3 Using E9300 E-Series Power Sensors
118 N1913/1914A EPM Series Power Meters User’s Guide
Accuracy
The value of –12 dBm lies in the lower range of the E- Series E9300
power sensor. In autoranging mode (“AUTO”), the power meter
determines the average power level is below –10 dBm and selects the low
power path. However, the peak amplitude of –6 dBm is beyond the
specified, square law response range of the low power path diodes.The
high power path (–10 dBm to +20 dBm) should be used to ensure a more
accurate measurement of this signal. However, range holding in “UPPER”
(the high power path), for a more accurate measurement, results in
considerably more filtering.
Speed and Averaging
The same signal also requires that consideration is given to measurement
speed. As shown above, in autoranging mode the power meter selects the
low power path in the E- Series E9300 power sensor. With auto- averaging
also configured, minimal filtering is applied. Values of 1 to 4 for average
power levels above –20 dBm are used in the low power path. (Refer to
“E9300 E- Series auto- averaging settings” on page 105.)
If the range is held in “UPPER” for more accuracy, the measurement is
slower. More filtering is applied due to the increase in noise susceptibility
at the less sensitive area of the high power path. Values of 1 to 128 for
average power levels less than –10 dBm are used. (Again, refer to “E9300
E- Series auto- averaging settings” on page 105.) Manually lowering the
filter settings speeds up the measurement but can result in an unwanted
level of jitter.
Summary
Attention must be paid to signals whose average power levels are in the
low power path range whilst their peaks are in the high power path range.
You can achieve best accuracy by selecting the high power path or best
speed by selecting the low power path.
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