HP 8153A - Page 56

2 The dB Key
This key switches the display to show results in dB. Results in dB are always
given with respect to another power-level. This can be a stored reference, or it,
can be a second power-level.
Using with a Two Sensor Instrument
For an instrument with two sensors, the dB result can be with respect to the
reference stored for the channel, or it can be with respect to the power-level of
the other channel.
. If the result is in dB with respect to the power-level of the other channel,
fdBl changes the result to dB with respect to the stored reference. The
reference-indicator shows A/REF or B/REF. To see the reference , use (Param) . To
set the reference you use (Param] or [Disp->Ref] .
= ^measured REF
Where,
Pdispiay is the displayed, relative power,
Pmeasured is the absolute powcr-level (see “GAL”), and
REF is the reference.
If the result is in dB with respect to the reference, (d|3 changes the result to dB
with respect to the power-level in the other channel. The reference-indicator
shows A/B or B/A. When the result is with respect to the power-level in the
other channel, the stored reference is also used in the calculation of the
displayed result.
Pdisplayi^^R) ~~ Pmsasitred^,ifj.f^,^^ Pmeasured^„4^^^^ ~ REF
Where,
Pdispiay is the displayed, relative power,
Pmeasured is the absolute power-levol (see “CAL”), and
REF is the reference.
If the result is in dBm or Watts, changes the result to dB.
2-8 Local Control - Measure Mode