STV0299B STMicroelectronics, STV0299B Datasheet - Page 14

• Manufacturer Part Number: STV0299B
• Manufacturer: STMicroelectronics

Specifications of STV0299B

• Pin Count: 64
• Screening Level: Commercial
• Lead Free Status / Rohs Status: Specific Sites Compliant

STV0299B
4
4.4 Carrier Recovery and Derotator Loop
The tracking range of the derotator is
( f
therefore be performed on several MHz ranges
without reprogramming the tuner.
Three phase detectors are selectable using
software:
• Phase detector algorithm 0: This algorithm
• Phase detector algorithm 1: This algorithm is
• Phase
The loop is controlled through
parameters.
The carrier loop control registers (the Alpha
Carrier Register, the Beta Carrier Register and the
Carrier Frequency Register) are in Addresses 13,
14, 22 and 23.
4.4.1
Like the timing loop, the carrier loop is a
second-order system where two parameters,
and
beta_car respectively.
The natural frequency (f
The damping factor is:
where
level in the AGC2 register.
4.4.2
The carrier lock detector provides an indicator
with a high value when the carrier is locked,
dependent on the channel noise. When the carrier
is not locked, the indicator value is low.
The
programmable 8-bit threshold (Register 15h). The
14/36
= (4+2c+d) 2
should only be used for BPSK reception.
used with QPSK reception, over a small range
of capture phases and with a channel noise
value over 4.5 dB.
reception, it is used after locking, to minimize
the bit error rate in low channel noise
conditions. Algorithm 2 is recommended for
most applications.
sampling
FUNCTIONAL DESCRIPTION (continued)
indicator
may be programmed with alpha_car and
Loop Parameters
Carrier Lock Detector
f
n
/2). The initial frequency search may
=
detector
= (2+a) 2
7 10
=
e
, with e
22 10
–
value
6
f
b
M_CLK
algorithm
–
2
6
14
n
) is:
,
1. m2 is the reference
is
m2
-------- -
m2
with
compared
----------------
f
M_CLK
2:
f
S
----------------
f
M_CLK
b
f
For
S
1,
f
M_CLK
and
QPSK
to
and
/2
a
result of this comparison (1 if greater than the
threshold, else 0 if not) is written as the Carrier
Found flag (CF), and may be read in the status
register. The CF signal may be permanently
routed on the output LOCK (see Register 08h).
The Lock Detector Threshold Register and Lock
Detector Value Register are in Addresses 15 and
1C.
4.4.3
The derotator frequency can be either measured
(read operation) or forced (write operation).
Derot_freq is a 16-bit signed value.
The Derot_freq Registers are Registers 22 and
23.
4.4.4
The carrier recovery loop features a carrier
frequency
detectors. When the carrier frequency offset
detector is enabled, the central loop frequency is
modified proportionally to the carrier offset. The
gain and time constants of the detector are set by
CFD[6:4] and CFD[3:2] respectively. When the
carrier loop is about to “phase lock” with the
carrier, the frequency detector stops automatically
and the phase lock is ensured by the selected
phase
determined by the threshold CFD [1:0].
For stability reasons, the gain CFD [6:4] should
not exceed the coefficient e[3:0] of Register
BCLC.
The carrier frequency offset detector is in Address
12.
4.5 Noise Indicator
The noise indicator may be used to facilitate the
antenna pointing or to give an idea of the RF
signal quality and of the front-end installation
(dish, LNB, cable, tuner or ADC).
A
implemented by comparing the current indications
with a primarily-recorded look-up table.
The time constant ranges from 4 k to 256 k
symbols. The 16 MSB of the result may be read by
the microprocessor (Registers 24 and 25).
simple
Derotator Frequency
Carrier Frequency Offset Detector
freq
detector.
offset
C/N
kHz
=
Derot_freq
----------------------------- -
This
estimator
detector
2
16
switchover
and
f
can
M_CLK kHz
two
be
point
phase
easily
is