High speed two wire modem

Claim 2

The two-wire modem in accordance with claim 1 wherein at least one of(A)-(C): (A) the estimating means includes means for computing a signal-to-noise ratio over a predetermined frequency spectrum from said received second line probing signal and an echo-to-noise ratio over the predetermined frequency spectrum from said received at least one echo signal and, where selected, the means for computing includes a Fast-Fourier Transform (FFT) processor; and wherein the selecting means includes means for determining at least one desirable communication frequency band of the communication media within the predetermined frequency spectrum based on the computed signal-to-noise and echo-to-noise ratios and for selecting the carrier frequency and baud rate based on said at least one desirable communication frequency band; (B) the estimating means estimates the signal characteristics including non-linear signal distortion of the communication media; and (C) the estimating means estimates the echo characteristics including non-linearities in at least one echo path of the first line probing signal in the communication media.

Claim 3

The two-wire modem in accordance with claim 1 wherein the first and second line probing signals include a chirp signal ranging from a first frequency to a second frequency which is repeated a plurality of times over said respective first and second predetermined time intervals; and wherein the estimating means estimates an average of the signal characteristics based on an analysis of the repetitive chirp signal of the second line probing signal and estimates an average of the echo characteristics based on an analysis of the repetitive chirp signal of the echo of the first line probing signal.

Claim 4

The two-wire modem in accordance with claim 1 wherein the selecting means includes means for selecting the carrier frequency and baud rate based also on at least one desired data bit rate, further including, where selected, at least one of (A)-(B): (A) a means for generating an error signal if the selecting means is unable to select a carrier frequency and baud rate in accordance with the desired data bit rate, and (B) means for receiving information from the other modem, said information including a carrier frequency, a baud rate and a data bit rate at which the other modem expects to communicate, and means for deciding which of the selected and received carrier frequency, baud rate and data bit rate will be ultimately used by the two-wire modem in communicating with the other modem over the communication media and, where selected, the deciding means decides which of the selected and received carrier frequency, baud rate and data bit rate will be ultimately used for communication based on a less than and equal to comparison criteria.

Claim 5

Method of combining the processes of estimating channel characteristics and estimating range in a common start up procedure characterized by a plurality of successive time segments for a call modem to communicate with an answer modem over a communication media, a frequency spectrum of which being the channel, and a round trip delay over the channel between the call and answer modems being the range, said method characterized by the steps of: estimating a range for one of the call and answer modems in one time segment of the plurality of successive time segments of the start up procedure; estimating signal characteristics of the channel for the one modem in a second time segment of said plurality while concurrently estimating echo characteristics of the channel for the other of the call and answer modems; estimating a range for the other modem in a third time segment of said plurality; and estimating signal characteristics of the channel for the other modem in a fourth time segment of said plurality while concurrently estimating echo characteristics of the channel for the one modem.

Claim 6

The method in accordance with claim 5 wherein at least one of (A)-(B): (A) the one, second, third and fourth time segments are successive in the start up procedure, and (B) the one modem is the call modem and the other modem is the answer modem.

Claim 7

The method in accordance with claim 5 including the steps of: selecting a carrier frequency and baud rate for the call modem based on the estimated signal and echo channel characteristics thereof; selecting a carrier frequency and baud rate for the answer modem based on the estimated signal and echo channel characteristics thereof; exchanging the information of respective carrier frequency and baud rate over the communication media between the call and answer modems; and determining a carrier frequency and baud rate for each of the call and answer modems from the selected and exchanged carrier frequencies and baud rates, respectively, wherein, where selected, at least one of(A)-(B): (A) the method steps recited above (in claim 7) are performed in a successive time segment to the one, second, third and fourth time segments of the start up procedure, and (B) further including a successive step of training a receiver and echo canceller of each of the call and answer modems by exchanging signals therebetween over the communication media at the respective determined carrier frequency and baud rate thereof, and where selected, further including the successive step of thereafter, exchanging data between the call and answer modems over the communication channel at the respective determined carrier frequency and baud rate thereof, and then, further including, where selected, one of the sets of steps of (C) and (D) below: (C) during the data exchanging step, requesting a retrain of the call and answer modems by either of the call and answer modems including the steps of estimating the range and channel characteristics of each modem, and, where selected, further including at least one of the steps (a) and (b): (a) requesting the steps of estimating the range and channel characteristics by the call modem, and (b) requesting the steps of estimating the range and channel characteristics by the answer modem, and (D) during the data exchanging step, requesting a retrain of the call and answer modems by either of the call and answer modems including the steps of estimating the range for both the call and answer modem without the steps of estimating channel characteristics.

Claim 8

In a data communications network, method of switching between primary and secondary communication media connections of said network, which connections are used for communication by first and second modems coupled to said network, said method characterized by the steps of: (a) communicating data between said first and second modems over said primary communication media connection; (b) detecting a failure in said primary connection; (c) in response to said failure detection, qualifying a secondary communication media connection; (d) switching communication of said first and second modems from said failed primary to said qualified secondary communication media connection; (e) while communicating data between said first and second modems over said qualified secondary communication media connection, qualifying said primary communication media connection; and (f) restoring communication of said first and second modems from said secondary to said qualified primary communication media connection and repeating step (a).

Claim 9

The method in accordance with claim 8 wherein at least one of (A)-(C): (A) the primary connection being communicated over by the first and second modems is a leased line connection, (B) the secondary connection being switched to is a dial-up line connection, and (C) the step of qualifying a secondary communication media connection includes the steps of: (g) selecting one secondary connection from a plurality of secondary connections; (h) determining if said selected secondary connection can support communication at a desired combination of carrier frequency, baud rate and data a bit rate in order to accept said selected secondary connection and, where selected, step (h) includes determining if the selected secondary connection can support a minimum data bit rate at a prespecified carrier frequency and baud rate for acceptance; (i) qualifying said selected secondary connection upon acceptance; and (j) Upon rejection of said selected secondary connection, selecting another secondary connection of said plurality and repeating steps (h) through (j).

Claim 10

The method in accordance with claim 8 wherein step (e) includes the steps of: (k) determining if said primary connection can support communication at a desired combination of carrier frequency, baud rate and data bit rate in order to accept said primary connection and, where selected, step (k) includes determining if the primary connection can support a minimum data bit rate at a prespecified carrier frequency and baud rate for acceptance; (l) qualifying said primary connection upon acceptance; and (m) upon rejection, maintain the communication of data over said selected secondary connection.