Abstract: Disclosed herein is a demodulating device including, first high-frequency receiving means and second high-frequency receiving means for receiving a high-frequency signal of one of a first frequency and a second frequency, first signal strength detecting means and second signal strength detecting means for detecting strengths of signals received by the first high-frequency receiving means and the second high-frequency receiving means, respectively, and strength determining means for performing control so as to make the second high-frequency receiving means receive a high-frequency signal of the first frequency when the first high-frequency receiving means is made to receive the high-frequency signal of the first frequency and the second high-frequency receiving means is made to receive a high-frequency signal of the second frequency and when the second signal strength detecting means does not detect a predetermined signal strength within a predetermined time after the first signal strength detecting means dete

Abstract: Disclosed herein is a demodulating device including, first high-frequency receiving means and second high-frequency receiving means for receiving a high-frequency signal of one of a first frequency and a second frequency, first signal strength detecting means and second signal strength detecting means for detecting strengths of signals received by the first high-frequency receiving means and the second high-frequency receiving means, respectively, and strength determining means for performing control so as to make the second high-frequency receiving means receive a high-frequency signal of the first frequency when the first high-frequency receiving means is made to receive the high-frequency signal of the first frequency and the second high-frequency receiving means is made to receive a high-frequency signal of the second frequency and when the second signal strength detecting means does not detect a predetermined signal strength within a predetermined time after the first signal strength detecting means dete

Abstract: A system for testing an overall system employing an integrated circuit with a modulator thereon is disclosed. The system for testing includes structure for causing the modulator to continually transmit data and structure for causing the continually transmitted data to exhibit extreme frequency deviation. In both instances the structure may be a single register. This register may also include a set of bits that may be set to select a continuous or an alternating pattern or, stated another way, a maximum or a minimum peak frequency deviation.

Abstract: A laser diode driving apparatus detects the laser power output of a semiconductor laser diode (13), irradiating a laser bean on a write-once or overwrite optical disk (11), by a detector (14), compares the resulting detection output signal by a comparator (17) with a laser power setting signal, modulates the resulting comparison output signal with record data by a modulating device (19), and drives the laser diode (13) by a driving device (22) with the resulting modulation output signal. By providing the modulation device (19) in the APC circuit adapted for controlling the output of the semiconductor laser diode (13), it becomes possible to automatically set the laser power necessary for recording to an optimum value, as well as to widen the temperature range and the working characteristics of the semiconductor laser diode.