Abstract: The invention relates to the realization of frequency hopping in radio transmitter, receiver or transceiver systems. In the system according to the invention, a separate fixed-frequency radio transmitter or radio receiver is provided for each frequency utilized in the frequency hopping. The frequency hopping is realized by switching received inbound signals or outbound signals as baseband signals to the different fixed-frequency transmitters or receivers in accordance with a frequency-hopping sequence.

Abstract: A base station is provided which supervises the quality of a radio link and including a generator circuit for generating a supervising signal having a desired baseband frequency, a measuring circuit for monitoring the level of the baseband supervising signal, and a transmitting circuit for frequency-modulating a transmitting-frequency carrier of said baseband supervising signal. The measuring circuit comprises an A/D converter for deriving digital sample values from the baseband supervising signal, and a control circuit which monitors the deviation of sample values from that of a digital sample value corresponding to a supervising signal level causing a desired deviation in the output signal of the transmitting circuit on the basis of at least one reference value stored in a memory in connection with the calibration so that the deviation is no more than a predetermined difference value.

Abstract: A method and an apparatus for identification of a monitoring signal at a base station in a radio telephone system, in which a number of monitoring signals having different frequencies are used for monitoring the quality of radio links between the base station and mobile stations. The apparatus includes a multipath-type bandpass filter having an adjustable bandwidth for filtering the monitoring signal, the filter being arranged to be adapted to a desired monitoring signal frequency and the bandwidth of the filter being arranged to be narrowed in a steplike manner during the filtration period. An indicator is provided for identifying the monitoring signal on the basis of the level of the bandpass-filtered signal.

Abstract: A method to be implemented in an integrated services network, such as the well known ISDN, GSM or CMS88 type networks, takes advantage of short message service technology to enable communication between terminal equipment units, i.e., between people using the network. This method makes possible (a) the use of a short message service to provide automatic answer transmission; (b) the use of a specified memory area, from which the content of the automatic answer transmission is automatically fetched; and (c) the storing, in advance, within the specified memory area, of any useful information for any potential caller, i.e., a calling subscriber. The calling subscriber will in turn automatically receive information, e.g., on how to reach the person not attending the terminal device for the moment, or any other such useful information.

Abstract: A communication system in which terminal equipments capable of both voice and data service are interconnectable through a full-duplex connection or leg rate-adapted in compliance with CCITT V.110 or in the like manner and arranged to be attached V.24 interfaces, and to a method for controlling the connection. To enable the use of terminal equipments for both voice and data service in conjunction with such a rate-adapted leg, adapters provided at both ends of the leg utilize V.24 status signal states in the leg for hand-shaking end-to-end signalling events between the terminal equipment.

Abstract: A radio transceiver system is provided with transceivers for transmitting an outbound signal at least at one transmitting frequency and for receiving an inbound signal at least at one receiving frequency. Baseband signal processors are also provided for baseband processing of the outbound signal before conversion up to the transmitting frequency and of the received inbound signal after conversion down from the receiving frequency. To reduce cable laying in equipment racks and to simplify the realization of baseband frequency hopping, a bidirectional serial digital transmission channel is provided between transceivers and baseband signal processors, whereby both the inbound signal from a transceiver and the outbound signal applied to the transceiver are time-division multiplexed to said bidirectional serial digital transmission channel.

Abstract: A voltage step-up regulator produces a frequency control voltage for a frequency synthesizer in a radio transmitter using a low operating voltage. To minimize the disturbances conveyed elsewhere in the radio device, the step-up regulator comprises an amplifying transistor controlled by an oscillator signal which operates as a class A amplifier, the output of amplifying transistor (Q1) including a diode and two selectively coupled capacitors for rectifying and filtering the amplified signal. The step-up regulator further comprising a feedback circuit for stabilizing the output voltage by adjusting the amplitude of the amplified signal.

Abstract: The invention relates to a high-frequency amplifier of a radio transmitter, comprising an amplifier stage the gain of which can be automatically controlled by a gain control feedback (L15, L16, D10, D11, A1, A2) coupled from a subsequent amplifier stage or the out-put of the high-frequency amplifier. The power consumption of the gain control is reduced, and the frequency stability of the amplifier stages and the preceding voltage-controlled oscillator is improved by the high-frequency amplifier according to the invention, wherein the amplifier stage comprises a two-gate field-effect transistor (Q1), the first gate (G1) of which constitutes the signal input, and the second gate (G2) of which constitutes the gain control input, to which said feedback (L15, L16, D10, D11, A1, A2) is coupled, and wherein the operating point of the transistor (Q1) is set by biasing the first gate (G1).

Abstract: The invention relates to a quadrature modulator comprising a circuit for the compensation of a local oscillator leak signal in an output signal of the modulator, which circuit adds different compensation voltages to two modulation signals. To provide an automatic compensation of the local oscillator leak signal, the quadrature modulator of the invention comprises a regulating circuit for the regulation of the intensity of the compensation voltages irrespective of each other on the basis of the correlation between the amplitude variation in the output signal and the corresponding modulation signal.