Effect of wavelength, building blockage and terminal antenna pattern upon LEO satellite coverage in urban and suburban environments
Bibliographic record
Abstract
While land mobile satellite systems operating at VHF (150 MHz) should provide better coverage in urban and suburban environments than similar systems that operate at L-band (1 GHz and above), previous work has not quantified the improvement. Here, we fill that gap by presenting results obtained with a 3D-satellite signal propagation simulation tool that we have developed around the NEC-BSC UTD code. Results obtained using a representative street geometry show that the mean signal at VHF may be as much as 6 dB stronger than that at L-band with a standard deviation that is almost 2 dB less. Results also show that an antenna with a hemispherical pattern can provide much more effective coverage than the λ/4 monopole antenna which has traditionally been the most popular antenna for ORBCOMM applications. I. INTRODUCTION Parametric models such as Loo Model and Lutz Model are based on measurements at UHF and L band and no parameter set is available for VHF band. A few exceptions, e.g., (2), only characterize building penetration at VHF band for indoor propagation. Therefore, little quantitative information exists to support LMSS system planning and performance prediction at VHF where propagation is expected to be somewhat easier. This study seeks to fill a gap in previous work by determin- ing the manner in which the coverage of LMSSs operating in urban and suburban environments are affected by both wavelength and building blockage. In particular, we compare the coverage obtained at both 138 MHz and 1.3 GHz under different degrees of buildup and using a realistic satellite con- stellation. We also consider the manner in which changing the pattern of the terminal antenna affects system coverage. Our Uniform Theory of Diffraction (UTD) based 3-D propagation simulation tool is based upon the NEC-BSC code developed at Ohio State University. We have validated the results with respect to measured data using the Feature Selective Validation method. Details of the effect of wavelength and building blockage on system coverage are presented.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".