
1996 Oct 29
86
Philips Semiconductors
Objective specification
GSM signal processing IC
PCF5083
Notes
1.
The on-chip firmware does not include the basic ciphering algorithms A5/1 and A5/2, which produce BLOCK1 and
BLOCK2 in accordance with “GSM recommendation 3.20” Therefore the firmware only works correctly, if encryption
and decryption is switched-off. If ciphering is required, a corresponding software module must be downloaded into
the on-chip program RAM. More information will be made available with application notes.
TG_tone_gen_init
This routine initialises TG_tone_gen. The parameters start_att_inc_factor
and start_att_factor indicate how the sine wave starts. Frequency, decay
and amplitude factor for each oscillation are set. If one of the sine values is
zero the state variables of this oscillation are not set. This can be used to
change parameters of the oscillation during tone generation.
The input signal is multiplied with the factor ampl_input. The ampl_input is
represented in 16-bit fixed-point arithmetic with 14 fractional bits (0X4000
corresponds to 1.0).
The parameter start_att is the factor for starting the generated tone softly.
Each sample of the generated tone signal is multiplied by start_att. The
start_att is multiplied by start_att_inc every sample. Both start_att and
start_att_inc are represented in 16-bit fixed-point arithmetic with
14 fractional bits (0X4000 corresponds to 1.0).
The parameter start_att_inc is the factor for increment of the
start_att_factor and is specified below:
0X4000: start_att_factor is not changed
0X4001 to 0X7FFF: start_att_factor is incremented
0X0000 to 0X3FFF: start_att_factor is decremented.
If start_att_inc_factor
×
start_att_factor is not greater than
start_att_factor + 0.5 there is no increment because of rounding.
cos_omega_1, cos_omega_2, cos_omega_3 = 32768 cos(
) is the value
to determine the oscillation frequency of the Nth sinus oscillation
= 2
×
D
×
f/f
s
, where f is the frequency of the oscillation, f
s
is the sampling
frequency.
sin_omega_1, sin_omega_2, sin_omega_3 = 32768 sin(
) is the value to
determine the amplitude of the oscillation.
decay_N = r is the value to determine the decay of the sinus oscillation (r is
the pole radius of the generating filter):
0X4000: no decay
0X0001 to 0X3FFF: decay
0X4001 to 0X7FFF: not stable.
ampl_sin_1, ampl_sin_2, ampl_sin_3 are the values to determine the
amplitude of the sine oscillation.
TG_tone_gen_off
57
ampl_input
start_att
start_att_inc
cos_omega_1
sin_omega_1
decay_1
ampl_1
cos_omega_2
sin_omega_2
decay_2
ampl_2
cos_omega_3
sin_omega_3
decay_3
ampl_3
This procedures switches off the tone generation. To restart tone
generation TG_tone_gen_init has to be called again.
33
DESCRIPTION
ID
PARAMETERS
RETURN
VALUES