Abstract: An adaptive signal level detector. The inventive detector includes a first circuit for receiving an input signal and providing a second signal identical to said input signal and delayed relative thereto. The amplitude of the delayed signal is compared to the maximum amplitude of the input signal. When the second signal is at a predetermined level relative to the input signal an output signal is provided. In a specific implementation, the invention (10) includes a first circuit (18) for detecting the signal level of the transmitted signal and providing a second signal in response thereto. The second signal is a logarithmic representation of the input signal The second signal is delayed (20) to provide a third signal. The third signal is subtracted (24) from the second signal to provide a fourth signal. When the fourth signal exceeds a predetermined threshold, an output signal is provided.

Abstract: A single sideband radio system. The system comprises a transmitter and a receiver. The transmitter comprises a transmitter baseband processing portion for generating a first baseband signal comprising first, second, and pilot components and modulating the first baseband signal in inverse proportion to the strength of the first component of the first baseband signal and an RF output stage for generating and transmitting a single sideband signal comprising first, second, and pilot portions corresponding to the first, second, and pilot components of the modulated first baseband signal. The receiver comprises an RF input stage for receiving the single sideband signal and a receiver baseband processing portion for generating a second baseband signal comprising first, second, and third components corresponding to the first, second, and third portions of the single sideband signal and for correcting the second baseband signal based on the pilot component of the second baseband signal.

Abstract: For suppressing interference signals in a multiplex signal an RC member which is preceded by a voltage divider is used. The voltage divider consists of a resistor and two diodes which are connected in parallel and in opposite directions and which perform a limitation with respect to a reference signal taken from the output of a fedback differential amplifier. The output signal of the RC member is applied to the non-inverting input of the differential amplifier. The limitation is carried out with respect to a reference signal corresponding to the signal smoothed by the RC member.

Abstract: A down converter device is disclosed which is used in a satellite communication system to convert a microwave signal to an intermediate frequency signal by the use of a standard signal having a frequency range of several to several tens of MHz, and to apply the intermediate frequency signal to a next stage component. The down converter includes a mixer for producing the intermediate frequency signal indicative of a frequency difference between the standard signal and the microwave signal. A separator is provided which includes a first terminal for receiving the intermediate frequency signal, a second terminal for producing and supplying the intermediate frequency signal to the next stage component and for receiving the standard signal from the next stage component, a first filter for separating the standard signal, and a third terminal for producing the standard signal to the mixing means.

Abstract: A method and apparatus for choosing the most optimum communication channel in a system (100) having a plurality of communication channels provides for reduced interference and increased system capacity. By establishing a set of threshold levels and comparing these threshold levels to receive signal strength level measurements for each of the communication channels, a communication device originating a call can be guaranteed of establishing communication using the communication channel with the least chance of being affected by interference or of affecting other channels already in use.

Abstract: A communication unit (114) operates in a communication system (100). The communication unit (114) communicates with a central communication controller via one of a plurality of a communication controllers (104, 108, or 112) that transmits information signals containing its identification along with other information. The communication unit (114) receives and determines the signal strength (RSS) of these information signals. A controller (412) monitors changes in the signal strength of the received information signals over time and determines whether the signal strength has fallen below a predetermined level at a rate of change higher than a predetermined rate. Such sharp fall in signal strength is communicated to a circuit which attempts to access a new channel after waiting for a random amount of time.