How much radio does an FM receiver actually need? Brian Greenforest fed RF into one FPGA input threshold and recovered audio from the resulting transitions, bypassing the conventional mixer-plus-ADC front end.

The result turns a provocative architecture question into a complete receiver path.

Start With the Information FM Carries

Frequency modulation encodes audio in the changing phase and timing of the carrier, not in preserved amplitude. A digital threshold can discard much of the amplitude information while retaining edge timing.

Four-phase sampling organizes those edges into quadrature structure. Digital integration, decimation, and cross-product processing then convert phase change into baseband audio.

Remove the Inherited Burden

A conventional path introduces oscillator leakage, analog containment, ADC drive requirements, amplitude fidelity, lookup tables, and significant DSP before audio appears.

The one-pin architecture replaces that stack with a direct transition-stream question. Read the full receiver article, inspect the Verilog, and build the radio whose complexity matches the information.

Reduce the Radio to Its Essential Signal Path

The companion system connects the design question to a one-pin FPGA receiver, host-side I/Q processing, and direct SDR measurement.

How Much Radio Do You Actually Need? · https://youtube.com/watch?v=V40N7XRGAOo&si=tWVTfPCmpbv4C9mw

Originally posted on LinkedIn

Brian Greenforest · Thursday, April 23, 2026 at 10:05:15 PM PDT (2026-04-24 05:05:15 UTC)

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How Much Radio Do You Actually Need? I fed FM RF into a single FPGA input pin and let the pin's logic threshold become the receiver's front edge. A conventional FM receiver usually begins with an analog front end, a local oscillator, a mixer, an ADC, and a digital recovery chain. I built around the transition stream from that pin instead of preserving RF amplitude through the usual mixer-plus-ADC path. Otherwise, the work stayed trapped in the familiar loop: oscillator leakage, analog containment, ADC drive requirements, and DSP burden before the real question was even answered.