Coherent lidars based on intracavity heterodyning of echo signals

The development and technical realization of the method of laser sounding of the atmosphere based on the effects of mixing of reference and external fields of scattering inside a laser cavity are presented. An approximate theory of the method was developed on the basis of the investigations using the model of a three-mirror laser. The nonlinear effect of a wideband laser on frequency-dependent external influences of the atmosphere was investigated. The field measurements of gaseous composition of the atmosphere were performed on the basis of a given method of coherent reception using a tunable CO2 laser

Определение скорости транспортного средства по звукозаписям видеорегистратора

The article offers a method for determining vehicle speed from the audio track recorded by the dashboard camera mounted on the car in question. The author analyzed the operation of a four-stroke internal combustion engine, and established a dependency between the number of rotations (rpm) of the engine crankshaft and the number of rotations transferred to the wheel by the manual transmission. The author presents a formula that helps to determine the static radius of the wheel from its marking symbols on the tire. He looks at examples from forensic casework and offers options for determining the ID number of an engaged gearbox. Furthermore, he reviews the possibilities of applying this method to vehicles with an automatic transmission. In conclusion, the article presents the results of tests of the proposed method conducted by leading experts from various forensic institutions of the Russian Ministry of Justice. They point to the consistency of results when engine rpm is calculated based on cepstral analysis and engine tachometer readings.Предложен способ определения скорости транспортного средства по звукозаписи с автомобильного видеорегистратора, установленного на нем. Автором проанализирован процесс работы четырёхтактного двигателя внутреннего сгорания и выявлена зависимость между количеством оборотов коленчатого вала двигателя и количеством оборотов, передаваемых механической коробкой передач на колесо. Приведена формула, позволяющая определять статический радиус колеса по его маркировочному обозначению на шине. Разобраны случаи из экспертной практики и предложены варианты определения номера включенной передачи на коробке переключения передач. Рассмотрены возможности применения метода на транспортных средствах с автоматической коробкой переключения передач. Приводятся результаты апробации метода экспертами судебно-экспертных учреждений Минюста России, отмечающих совпадение результатов при вычислении количества оборотов двигателя автомобиля посредством кепстрального анализа и показаний приборов контроля оборотов двигателя автомобиля

Возможности комплексных исследований экспертизы видеозаписи и автотехнической экспертизы

In some cases, the material provided for a forensic vehicle examination may be insufficient to answer the questions placed before the experts. However, sometimes there are some multimedia files presented which by means of forensic video examination can help to discover the information missing for implementation of the vehicle expertise. This article reviews the potential of forensic video and vehicle investigations when conducting an integrated research including the investigation of circumstances of a road traffic accident. The examples from the state experts’ practice of the forensic institutions of the Russian Ministry of Justice are provided. This review is intended to introduce the video experts and the vehicle experts to the opportunities there are in the integrated research of the mechanism of road accidents.В ряде случаев материалов, предоставляемых на автотехническую экспертизу, может быть недостаточно для ответа на все поставленные перед судебными экспертами вопросы. Но иногда в материалх дела присутствуют файлы видеозаписей и фотоизображений, по которым методами криминалистической экспертизы видеозаписей возможно установить недостающие для производства автотехнической экспертизы параметры. В статье рассмотрены возможности криминалистической экспертизы видеозаписей и автотехнической экспертизы при производстве комплексных экспертиз, в том числе при исследовании обстоятельств дорожно-транспортного происшествия. Приведены примеры из практики государственных экспертов судебно-экспертных учреждений Минюста России. Эта обзорная работа предназначена для ознакомления экспертов-видеотехников и экспертов-автотехников с возможностями, которые появляются при проведении комплексного исследования механизма дорожно-транспортных происшествий

Determining Vehicle Speed from Dashcam Audio Analysis

The article offers a method for determining vehicle speed from the audio track recorded by the dashboard camera mounted on the car in question. The author analyzed the operation of a four-stroke internal combustion engine, and established a dependency between the number of rotations (rpm) of the engine crankshaft and the number of rotations transferred to the wheel by the manual transmission. The author presents a formula that helps to determine the static radius of the wheel from its marking symbols on the tire. He looks at examples from forensic casework and offers options for determining the ID number of an engaged gearbox. Furthermore, he reviews the possibilities of applying this method to vehicles with an automatic transmission. In conclusion, the article presents the results of tests of the proposed method conducted by leading experts from various forensic institutions of the Russian Ministry of Justice. They point to the consistency of results when engine rpm is calculated based on cepstral analysis and engine tachometer readings

The Potential of Integrated Video and Vehicle Forensic Investigation

In some cases, the material provided for a forensic vehicle examination may be insufficient to answer the questions placed before the experts. However, sometimes there are some multimedia files presented which by means of forensic video examination can help to discover the information missing for implementation of the vehicle expertise. This article reviews the potential of forensic video and vehicle investigations when conducting an integrated research including the investigation of circumstances of a road traffic accident. The examples from the state experts’ practice of the forensic institutions of the Russian Ministry of Justice are provided. This review is intended to introduce the video experts and the vehicle experts to the opportunities there are in the integrated research of the mechanism of road accidents