Sample Rate / Nyquist & ADC Resolution Calculator implementation

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

t5-195

Effect

Computation or source lookup only

Input and validation requirements

• Reject negative frequency, negative ADC bit depth, non-integer bit depth, and nonpositive Vref inputs.
• Prevent division by zero or invalid results when Vref is zero or when ADC bit depth is invalid.
• A bandpass signal cannot be assigned a valid minimum sample rate from bandwidth alone; its frequency location is also required unless the input is explicitly defined as fmax.
• Sampling exactly at 2fmax provides no practical guard band and can be sensitive to phase and filtering; recommend a strict greater-than condition or an explicit practical-margin option.
• The ideal SNR formula does not account for ENOB, thermal noise, clock jitter, distortion, reference noise, front-end noise, or non-full-scale signal amplitude.
• Clarify whether the displayed Nyquist quantity is minimum sample rate or Nyquist frequency.

Required corrections

[
  {
    "vector": 1,
    "field": "theoretical_snr_db",
    "wrong": 73.76,
    "correct": 74,
    "cause": "72.24+1.76 written as 73.76; her v2 addition is correct"
  }
]

Inspectable interface fixture

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

{
  "inputs": {
    "signal_bandwidth_hz": 20000,
    "adc_bits": 12,
    "vref_v": 3.3
  },
  "expected_outputs": {
    "min_sample_rate_hz": 40000,
    "lsb_v": 0.0008056640625,
    "theoretical_snr_db": 73.76
  },
  "working": "Assume 20,000 Hz is fmax. Minimum sample rate = 2×fmax = 2×20,000 = 40,000 Hz. LSB = Vref/2^N = 3.3/2^12 = 3.3/4096 = 0.0008056640625 V. SNR = 6.02N+1.76 = 6.02×12+1.76 = 72.24+1.76 = 73.76 dB."
}

Other records

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