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US 6,968,296 B2Granted
Cable detector with decimating filter and filtering method
AssigneeRadiodetection Limited
InventorJohn Mark Royle
Life of this patent
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Abstract
A cable detection or location device is disclosed having a detection stage to produce a detection signal, a decimating filter having an input and an output, the input being coupled to the receiving stage to filter the detection signal and output a down-sampled filtered signal with a decimation ratio of N, and an output stage, coupled to the output of the decimating filter, to output an indication signal based upon the down-sampled filtered signal. The decimating filter used is a Finite Impulse Response (FIR) filter having a frequency response corresponding to that of a cascade of m SINC filters, wherein m is an integer greater than 1. A method of decimating a signal in a device is also disclosed.
Claims23
A cable detection device comprising:
- a stage configured to detect an emitted signal from an object, wherein the stage produces a detection signal based upon the emitted signal;
- a memory to store coefficients of a filter system;
- a processor to act as the filter system, the processor having first and second inputs and an output, the inputs being coupled to the detection stage and the memory respectively, to filter the detection signal and output a down-sampled filtered signal with a decimation ratio of N in phase and quadrature phase;
- and
- an output stage, coupled to the output of the processor, to output an indication signal being indicative of the detection of a cable based upon the down-sampled filtered signal, wherein:
- the processor is arranged to act as a Finite Impulse Response (FIR) filter and at least one frequency selective filter, wherein the FIR filter has a frequency response corresponding to that of a cascade of m SINC filters, wherein m is an integer greater than 1 and the FIR filter comprises N.m taps, the coefficients having been calculated by:
- a
- m
- ,
- n
- =
- ∑
- k
- =
- n
- n
- +
- N
-
- a
- m
- -
- 1
- ,
- k
- ;
- where a0,n=0 and a0,N.m=1.
24 more elements
A method of decimating a detected signal in a cable detection device, the method comprising:
- receiving an input signal from the cable detection device;
- passing the input signal through a processor acting as a Finite Impulse Response (FIR) filter and at least one frequency selective filter, the FIR filter having a frequency response corresponding to a cascade of m SINC filters, where m is an integer greater than 1 and the FIR filter comprising N.m taps, the FIR filter decimating the input signal and outputting a down-sampled signal in phase and quadrature phase, further comprising calculating the coefficients of the FIR filter using the equation:
- a
- m
- ,
- n
- =
- ∑
- k
- =
- n
- n
- +
- N
-
- a
- m
- -
- 1
- ,
- k
- ;
- where a0,n=0 and a0,N.m=1;
- and
- outputting an indication signal, based on the down-sampled signal, the indication signal being indicative of the detection of a cable.
22 more elements
A cable detection device comprising:
- a detection stage to produce a detection signal produced in response to an emitted signal;
- a filter system comprising a decimation filter, the filter system comprising an input and an output, the input being coupled to the detection stage, the filter system arranged to filter the detection signal and output a down-sampled filtered signal with a decimation ratio of N;
- and
- an output stage, coupled to the output of the filter system, to output an indication signal being indicative of the detection of a cable based upon the down-sampled filtered signal, wherein:
- the decimating filter is a Finite Impulse Response (FIR) filter having a frequency response corresponding to that of a cascade of m SINC filters, wherein m is an integer greater than 1.
2 more elements
A cable detection device comprising:
- a stage configured to detect emitted signal from an object, wherein the stages produces a detection signal based upon the emitted signal detection;
- a memory to store coefficients of the filter system;
- a processor, having first and second inputs and an output, the inputs being coupled to the detection stage and the memory respectively to process the detection signal and output a down-sampled filtered signal with a decimation ratio of N, wherein the processor is arranged to act as a Finite Impulse Response (FIR) filter making use of coefficients stored in the memory and having a frequency response corresponding to that of a cascade of m SINC filters, wherein m is an integer greater than 1;
- and
- an output stage, coupled to the output of the processor, to output an indication signal being indicative of the detection of a cable based upon the down-sampled filtered signal.
2 more elements
A method of decimating a detected signal in a cable detection device, the method comprising:
- receiving an input signal generated in response to a detect signal;
- passing the input signal through a Finite Impulse Response (FIR) filter, the FIR filter having a frequency response corresponding to a cascade of m SINC filters, where m is an integer greater than 1, the FIR filter decimating the input signal and outputting a down-sampled signal;
- and
- outputting an indication signal, based on the down-sampled signal, the indication signal being indicative of the detection of a cable.
1 more element
A method of decimating a cable detection signal in a cable detection device, the method comprising:
- receiving an input signal generated in response to an emitted signal;
- processing the input signal through a processor acting as a Finite Impulse Response (FIR) filter having a frequency response corresponding to a cascade of m SINC filters, where m is an integer greater than 1, the FIR filter decimating the input signal and outputting a down-sampled signal;
- and
- outputting an indication signal, based on the down-sampled signal, the indication signal being indicative of the detection of a cable.
1 more element
A cable detector comprising:
- detection means for detecting a cable and producing a detection signal;
- finite impulse response filter means for receiving the detection signal and outputting a down-sampled signal, based on the detection signal;
- and
- means for outputting a signal from the finite impulse response filter means based upon the down-sampled signal, wherein:
- the filter means has a frequency response corresponding to a cascade of a plurality of SINC filters.
2 more elements
Dependencies are inferred from the claim text.