Arrangement for reduction of noise transmitted from a local cable tv network

• US 20040172659A1
• Filed: 01/12/2004
• Published: 09/02/2004
• Est. Priority Date: 07/13/2001
• Status: Abandoned Application

• Current Assignee: Spacenet Proxilliant Systems AB
• Original Assignee: Spacenet Proxilliant Systems AB
• Inventors: Carlsson, Lars A. P., Cullblom, Bo Peter, Ljungdahl, Kjell Arne
• Application Number:
  US10/483,591
• Publication Number:
  US 20040172659A1
• Time in Patent Office: Days
• US Class Current: 725/124
• CPC Class Codes: H04N 7/102 Circuits therefor, e.g. noise reducers, equalisers, amplifiers H04N7/108 takes precedence
• CPC Class Codes: H04N 7/17309 Transmission or handling of upstream communications

Abstract

An arrangement for the reduction of noise transmitted in the return direction fron a local cable TV network (10) comprises an input (14), an output (16), means (21) for evaluating signals incoming at the input (14), and blocking means (17) controllable by said evaluation means (21). Said blocking means are formed by a reprogrammable digital signal processing unit (17), which is connected to the input (14) via an analog-to-digital converter (19) and which is arranged to generate digital output signals corresponding to portions of the incoming signals, depending upon the existing programming of the signal processing unit (17) and the result of the evaluation of the incoming signals effected by the evaluation means (21), and to deliver said digital output signals to a digital-to-analog converter (24) connected to the output (16).

Claims

1. Arrangement for the reduction of noise transmitted from a local cable TV network (10) within a carrier frequency band serving for the transmission of signals in the return direction from subscriber lines (13) contained in said network (10) to a headend (11) connected to the network, said arrangement comprising an input (14) intended to be connected to the subscriber lines (13), an output (16) intended to be connected to the headend (11), means (21) for evaluating signals incoming at the input (14), and blocking means (17) controllable by said evaluation means (21) and arranged to permit or prevent a transmission of signals corresponding to the incoming signals at the output (16) in dependence upon the evaluation of the incoming signals effected by the evaluation means (21), characterized in that said blocking means are formed by a reprogrammable digital signal processing unit (17), which is connected to the input (14) via an analog-to-digital converter (19) in order hereby to receive the incoming signals in a sampled digital form and which is arranged to generate digital output signals corresponding to portions of the incoming signals, depending upon the existing programming of the signal processing unit (17) and the result of the evaluation of the incoming signals effected by the evaluation means (21), and to deliver said digital output signals to a digital-to-analog converter (24) connected to the output (16).

2. Arrangement according to claim 1, characterized in that it is arranged to permit a remote controlled programming or reprogramming, respectively, of the signal processing unit (17).

3. Arrangement according to claim 1 or 2, characterized in that the signal processing unit (17) is capable of acting as a frequency converter that can cause a change in the carrier frequency of an incoming signal during the passage of said signal in digital form through said unit.

4. Arrangement according to any of the preceding claims, characterized in that the signal processing unit (17) is arranged to cause a delay of the incoming signals transmitted in digital form thereto before generating any corresponding digital output signals from said unit.

5. Arrangement according to any of the preceding claims, characterized in that the signal processing unit (17) contains one or more FIR-filters.

6. Arrangement according to claim 5, characterized in that the signal processing unit (17) contains a FIR-filter which is arranged, in response to each sample X(k) of an incoming signal generated by the analog-to-digital converter, to generate an output signal Y(k) according to the equation

Y(k)=a₀·

X(k)+a₁·

X(k−

1)+a₂·

X(k−

2) . . . +a<sub>n−

1</sub>·

X(k−

(n−

1))

where k designates the order number of the sample in question, a₀, a₁. . . a<sub>n−

1</sub> consist of a set of multiplication coefficients selectable in dependence upon the result of the evaluation of the incoming signal effected by the evaluation means and previously stored in a memory contained in the arrangement.

7. Arrangement according to any of the preceding claims, characterized in that the evaluation means (21) consist of analog means which are arranged to receive the incoming signals in their original analog form.

8. Arrangement according to any of claims 1-6, characterized in that the evaluation means (21) consist of reprogrammable digital means which are arranged to receive the incoming signals in a sampled digital form.

9. Arrangement according to claim 8, characterized in that it is arranged to permit a remote controlled programming or reprogramming, respectively, of the evaluation means (21).

10. Arrangement according to any of claims 7-9, characterized in that the evaluation means (21) are arranged to determine whether an incoming signal satisfies one or more predetermined conditions and to cause the signal processing unit (17) to deliver a digital output signal corresponding to the incoming signal only when said condition or each of said conditions, respectively, is satisfied.

11. Arrangement according to claim 10, characterized in that the evaluation means (21) are arranged to determine whether an incoming signal has a frequency falling within a predetermined permitted portion of said carrier frequency band.

12. Arrangement according to claim 10 or 11, characterized in that the evaluation means (21) are arranged to determine whether an incoming signal has an amplitude amounting to a predetermined lowest permitted value.

13. Arrangement according to any of claims 7-12, characterized in that the evaluation means (21) are arranged to deliver information, depending upon the result of the evaluation effected by said means, to storage means (25) contained in the arrangement and from which said information can be fetched in to the headend (11).