Ratio And Log/Lin - HP 8901B Operation And Calibration Manual

Model 8901B
Operation
Ratio and Log/Lin
FUNCTIONS
RATIO, PREVIOUS RATIO, LOG/LIN, Special Function
1 1
(Previous Ratio)
DESCRl PTl ON
The Ratio and Previous Ratio functions permit any measurement result to be scaled to a reference.
The reference may be either a measurement result or a keyboard entry. Special b c t i o n 11.2 displays
the current ratio reference.
The LOG/LIN key enables measurement results
to
be displayed in linear or logarithmic units, both
absolute and relative. Examples of absolute units are kHz and mV (linear), or dBm (logarithmic).
Examples of relative units are
%
and
dB.
For purposes of discussion, basic measurement units, such as
?Z
for AM or distortion,
dB
for SINAD, etc., (though actually relative units), are treated as absolute
units. When the instrument displays
5%
and
dB
as ielative units (that is, when the ratio function is
used), annunciator
REL
is added to the display.
All modulation and all frequency measurement results cannot be displayed with absolute, logarithmic
units even though they can be displayed in relative, logarithmic units. (The LOG/LIN key is ignored.)
The Ratio function can be used with the following measurements:
AM SINAD (29.0 SPCL)
FM Ext Audio RMS Level (30.0 SPCL)
@M
LO Frequency (33.0 SPCL)
RF POWER
IF
Frequency (34.0 SPCL)
FREQ RF Level (35.0 SPCL)
AUDIO FREQ
AUDIO DISTN
IF
LEVEL
TUNED RF LEVEL
FREQ ERROR
The Ratio function is exited when:
0
the RATIO key is pressed a second time,
0
a new measurement
is selected, or
0
other measurement units are selected.
PROCEDURE
Select LOG/LIN anytime during a measurement to change the display between linear and logarithmic
units, where permitted, for both absolute and relative (Ratio) displays.
To use the Ratio function:
in "DESCRIPTION."
1. Select the desired Measurement mode. Measurements possible with the ratio function are listed
Ratio and Log/Lin 3-215