Abstract: For digital transitions from one binary logic level to another by frequency or phase shift of an electric carrier wave the modulation sidebands are reduced by performing each transition by means of several phase steps at small intervals. Equal phase steps at varying intervals are preferred over equal intervals between varying phase steps although both procedures can provide a low-bandwidth transition. This procedure is readily incorporated at low cost in frequency synthesizers. The use of a higher-frequency master oscillator (16) followed by a fixed-ratio frequency divider (17) ahead of a variable-ratio frequency divider (18) makes it easy to shift phase or frequency digitally by small quick steps. Another variable-ratio frequency divider (13) is desirable but not essential in the final PLL between a ultimately controlled oscillator (10) and a loop filter (12) connected to a phase discriminator (11).

Abstract: A mobile radio equipment has a built-in storage battery that permits radio equipment to be used outside of the vehicle, but the vehicle's battery and charger are needed to charge up or maintain the charge of the internal storage battery of the radio equipment most of the time. A d.c. voltage converter is used when the radio equipment is in the vehicle to provide at least one voltage which the internal storage battery provides to the radio equipment and that voltage of the internal battery is connected, when the radio equipment is in the vehicle, to the radio equipment through a control switch which is closed only when the output of the voltage converter is less than the voltage of the internal storage battery of the radio equipment. In the power supply located in the vehicle the output of the voltage converter also needs a regulator to supply a regulated voltage to the radio equipment, in addition to the prior unregulated voltage.

Abstract: A digitally modulated signal of the FSK type is subjected to limiting and linear FM demodulation to produce a baseband signal which often fails to show clearly the serial binary digital signal because of distortion and disturbances prior to its reception. The amplitude of the base-band signal is digitally sampled (quantized) at a uniform sampling rate which is an integral multiple of the symbol rate of the base-band signal. A sequence of successive amplitude samples spanning at least a symbol period addresses, at twice the symbol rate a look-up table containing a set of stored signal patterns and correspondence of patterns within a predetermined degree of similarity is elicited at twice the symbol rate along with information on the degree of similarity, and also a synchronizing pulse when the amplitude pattern shows that a binary signal transition is detected at a particular part of the pattern of the amplitude sample sequence.