Technical data

Specifications 1
N1911A/1912A P-Series Power Meters Service Guide 17
Noise and drift
12
Within 1 hour after a zero, at a constant temperature, after 24 hour warm up of the power meter.
This component can be disregarded with Auto zero mode set to ON.
13
Measured over a one minute interval, at a constant temperature, two standard deviations, with
averaging set to 1.
Effect of video bandwidth setting
The noise per sample is reduced by applying the meter video bandwidth
filter setting (High, Medium or Low). If averaging is implemented, this will
dominate any effect of changing the video bandwidth.
Effect of time-gating on measurement
The measurement noise on a time- gated measurement will depend on the
time gate length. 100 averages are carried out every 1 μs of gate length.
The Noise per Sample contribution in this mode can approximately be
reduced by √(gate length/ 10 ns) to a limit of 50 nW.
Sensor Model Zeroing Zero set Zero drift
12
Noise per
sample
Measurement
noise (Free
run)
13
< 500 MHz > 500 MHz
N1921A/
N1922A
No RF on input
RF present
200 nW 100 nW 2 μW50 nW
550 nW 200 nW
Measurement average
setting
12481632641282565121024
Free run noise multiplier
1 0.9 0.8 0.7 0.6 0.5 0.45 0.4 0.3 0.25 0.2
Video BW setting Low 5 MHz Medium 15 MHz High 30 MHz Off
Noise per sample multiplier
< 500 MHz 0.5 1 2 1
> 500 MHz 0.45 0.75 1.1 1