mytec
defa3ad440
Major refactoring of RFCP backend: - Modular propagation models (8 models) - SharedMemoryManager for terrain data - ProcessPoolExecutor parallel processing - WebSocket progress streaming - Building filtering pipeline (351k → 15k) - 82 unit tests Performance: Standard preset 38s → 5s (7.6x speedup) Known issue: Detailed preset timeout (fix in 3.1.0)
75 lines
2.2 KiB
Python
75 lines
2.2 KiB
Python
"""
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Okumura-Hata empirical propagation model.
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Valid for:
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- Frequency: 150-1500 MHz
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- Distance: 1-20 km
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- TX height: 30-200 m
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- RX height: 1-10 m
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Reference: Hata (1980), "Empirical Formula for Propagation Loss
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in Land Mobile Radio Services"
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"""
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import math
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from app.propagation.base import PropagationModel, PropagationInput, PropagationOutput
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class OkumuraHataModel(PropagationModel):
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@property
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def name(self) -> str:
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return "Okumura-Hata"
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@property
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def frequency_range(self) -> tuple:
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return (150, 1500)
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@property
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def distance_range(self) -> tuple:
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return (100, 20000) # Extended to 100m minimum for practical use
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def calculate(self, input: PropagationInput) -> PropagationOutput:
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f = input.frequency_mhz
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d = max(input.distance_m / 1000, 0.1) # km, min 100m
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hb = max(input.tx_height_m, 1.0)
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hm = max(input.rx_height_m, 1.0)
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# Mobile antenna height correction factor
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if input.environment == "urban" and f >= 400:
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# Large city
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a_hm = 3.2 * (math.log10(11.75 * hm) ** 2) - 4.97
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else:
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# Medium/small city
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a_hm = (1.1 * math.log10(f) - 0.7) * hm - (1.56 * math.log10(f) - 0.8)
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# Basic path loss (urban)
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L_urban = (
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69.55
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+ 26.16 * math.log10(f)
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- 13.82 * math.log10(hb)
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- a_hm
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+ (44.9 - 6.55 * math.log10(hb)) * math.log10(d)
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)
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# Environment correction
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if input.environment == "suburban":
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L = L_urban - 2 * (math.log10(f / 28) ** 2) - 5.4
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elif input.environment == "rural":
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L = L_urban - 4.78 * (math.log10(f) ** 2) + 18.33 * math.log10(f) - 35.94
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elif input.environment == "open":
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L = L_urban - 4.78 * (math.log10(f) ** 2) + 18.33 * math.log10(f) - 40.94
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else:
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L = L_urban
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return PropagationOutput(
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path_loss_db=L,
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model_name=self.name,
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is_los=False,
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breakdown={
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"basic_loss": L_urban,
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"environment_correction": L - L_urban,
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"antenna_correction": a_hm,
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},
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)
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