Request PDF on ResearchGate | Binary Offset Carrier Modulations for Radio Navigation | Current signaling for GPS employs phase shift keying (PSK). Abstract: Current signaling for GPS employs phase shift keying (PSK) modulation using conventional rectangular (non – return to zero) spreading symbols. The first model defines the BOC modulation as the result of . The Binary Offset Carrier Modulation can be expressed as a BCS sequence . [J.W. Betz, a] J.W. Betz, Binary Offset Carrier Modulations for Radionavigation.
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For early — late spacing of less than 45 ns, the code-tracking accuracy closely approaches the information-theoretic lower bound computed using equation 14indicating little benefit from using smaller early — late spacings.
Still others, such as the spectral separation coefficient, were formalized more recently. A BOC modulation is denoted BOC fs,fcwhere fs is the subcarrier frequency, and fc is the code rate, defined by fs 1 2Ts 2 Consistent with the convention introduced in  and followed subsequently in work on GPS and elsewhere, the designation BOCused in this paper is an abbreviation.
In contrast, modulations designed specifically for radionavigation can outperform existing modulation designs while using the same or modulationz less bandwidth and enabling simple transmitter and receiver designs.
Some measures, such as those of spectral occupancy, have been used extensively for many years in assessment of modulations for radionavigation. When n 1, equation 8 becomes sin f Ts f Ts 2 so that qnTs t consists of n half-cycles of a square wave, that is, n alternating values of 1 and 1.
The curves are well-behaved for early — late spacings of less than 50 ns, but the slope reverses for early — late spacings of 50 — 60 ns.
Binary offset carrier modulation
The results presented here demonstrate that this relationship does not apply once the early — late spacing is less than the reciprocal radionavlgation the receiver front-end bandwidth. The effect of specular multipath environment on bias errors in code tracking is then examined. While this reduction in front-end bandwidth causes the worst-case multipath error for 1.
This representation shows that, when the carrrier symbol is rectangular, offset carrier signals are conventional PSK-R signals modulating a periodic signal. The calculation assumes the receiver has a 24 MHz front-end bandwidth, and that NELP uses good choices of early — late spacing — 0. For early — late spacing of less than 80 ns, the code-tracking accuracy closely approaches the information-theoretic lower bound computed using equation 14indicating little benefit from using smaller early — late spacings.
Figure 19 shows the worst-case multipath bias errors for specular reflection received 6 dB weaker than the direct path for 1. A similar approach could employ a discriminator that would operate on the correlation function for one sideband or the noncoherently combined correlation functions from each sideband to maintain the coarse track of the main peak, cross-coupled with a fine tracking discriminator operating on the wideband signal, for best performance.
Binary offset carrier modulation – Wikipedia
Others, such as bunary rectangular bandwidth and RMS bandwidth, were introduced to this design space as part of the effort for military signal design. Another degradation radionavjgation due to the change in spectral shape and the resulting reduction in RMS bandwidth.
While the 90 percent power bandwidth of BOC 10,5 is much wider than that of When the RMS bandwidth is computed over finite bandwidth, two separate effects occur: Adopting the notation that is the index of the normalized correlation function peak with 0 indicating the main peak, 1 being the index of the first peak to the right of the main peak, etc.
Simple logic indicates whether the prompt tap is no longer tracking the main peak and directs how to maintain track of the main peak. This section outlines a procedure for selecting early — late spacing for NELP based on the theory presented in  and , radionavigaiton illustrates the Vol.
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The quantities and t0 reflect arbitrary offsets in phase and time, respectively, in the complex envelope relative to some reference. The final section summarizes the findings of this work. While there has been previous consideration of subcarrier modulations for civilian signals e.
But bandwidth limitations xarrier further improvements that might be obtained using PSK-R modulations with faster keying rates.
Attention has been focused primarily on the design of the spreading code and selection of the keying rates. Figure 13 shows results for BOC 10,5 modulation, computed using equation However, studies and hardware testing have demonstrated that the BOC modulation designs described in this section provide robust and practical performance. Further, carriet BOC 10,5 modulation of the M-code signal offers significant advantages in terms of code-tracking accuracy and mitigation of multipath effects.
Betz_Binary Offset Carrier Modulations for Radio Navigation_百度文库
For example, while Figure 10 shows that discriminator gain increases as early — late spacing decreases from 40 ns, Figure 13 shows mmodulations there is no further reduction in code-tracking error.
The S-curve relates the correction produced by a discriminator for a given error. This page was last edited on 24 Novemberat This approach can provide substantial immunity to some types of interference without the complexity of interference mitigation circuitry.
This paper has provided two categories of fundamental results in modulation design.