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BINARY OFFSET CARRIER MODULATIONS FOR RADIONAVIGATION PDF

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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Design [ edit ] The main idea behind BOC modulation is modulatinos reduce the interference with BPSK -modulated signal, which has a sinc function shaped spectrum.

The support of the BOC 5,2 autocorrelation function is half that of the autocorrelation function for 1. Simple circuitry in a receiver can detect when partial-band interference is encountered that obscures only one sideband of the BOC modulation, and can reconfigure the receiver to process only the sideband not being interfered with.

A very small antenna and simple RF electronics having only enough bandwidth to pass one sideband, combined with the reduced sampling rate and processing throughput requirements associated with the bandwidth of one sideband, would help minimize the cost, size, and power radionavigatioh of the receiver.

Binary offset carrier modulation – Wikipedia

Sidelobe peaks that are close both in delay and in magnitude can make it challenging for code tracking cqrrier maintain track on the main lobe of the correlation function. However, the worst-case bias error is slightly greater 5. Initial work on offset carrier modulations focused on a sinusoidal subcarrier and a csrrier spreading symbol.

While the signals are designed to occupy the 24 MHz allocation, the 30 MHz bandlimiting approximates that which occurs at GPS satellites.

From Wikipedia, the free encyclopedia. Another degradation is due to the change in spectral shape and the resulting reduction in RMS bandwidth. The other is that the errors at the early and the late tap become more positively correlated so that they tend to cancel more in the difference, causing the variance of the difference signal to diminish.

A conventional code-tracking loop can be used with a discriminator based on early — late processing or an analogous approach. More recent work suggests that BOC modulations may allow yet another signal, in addition to heritage signals and the new military signal, to be added to midulations allocated GPS bands [4]. Before being selected, it was subjected to rigorous scrutiny, ranging from analysis to hardware demonstrations, as were other candidate modulations.

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The 90 percent power bandwidth of BOC 5,2 radionafigation less than half the 24 MHz registered band, and even smaller kffset that of a The locations of spectral peaks and their maximum power spectral densities are selfexplanatory. In many respects, including maximum offsdt spectral density, out-of-band loss, and spectral separation with itself, the two modulations are very similar.

Betz_Binary Offset Carrier Modulations for Radio Navigation_百度文库

Current modulation designs have been restricted to phase shift keying with rectangular spreading symbols referred to here as PSK-Rduplicating early modulation designs for digital communications. Engineering judgment is still needed in pffset practical BOC modulations. Many of the advantages of BOC modulations are clear in the examples presented in this paper. Simpler receivers can process only one sideband of the signal, using front-end bandwidths as low as 2 Modulatons.

Retrieved from ” https: Eurasip Journal on Wireless Communications and Networking. More significant, BOC 10,5 offers 17 dB better spectral separation from civilian signals that use 1.

Binary offset carrier modulation

This page was last edited on 24 Novemberat This section outlines a procedure for selecting early — late spacing for NELP based on the theory presented in [7] and [8], and illustrates the Vol. 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 [2] and followed subsequently in work on GPS and radinoavigation, the designation BOCused in this paper is an abbreviation.

Some measures, such as those of spectral occupancy, have been used extensively for many years in assessment of modulations for radionavigation. The cwrrier of specular multipath environment on bias errors in code tracking is then examined. But better modulation designs are available for next-generation radionavigation systems, offering improved performance and the opportunity for spectrum sharing while retaining implementation simplicity.

Blind estimation of sy BOC modulation has several variants: Further, more advanced modulations can better share existing frequency allocations with each other and with heritage signals, thus preserving spectrum. The final section summarizes the findings of this work. The error becomes very large for early — late spacing near ns, corresponding to the slope reversal in the S-curves observed in Figure While the set of measures does not completely define the design space, it mmodulations provide important insights into the suitability of a modulation for radionavigation.

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The BOC 10,5 modulation was designed to allow the new military signal to be transmitted at much higher power while minimizing interference with existing signals and providing many other benefits, ranging from implementation ease to performance. If desired, filtering can be used to select only the desired sideband and prevent aliasing at lower sampling rates.

Conventional thinking has indicated that codetracking accuracy can be inferred from discriminator gain, with larger discriminator gain indicating smaller code-tracking errors. Consequently, the out-of-band loss is only 0. Figure 21 shows the worst-case multipath bias errors for specular reflection received 6 dB weaker than the direct path for Figure 1 provides a block diagram of BOC signal generation. Since the equivalent rectangular bandwidths of these two modulations are almost identical, they have almost the same processing gain against narrowband interference.

The resulting binary-valued modulation, referred to as binary offset carrier, is the subject of this paper. 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.

Quantized radio modulation modes. In fact, use of a BOC 5,1 or BOC 5,2 modulation allows high-performance receivers to employ front-end bandwidths as narrow as 12 MHz with almost no performance degradation as compared with wider bandwidths, offering the opportunity for exceptional performance with compact antennas and lower-power electronics.

The smaller is the spectral separation coefficient of the modulation with 1. Definition of Binary Offset Carrier Modulation The complex envelope of an offset carrier signal is given by [2] note that all the analysis here uses analytic signal representations and lowpass-equivalent representations of linear time-invariant systems: The greater is the equivalent rectangular bandwidth, defined in equation 18the greater is the resistance to narrowband interference at the worst-case frequency.