 W. M. Goodall

W. M. Goodall reported an experimental speech-transmission system in the 1947 paper Telephony by Pulse Code Modulation by W. M. Goodall. The study concerned pulse-code modulation: sampled speech amplitudes are represented by a multi-unit code of on-or-off pulses, then decoded to reconstruct an output waveform. It connected a coding principle to an operating communications experiment.^[ref]

The basic engineering tradeoff can be illustrated independently of the paper's hardware settings. If a sample is assigned one of $L=2^b$ codes, increasing $b$ creates more distinguishable amplitude levels but requires more transmitted bits. At sampling rate $f_s$, a fixed-length code needs raw payload bit rateFor example, eight bits per sample at $8000{\mathrm{s}}^{-1}$ require $64000\mathrm{bit}{\mathrm{s}}^{-1}$ before synchronization, framing or other overhead. These are illustrative choices, not a claim about Goodall's exact experimental format.

A uniform quantization of a one-volt input range into 256 equal-width bins has step size $1/256\mathrm{V}$. With midpoint reconstruction and no overload, its maximum amplitude error is half that step. A receiver can reproduce the selected code exactly while still retaining this finite amplitude approximation. More code levels and more transmitted pulses therefore address different parts of the design from the analog signal-to-noise ratio.

Goodall's scientific contribution in the cited record is a documented experimental implementation of coded speech transmission. The byline's initials are retained here; a broader personal identity is not needed to explain the experiment's quantitative principle.