Decimation: lower the rate without folding noise in

Pick a decimation factor and a band to keep. See every input frequency that would fold onto that band, and where a tone lands after the rate drops.

This page sets no cookie and sends nothing anywhere.

Where the numbers come from

gHashTag/t27 specs/fpga/dsp/signals.t27 (t27#8985): every value on the page is its fn bodies, compiled to wasm (logic.js)
R. E. Crochiere, L. R. Rabiner, Multirate Digital Signal Processing, Prentice Hall, 1983: decimation and polyphase structures
R. G. Lyons, Understanding Digital Signal Processing, 3rd ed., ch. 10: sample rate conversion