HP 437B Service Manual

HP 437B
Service Sheet BD1
Table 8-3. Number of Averages vs. Range and Resolution
(Auto Filter Mode)
Number of Averages Number of Averages Number of Averages
8 128 128
8
2
1
1
The output of the low pass filters is a de voltage that is proportional to the
power of the input signal. The output of the low pass filters is fed into the
A-to-D input multiplexer.
The A-to-D input multiplexer can select any one of the following signals as
the input to the analog-to-digital converter:
1. The low pass filter output.
2. The front or rear sensor resistor.
3. The B-GND (OV).
4. The +2.5V reference voltage (only selected during the CAL routine).
6. The RECORDER output (only selected during the CAL routine).
7. The Offset DAC output (only selected during the ZERO and CAL
routines).
During the normal measurement cycle, the A-to-D input multiplexer selects
the inputs in the following pattern:
1. B-GND.
2. Front sensor resistor.
3. Rear sensor resistor.
4. Low pass filter output.
The B-GND is selected for a reference for power measurement. The front
and rear sensor resistors are checked to determine what sensor is attached
and if the sensor has been changed since the last measurement. The low pass
filter output is then selected to be sent to the A-to-D converter for
measurement.
SERVICE 8-19

HP 437B Specifications

General

Brand	HP
Model	437B
Category	Measuring Instruments
Language	English