Measuring Rx Module Manually Using Oscilloscope And Spectrum Analyzer (Gsm1800) - Nokia 6260 RM-25 Service Manual

RM-25
RF troubleshooting
• Signal amplitude: 180 ~ 600mVpp
• DC offset: 1.2 ~ 1.4V
• Frequency: approximately 67KHz

Measuring Rx module manually using oscilloscope and spectrum analyzer (GSM1800)

Context
Spectrum analyzer level values depend on the probe type and should be validated using a known good sample.
The levels that are given here are measured using a high frequency probe.
Measuring with an oscilloscope at test points RXI (730) or RXQ (J731) ) and RXID (J261) or RXQD (J262) is
recommended only if RSSI reading does not provide enough information.
Steps
1. Start Phoenix Service software.
2. Establish connection to the phone.
From the File menu, choose Open Product.
From the list, choose RM-25.
3. From the Testing menu, choose RF Controls.
4. In the RF Controls window:
i Select Band GSM1800.
ii Set Active unit to Rx.
iii Set Operation mode to Continuous.
iv Set RX/TX channel to 700.
v Set AGC to 12.
The frequency or level of signal generator is 1842.8677MHz, -60dBm.
Note: Because DC compensation does not work during continuous mode, DC offset level at RXI and
RXQ will gradually shift from the optimized level.
To have the most reliable result, it is highly advisable to set the operation mode from burst to
continuous just before measuring values and complete measurement within no longer than 30
seconds.
9235618 (Issue 2)
Figure 112 Probed Rx I/Q signals J730, J731
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