Data modems having data drop-out and data echo protection

摘要: Disclosed is an automatic data communication system having communicating modems equipped with equalizers. The equalizers respond to a first long equalization sequence automatically transmitted from another modem. In response that sequence, the equalizer starts preset non-equalized condition and assumes fully equalized condition. That modem also capable of transmitting its own other Thereafter, second short sequences are employed at receiving enable memory storage associated stores, in signals which indicative Accordingly, do not have start for each new message unless dramatic distortion occurs. If such does occur, it detected again re-equalize. disclosed detection means distinguishing between sequences, line drop-outs, echoes.