Source: https://guthlabs.ai/docs/instruments/doppler-effect-calculator-sound/implementation/

instrument implementation / implementation-contract

# Doppler Effect Calculator (sound) implementation

A source-bound implementation contract for Doppler Effect Calculator (sound); deployment and executable qualification remain separate.

Status: **VERIFIED_WITH_ERRATA**Lifecycle: **implementation-contract**

## Binding contract

This record describes what an executable surface must bind and validate. It does not claim that a public calculator, package, or production route is deployed.

**Record owner**: Guth Instruments

**Lifecycle**: verified-with-binding-errata

**Evidence ID**: t5-075

**Effect**: Computation or source lookup only

## Input and validation requirements

The calculator breaks or must reject an exactly sonic approaching source because the Doppler denominator becomes zero. It is also vulnerable to materially incorrect results if the approaching/receding branch or velocity sign convention is inferred ambiguously.

## Required corrections

````
[
  {
    "vector": 2,
    "field": "observed_frequency_hz / shift_percent",
    "wrong": "1029.1545 / 2.9155",
    "correct": "1030.0300 / 3.0030",
    "cause": "used the observer-motion formula (c+v)/c for a MOVING SOURCE; her own v3 applies the correct source formula c/(c−vs)"
  }
]
````

## Inspectable interface fixture

The sample below is evidence for interface and validation tests, not a production implementation.

````
{
  "inputs": {
    "source_frequency_hz": 440,
    "speed_of_sound_m_s": 343,
    "source_velocity_m_s": 0,
    "observer_velocity_m_s": 0,
    "motion": "stationary"
  },
  "expected_outputs": {
    "observed_frequency_hz": 440,
    "shift_percent": 0
  },
  "working": "Stationary case: f_obs=440*(343+0)/(343-0)=440*343/343=440 Hz. shift%=100*(440-440)/440=0%."
}
````

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/doppler-effect-calculator-sound/>)[02**Mechanism**](<https://guthlabs.ai/docs/instruments/doppler-effect-calculator-sound/mechanism/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/doppler-effect-calculator-sound/qualification/>)

## Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

- `VERIFIED_LEDGER.json`

- `evidence-tranche5/tranche5-results.json`

- `tranche errata record`