Global Positioning System Reference
In-Depth Information
sign(dot)(cross) cross ATAN2(dot,cross)
Predetection integraton time=5ms
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0
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120
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−4
0
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120
True input frequency error (Hz)
(a)
sign(dot)(cross) cross ATAN2(dot, cross)
Predetection integration time = 10 ms
50
40
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20
10
0
−
10
−
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−
30
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0
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True input frequency error (Hz)
(b)
Figure 5.11
Comparison of frequency lock loop discriminators: (a) 5-ms predetection integration
time, and (b) 10-ms predetection integration time.
tion (noisy) process, detecting the change in sign of the phasor in a FLL is noisier
than detecting the sign of the integrated (lower noise)
I
PS
in a PLL. Therefore, for the
same signal quality, FLL data detection has a much higher bit and word error rate
than PLL data detection.
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