Abstract: A communications system having a plurality of different radio-types (528, 530 and 532) when integrated into a single node or control module (500) provides communications with a plurality of different end users (502, 506 and 508) having different transmission protocols. The steps involved comprise coupling the plurality of communication devices (528, 530 and 532) together via a bus (526) and coupling at least one processing unit (517) to the bus (526). Signals received by RF devices (528, 530 and 532) are communicated onto the bus (526) and processed by the processing unit (517) into processed signals. Processed signals comprise data and control information which are stored in memory (522). Thereafter, the processed signals stored in memory (522) are returned back onto the bus (526) for use by at least one of the plurality of communication devices (528, 530 and 532).

Abstract: There is provided a scheme for centering data prior to detection. It comprises: determining carrier frequency error, and pre-adjusting the data detection process to compensate for that error throughout the ensuing data detection. This scheme for reliable multi-level data detection further comprises: upon detection of carrier presence, determining carrier frequency error, gating a voltage associated with the frequency error to the differential amplification process to establish common mode rejection and compensating for that error throughout the ensuing multi-level data detection, and then analog-to-digital conversion of the differentially amplified multi-level data. A scheme for computationally centering the subsequent data detected to compensate for the error is also provided.

Abstract: An improved multilevel FSK demodulator, according to the invention, is provided that down-converts the IF frequency back to baseband quadrature via dual mixers. The improved multilevel FSK demodulator uses controllable time-delay in the demodulation process. This method requires a 90.degree. phase difference between 2 modulated signals to produce a maximum demodulated output amplitude at the maximum frequency deviation. Since the IF frequencies have been down-converted back to baseband quadrature, these 2 signals are only "out of phase" by an amount .DELTA.t that is equal to 90.degree./d.omega.. A further aspect of this invention addresses minimizing the DC offset from the demodulator by providing a feedback signal which controls the amount of delay provided to one of the quadrature signals.

Abstract: An improved multilevel FSK demodulator, according to the invention, is provided that down-converts the IF frequency back to baseband quadrature via dual mixers. The improved multilevel FSK demodulator uses time-delay demodulation. This method requires a .+-.90.degree. phase difference between 2 modulated signals to produce a maximum demodulated output amplitude at the maximum frequency deviation. Since the IF frequencies have been down-converted back to baseband quadrature, these 2 signals are only "out of phase" by an amount .DELTA.t that is equal to 90.degree./d.omega.. For a .DELTA..omega.of 4 MHz, this gives a .DELTA.t=62.5 nonoseconds. As a result, it is easy to achieve a delay line using multiple tap positions for 62.5 nonoseconds total delay.

Abstract: A cable converter produces a 4.5 MHz intercarrier sound signal from a received television signal for application to one input of a phase lock loop circuit, the other input of which is supplied from a voltage controlled oscillator producing a regenerated 4.5 MHz intercarrier signal. The output of the phase lock loop is supplied through a loop filter to the input of the voltage controlled oscillator to control its frequency. The regenerated 4.5 MHz intercarrier signal is thus stabilized by the received 4.5 MHz intercarrier signal.

Abstract: A means for scrambling video signals by the application of a periodic scrambling waveform which has the effect of altering the normal amplitude relationship between horizontal sync and the video picture portion of a horizontal line uses the comparison between the brightness level of the video signal during a predetermined time period with a reference as a means for varying the amplitude of the periodic scrambling waveform.