Modem line probing signal techniques
AssigneeU.S. Robotics, Inc.
InventorsDale M. Walsh, Vladimir Parizhsky
Life of this patent
Estimating the term…
Abstract
Techniques for generating a line probing signal. The probing signal is comprised of a plurality of different tones, where the tones have a predetermined phase relationship. The signal may be sent over a communication channel, such as a telephone line. By so using the line probing signal, the non-linearity of the electrical characteristics of the telephone line may be measured with increased accuracy.
Claims12
A modem, associated with a computer, for generating a line probing signal over a communication channel for use by a receiving modem to determine the non-linearity of the electrical characteristics of said communication channel comprising, in combination:
- a first bus for communicating with said computer;
- a transmitter for generating a finite plurality of different tones, said tones having a predetermined relative phase relationship;
- and
- a second bus for delivering signals, including said tones, to said communication channel,
- said tones being divided into a first group having a first predetermined phase and a second group having a second predetermined phase, said first and second predetermined phases having a predetermined phase relationship, said predetermined phase relationship arranged to substantially minimize the peak to root mean square average value of said line probing signal;
- wherein said transmitter comprises a signal generator for generating said line probing signal at a first power level for a first predetermined time period and for generating said line probing signal at a second power level for a second predetermined time period later than said first predetermined time period;
- said line probing signal at said first power level comprising tones having a plurality of amplitude peaks at a power level above the average signal power level of a nominal transmission data signal so as to attain peak amplitudes in the non-linear region of said communication channel.
A method for a modem, associated with a computer, for generating a line probing signal over a communication channel for use in determining the non-linearity of the electrical characteristics of said communication channel comprising, in combination, the steps of:
- (a) generating a finite plurality of different tones, said tones
- (1) having a predetermined relative phase relationship and
- (2) being divided into a first group having a first predetermined phase and a second group having a second predetermined phase, said first and second predetermined phases having a predetermined phase relationship, said predetermined phase relationship arranged to substantially minimize the peak to root mean square average value of said line probing signal;
- (b) generating said line probing signal at a first power level for a first predetermined time period, said first power level being above the average signal power level of a nominal transmission data signal so as to attain peak amplitudes in the non-linear region of said communications channel, and generating said line probing signal at a second power level different from said first power level for a second predetermined time period later than said first predetermined time period;
- and
- (c) delivering said tones to said communication channel.
Dependencies are inferred from the claim text.