Racal Instruments 2461 User Manual page 30

2461Type C User Manual
Racal Instruments  1998
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threshold, the latch is set and the channel output is inhibited by
the signal gate. When the detector output goes above the
threshold, the low signal latch is armed and opens the signal
gate on the next signal edge from the pre-scaler. This enables
the instrument to make measurements on signal bursts.
The detector output is also applied to the continuous signal
latch. This latch is reset at the beginning of each gate period
and is set if the detector output falls below the threshold level.
The microprocessor samples the latch output throughout the
gate period. If the measured signal falls below the threshold
level during this period, the measured result it set to zero.
When Channel 3 is not selected, the low signal latch is held in
reset by a control signal from the microprocessor and the
output to the measurement block is inhibited. The same control
signal is used to enable Channel 1 so that the two channels
cannot be enabled at the same time.
Theory of Operation 3-3