Характеристика временного регулирования ультразвука Опции

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Из prowave вовского аппнота выдрал формулу для расчета затухания ультразвука :

SPL_gain = 20*log(V/Vdefault) - усиление по выходной мошности

SPL_loss = 20*log(0.3/Distance) - уменьшение сигнала вследствии распространения волн (0.3 cm per SPL from datasheet)

Absorption = 0.1886 DB/meter * Distance - уменьшение сигнала вследствии затухания в воздухе

SPL = SPL_default + SPL_gain + SPL_loss - Absorpion - нормализованное давление в точке приема

Pressure = 0.0002*10^(SPL/20) - пересчет СПЛ в микробары

V_rx = Pressure * 10^(Sensitivity/20) - выходное напряжение сенсора в точке приема

Кто нибудь может подтвердить правильность написанных выкладок ? Или ссылки на другие источники .

Полученная таким образом характеристика ВАРУ приведена ниже :

Tap position = 0.000000, Distance = 0.310000, Gain = 1.007720
Tap position = 1.000000, Distance = 0.320000, Gain = 1.015560
Tap position = 2.000000, Distance = 0.330000, Gain = 1.023524
Tap position = 3.000000, Distance = 0.340000, Gain = 1.031613
Tap position = 4.000000, Distance = 0.350000, Gain = 1.039831
Tap position = 5.000000, Distance = 0.360000, Gain = 1.048181
Tap position = 6.000000, Distance = 0.370000, Gain = 1.056666
Tap position = 7.000000, Distance = 0.380000, Gain = 1.065290
Tap position = 8.000000, Distance = 0.390000, Gain = 1.074055
Tap position = 9.000000, Distance = 0.400000, Gain = 1.082966
Tap position = 10.000000, Distance = 0.410000, Gain = 1.092026
Tap position = 11.000000, Distance = 0.420000, Gain = 1.101239
Tap position = 12.000000, Distance = 0.430000, Gain = 1.110609
Tap position = 13.000000, Distance = 0.440000, Gain = 1.120140
Tap position = 14.000000, Distance = 0.450000, Gain = 1.129835
Tap position = 15.000000, Distance = 0.460000, Gain = 1.139700
Tap position = 16.000000, Distance = 0.470000, Gain = 1.149739
Tap position = 17.000000, Distance = 0.480000, Gain = 1.159956
Tap position = 18.000000, Distance = 0.490000, Gain = 1.170356
Tap position = 19.000000, Distance = 0.500000, Gain = 1.180944
Tap position = 20.000000, Distance = 0.510000, Gain = 1.191726
Tap position = 21.000000, Distance = 0.520000, Gain = 1.202707
Tap position = 22.000000, Distance = 0.530000, Gain = 1.213891
Tap position = 23.000000, Distance = 0.540000, Gain = 1.225286
Tap position = 24.000000, Distance = 0.550000, Gain = 1.236897
Tap position = 25.000000, Distance = 0.560000, Gain = 1.248730
Tap position = 26.000000, Distance = 0.570000, Gain = 1.260791
Tap position = 27.000000, Distance = 0.580000, Gain = 1.273088
Tap position = 28.000000, Distance = 0.590000, Gain = 1.285627
Tap position = 29.000000, Distance = 0.600000, Gain = 1.298415
Tap position = 30.000000, Distance = 0.610000, Gain = 1.311460
Tap position = 31.000000, Distance = 0.620000, Gain = 1.324770
Tap position = 32.000000, Distance = 0.630000, Gain = 1.338353
Tap position = 33.000000, Distance = 0.640000, Gain = 1.352218
Tap position = 34.000000, Distance = 0.650000, Gain = 1.366373
Tap position = 35.000000, Distance = 0.660000, Gain = 1.380827
Tap position = 36.000000, Distance = 0.670000, Gain = 1.395590
Tap position = 37.000000, Distance = 0.680000, Gain = 1.410672
Tap position = 38.000000, Distance = 0.690000, Gain = 1.426084
Tap position = 39.000000, Distance = 0.700000, Gain = 1.441837
Tap position = 40.000000, Distance = 0.710000, Gain = 1.457941
Tap position = 41.000000, Distance = 0.720000, Gain = 1.474409
Tap position = 42.000000, Distance = 0.730000, Gain = 1.491254
Tap position = 43.000000, Distance = 0.740000, Gain = 1.508487
Tap position = 44.000000, Distance = 0.750000, Gain = 1.526124
Tap position = 45.000000, Distance = 0.760000, Gain = 1.544178
Tap position = 46.000000, Distance = 0.770000, Gain = 1.562664
Tap position = 47.000000, Distance = 0.780000, Gain = 1.581598
Tap position = 48.000000, Distance = 0.790000, Gain = 1.600997
Tap position = 49.000000, Distance = 0.800000, Gain = 1.620878
Tap position = 50.000000, Distance = 0.810000, Gain = 1.641258
Tap position = 51.000000, Distance = 0.820000, Gain = 1.662157
Tap position = 52.000000, Distance = 0.830000, Gain = 1.683596
Tap position = 53.000000, Distance = 0.839999, Gain = 1.705595
Tap position = 54.000000, Distance = 0.849999, Gain = 1.728176
Tap position = 55.000000, Distance = 0.859999, Gain = 1.751363
Tap position = 56.000000, Distance = 0.869999, Gain = 1.775181
Tap position = 57.000000, Distance = 0.879999, Gain = 1.799656
