Abstract: A redundant system, such as a redundant-modem system, having a plurality of similar components capable of operating independently of each other. At least one of the components serves as a spare component. The system further includes a plurality of switches connected to the inputs and outputs of the components such that the inputs and outputs of each of the components may be rerouted through the component operating as the spare. When operating as a spare, a component monitors status information received from the other components and detects when one of the other components has failed. When one of the components has failed, the component acting as a spare controls the switches such that the spare component (20b) replaces the failed component.

Abstract: An alarm system for an automotive vehicle including direct coupled input connections which provide a voltage proportional to the amount of current interchanged between, the battery and the electrical system of the vehicle. An arming circuit is responsive to the voltage and arms the burglar alarm only when less than a predetermined current is interchanged between the battery and the electrical system. An alarm circuit produces an alarm when the alarm system is armed and more than a predetermined amount of current is drawn from the battery.

Abstract: An alarm system for an automotive vehicle including direct coupled input connections which provide a voltage proportional to the amount of current interchanged between the battery and the electrical system of the vehicle. An arming circuit is responsive to the voltage and arms the burglar alarm only when less than a predetermined current is interchanged between the battery and the electrical system. An alarm circuit produces an alarm when the alarm system is armed and more than a predetermined amount of current is drawn from the battery.

Abstract: Apparatus for maintaining a transmit radio signal frequency in a predetermined frequency relationship with a received radio signal. A common voltage controlled frequency source serves as an Lo signal generator for both the receiver and transmitter. A reference frequency oscillator is phase compared with a receive IF signal to derive a control voltage for the voltage controlled frequency source. The resulting phase lock loop provides transmit signal frequency control with respect to a received signal.

Abstract: An on-line channel monitor, for measuring E.sub.b /N.sub.O, measures the quality of a communication channel while the channel is in use. The channel monitor employs a soft-decision demodulator so as to compare analog signal levels of an AGC compensated signal in a demodulator with the desired signal level. Deviations, termed pseudo-errors, are counted and the number of counts integrated. The result is employed to drive a meter calibrated in terms of E.sub.b /N.sub.O.

Abstract: The digital demodulator produces an information bearing analog signal which is controlled in peak-to-peak amplitude. The signal is coupled to a soft-decision demodulator which provides a multi-bit output representative of magnitude (polarity and amplitude) of the analog signal at a rate determined by the symbol clock derived from the digital demodulator. Logic means produces a logic signal of a first or second type in response to selected multi-bit outputs of the soft-decision demodulator. A logic output of the first type is produced if either the multi-bit output represents an analog signal of one polarity and amplitude greater than a predetermined amplitude, or if the multi-bit output represents an analog signal of the other polarity and amplitude less than an equal predetermined amplitude of the other polarity. The logic output is coupled to an integrating means which produces a control signal representative of deviations of the logic signal of the first type from 50% duty cycle.