HDM8515 Datasheet, PDF (68/75 Pages) Hynix Semiconductor – DVB/DSS Compliant Receiver

Figure A2 illustrates the transient response of the carrier tracking loop with the same loop
bandwidth settings at high signal-to-noise ratio. The phase step for this test corresponds to 45
degrees. The actual bandwidth of the carrier loop is greater than that of the symbol loop for the
same settings because the carrier loop must cope with greater dynamics (such as frequency offset
and drift). Figure A3 illustrates the transient response of the carrier phase tracking loop under the
same conditions at minimum signal-to-noise ratio (Eb/N0 of 4 dB with rate 1/2 coding). The
highest bandwidth case will pull in with a carrier frequency error of + or - .005 of the symbol rate at
this minimum signal level. Higher loop bandwidth may be programmed to provide greater pull-in
with higher signal-to-noise ratio conditions.
FIGURE A2: CARRIER PHASE RECOVERY TRANSIENT RESPONSE
68