Series 8650A Universal Power Meters
3-34
Manual 31470, Rev. E, April 2001
3.2.19
Relative or Referenced Measurements
CALCulate:REFerence
Relative and referenced measurements are used when one measured value needs to be compared to
another measured value on the same channel. For example, this function is used when it is desired to
monitor the power level variation around an initial turn on or reference set value.
Referenced measurements are performed when finding the 1 dB compression power of an amplifier or
using a return loss bridge. When a stable source is used, a relative measurement is useful for measuring
the loss through an attenuator with a single sensor or channel.
Due to the ability to set a specific value of reference using the CALC:REF[:MAG] # command, this
reference measurement function can also be used to set your own calibration factors. Thus the channel
and sensor offset functions can remain dedicated to other setup dependent controls in your
programming.
Syntax
:
CALCulate<channel 1 or 2>:REFerence:STATe
space
<ON or OFF>
Example
:
OUTPUT @Pwr_mtr;CALC2:REF:STAT ON
! Activate level reference for relative
! measurements
Description
: This command activates the meter’s level reference to give it the ability to perform relative
measurements.
Syntax
:
CALCulate<channel 1 or 2>:REFerence [:MAGnitude] <dB Offset value from -299.999 to
299.999>
Example
:
OUTPUT @Pwr_mtr;CAL2:REF -30.11
! Set channel 2 reference offset value in dB
Description
: This command sets the value to subtract from the channel measurement value. This
command applies to the channel (1, or 2, or 1/2, ...), not the sensor (1 or 2, only).
Syntax
:
CALCulate<channel 1 or 2>:REFerence:COLLect
Example
:
OUTPUT @Pwr_mtr;CALC2:REF:COLL
! Current Rdg. ==> Ref level.
! Take channel 2 reading as reference value
Description
: The CALCulate:REFerence:COLLect command will cause the level of the current power
measurement to become the reference level. There is no query form of this command.
After you send this command, the channel measurement will be zero, assuming the power
levels at the sensor(s) did not change and REF:STAT is ON.
Error Control
Selected basic SCPI syntax and execution error apply to these commands.
Device-specific errors include the following and other -300 level errors.
Use CALC:REF commands only in the NORMal Mode. Attempts to use these commands in the SWIFt
and BURSt modes will be ignored and the error, -300, Device-specific error; Normal mode is off. will be
generated.
Summary of Contents for 8650A Series
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