Tap position = 58.000000, Distance = 0.889999, Gain = 1.824815
Tap position = 59.000000, Distance = 0.899999, Gain = 1.850688
Tap position = 60.000000, Distance = 0.909999, Gain = 1.877304
Tap position = 61.000000, Distance = 0.919999, Gain = 1.904698
Tap position = 62.000000, Distance = 0.929999, Gain = 1.932902
Tap position = 63.000000, Distance = 0.939999, Gain = 1.961955
Tap position = 64.000000, Distance = 0.949999, Gain = 1.991894
Tap position = 65.000000, Distance = 0.959999, Gain = 2.022761
Tap position = 66.000000, Distance = 0.969999, Gain = 2.054600
Tap position = 67.000000, Distance = 0.979999, Gain = 2.087458
Tap position = 68.000000, Distance = 0.989999, Gain = 2.121383
Tap position = 69.000000, Distance = 0.999999, Gain = 2.156429
Tap position = 70.000000, Distance = 1.009999, Gain = 2.192652
Tap position = 71.000000, Distance = 1.019999, Gain = 2.230114
Tap position = 72.000000, Distance = 1.029999, Gain = 2.268877
Tap position = 73.000000, Distance = 1.039999, Gain = 2.309012
Tap position = 74.000000, Distance = 1.049999, Gain = 2.350593
Tap position = 75.000000, Distance = 1.059999, Gain = 2.393698
Tap position = 76.000000, Distance = 1.069999, Gain = 2.438414
Tap position = 77.000000, Distance = 1.079999, Gain = 2.484832
Tap position = 78.000000, Distance = 1.089999, Gain = 2.533052
Tap position = 79.000000, Distance = 1.099999, Gain = 2.583181
Tap position = 80.000000, Distance = 1.109999, Gain = 2.635334
Tap position = 81.000000, Distance = 1.119999, Gain = 2.689635
Tap position = 82.000000, Distance = 1.129999, Gain = 2.746222
Tap position = 83.000000, Distance = 1.139999, Gain = 2.805241
Tap position = 84.000000, Distance = 1.149999, Gain = 2.866853
Tap position = 85.000000, Distance = 1.159999, Gain = 2.931231
Tap position = 86.000000, Distance = 1.169999, Gain = 2.998567
Tap position = 87.000000, Distance = 1.179999, Gain = 3.069070
Tap position = 88.000000, Distance = 1.189999, Gain = 3.142968
Tap position = 89.000000, Distance = 1.199999, Gain = 3.220513
Tap position = 90.000000, Distance = 1.209999, Gain = 3.301980
Tap position = 91.000000, Distance = 1.219999, Gain = 3.387677
Tap position = 92.000000, Distance = 1.229999, Gain = 3.477940
Tap position = 93.000000, Distance = 1.239999, Gain = 3.573144
Tap position = 94.000000, Distance = 1.249999, Gain = 3.673708
Tap position = 95.000000, Distance = 1.259999, Gain = 3.780096
Tap position = 96.000000, Distance = 1.269999, Gain = 3.892830
Tap position = 97.000000, Distance = 1.279999, Gain = 4.012494
Tap position = 98.000000, Distance = 1.289999, Gain = 4.139749
Tap position = 99.000000, Distance = 1.299999, Gain = 4.275340
Tap position = 100.000000, Distance = 1.309999, Gain = 4.420114
Tap position = 101.000000, Distance = 1.319999, Gain = 4.575036
Tap position = 102.000000, Distance = 1.369999, Gain = 4.741213
Tap position = 103.000000, Distance = 1.419999, Gain = 4.919916
Tap position = 104.000000, Distance = 1.469999, Gain = 5.112618
Tap position = 105.000000, Distance = 1.529999, Gain = 5.321031
Tap position = 106.000000, Distance = 1.589999, Gain = 5.547158
Tap position = 107.000000, Distance = 1.659999, Gain = 5.793357
Tap position = 108.000000, Distance = 1.729999, Gain = 6.062425
Tap position = 109.000000, Distance = 1.809999, Gain = 6.357704
Tap position = 110.000000, Distance = 1.889999, Gain = 6.683220
Tap position = 111.000000, Distance = 1.989998, Gain = 7.043867
Tap position = 112.000000, Distance = 2.099998, Gain = 7.445658
Tap position = 113.000000, Distance = 2.209998, Gain = 7.896059
Tap position = 114.000000, Distance = 2.339998, Gain = 8.404459
Tap position = 115.000000, Distance = 2.489998, Gain = 8.982833
Tap position = 116.000000, Distance = 2.659998, Gain = 9.646695
Tap position = 117.000000, Distance = 2.849998, Gain = 10.416510
Tap position = 118.000000, Distance = 3.079998, Gain = 11.319844
Tap position = 119.000000, Distance = 3.339997, Gain = 12.394733
Tap position = 120.000000, Distance = 3.639997, Gain = 13.695173
Tap position = 121.000000, Distance = 4.019997, Gain = 15.300481
Tap position = 122.000000, Distance = 4.480008, Gain = 17.332098
Tap position = 123.000000, Distance = 5.050021, Gain = 19.985844
Tap position = 124.000000, Distance = 5.810038, Gain = 23.599148
Tap position = 125.000000, Distance = 6.830061, Gain = 28.807314
Tap position = 126.000000, Distance = 8.300095, Gain = 36.965294
Tap position = 127.000000, Distance = 10.620148, Gain = 51.569257
Maximum gain 23130.758441
Minimum gain 448.537740
TVG gain max = 51.569256, min = 1
Constant gain = 448.537750

