Abstract: The system and method of the present invention include a modulator which encodes data on a communication signal using angle modulation. The demodulator, receiving the angle modulated communication signal, angle demodulates the angle modulated communication signal to obtain the data. In this manner, separate frequency bands are not required to transmit both the communication signal and the data. The bandwidth of the transmission from the modulator is reduced to the frequency band of the angle modulated communication signal. Additionally, since angle modulations of an audio signal are inaudible to a listener, when the communication signal is an audio signal, the angle modulated audio signal may be directly output to a listener at the demodulator. A multitude of applications exist for the present invention including Lincompex communication.

Abstract: At least two information waveforms are transmitted over the same communications channel using Lincompex techniques. Each of the information waveforms are modulated using Lincompex techniques to generate compressed information waveforms and associated control tones. The compressed information waveforms have the same frequency band. The compressed information waveforms and associated control tones are arithmetically combined, and transmitted over a transmission medium. These signals are then received from the transmission medium. A plurality of Lincompex expanders demodulate the received signals using Lincompex techniques and one of the associated control tones.

Abstract: A system and method for calibrating telecommunications systems employs frequency hopping techniques, and more particularly, employs linked compressor-expander (Lincompex) techniques in the transmission of any combination information waveform such as that generated by voice or digital data. A calibration tone sent at each channel frequency is compared against a reference frequency. Based on the results of the comparison, the information waveform is frequency compensated. Alternately, a calibration tone sent at an initial channel frequency is compared to a reference frequency to determine at total frequency error. The system then predicts the total frequency errors for successive channel frequencies. The system frequency compensates the information waveform based on the determined and predicted total frequency errors.

Abstract: A linked compressor-expander (LINCOMPEX) circuit for use in telecommunications is implemented digitally. A speech compressor circuit in a modulator and a speech expander circuit in a demodulator controllably attenuate given syllables of a speech signal by values determined in response to binary input signals which collectively represent the amplitude of a given symbol of the speech signal. A control tone signal is generated by the modulator, and the demodulator is responsive to the control tone signal for operating the voltage attenuator circuit of the digital expander to thereby reconstruct the speech signal. Calibrate circuitry is provided for periodically detecting a test frequency of the control tone generator during a brief period prior to transmission of syllables of the speech signal. Also included is a data multiplexing circuit for transmitting and receiving data between speech syllables to optimize transmitter loading.

Abstract: A phase locked loop signal generator is especially adapted for synthesizing a selectable frequency signal for exciting an HF radio frequency transmitter to transmit over the seven marine telegraph bands. The signal generator includes an oscillator for providing a highly stable frequency standard. Another signal generator is responsive to the frequency standard and to frequency selector signals input by the operator for generating an exciter signal which is coupled to the transmitter for effecting the RF transmission within a predetermined frequency range.