Data communication having transmitter-controlled mode switching from compressed-to-transparent mode but local synchronous transmitter-controlled and receiver-controlled mode switching from transparent-to-compressed mode

A method of effecting efficient data communication from a data transmitter to a data receiver, which communication alternates between (i) an uncompressed or transparent mode and (ii) a compressed mode, said method comprising the steps of:

• (a) switching the data transmitter from the compressed to the transparent mode of data transmission based on locally detected loss of data compression efficiency at the transmitter site and also transmitting to the receiver a code indicative of such switched transmission mode;
• (b) switching the data receiver from the compressed to the transparent mode of data reception based on detection of said code in received data;
• and
• (c) independently but synchronously switching the data receiver and data transmitter from the transparent to the compressed mode of data transmission and data reception respectively based on detected loss of data transmission efficiency in the transparent mode as locally detected by each of the data receiver and data transmitter.

Apparatus for effecting efficient data communication from a data transmitter to a data receiver, which communication alternates between (i) an uncompressed or transparent mode and (ii) a compressed mode, said apparatus comprising:

• (a) means at the transmitter for switching from the compressed to the transparent mode of data transmission at the transmitter site based on locally detected loss of data compression efficiency and for transmitting a code indicative of such switched transmission mode;
• (b) means at the receiver for switching from the compressed to the transparent mode of data reception at the receiver site based on detection of said code in received data;
• and
• (c) means at the transmitter and means at the receiver, each receiver for synchronously switching from the transparent to the compressed mode of data transmission and reception at the transmitter and receiver sites respectively based on locally detected loss of data transmission efficiency in the transparent mode.