3.4.3.2.1.4 DMDRB – Demodulator Data Rate on Path B

The target symbol rate for the receiving path B is configured in this register. This register must only be modified if the block receiving the settings is disabled (RDPR.PRPTB = 1). Modifying the settings during operation may lead to unstable operation.

Name:	DMDRB
Offset:	0x0A7
Reset:	0x00


Bit	7	6	5	4	3	2	1	0
	DMDNB[3:0]				DMAB[3:0]
Access	R/W	R/W	R/W	R/W	R/W	R/W	R/W	R/W
Reset	0	0	0	0	0	0	0	0

Bits 7:4 – DMDNB[3:0] Demodulator Down-Sampling on Path B

Selects the down-sampling and cut-off frequency of the first stage of the data filter.

Table 3-16. DMDNB Setting versus Amplitude Threshold Scaling on Path B (ATSCAL_B)
DMDNB	ATSCAL_B
0	1
1	1
2	2
3	2
4	4
5	4
6	8
7	8
8	16

The recommended down-sampling for a target symbol rate is:

$D M D N B = f l o o r [I d (20) + I d (\frac{C L K_B B}{S y m b o l R a t e P a t h B \times 128})] ......(20)$

If the result is -1, set DMDNB = 0.

Equation parameters:
- SymbolRatePathB: Maximum expected symbol rate in Hz on the useful signal for path B
- CLK_BB: Baseband clock frequency in Hz. See equation (13) in the section Bandwidth Scaling
- ld(): Logarithm to the base 2

Bits 3:0 – DMAB[3:0] Demodulator Moving Average Data Rate Factor on Path B

Selects the moving average filter length for the data filter and initial data rate for the clock recovery on path B.

Table 3-17. DMAB Setting versus Moving Average Filter Length and Symbol Rate Factor on Path B (MAVFL_B, SR_F_B)
DMAB	MAVFL_B	SR_F_B
0	12	10
1	11	11
2	10	12
3	9	13
4	9	14
5	8	15
6	8	16
7	7	17
8	7	18
9	6	19
10	6	20
11	6	21
12	5	22
13	5	24
14	4	26
15	4	28

The recommended settings for this register are provided by the configuration tool after selecting the desired target data rate for path B. Symbol Rate Factor can also be calculated using the following equation. Use the corresponding value for DMAB from the preceding table.

Equation 3-1. Symbol Rate Factor

$S R_F_B = r o u n d (S y m b o l R a t e P a t h B \times 2^{D M D N B} \times \frac{128}{C L K_B B}) ......(21)$

Equation parameters:
- SymbolRatePathB: Maximum expected symbol rate in Hz on the useful signal for path B
- CLK_BB: Baseband clock frequency in Hz. See equation (13) in the section Bandwidth Scaling
- SR_F_B: Must be in the range of 10 to 28, if possible 10 to 19

DMAB	MAVFL_B	SR_F_B
0	12	10
1	11	11
2	10	12
3	9	13
4	9	14
5	8	15
6	8	16
7	7	17
8	7	18
9	6	19
10	6	20
11	6	21
12	5	22
13	5	24
14	4	26
15	4	28

DMAB	MAVFL_B	SR_F_B
0	12	10
1	11	11
2	10	12
3	9	13
4	9	14
5	8	15
6	8	16
7	7	17
8	7	18
9	6	19
10	6	20
11	6	21
12	5	22
13	5	24
14	4	26
15	4	28

DMAB	MAVFL_B	SR_F_B
0	12	10
1	11	11
2	10	12
3	9	13
4	9	14
5	8	15
6	8	16
7	7	17
8	7	18
9	6	19
10	6	20
11	6	21
12	5	22
13	5	24
14	4	26
15	4	28