Did commercial deployment of Lucky's adaptive equalizer raise voiceband data rates to 9600 bps (4× the ~2400 ceiling), and is that figure in any primary source?
Raised while promoting the capture behind
claim-voiceband-distortion-barrier-capped-data-at-2400-bps and
claim-lucky-1965-adaptive-equalizer-steepest-descent-transversal-filter. The
capture carried a third claim, flagged [unverified-quant — needs primary]:
secondary sources (Wikipedia, ETHW-derived bios) report that commercial deployment
of the adaptive equalizer enabled a jump to 9600 bits per second — 4× the prior
~2400 bps ceiling. That figure was not located in Lucky's 1965 paper and was
left in the inbox rather than promoted, because a specific "Nx" multiplier is
exactly the kind of quantitative claim the sourcing floor requires Tier 1–2 to
carry.
Two things to establish before this number is load-bearing:
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Is the figure real and correctly attributed? 9600 bps voiceband modems (e.g. the CCITT V.29 family) arrive in the 1970s–80s, well after Lucky's 1965 paper — so "the equalizer enabled 9600 bps" may be compressing a decade of incremental modem engineering into a single attribution. Determine what rate Lucky's own 1965/1966/1967 equalizer work actually claimed or demonstrated.
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Where is the primary? Candidates: Lucky's own follow-up BSTJ papers (1966/1967 general-purpose automatic equalizers), Lucky, Salz & Weldon's 1968 textbook Principles of Data Communication, or the relevant CCITT/Bell modem specifications. Read directly and pin the rate to a dated primary before any note rests on it.
Medium priority — the mechanism and the 2400 bps barrier are already Tier-1 confirmed; this only concerns the downstream throughput number.