak detector which compares the peak
level of the incoming signal with a predefined level from the Reference Voltage
Generator, selected by the Voltage Selector. The result of this check is ANDed
with the results from the ten other input sets and sent to the Decision Logic
circuit that determines the state of the relays. Additional circuitry runs the Alarm
Driver for the remote output and the fault indicators on the front panel.