Joseph Joseph Rizzo

US Patent:

42752760, Jun 23, 1981

Filed:

Aug 6, 1979

Appl. No.:

6/064042

Inventors:

Joseph F. Rizzo - Lodi NJ

Assignee:

Bell Telephone Laboratories, Incorporated - Murray Hill NJ

International Classification:

H04B 158

US Classification:

179170D

Abstract:

Transhybrid loss is maximized in a transmission network (FIG. 1, 101) of the type for coupling a bidirectional transmission facility (102, 2-wire) to receive (103) and transmit (104) unidirectional transmission facilities (4-wire) by automatically adjusting impedance elements (RKL and RZL) of an impedance network (202, FIG. 3) to obtain an optimum match to the impedance of the bidirectional facility (102). To this end, a plurality of tones (107) are individually supplied to a receive port (111) of the transmission network (101) and the impedance elements (RKL and RZL) are controllably adjusted in a prescribed sequence (FIGS. 7-10) to obtain amplitude nulls at a transmit port (112) of the transmission network (101). Then, an additional signal having a plurality of predetermined frequency components which repeat periodically is supplied to the receive port (111) and a predetermined one of the impedance elements (RKL) is again adjusted to obtain an average value amplitude null at the transmit port (112). In one embodiment of the invention, the additional signal is a pseudo-random noise signal having frequency components at a fixed spacing in a predetermined frequency band.

US Patent:

42788480, Jul 14, 1981

Filed:

Aug 6, 1979

Appl. No.:

6/064041

Inventors:

Joseph F. Rizzo - Lodi NJ
John A. Rudisill - Flanders NJ

Assignee:

Bell Telephone Laboratories, Incorporated - Murray Hill NJ

International Classification:

H04B 158

US Classification:

179170D

Abstract:

Transhybrid loss is maximized in a transmission network (FIG. 1, 101) of the type for coupling a bidirectional transmission facility (102, 2-wire) to receive (103) and transmit (104) unidirectional transmission facilities (4-wire) by automatically adjusting impedance elements (RKN, RZN, etc. ) of an impedance network (202, FIG. 3, FIG. 4) to obtain an optimum match to the impedance of the bidirectional facility (102). To this end, individual ones of a plurality of tones (107) are supplied to a receive port (111) of the transmission network (101) and the impedance elements (RKN, RZN, etc. ) are controllably adjusted in a prescribed sequence (FIGS. 8-16) to obtain amplitude nulls at a transmit port (112) of the transmission network (101). In one embodiment, predetermined ones of the impedance adjustments (RKN, RZN, etc. , 820-823, 828-831) are iterated with predetermined ones of the tone signals being supplied to the receive port (111) further to optimize the impedance match.