Satellite Signal Acquisition, Tracking, and Data Demodulation - Understanding GPS: Principles and Applications - page 198

DLL noise bandwidth

B n = 0.2 Hz B n = 2.0 Hz

1

0.9

0.8

Modulation: BPSK-R( )
Predetection integration time: = 0.020 s
E-L correlator spacing: = 1 chip
Normalized front end bandwidth:

n

T

0.7

D

b = 2

0.6

Db =2

0.5

0.4

0.3

1/6 chip threshold

12.4 dB-Hz 18 dB-Hz

0.2

0.1

0

10 15 20 25 30 35

( C/N 0 dB ) (dB-Hz)

(c)

Predetection integration time

T = 0.005 s T = 0.010 s T = 0.020 s T =1s

0.2

11.8 dB-Hz
6.5 dB-Hz

14.6 dB-Hz
13.2 dB-Hz

1/6-chip threshold

0.15

Modulation: BPSK-R( )
E-L correlator spacing: = 1-chip
Normalized front end bandwidth:b=1
=1
DLL noise bandwidth:

n

D

Db

0.1 B n = 0.2 Hz

0.05

0

5 10 15 20 25 30

( C/N 0 dB ) (dB-Hz)

(d)

Figure 5.28 (Continued.)

compare the DLL performance for BPSK-R modulations with different correlator
spacings and an extremely wide receiver bandwidth ( b 17). Note that both the

thermal noise jitter and the rule-of-thumb thresholds are reduced when the

=