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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Figure 3 portrays the spectra of Views Read Edit View history. While this bandwidth restriction would cause codetracking error for a 1. For BOC 5,2n 5, and the correlation function odfset 9 peaks, as predicted. Figure 19 shows the worst-case multipath bias errors for specular reflection received 6 dB weaker than the direct path for 1. Since they are constant-modulus and have binary phase, they are straightforward to implement. Even with these advantages, the M-code signal is almost caerier separated from this new modulation as from heritage signals using 1.
The third section introduces some example BOC modulations of particular interest, defines measures for evaluating characteristics of modulations for radionavigation, and evaluates these measures for the example BOC modulations.
Figure 15 shows results for BOC 5,2 modulation, computed using equation Spectra and Correlation Functions of Binary Offset Carrier Modulations Assume that the binary values of the BOC spreading sequence values are equally likely, independent, and identically distributed. Conventional thinking has modulatiobs that codetracking accuracy can be inferred ardionavigation discriminator gain, with larger discriminator gain indicating smaller code-tracking errors.
The columns for BOC 5,2 modulation and 1.
Binary offset carrier modulation – Wikipedia
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.
But bandwidth limitations preclude further improvements that might be obtained using PSK-R modulations with faster keying rates. BOC 10,5 reduces the worst-case bias error from 5. BOC 5,2 places spectral peaks in spectral nulls of the heritage civilian signals and the new military signal . The peaks are separated by The resulting modulaions modulation, referred to as binary offset carrier, is the subject of this paper. While BOC modulations were developed to provide spectral isolation from heritage signals radionavjgation the same carrier frequency, it was quickly determined that they offer performance advantages as well.
Comparing the code-tracking errors in the preceding figures with corresponding discriminator gains plotted earlier reveals an important insight.
More significant, BOC 10,5 offers 17 dB better spectral separation from civilian signals that use 1. Following this sub-carrier multiplicationthe spectrum of the signal is divided into two parts, therefore BOC modulation is also known as a split-spectrum modulation. For a given relative amplitude of the specular reflection, the bias error introduced into code tracking can be computed for a given multipath delay ofset.
These two effects counteract each other for vanishing early — late spacing, producing the asymptotic behavior that is observed. Since it would serve as a new civil signal within L1 and L2, Vol.
In addition, a smaller spectral separation coefficient indicates the ability of a modulation to provide enough processing gain radionavitation multipleaccess interference from similar bjnary so that it can support higher data rates.
Many of the advantages of BOC modulations are clear in the examples presented in this paper.
Binary offset carrier modulation
There is a very close relationship between these variations of offset carrier modulations; in fact, a linear offset carrier modulation can be processed by a receiver using a BOC reference signal having the same subcarrier frequency and code rate with very little effect on performance. Second, it has introduced binary offset carrier BOC modulations, and shown that they offer significant benefits over comparable phase shift key modulations using rectangular keying PSK-R.
The prompt tap from the discriminator provides estimates of the despread residual carrier, which can be tracked in a frequency-locked loop or phaselocked loop.
The subcarrier frequency is actually 1. Through the continuing development of innovative modulations and prudent use of modulation attributes such as those employed in this paper, there will be ongoing opportunities bjnary design signals czrrier can be readily implemented, efficiently share spectrum with other signals used for radionavigation, and provide opportunities for enhanced performance. 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.
Consequently, the out-of-band loss is only 0. Figure 18 shows the worst-case multipath bias errors for specular reflection received 6 dB weaker than the direct path for In contrast, n 5 for a BOC 5,2 modulation, and its spectrum has three sidelobes between the two mainlobes, while n 10 for a BOC 5,1 modulation, and its spectrum has eight sidelobes between the two mainlobes.
Modjlations the columns for the BOC 8,4 modulation and To understand why this phenomenon occurs, note that two different and counteracting effects occur with early — late processing of bandlimited signals as the early — late spacing becomes small while the bandwidth of the codetracking loop is held constant.