
1996 Oct 29
77
Philips Semiconductors
Objective specification
GSM signal processing IC
PCF5083
EM_normal_burst
Adaptive viterbi equalizer for normal bursts. The 149 I and Q pairs in
IQ_BUFF are demodulated. The parameter cmi_buff_id determines the
buffer where the demodulated CMI values should be stored. The following
values for cmi_buff_id are allowed:
TCH_CMI_BUFFx for sub-block number x of a TCH.
CCH_CMI_BUFFx for sub-block number x of a CCH.
The parameter tsc determines the training sequence code. Valid range:
0
≤
tsc
≤
7.
The snr is an estimation for the signal-to-noise ratio (0
≤
snr
≤
255).
The toi denotes the measured time difference (in quarterbits) between the
first information bit of the burst and the start of the sampling window.
Range: 0
≤
toi
≤
28. A toi value of 12 is the optimal position.
For output_mode = 1; (see EM_init) foi_re and foi_im denote the real and
imaginary part of the frequency offset information. The frequency offset df
(Hz) can be calculated in accordance with equation:
For output_mode = 0; the frequency offset df in Hz is returned instead of
foi_im as the 4th return values.
It should be noted that the frequency offset output (for both output modes)
only contains meaningful information, if foi_re > 450.
EM_offset_measurement
34
cmi_buff_id
tsc
snr
toi
foi_re
foi_im df
This procedure measures the offset of the complex baseband signal
located in IQ_BUFF.
The parameter n_samples is the number of complex I and Q samples to be
used for averaging; n_samples must be one of the following values: 64 or
128. If n_samples is not specified, then a default value of 128 is used.
The i_offset and q_offset is the time averaged value of the complex
baseband signal.
EM_power_measurement
79
[n_samples]
i_offset
q_offset
Power measurement for RXLEV calculation of serving and neighbouring
cells.
The agc_gain is the gain of the current AGC range in
1
8
dB.
The parameter n_samples is the number of I and Q samples located in
IQ_BUFF to be used for averaging; n_samples must be one of the following
values: 80 or 144. If the parameter n_samples is not specified, then a
default value of 80 is used.
The power_dBm is the time averaged value of the complex baseband
signal in
1
8
dBm steps (range:
722+agc_gain to agc_gain).
35
agc_gain
[n_samples]
power_dB
DESCRIPTION
ID
PARAMETERS
RETURN
VALUES
f
df
foi_re
663
×
------foi_im
=