
1999 March 01
21
Philips Semiconductors
Product specication
Single chip DVB-C channel receiver
VES1820X
Bw
RS
=
10
Range
10240 - 1
è
÷.AGCREF
2
13
+2.Kagc
where Range is the total AGC range in dB.
PWMA
PWMA indicates the polarity of the VAGC output. When PWMA =1 (default) the
higher the DC level is, after low pass filtering on VAGC output, the lower the gain
must be. It is the opposite when PWMA=0.
SELAGC
SELAGC determines which kind of information is provided on output pin VAGC.
When SELAGC = 0 (default), VAGC is the PWM encoded AGC value. When
SELAGC = 1, VAGC is the sign of the amplitude error. (See FIGURE 11 and
FIGURE 12 page 16).
ADCSEL
ADCSEL selects if the internal ADC is used (ADCSEL = 0) or if an external ADC is
used (ADCSEL = 1).
FELPWM
FELPWM determines the functionality of output pin FEL.
When FELPWM = 0 (default), FEL is a front end lock indicator.
When FELPWM = 1, FEL is a PWM encoded output, which value is programmed
in register PWMREF (index 34
16).
4. CLKCONF
03
16
READ/WRITE
CLK_C
CLK_C[2:0] must be set to 2
16.
DYN
DYN determines if the acquisition range for clock recovery is ± 120 ppm (DYN = 0,
default) or ± 240 ppm (DYN = 1).
GAIN2
GAIN2 allows to program the gain of the second decimation filter. When GAIN2 =
0 (default), the gain is 1 and when GAIN2 = 1, the gain is 2.
GAIN3
GAIN3 allows to program the gain of the third decimation filter. When GAIN3 = 0
the gain is 1 and when GAIN3 = 1 (default) the gain is 2.
NDEC[1:0]
NDEC[1:0] determines the number of decimations according to the following table
Symbol Rate (SR)
NDEC[1 :0]
SACLK/8 < SR < SACLK/4
00 (0)
SACLK/16 < SR < SACLK/8
01 (1)
SACLK/32 < SR < SACLK/16
10 (2)
SACLK/64 < SR < SACLK/32
11 (3)
5. CARCONF
04
16
READ/WRITE
CAR_P[2]
CAR_P[2] determines whether the carrier acquisition range is ± 2.5% of the
Symbol Rate (CAR_P[2]=0) or ± 8% (CAR_P[2]=1). Default is CAR_P[2]=0.
CAR_P[1:0]
CAR_P[1:0] must be set to 1
16
.
CAR_C[3:0]
CAR_C[3:0] configures the coefficients of the carrier recovery loop filter, according
to the table below :