| 摘要 |
1, 064,226. Correlation detectors. NEDERLANDSE ORGANISATIE VOOR TOEGEPASTNATUURWETENSCHAPPELIJK ONDERSOEK TEN BEHOEVE VAN DE RIJKSVERDEDING. Nov.12, 1964 [Nov.12, 1963], No.46164/64. Heading G1U. In a method of sampling a signal having a bandwidth B centred on a frequency f o , the sample rate f s satisfies the condition where m is an integer. It is shown that if the above condition is satisfied only one sampling series is required to represent the signal, resulting in simplified circuitry of, for example, correlation and matched filter arrangements. In one arrangement, Fig. 5b, in which the function is to be derived the signal s(t) is fed to a chain of f s T delay elements 7, each producing a delay of 1/f s seconds and the outputs from these elements are multiplied in 8 with weighting coefficients p(T k ) which are samples of p(T). The resulting signals are then summed in unit 9 to give a continuous output #(t). Where a sampled output Ï(t) is required, Fig. 6b the input signal s(t) is sampled at a rate f s by switch 2 and the samples fed to a chain of storage elements 5 which shift the stored information along one unit every 1/f s th second. The output from each store is then multiplied by weighting coefficients p(T k ) in units 12 and the resulting signals summed in adder 13. The system may also be applied to limit narrowband signals. |
