Method and apparatus compensating for effects of digital loss insertion in signal transmission between modems
First Claim
1. A digital modem adapted to communicate with an analog modem via a digital network that inserts a selectable loss in the amplitude levels of μ
- -law encoded signals transmitted from the digital modem, with the digital modem having a μ
-law encoder and decoder for signals transmitted and received by the digital modem, respectively, and with the digital modem comprising;
means for receiving from the analog modem a control signal for detecting the amount of digital loss inserted by the digital network in signals transmitted from the digital modem to the analog modem; and
an inversion mapper that maps a first μ
-law encoded signal into a second μ
-law encoded signal prior to its transmission to the analog modem to scale the amplitude level of the first μ
-law encoded signal by an inversion factor corresponding to the detected amount of the loss inserted by the digital network.
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Accused Products
Abstract
The present invention provides a method and apparatus for minimizing quantization noise in signal transmissions between modems coupled together via a digital network resulting from the performance of digital loss insertion in μ-law encoded signal transmissions when the receiving modem is coupled to the digital network via an analog subscriber loop. In a preferred embodiment, the minimization of quantization noise is effected by providing a digital modem capable of μ-law encoding and decoding a signal transmission; and capable of scaling the amplitude levels of signals generated by the modem; and capable of performing an inversion mapping.
19 Citations
18 Claims
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1. A digital modem adapted to communicate with an analog modem via a digital network that inserts a selectable loss in the amplitude levels of μ
- -law encoded signals transmitted from the digital modem, with the digital modem having a μ
-law encoder and decoder for signals transmitted and received by the digital modem, respectively, and with the digital modem comprising;means for receiving from the analog modem a control signal for detecting the amount of digital loss inserted by the digital network in signals transmitted from the digital modem to the analog modem; and
an inversion mapper that maps a first μ
-law encoded signal into a second μ
-law encoded signal prior to its transmission to the analog modem to scale the amplitude level of the first μ
-law encoded signal by an inversion factor corresponding to the detected amount of the loss inserted by the digital network.- View Dependent Claims (2, 3, 4)
- -law encoded signals transmitted from the digital modem, with the digital modem having a μ
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5. A method for communicating between a digital modem and an analog modem via a digital network that inserts a selectable digital loss in the amplitude levels of μ
- -law encoded signals transmitted from the digital modem, with the digital modem having a μ
-law encoder and decoder for signals transmitted and received by the digital modem, respectively, and comprising the steps of;determining the amount of digital loss inserted by the digital network in signals transmitted from the digital modem to the analog modem; and
inversion mapping a first μ
-law encoded signal into a second μ
-law encoded signal prior to its transmission to the analog modem to scale the amplitude level of the first μ
-law encoded signal by an inversion factor corresponding to the amount of the digital loss inserted by the digital network.- View Dependent Claims (6, 7, 8)
- -law encoded signals transmitted from the digital modem, with the digital modem having a μ
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9. A digital modem adapted to communicate with an analog modem via a digital network that inserts a selectable digital loss in the amplitude levels of μ
- -law encoded signals transmitted from the digital modem, with the digital modem having a μ
-law encoder and decoder for signals transmitted and received by the digital modem, respectively, and with the digital modem comprising;means for receiving from the analog modem a control signal to determine the amount of digital loss inserted by the digital network in signals transmitted from the digital modem to the analog modem;
means for scaling down the amplitude of the signals to be transmitted by a reduction factor based on the amount of digital loss to adjust a transmitted signal power to the analog modem;
an inversion mapper that maps a first μ
-law encoded signal into a second μ
-law encoded signal prior to their transmission to the analog modem, in order to scale the amplitude level of the first μ
-law encoded signal by an inversion factor corresponding to the amount of the digital loss inserted by the digital network.- View Dependent Claims (10, 11, 12)
- -law encoded signals transmitted from the digital modem, with the digital modem having a μ
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13. A method of communicating between a digital modem and an analog modem via a digital network that inserts a selectable digital loss in the amplitude levels of μ
- -law encoded signals transmitted from the digital modem, with the digital modem having a μ
-law encoder and decoder for signals transmitted and received by the digital modem, respectively, and comprising the steps of;determining the amount of digital loss inserted by the digital network in signals transmitted from the digital modem to the analog modem;
scaling down the amplitude of the signals to be transmitted by a reduction factor based on the amount of digital loss in order to adjust a transmitted signal power to the analog modem; and
inversion mapping a first μ
-law encoded signal into a second μ
-law encoded signal prior to their transmission to the analog modem in order to scale the amplitude level of the first μ
-law encoded signal by an inversion factor corresponding to the amount of the digital loss inserted by the digital network.- View Dependent Claims (14, 15, 16)
- -law encoded signals transmitted from the digital modem, with the digital modem having a μ
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17. A digital modem operably coupled to a digital network that inserts a selectable loss in the amplitude levels of a μ
- -law encoded signal transmitted from the digital modem, the digital modem comprising;
means for receiving a control signal for detecting the amount of digital loss inserted by the digital network in signals transmitted from the digital modem; and
an inversion mapper that maps a first μ
-law encoded signal into a second μ
-law encoded signal prior to its transmission to scale the amplitude level of the first μ
-law encoded signal by an inversion factor corresponding to the detected amount of loss inserted by the digital network.- View Dependent Claims (18)
- -law encoded signal transmitted from the digital modem, the digital modem comprising;
Specification