Abstract: The invention relates to a radio transmitter, including means for up-converting an input signal by mixing the input signal with a local oscillation signal, means for extracting an observation signal from the up-converted signal, means for switching the observation signal between an ON state allowing throughput of the observation signal and an OFF state preventing throughput of the observation signal, means for down-converting the observation signal by mixing the observation signal with the local oscillation signal, means for filtering signal components around the down-converted oscillation signal, means for generating a compensation signal by using the filtered signal in the ON and OFF states of the observation signal throughput, and means for modifying the input signal with the compensation signal.

Abstract: The invention is a method and transmission system which transmits an analog composite signal, including carriers which are respectively modulated with different digital data signal.

Abstract: The invention relates to methods for determining the separate radio frequency gains for carriers in a multi-carrier transmitter of a radio transmission unit of a radio communications system. In order to enable a simple and accurate estimation of the gains, it is proposed to determine the individual gains (G1-GN) of the different carriers mathematically from different sets of powers (REF1-REFN) at some point in each single carrier unit and the corresponding total output powers of the transmitter. Alternatively, the relation of the powers of the different carriers to each other is determined just before the carriers are combined to a single multi-carrier signal. This relation is used for determining the contribution of the different carriers to the transmission power of the multi-carrier signal and for therefrom determining the radio frequency gains for the different carriers. The invention equally relates to corresponding radio transmission units and modules of such radio transmission units.

Abstract: The invention relates to methods for determining the separate radio frequency gains for carriers in a multi-carrier transmitter of a radio transmission unit of a radio communications system. In order to enable a simple and accurate estimation of the gains, it is proposed to determine the individual gains (G1–GN) of the different carriers mathematically from different sets of powers (REF1–REFN) at some point in each single carrier unit and the corresponding total output powers of the transmitter. Alternatively, the relation of the powers of the different carriers to each other is determined just before the carriers are combined to a single multi-carrier signal. This relation is used for determining the contribution of the different carriers to the transmission power of the multi-carrier signal and for therefrom determining the radio frequency gains for the different carriers. The invention equally relates to corresponding radio transmission units and modules of such radio transmission units.

Abstract: A multi-carrier transmitter has combination means for receiving and combining a plurality of carriers including a first modulated carrier for transmission in a first channel and a second modulated carrier for transmission in a second channel, to create a multi-carrier signal. Power control means are arranged to individually vary the power of each of the plurality of carriers before combination.

Abstract: The invention is a method and transmission system which transmits an analog composite signal, including carriers which are respectively modulated with different digital data signal.

Abstract: The invention relates to a method and an arrangement implementing the method for gain control. In the method, a signal is modulated and the modulated signal is amplified with a power amplifier (312) to an output (313). A modulated signal of a given timeslot is applied to a control unit (323) before the power amplifier (312). Said amplified modulated signal is applied from the output (313) to the control unit (323). The signals are compared in the control unit, in which a control signals is also generated based on the comparison. The gain is controlled based on the control signal in a following at least one timeslot. The gain may also be controlled between timeslots, based on the control signal.

Abstract: A multi-carrier transmitter has combination means for receiving and combining a plurality of carriers including a first modulated carrier for transmission in a first channel and a second modulated carrier for transmission in a second channel, to create a multi-carrier signal. Power control means are arranged to individually vary the power of each of the plurality of carriers before combination.

Abstract: A method of controlling a frequency synthesizer and a frequency synthesizer having a controllable output signal frequency and including a direct digital synthesizer whose output signal is coupled to the input of a phase-locked loop. To reduce the settling time of the synthesizer, the direct digital synthesizer includes a control circuit for controlling the frequency of the direct digital synthesizer from a first frequency to a second frequency in accordance with predetermined frequency steps.

Abstract: A method and an equipment for controlling a multi-branch frequency-hopping receiver equipment used in a radio station, especially in a base station of a cellular radio system onto a desired frequency when a band-pass filter (BPF2) responsive to an external control signal (VBPF) has been arranged for each branch of the receiver equipment, the control signal (VBPF) of the band-pass filter being controlled in sync with frequency hopping. The control signals (VBPF) of the band-pass filter (BPF2) are determined for each frequency (C) and each filter (BPF2) and this information is stored in a tuning voltage memory (TVM) from which it is retrieved in sync with frequency hopping.

Abstract: Non-linearity of a voltage-controlled non-linear amplifier/attenuator is compensated by placing a non-linear circuit in the feedback path of an operation amplifier of a linearizer, the circuit including one or more differential amplifiers connected in parallel. For example, one amplifier can be a low-gain amplifier whose exponential range is at the lower end of the control voltage range, and another can be a high-gain amplifier whose exponential range is at the upper end of the control voltage range. When a necessary number of differential amplifiers are used in the feedback path, it is possible to compensate for the non-linearity of the non-linear component to a desired extent.

Abstract: In a phase locked loop, a loop filter is provided between a charge pump and a VCO. The loop filter includes a passive integrator connected to a non-inverting input of an operational amplifier which supplies a tuning voltage to the VCO. The passive integrator functions to short-circuit pulses from the charge pump to ground, to prevent them from appearing at the output of the operational amplifier. The VCO tuning voltage area may be expanded by shifting a DC voltage level at the inverting input of the operational amplifier. Further low-pass filtering may be provided at the output of the operational amplifier.

Abstract: A phase locked loop (PLL) includes a phase comparator (12), a charge pump (13), a loop filter (14) and a voltage controlled oscillator (15). In order to minimize the lock-in time of the PLL under conditions of varying external temperatures, the PLL is supplied with temperature measurements, and the output of the charge pump is controlled according to both the external temperature and a desired frequency.