Measurement Considerations
Using the Power Sensor
3-16
PN: 10585-00016, Rev. A
MA24104A UG
Settling Time
The MA24104A samples power continuously every 70 ms in the Low Aperture Time (LAT) mode and 700 ms in
the High Aperture Time (HAT) mode. The sensor’s front end and digitizer settles completely to a step change in
power in this amount of time. However, there is no way to synchronize the sensor’s sampling to any other
event, such as a power step or bus request for a measurement. Therefore, the first measurement requested
from the sensor after a power step may not be fully settled. To ensure a fully settled measurement when
operating the sensor over the bus, wait 70 ms (700 ms if in HAT) after a power step before requesting the
measurement from the sensor. Alternatively, request two measurements from the sensor and discard the first.
If averaging is required as described above, settling time increases by N × sample period, where N is the
number of averages and the sample period is the time is milliseconds. The measurement sample period is
70 ms for LAT and 700 ms for HAT. When operating the sensor over the bus, request N+1 measurements from
the sensor, discard the first, and then average the subsequent readings. The settling time is approximately
(N+1) × sample period.
Maximum Power
The MA24104A is rated to meet all specifications up to an average input power level of 150 Watts. Although
the average power of all signals should be kept at or below this level, time varying and burst signals having
peak powers less than the limits shown in the figure below can be measured. To ensure accurate readings, the
peak-to-average ratio (crest factor) of signals must be less than 12 dB.
Figure 3-21. Maximum Power Handling Capacity (with Load VSWR less than 1.5:1 and 3.0:1)
1000
500
500
5000
2000
1000
200
100
VSWR ≤ 3.0
VSWR ≤ 1.5
Maximum Power
Frequency [MHz]
RF P
ow
er [
W
]
