Establishing a return path in a forward path cable television testing environment

• US 7,707,615 B2
• Filed: 06/10/2004
• Issued: 04/27/2010
• Est. Priority Date: 06/10/2004
• Status: Active Grant

• Current Assignee: Time Warner Cable Enterprises LLC (Charter Communications Incorporated)
• Original Assignee: Time Warner Cable Inc. (Charter Communications Incorporated)
• Inventors: Musser, Dennis, Moreno, Marin
• Primary Examiner(s): Pendleton; Brian T
• Assistant Examiner(s): CHEN, CAI Y
• Application Number:
  US10/865,167
• Publication Number:
  US 20050276226A1
• Time in Patent Office: 2,147 Days
• Field of Search: 370/229, 370/230, 370/235, 370/254, 370/468, 370/241, 709/208, 725/107
• US Class Current: 725/107
• CPC Class Codes: H04L 1/243 at the transmitter, using a loop-back
• CPC Class Codes: H04N 17/00 Diagnosis, testing or measuring for television systems or their details
• CPC Class Codes: H04N 17/004 for digital television systems
• CPC Class Codes: H04N 21/6168 involving cable transmission, e.g. using a cable modem
• CPC Class Codes: H04N 7/17309 Transmission or handling of upstream communications

Abstract

A system and method for establishing a return path in a cable television test environment. A cable television test environment comprising a plurality of head-ends connected to a plurality of set top boxes through a one-way forward matrix switch having “M” inputs and “N” outputs is adapted to provide a reverse path for each of the available “N” outputs. A low band reverse signal is received from each of a plurality of set top boxes. The low band reverse signal from each of the plurality of set top boxes is combined to produce a composite signal. The composite signal is split into a plurality of composite signal sources. Each of the composite signal sources is sent to each of the plurality of head-ends (M) via the transmission means connecting that head-end to the matrix switch. The low band composite QPSK signal from the source diplexer travels in the reverse direction to the head-end. Each head-end is assigned a unique set of frequencies for return communications from the STBs serviced by that head-end. A QPSK demodulator in a head-end demodulates its assigned return frequencies as they appear in the low band composite QPSK signal.

Claims

1. A cable television testing environment with a return path comprising:

a one-way RF matrix switch comprising;

an input terminal, wherein the input terminal receives a high-band input signal from a head-end via a transmission path; and

an output terminal, wherein the output terminal is assigned to a selected set top box and is connected to the selected set top box via an output module assigned to the selected set top box,

and wherein the one-way RF matrix switch maps the high-band input signal from the head-end as received by the input terminal forward to the output terminal assigned to the selected set top box; and

wherein the output module;

passes the high band input signal to the selected set top box;

passes a low band reverse signal from the selected set top box to a combining/splitting module; and

wherein the combining/splitting module;

combines the low band reverse signal from the selected set top box with one or more other low band reverse signals from other set top boxes to produce a composite signal; and

splits the composite signal into a plurality of composite signal sources, wherein one of the plurality of composite signal sources is connected to the head-end via the transmission path thereby providing the return path from the selected set top box to the head-end, and wherein the return path does not pass through the one-way RF matrix switch.

2. The cable television testing environment of claim 1 wherein the output module isolates the low band reverse signal from the set top box from the output terminal to which the set top box is connected.

5. The cable television testing environment of claim 1, wherein the RF high-band input signal is a QPSK/QAM signal and the low band reverse signal is a QPSK signal.

7. The cable television testing environment of claim 1, wherein the headend is assigned a set of frequencies within the composite signal, wherein the headend comprises a demodulator and wherein the demodulator demodulates the assigned set of frequencies when they appear in a composite signal source received by the set top box.

3. A method for testing a selected set top box in a cable television testing environment comprising:

configuring an input terminal of one-way RF matrix switch to receive a high-band input signal from a head-end via a transmission path;

assigning an output terminal of the one-way RF matrix switch to the selected set top box;

mapping the high-band input signal from the head-end as received by the input terminal forward to the output terminal assigned to the selected set top box;

passing the high-band input signal to the selected set top box;

receiving a low band reverse signal from the selected set top box;

combining the low band reverse signal from the selected set top box with one or more other low band reverse signals from other set top boxes to produce a composite signal;

splitting the composite signal into a plurality of composite signal sources; and

connecting one of the plurality of composite signal sources to the head-end via a transmission path connected to that head-end thereby providing the return path and wherein the return path does not pass through the one-way RF matrix switch.

4. The method for establishing a return path in a cable television testing environment as in claim 3, the method further comprising:

isolating the low band reverse signal from the set top box from the output terminal to which the set top box is connected.

6. The method of claim 3, wherein the high-band input signal is a QPSK/QAM signal and the low band reverse signal is a QPSK signal.

8. The method of claim 3 further comprising:

assigning the head-end a set of frequencies within the composite signal; and

demodulating the assigned set of frequencies at the head-end when they appear in a composite signal source received by the set top box.

9. A cable television testing environment with a return path comprising:

a one-way RF matrix switch comprising;

a plurality of “

M”

input terminals, wherein each of the “

M”

input terminals is associated with, and receives a high-band input signal from, one of “

M”

head-ends via a transmission path; and

“

N”

output terminals, wherein N≧

M and wherein each of the “

N”

output terminals is associated with, and is assigned to, at least one selected set top box and is connected to the at least one selected set top box via an output module assigned to the selected set top box,

and wherein the one-way RF matrix switch maps the high-band input signal from each of the “

M”

head-ends as received by its associated input terminal forward to the output terminal assigned to the at least one selected set top box; and

wherein the output module;

passes the high band input signal from the output terminal associated with the at least one selected set top box to the at least one selected set top box; and

passes a low band reverse signal from the at least one selected set top box to a combining/splitting module; and

wherein the combining/splitting module;

combines the low band reverse signal from the at least one selected set top box with one or more other low band reverse signals from other set top boxes to produce a composite signal; and

splits the composite signal into a plurality of composite signal sources, wherein one of the plurality of composite signal sources is connected to the head-end via the transmission path thereby providing the return path from the selected set top box to the head-end.

10. A cable television testing environment with a return path comprising:

a one-way RF matrix switch comprising;

an input terminal, wherein the input terminal receives a high-band input signal from a head-end via a transmission path; and

an output terminal, wherein the output terminal is assigned to a selected set top box and is connected to the selected set top box via an output module assigned to the selected set top box,

and wherein the one-way RF matrix switch maps the high-band input signal from the head-end as received by the input terminal forward to the output terminal assigned to the selected set top box; and

wherein the output module;

passes the high band input signal to the selected set top box;

passes a low band reverse signal from the selected set top box to a combining/splitting module; and

wherein the combining/splitting module;

combines the low band reverse signal from the selected set top box with one or more other low band reverse signals from other set top boxes to produce a composite signal; and

splits the composite signal into a plurality of composite signal sources, wherein one of the plurality of composite signal sources is connected to the transmission path via an unswitched path thereby providing the return path from the selected set top box to the head-end.