Есше один вопрос - предусматривал использование ад5220, но он немного тухтоват вследствии наводок во времмя переключения усиления . АД 603 еще не прибыл.
Кто работал с максовскими цифровыми потенсами - как они без цифровых наводок на аналоговые цепи работают ? А то у АД5220 20 мВ пика во время изменения сопротивления , правда 2 микросекунды длительности и еще одна большая при 0x3f на 0x40 переходе .



Для ад5220 выход видится в запрешении прерывания компаратора во время переключения , пока переходной процесс длится . А если сигнал произошел в этот момент - то последуюшее детектирование во временном окне с постоянным коэффициэнтом усиления.

[_artem_]

Тайваньцы явно воздуха поднапустили, чтот 0.1886 дБ как мыльный пузырь.
Блин, а Масса говорит о коэффициенте абсорбции как :
good estimate ~ 0.01*f(kHz)/ft что в пересчете на метры 1.31 dB/meter
плюс к этому Масса вводит в вычисления target strenght оцениваюший рефлективность предмета при отражении

А в другом доке читаю аж больше 2 dB/meter при определенном давлении температуре и влажности. Что брать то господа эксперты по ультразвуку? Если по худшему то на расстоянии в 5 метров прихожу на микровольты для недорогих влагозашишенных датчиков. Если же по лучшему - то можно и Луну запеленговать (шутка)