Patent ID: 6968296

Claim:
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 a 0,n =0 and a 0,N.m =1.