US 2003/0154498 A1 · Efficient transmission of digital return path data in cable television return path

Abstract

An efficient means for transmitting digitized return path signals over a cable television return path is disclosed. In one embodiment of the invention, the cable television return path includes a node that receives an analog return signal from a subtree of the cable television system and generates a digital transport signal representative of the analog return path signal. The digital transport signal, however, is not a digitized form of the analog return signal. Rather, the digital transport signal is encoded such that fewer bits are used to represent the analog return signal without substantially impacting the accuracy and dynamic range of the signal. At the hub, the digital transport signal is decoded and converted to produce an analog signal that is a close approximation of the analog return signal.

Claims14

Dependent claims

A signal encoder for use in a cable television return path, comprising:

an input configured to receive an N-bit digital input sample from an analog-to-digital converter, the N-bit digital input sample having N bits;
logic configured to determine whether the N-bit digital input sample has an amplitude that is larger than a predefined threshold, the logic further configured to generate at least one selection output bit indicative of whether the amplitude is larger than the predefined threshold;
and
logic configured to produce a digital output sample representative of the N-bit digital input sample in response to the at least one selection output bit, the digital output sample having one of a first subset and a second subset of the N bits, the digital output sample having the at least one selection output bit but having fewer bits than N;
and
an output, coupled to the logic, configured to provide the digital output sample to an optical transmitter.

3 more elements

A cable television return path of a cable television system, comprising:

an analog-to-digital converter configured to receive an analog return signal from a subtree of the cable television system and configured to generate a first digital signal representative of the analog return signal, the first digital signal having a stream of first digital samples each having N bits;
an encoder configured to receive the first digital signal and to generate a second digital signal that includes a stream of second digital samples each having a fewer number of bits than N, each of the second digital samples including one of a first subset of most significant bits and a second subset of least significant bits of a corresponding one of the first digital samples;
an optical transmitter configured to convert the second digital signal into an optical signal;
an optical receiver configured to receive the optical signal and to convert the optical signal into a replica of the second digital signal;
a decoder configured to recover a third digital signal from the replica of the second digital signal, the third digital signal including a stream of third digital samples, wherein each of the third digital samples includes N bits;
and
a digital-to-analog converted configured to convert the third digital signal to an analog signal that is substantially equivalent to the analog return signal.

4 more elements

Dependencies are inferred from the claim text.

Efficient transmission of digital return path data in cable television return path

Life of this patent

Efficient transmission of digital return path data in cable television return path

Life of this patent

Abstract

Claims14