Tel: 886.909 602 109 Email: [email protected]
59
3.12 Test of Low Power Signal
When the S2438 microwave power meter is connected to a S71710 series CW power sensor and a S81702 or
S81703 series peak power sensor to measure low power signals, additional settings are required to ensure the power
measurement accuracy.
3.12.1 Measurement of low power signal with a S71710 series CW sensor
When the S71710 series CW power sensor is used for power measurement of the signal with a power less than
-60dBm, the following operations are required:
1) Warm up the instrument for at least 15 min after powering it on to ensure a stable temperature for the
microwave power meter and power sensor;
2) Manually set the average count, press[Channel]>[Channel A] >[Average] >[Manu], and set [Avg Count] to
1,000;
3) Set [ChA Set] >[Step Detect Off];
4) Zero the sensor, connect the sensor to the device under test, disable its output, and press [Cal]>[Channel
A] >[Zero];
5) Observe the power displayed on the screen after zeroing. When the displayed noise is below -75 dBm, enable
the power output of the device under test, wait for about 20 s, and read the displayed power value.
If the measurement is performed for a long time, it is recommended to perform the zeroing and calibration
operation again according to the above steps.
3.12.2 Measurement of low power signal with a S81702 or S81703 series peak power sensor
When the S81702 series peak power sensor is used to measure the pulse signal with a power less than
-10 dBm, internal trigger will fail, and external trigger will be required at this time; the 81703 series peak power sensor
has an internal trigger level of -25 dBm.
Taking the S81703 series power sensor with a measurement period of 100 us, a pulse width of 50 us and a peak power of
-26 dBm as an example, the measurement process of low peak power signals is illustrated hereinafter.
1)
Connect “Pulse Sync Output” of the signal generator to “Trig Input” of the instrument with a BNC cable;
2)
Set the trigger source as „Ext”: press [Menu]>[Trigger] >[Trig Set] >[Trig Source Ext], and set [Trig Level 1V];
3)
Set [Average] as “On”, and set the average count to 50;
4)
Set the channel trace: press [Channel]>[Trace Ctrl] >[Trace Set] >[Vert Cent -30dBm], and set [Vert Scale 2dB/]
and [X Scale 20us/].
Fig. 3.18 shows the test graph.
