Theory of Operation
Analog Section
Table 5-2
VCO and measurement frequencies for each band
Band1
Band2
Band3
Band4
The filtered signal goes through an attenuator variable from 0 dB to 35 dB in 5 dB steps,
and is output to RF Out port. Attenuation is controlled depending on the output power
setting as shown in Table 5-3.
Table 5-3
Output Attenuator
Nominal Setting of
Output Power Level
7.9 dBm ~ +1 dBm
12.9 dBm ~ 8 dBm
17.9 dBm ~ 13 dBm
22.9 dBm ~ 18 dBm
27.9 dBm ~ 23 dBm
32.9 dBm ~ 28 dBm
37.9 dBm ~ 33 dBm
40 dBm ~ 38 dBm
The A3 VCO signal is also mixed with RF1 signal which is supplied to A4 receiver board.
A4 Receiver Board
A4 receiver board receives the Vch and Ich signals from the A6 test head through PORT1
and PORT2, mixes down them into 12.5 KHz IF signals, and converts the analog signals to
digital data. The receiver has two signal flow to measure Vch and Ich signals.
The input attenuators on A4 board are controlled to optimize the receiver input signal
levels(the signal to noise ratios) for accurate measurements. These attenuators are set
depending on the output power setting as shown in Table 5-4.
228
Measurement Frequency
1 MHz 1739.9 MHz
1740 MHz 2259.9 MHz
2260 MHz 2679.9 MHz
2680 MHz 3000 MHz
Output Attenuator
on A3
0 dB
5 dB
10 dB
15 dB
20 dB
25 dB
30 dB
35 dB
VCO Frequency
2305 MHz 4043.9 MHz
2892 MHz 3411.9 MHz
3412 MHz 3831.9 MHz
3832 MHz 4152 MHz
Chapter 5