Ceyear 3943B, Руководство по эксплуатации

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8 Technical indicators and testing methods
8.5 Performance characteristics test
107
Fig. 8.4 Display average noise level test schematic diagram
c) Test procedure
1)
Connect a 50Ω load to the RF input port of the device to be tested in accordance with Fig. 8.4.
2) Reset the device to be tested. Set the device to be tested to panoramic scan mode (PSCAN). Set
the level unit to dBm. Set the start frequency, end frequency, attenuator state and resolution bandwidth
of each band in the RF Panorama window according to the auxiliary table B.4. Set the maximum level
-60dBm.
3) Set the detection type to average, measurement time mode manual, and set the measurement time
according to auxiliary table B.4. Set the filter selectivity to narrow. Use the peak frequency scale to
search for the maximum frequency point of the noise level and record the level reading of that frequency
point in the auxiliary table B.4. If there are remaining response frequencies, the remaining response
frequencies should be removed.
d) Test record and data processing
Process the data in Auxiliary Table B.4 according to the following formula, and record the calculation
results in Auxiliary Table B.4 and summarize them in Functional Performance Test Record Table A.1.
 
8 . 0 log 10
   
RBW P DANL
...................................
（
1
）
Where:
DANL - is the detection sensitivity;
P - is the peak frequency scale magnitude;
RBW - is the resolution bandwidth.
8.5.1.5 Noise factor (level channel)
a) Description of the test items
The noise factor (NF) is a parameter that measures the receiver's ability to receive weak signals. The
ITU recommends three methods for measuring this parameter, of which this device uses the "gain"
method for measurement. The physical gain of the level channel of this device is compensated in the
measurement result, which is equivalent to the full channel gain of 0. Therefore, NF=174+Pout in dB,
and Pout is the noise floor power density.
b) Test equipment
50Ω load
3.5mm(f)-N type(m) connector
Fig. 8.5 Schematic diagram of the noise factor test
c) Test procedure