Benefon TGP-65-EU iO, Руководство по обслуживанию

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15.1.1999
3GP_60GB 7
Product: TGP-60-EU (Vega) / Local Service Mode
4.4 TUNING INSTRUCTIONS
4.4.1 General
This is only a short overview of the tuning procedures. Please follow the more spe-
cific instructions in your service software.
4.4.2 Base frequency
This is the initial TCXO frequency correction value. A GSM mobile must adjust the
base frequency according to the frequency synchronisation burst of the base station
whenever it can hear one. Thus, this value is used only when the phone is searching
for the first base station.
Exact tuning of this value may look useless when compared to the modulation band-
width of GSM. However, a decent initial value may help synchronisation with the net-
work on some conditions and it is a good idea to check that the TCXO control circuit
is working.
4.4.2.1 Tuning
Connect the GSM tester or frequency counter to the phone and select item "Tuning-
Base frequency" from the menu. Adjust the frequency up or down until it is 902.0000
MHz +/- 100 Hz and save the value.
4.4.3 TX power
The transmitter power ramp has three specifications: power must be within the spec-
ified limits, the power curve must fit the power template, and spectrum due switching
must be below the given maximum values.
The transmitter power ramp is controlled by an array of 32 register values. At the
start of one transmitter burst, the first 15 values are assumed by the power control
register to increase the power smoothly. The 16th value is used during actual data
transmission. Values 17-32 are used after data transmission to decrease the power.
Because each value affects the power template and spectrum, adjusting the values
individually is a very difficult and time-consuming job. Therefore, the ramp values are
controlled with five parameters in the tuning software:
- Continuous power level
- Corner position of rising and falling edge
- Slope (speed) for rising and falling edge
For maximum battery life the highest power (PL 5) should be at a range 32.0 - 32.5
dBm on middle channel. Difference between power levels should be 1.8 - 2.0 dB.