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9 Calibration Intermediate Power
9.1
What is Intermediate Power
Intermediate Power is a calibration necessary to do to fulfil the demands of the GSM-
specification for the up- and down-ramping of the power and to minimise the transient spectra at
it.
The up- and down-ramping of the control voltage of the power amplifier does not change
momentarily from zero-to-max/max-to-zero, that would cause a large number of over tones due
to the switch.
The up- and down ramping of the control voltage are instead performed with two help steps.
The control voltage then passes through an exponential amplifier and a Bessel low pass filter in
N450 where the transient disturbance is reduced.
This gives a control voltage without the straight, vertical edges and the sharp corners that
produces the over tones.
The two help steps in the up- and down ramping of the power are called Intermediate Power
level.
The figure below Fig.9.1. shows the up ramping of the control voltage before it passes through
the exponential amplifier and the low pass filter, i.e. what the up-ramping steps looks like.
The three power steps Low Intermediate Power level, High Intermediate Power level and
Full Power level are set by the power level DAC in N800 and are amplified and filtrated in
N450.
Low and High Intermediate Power level uses default values to generate the voltage.
Power level is full power level, 5 – 19 for GSM 900 and 0 – 15 for GSM 1800, and the DAC
values are calibrated so that the Power levels are according to the GSM – specification.
Intermediate Power level are calculated at the power calibration and are not shown in the test
protocol.
4/00021-3/FEA 209 544/18 B
Trouble Shooting Guide, Advanced
Fig.9.1
42(121)
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