Modem line probing signal techniques
First Claim
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1. 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.
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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.
42 Citations
12 Claims
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1. 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:
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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. - View Dependent Claims (2, 3, 4, 5, 6)
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7. 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:
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(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. - View Dependent Claims (8, 9, 10, 11, 12)
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Specification