Functions/GenXdev.Helpers.Physics/Get-DopplerFrequencyShiftBySourceSpeedAndObserverSpeed.cs
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// ################################################################################
// Part of PowerShell module : GenXdev.Helpers.Physics // Original cmdlet filename : Get-DopplerFrequencyShiftBySourceSpeedAndObserverSpeed.cs // Original author : René Vaessen / GenXdev // Version : 3.28.2026 // ################################################################################ // Copyright (c) 2026 René Vaessen / GenXdev // // Licensed under the Apache License, Version 2.0 (the "License"); // you may not use this file except in compliance with the License. // You may obtain a copy of the License at // // http://www.apache.org/licenses/LICENSE-2.0 // // Unless required by applicable law or agreed to in writing, software // distributed under the License is distributed on an "AS IS" BASIS, // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. // See the License for the specific language governing permissions and // limitations under the License. // ################################################################################ using System.Management.Automation; namespace GenXdev.Helpers.Physics { [System.ComponentModel.Description(@" .SYNOPSIS Calculates Doppler shifted frequency. .DESCRIPTION Uses f' = f * (v + vo) / (v - vs), speeds positive towards each other. .EXAMPLE ```powershell Get-DopplerFrequencyShiftBySourceSpeedAndObserverSpeed -OriginalFrequencyInHertz 440 -SourceSpeedInMetersPerSecond 10 -ObserverSpeedInMetersPerSecond 5 -Medium ""water"" -As ""kilohertz"" ``` Calculates the Doppler shifted frequency for a 440 Hz tone with source moving at 10 m/s towards observer, observer moving at 5 m/s towards source, in water medium, output in kilohertz. .EXAMPLE ```powershell Get-DopplerFrequencyShiftBySourceSpeedAndObserverSpeed 440 10 0 -SpeedOfSoundInMetersPerSecond 1480 ``` Calculates the Doppler shifted frequency for a 440 Hz tone with source moving at 10 m/s, observer stationary, speed of sound 1480 m/s. ")] [Cmdlet(VerbsCommon.Get, "DopplerFrequencyShiftBySourceSpeedAndObserverSpeed")] [OutputType(typeof(double))] public class GetDopplerFrequencyShiftBySourceSpeedAndObserverSpeedCommand : PSGenXdevCmdlet { /// <summary> /// Original frequency in Hz /// </summary> [Parameter( Mandatory = true, Position = 0, HelpMessage = "Original frequency in Hz" )] public double OriginalFrequencyInHertz { get; set; } /// <summary> /// Source speed in m/s (positive towards observer) /// </summary> [Parameter( Mandatory = true, Position = 1, HelpMessage = "Source speed in m/s (positive towards observer)" )] public double SourceSpeedInMetersPerSecond { get; set; } /// <summary> /// Observer speed in m/s (positive towards source) /// </summary> [Parameter( Mandatory = true, Position = 2, HelpMessage = "Observer speed in m/s (positive towards source)" )] public double ObserverSpeedInMetersPerSecond { get; set; } /// <summary> /// Speed of sound in m/s (default: 343) /// </summary> [Parameter( Mandatory = false, Position = 3, ParameterSetName = "BySpeed", HelpMessage = "Speed of sound in m/s (default: 343)" )] public double SpeedOfSoundInMetersPerSecond { get; set; } = 343; /// <summary> /// The medium /// </summary> [Parameter( Mandatory = true, Position = 3, ParameterSetName = "ByMedium", HelpMessage = "The medium" )] [ValidateSet("air", "water", "seawater", "steel", "glass", "lead", "gold", "copper", "rubber", "vacuum", "helium", "co2", "methane")] public string Medium { get; set; } /// <summary> /// Output unit for frequency /// </summary> [Parameter( Mandatory = false, Position = 4, HelpMessage = "Output unit for frequency" )] [ValidateSet("hertz", "kilohertz", "megahertz")] public string As { get; set; } = "hertz"; /// <summary> /// Begin processing - set speed of sound based on medium if specified /// </summary> protected override void BeginProcessing() { if (ParameterSetName == "ByMedium") { switch (Medium) { case "air": SpeedOfSoundInMetersPerSecond = 343; break; case "water": SpeedOfSoundInMetersPerSecond = 1480; break; case "seawater": SpeedOfSoundInMetersPerSecond = 1530; break; case "steel": SpeedOfSoundInMetersPerSecond = 5960; break; case "glass": SpeedOfSoundInMetersPerSecond = 4540; break; case "lead": SpeedOfSoundInMetersPerSecond = 1210; break; case "gold": SpeedOfSoundInMetersPerSecond = 3240; break; case "copper": SpeedOfSoundInMetersPerSecond = 4600; break; case "rubber": SpeedOfSoundInMetersPerSecond = 60; break; case "vacuum": SpeedOfSoundInMetersPerSecond = 0; break; case "helium": SpeedOfSoundInMetersPerSecond = 965; break; case "co2": SpeedOfSoundInMetersPerSecond = 259; break; case "methane": SpeedOfSoundInMetersPerSecond = 430; break; } WriteVerbose($"Using speed of sound in {Medium}: {SpeedOfSoundInMetersPerSecond} m/s"); if (SpeedOfSoundInMetersPerSecond == 0) { ThrowTerminatingError(new ErrorRecord( new Exception("No sound propagation in vacuum"), "VacuumError", ErrorCategory.InvalidArgument, null )); } } } /// <summary> /// Process record - calculate Doppler shift and convert unit /// </summary> protected override void ProcessRecord() { // Calculate the shifted frequency double shifted = OriginalFrequencyInHertz * (SpeedOfSoundInMetersPerSecond + ObserverSpeedInMetersPerSecond) / (SpeedOfSoundInMetersPerSecond - SourceSpeedInMetersPerSecond); // Convert to desired unit using PowerShell function var convertScript = ScriptBlock.Create("param($value, $fromUnit, $toUnit) GenXdev\\Convert-PhysicsUnit -Value $value -FromUnit $fromUnit -ToUnit $toUnit"); var result = convertScript.Invoke(shifted, "hertz", As); WriteObject(result[0]); } /// <summary> /// End processing - no cleanup needed /// </summary> protected override void EndProcessing() { } } } |