In providing digital filters for remote control receivers, in particular, for audio-frequency centralized ripple control receivers in an economic manner, it is advantageous to be able to use a processor unit with as low a bit number as possible (for example, an 8-bit microcomputer). In a conventional design of a filter according to the prior art, the dynamic range which is provided with an 8-bit processor element is insufficient in ensuring a perfect operation of the filter when a quality factor Q of about 30 is needed for the intended purpose of use and, on the other hand, when the dynamic range of the wanted signal which is given in practice is taken into consideration. A solution is indicated which overcomes these difficulties, which particularly involves the selected arrangement of zeros in the pass-band of the filter.
A programmable logic controller (PLC) device for effecting arithmetic operations of a sequential program by a microprocessor (1). The PLC device comprises a periodic signal generating circuit (2) for generating an interruption signal at a predetermined time interval, an input circuit (7) for receiving an external input signal, and circuits for effecting filter processing by reading a signal output by the input circuit at a predetermined time interval in response to the interruption signal. Since the filtering processing is effected by the microprocessor, a time constant of a filter can be changed by a program and can be also changed for each signal.
A lighting system having an electric lamp controlled by an infrared remote controller. The remote controller incorporates a commercially available transmitter and receiver which reliably functions in the presence of infrared noise having frequencies at and about the carrier frequency of the transmitted signal. The remote controller receiver outputs a demodulated signal and a filter acts on the demodulated signal to remove noise present in the demodulated signal caused by the electric lamp by comparing measured time intervals between leading and trailing edges of the demodulated signal to predetermined values defining data elements.
A sampled data tone control circuit is implemented using a two pole canonic recursive/non-recursive filter. The filter is programmed with predetermined sets of sample weighting coefficients to selectively cut or boost either the base or treble band of frequencies.
A band pass digital filter which may be straightforwardly implemented. Considering successive samples I the last of which is N and input samples XI and output samples YI, the filter, in one embodiment, conforms to the expression: where J and F are integers.
