Powerful Arming Capability; High Stability Time Base; Special Configurations; Measurement Block - Racal Instruments 2461 User Manual

2461Type C User Manual
Powerful Arming
Capability
High Stability
Time Base
Special
Configurations
Measurement
Block
Racal Instruments  1998
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The 2461 Type C card offers powerful arming capability. Different
modes are provided with the ability to select the arming source
among the external arming input and the VXI TTLtrig lines.

Figure 1-6, Powerful Arming Capability

Counter measurement stability can be improved by using an
external clock or an optional internal high stability time base. Two
types of internal time base are optional:
•
TCXO (Ce card)
•
OCXO (Cf card)
The Cd, Ce and Cf cards are fitted with additional internal
connectors for future applications.
The measurement block is mainly implemented with an Altera
Erasable Programmable logic Device (EPLD). The Timing Error
Correction (TEC) circuit is external to this.
Referring to the block diagram Figure 1-7, the measurement block
consists of a high speed front end which takes in Inputs 1 & 2 after
conditioning by the input amplifiers. This front end connects to the
microprocessor data bus to allow the micro to configure the
measurement block for the type of measurement to be taken. The
micro also drives the measurement process by controlling the
arming of the start and stop of the measurement.
After a measurement has taken place, the micro reads the values
in the various counting chains via the data bus. The measurement
block uses interrupts to communicate the various events that occur
in the measurement block.
General 1-5