S5H1420 Datasheet, PDF (7/31 Pages) Samsung semiconductor – Channel Decoder for DVB-S/DSS

S5H1420
DBS Channel Decoder for DVB-S/DSS
3.2.2 Loop equation
The timing loop may be considered as a second order loop. The loop equation may be calculated using
the following formula:
ε = 1<< ((P_g+8) – I_g)
ω = Φ_t^ĕ(1<< I_g)
Where, P_g is propagational gain, I_g is integral gain and Φ_t is timing factor.
× Φt = 5.0
1
2 ²⁴
f sym
And we can choose Loop ^{f clk} Bandwidth (BL), as follows:
BL = ω × ¹ × ξ × (1 + ¹ )
2
4ξ ²
Where ξ is the reference level of the ε and ω .
ξ = ^{ω ×ε}
2
3.2.3 Timing lock indicator
The timing detector need to a lot of symbols for stabilization in order to lock after tuning frequency
change of RF and it takes a 1-bit input signal, and uses the presence or absence of locking information
to either count up or count down respectively.
The counter operates up to reaches its maximum value when the lock signal goes active. Two cases
can cause the lock signal to go to unlocked state; one is assertion of the active-low reset and the other
the counter go zero again. User can monitor the MSB 8 bits of TLL (timing lock loop) counter in
Address 0x1a and the TLL lock flag in Address 0x14.
3.3 Carrier recovery
The tracking range of the derotator is ± f_clk /2 (± f_sampling/2).
This algorithm is used with QPSK reception, over a small range of capture phases and with a channel
noise value over 3.0 dB.
3.3.1 Loop equation
Like the timing loop, the carrier loop is a second-order system where two parameters, ε and ω.
ε = 1<< ((P_g+8) – I_g)
ω = Φ_p^ĕ(1<< I_g)
Where, P_g is propagational gain, I_g is integral gain and Φ_p is phase factor.
× Φp = 75.4
1
2 ²⁴
f sym
f clk
Also, we can choose Loop Bandwidth (BL), as follows:
BL = ω × ¹ × ξ × (1 + ¹ )
2
4ξ ²
Where ξ is the reference level of the ε and ω .
ξ = ^{ω ×ε}
2
3.3.2 Carrier lock detector
Samsung Electronics Co, Ltd. Proprietary Information
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