TIA Committee TR41 tried for years to reach agreement on a TDD Standard. They never succeeded because the hearing-impaired community did not agree with the proposed standard. The issue was that the transmit power restrictions imposed by Part 68 of the FCC Rules and Regulations do not allow enough power for analogue TDDs, to ensure relaibale operation over the longest possible/permissable loops in North America. TIA could not produce a national standard that would violate the law of the land and indeed cover the longest loops.
Don't know that anybody still has a copy of the drafts, but it covers all you want to know about analog TDDs. Ciao, Vic
