MODEM — dial-up sample collection #

20 dial-up modem sounds from Freesound — 56k handshakes, RTTY/BPSK carriers, a 1200-baud carrier, dial sequences, data-click bursts, and a disconnect — with per-sample pitch analysis so tracks can paste them in pitch-matched to an E-rooted composition (FEM bells, guitar power chords on E).

Fetch: node fetch.mjs (re-runnable; dedupes by Freesound id; pruned ids stay pruned via the EXCLUDE list).
Analyze: node analyze.mjs → regenerates manifest.json (Goertzel scan 80–3600 Hz in 4 Hz steps, up to 3 s windows, first 0.3 s skipped; long handshakes get 2–3 windows since they change character over time).
License/attribution: all samples are CC0 or CC-BY previews; full attribution records (author, license URL, source URL) live in the vault at ~/aesthetic-computer-vault/personal/pop/freesound-cache/_attributions.json, keyed by the numeric id prefix of each filename. CC-BY samples need credit in release notes.

Samples #

File	Dur	Tags	Dominant tone	Best E-world rates
109143-bpsk125_ogg.mp3	4.6s	carrier	1012 Hz · B5 +42¢	E5 ×0.6514
109145-bpsk31_ogg.mp3	8.0s	carrier	1016 Hz · B5 +49¢	E5 ×0.6489
109147-rtty_45_1000hz_ogg.mp3	9.0s	carrier	1008 Hz · B5 +35¢	E5 ×0.6540
158621-dialup_call.mp3	25.8s	mixed, dialing, handshake	440 Hz · A4 +0¢	E4 ×0.7492 · B4 ×1.1225 · E5 ×1.4983
16475-dialup_mp3.mp3	27.6s	handshake, dialing	440 Hz · A4 +0¢	E4 ×0.7492 · B4 ×1.1225 · E5 ×1.4983
188828-modem_dial_wav.mp3	18.6s	handshake, dialing	1300 Hz · E6 −24¢	E5 ×0.5071
397079-digitalradio_noise4_wav.mp3	13.2s	clicks	900 Hz · A5 +39¢	B4 ×0.5488 · E5 ×0.7325
42996-alienfaxstereo_wav.mp3	15.0s	carrier, mixed	768 Hz · G5 −36¢	G4 ×0.5104 · B4 ×0.6431 · E5 ×0.8584
454649-modem_3_aif.mp3	17.8s	handshake	120 Hz · B2 −49¢	E2 ×0.6868 · B2 ×1.0289 · E3 ×1.3734
454650-modem_2_aif.mp3	16.6s	handshake	480 Hz · B4 −49¢	E4 ×0.6867 · B4 ×1.0289 · E5 ×1.3735
454651-modem_1_aif.mp3	21.8s	handshake	440 Hz · A4 +0¢	E4 ×0.7492 · B4 ×1.1225 · E5 ×1.4983
49608-dialup_login_dec_2001_24_bit_wav.mp3	22.5s	handshake, dialing	924 Hz · A♯5 −16¢	B4 ×0.5345 · E5 ×0.7135
586442-fake_dial_up_modem_sound_tape_recorded.mp3	20.5s	mixed	432 Hz · A4 −32¢	E4 ×0.7630 · B4 ×1.1432 · E5 ×1.5261
591324-vara_fm_hello_world_wav.mp3	26.6s	carrier, handshake	1780 Hz · A6 +20¢	B5 ×0.5549 · E6 ×0.7407
62843-modem_mp3.mp3	28.6s	handshake	852 Hz · G♯5 +44¢	B4 ×0.5797 · E5 ×0.7738
658932-dial_up_sound_mp3_flac.mp3	19.3s	handshake, dialing	440 Hz · A4 +0¢	E4 ×0.7492 · B4 ×1.1225 · E5 ×1.4983
78657-modem1200_wav.mp3	5.6s	carrier	2064 Hz · C7 −24¢	E6 ×0.6388
8037-modem_1_53_wav.mp3	2.2s	clicks	1200 Hz · D6 +37¢	E5 ×0.5494
8055-modem_1_97_wav.mp3	2.6s	clicks (noisy)	—	none needed
844723-at_t_internet_gateway_modem…mp3	11.3s	disconnect, clicks	644 Hz · E5 −41¢	E5 ×1.0237 (nearly in tune!)

Notes on what the numbers mean: the classic US dial tone (350+440 Hz) shows up as an exact A4 in four of the handshakes, the V.25 answer-tone region puts several carriers near B5, and the RTTY/BPSK trio sits tightly at ~1010 Hz — one rate (≈0.65) drops all three onto E5. The AT&T disconnect already rings 41¢ flat of E5; a 1.0237 rate tunes it exactly.

How to use #

Paste a sample into a composition by rate-resampling so its dominant tone lands on a scale tone of the E-rooted world (rate = target Hz ÷ peak Hz — resample the buffer by that factor, or play it back at that rate). The rates map in manifest.json is precomputed from the strongest stable peak, kept within [0.5, 2.0] so material never smears more than an octave:

Tonal carriers (RTTY/BPSK, modem1200, VARA FM) hold a steady pitch — tune them to E or B and they read as synth drones/pads that chord with the FEM bells. Carriers above ~1.3 kHz get fallback targets G5/B5/E6, still E-minor chord tones.
Handshakes change pitch over time (dial tone → answer tone → carrier); the manifest records 2–3 analysis windows so you can pick which phase to tune (e.g. tune the 440 Hz dial-tone phase to E4 with ×0.7492, or slice the carrier phase out and tune that instead).
Clicks/noisy bursts (8055, and the click layers of 397079/844723) need no tuning — use them raw as percussion: data-burst hats, negotiation-chirp fills, disconnect as a stop/fill hit.

Example (any /pop C or JS engine): to put the BPSK31 carrier on E5, resample 109145-bpsk31_ogg by 0.6489 (its 1016 Hz peak → 659.26 Hz). Stack the RTTY at ×0.6540 for a phasing unison. Drop 454649-modem_3 at ×0.6868 for an E2 sub-layer under the power chords.