ACCEPTANCE TESTING
6-31
Level accuracy
Because of the presence of frequency conversion products in digital modulation mode, it is
necessary to calibrate the RF levels on a spectrum analyzer. The first part of this process, steps (1)
to (8), calibrates the spectrum analyzer against a power meter using CW only. Taking a
photocopy of Table 6-20 will greatly assist when performing this procedure.
Specification
Level accuracy
±1.5 dB for carrier frequencies to 2 GHz,
±2 dB for carrier frequencies to 2.7 GHz
at 23° ±5°C.
The temperature coefficient is ±0.04 dB/°C
Test equipment
Description Minimum
specification Example
RF power meter
±0.1 dB from 30 kHz to 2.7 GHz
Aeroflex 6960B and
6912 Sensor
Spectrum analyzer
30 kHz to 2.7 GHz freq coverage
Aeroflex 2383
Function generator
DC to 10 MHz freq coverage,
±0.6 dB flatness
HP3325B
Test procedures
(1) Connect the test equipment as shown in Fig. 6-1.
(2) Set the UUT to CW mode (not digital or vector) then:
[RF Level]
0 dBm
[Carrier Freq.]
10 MHz
(3) Measure and record the level in Table 6-20, column
2
.
(4) Repeat at the frequencies listed in Table 6-20, column
1
.
Steps (5) to (9) which follow calibrate the spectrum analyzer.
(5) Connect the test equipment as shown in Fig. 6-13.
Table 6-20 Calculating level accuracy in digital modulation mode
1
2
3
4
5
6
Carrier
frequency
Level measured
on power meter
(dBm)
Level measured
on spec anal
(dBm)
Difference
(dB)
Level recorded on
spec anal with UUT in
digital mode
(dBm)
Result
(dBm)
Example
−
0.17
−
0.24
+0.07
−
0.38
−
0.31
RF level
0 dBm
10 MHz
850 MHz
1750 MHz
2000 MHz
2700 MHz
RF level
+6 dBm
10 MHz
850 MHz
1750 MHz
2000 MHz
2700 MHz