An amplifier has a band pass response. The band pass response may be set by setting corner frequencies of low pass filters.

In an AM radio signal receiver, the value of Q of the input tuning circuit is varied in accordance with information indicative of the magnitude of the received signal. This information may be derived from the intermediate frequency (IF) signal processing stage of a superheterodyne receiver. In such a case, the IF signal is applied to a narrow-band filter having a pass band which is narrower than that of the IF signal processing stage. The amplitude of the output signal from the narrow-band filte...

The invention relates to a method for tuning a filter (5). The filter has at least one variable time constant, by which the location of the pass band (pc) of said at least one filter can be changed. In the method, at least one reference signal is inputted in said filter (5), and the frequency of said at least one reference signal is changed, and/or said at least one time constant of the filter (5) is changed. The method also comprises the steps of measuring the strength of the output signal of t...

An impulse radio system estimates a separation distance between an impulse radio transmitter and an impulse radio receiver. The system includes an impulse transmitter that transmits an impulse signal having an ultra-wideband frequency characteristic. An impulse receiver spaced from the transmitter receives the transmitted impulse signal and measures a signal strength of the received impulse signal. The receiver estimates the separation distance based on the measured signal strength. The receiver...

A switched bandwidth filter in a digital signal processor selectively provides a first bandwidth characteristic or a second bandwidth characteristic by loading separate first and second sets of filter coefficients into the digital filter. When switching between bandwidth characteristics, the coefficients of a selected filter section are slewed and the coefficients of all other sections are swapped at a time separate from the slewing. Thus, the benefits of slewing are obtained with minimal comput...

An adaptive audio processor for stereo AM broadcast signals includes independent signal processing paths. Each path has a variable lowpass filter and a matrix and variable Q 10 kHz notch filter to form LEFT and RIGHT channel signals with a 10 kHz notched pass band determined by adjacent channel noise. A 10 kHz pass band signal representative of adjacent channel noise from one of the signal processing paths is compared to a reference to generate a correction signal that is fedback to control the ...

An FM receiver includes an IF unit followed by an LF unit. The receiver has circuitry for changing the signal transmission characteristic of the IF and/or LF units, including a detector module with detector circuits for detecting values characteristic of receiving or interference states, with the inputs of these detector circuits each being connected with a circuit point of the IF or LF unit carrying the signal to be processed and with the outputs of these detector circuits providing signal char...

An occupant seat of vehicles including a spring structure having a buffer body mounted thereon, said spring structure including a plurality of spring elements juxtaposed in a horizontal plane, each of which is integrally formed of supporting hooks disposed at both ends and a pair of coil spring portions positioned near the hooks.

The invention relates to a method for filtering radio frequency signals in so called multiband radio communication devices that operate in several frequency ranges and to a communication device operating in several frequency ranges. In the method according to the invention, the desired frequency range is selected so that of the amplifiers (62a, 62b, 62c; 72a, 72b, 72c) placed between the filters (61, 63) on the reception branch (11) or correspondingly between the filters (71, 73) on the transmis...

A heterodyne receiver includes a tuner to select a frequency of a received signal and a converter to change the frequency of the received signal to an intermediate frequency. A single-pole/double throw switch has an input coupled to an output of the converter, a first output connected to a first band-pass filter and a second output connected to an amplifier. A second band-pass filter is coupled to an output of the amplifier, and a demodulator is coupled to an output of the second band-pass filte...