Global Positioning System Reference
In-Depth Information
A
B
best improvement
9
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1000
2,000
0
Frequency in Hz
FIGURE 10.9
Filter bank outputs after compensation.
of 100 Hz. There are three wideband filters separated by 1 kHz, and in each of
them there are 10 narrow band filters. Figure 10.10a shows the filter response
without remediation through the loss recovery method. The maximum output
difference is about 6 dB, which is caused by the wideband and narrow band
filter responses. In Figure 10.10b the wideband filter responses are remediated.
The maximum output difference is reduced to about 4.8 dB. In Figure 10.10c
the outputs are remediated for both the wideband and narrow band filters. The
maximum output difference is reduced to about 2.8 dB. From these results one
can conclude that the remediation can recover about 3.2 dB of loss from 6 to
2.8 dB for the worst case. It is expected that acquisition through this method
will provide a frequency accuracy of about 100 Hz. The sensitivity can vary
about 2.8 dB.
10.12 TIME FREQUENCY ADJUSTMENT IN NONCOHERENT
INTEGRATION
(
14
)
In the previous sections the coherent integration performed on 10 ms of data is
discussed. Successive 10 ms of data will be coherently processed and their output
amplitude will be obtained as the final results. If the search frequency range is
±
5 to 5 kHz. The
total outputs from 10 ms of data can be represented by a 100 by 2500 matrix
5 kHz, there are eleven 1-kHz coarse frequency bins from
−
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