a correlative interferometer (CI) AOA system. Correlative interferometry is a widely implemented AOA technique in modern radio monitoring. The correlative interferometer is introduced and discussed in Chapter 4.7.2.2.5 of the ITU Handbook on Spectrum Monitoring, Edition 2011. (NOTE 1 references in Tables 3-1 and 3-2 refer to the ITU Handbook on Spectrum – “Chapter” Monitoring, Edition 2011. Numbers in parentheses in Tables refer to References listed in § 6.) TABLE 3-1 TDOA strengths Simpler antenna The antenna is low cost, low complexity, and may be in size. requirements TDOA receivers may employ a single simple antenna (such as a monopole or dipole). Unlike AOA systems, the antenna does not require high mechanical tolerances and electrical precision, and does not require operational test and measurement for calibration. An benefit is that the antenna may be made small in size and made inconspicuous. This is important when deploying monitoring systems in historical or architecturally restricted sites or when negotiating siting agreements with 3rd parties. Simpler siting and Siting requirements are less restrictive than AOA and require little to no calibration calibration. requirements This allows more flexibility in choosing TDOA sites. As a result, TDOA installations are faster to deploy. In urban installations, additional TDOA receivers may be placed to overcome the shadowing effects of tall structures. In contrast, AOA sites must be chosen to minimize wave front distortion due to re-emanation from local obstacles, ground reflections, and ground conductivity changes. Some AOA antenna arrays must be calibrated after site installation to minimize the resulting frequency and direction dependent errors. Antenna array calibration is one of the most important performance limiting issues in AOA [2]. AOA siting issues are discussed in further detail in Chapters 4.7.2.3.1.2 and 2.6.1.3.
a correlative interferometer (CI) AOA system. Correlative interferometry is a widely implemented AOA technique in modern radio monitoring. The correlative interferometer is introduced and discussed in Chapter 4.7.2.2.5 of the ITU Handbook on Spectrum Monitoring, Edition 2011. (NOTE 1 – “Chapter” references in Tables 3-1 and 3-2 refer to the ITU Handbook on Spectrum Monitoring, Edition 2011. Numbers in parentheses in Tables refer to References listed in § 6.) TABLE 3-1 TDOA strengths Simpler antenna requirements The antenna is low cost, low complexity, and may be in size. TDOA receivers may employ a single simple antenna (such as a monopole or dipole). Unlike AOA systems, the antenna does not require high mechanical tolerances and electrical precision, and does not require operational test and measurement for calibration. An benefit is that the antenna may be made small in size and made inconspicuous. This is important when deploying monitoring systems in historical or architecturally restricted sites or when negotiating siting agreements with 3rd parties. Simpler siting and calibration requirements Siting requirements are less restrictive than AOA and require little to no calibration. This allows more flexibility in choosing TDOA sites. As a result, TDOA installations are faster to deploy. In urban installations, additional TDOA receivers may be placed to overcome the shadowing effects of tall structures. In contrast, AOA sites must be chosen to minimize wave front distortion due to re-emanation from local obstacles, ground reflections, and ground conductivity changes. Some AOA antenna arrays must be calibrated after site installation to minimize the resulting frequency and direction dependent errors. Antenna array calibration is one of the most important performance limiting issues in AOA [2]. AOA siting issues are discussed in further detail in Chapters 4.7.2.3.1.2 and 2.6.1.3.
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