Bbc Brown, Boveri & Company, Limited

Bbc Brown Boveri Ag

Patelhold Patentverwertungs & Elektro-holding Ag

Thomcast Ag

Bohumil Kyrian

Wilhelm Tschol

Johann Ferdinand Milavec

Juraj Tomljenovic

Nenad Tomljenovic

Patrick Gehri

Peter Niklaus

Narindra N Puri

Modulation amplifier for radio transmitters

In an AM broadcast transmitter having a switching amplifier as main modulator (12), an additional modulator (18) is used in the radio frequency circuit in order to achieve a steady 100% modulation at the modulation minima, with the aid of which additional modulator the carrier signal is also modulated at the modulation minima. The LF signal needed for controlling the additional modulator (18) passes through a delay circuit (16) and a correction circuit (17).

Amplitude modulated broadcast transmitter

An amplitude-modulated transmitter wherein the carrier value (T) is controlled in accordance with an improved HAPUG (controlled-carrier) method. Increased energy saving with simultaneous increase of the signal-to-noise ratio at the reception site is achieved by controlling the carrier along a static characteristic (SK) which begins, with a decreasing modulation level (P), with a residual carrier value (R), drops with increasing modulation levels to a minimum carrier value (T.sub.min) and passes into an ideal carrier-control characteristic only above a first level value (P.sub.1). Additional dynamic control results in a reduction in cross-over distortions.

Amplitude-modulated transmitter with controlled carrier value

A transmitter for single-sideband broadcast transmission which operates in accordance with the principle of combined amplitude and phase modulation generating a single-sideband signal and splitting this signal into an amplitude-modulated component applied to an amplitude-modulated path and a phase-modulated component applied to a phase-modulated path. An amplitude-modulation path is a D.C. voltage-coupled signal path from an envelope-curve detector to a radio-frequency amplifier (2). This results in direct floating-carrier modulation in a radio frequency amplifier in which the amplitude-modulated and phase-modulated components are amplified and recombined.

Single-sideband transmitter and method for operating this transmitter

A method for amplifying electric signals, an amplifier circuit and application of this amplifier circuit as the modulator stage of a subsequent amplifier, employing a variable anode voltage for the purpose of improving the efficiency of amplifiers and particularly of high-power modulation amplifiers which are used, for example, in broadcast transmitters for the amplitude modulation of the radio-frequency output stage. From the modulation signal to be amplified, a control signal is derived in a control stage, this control signal being associated with the amplitude of the envelope of this modulation signal and being used for controlling the output voltage of a modulator/rectifier. The control signal is caused to follow the modulation signal within a presettable response time.

High power class B modulation amplifier for a broadcast transmitter

A compact and inexpensive LF power amplifier is disclosed. A plurality of pulse trains which are phase shifted relative to each other are width-modulated by an input LF signal. The modulated pulse trains are individually amplified, preferably by means of a plurality of respective power transformers and switch elements. The switch elements include any suitable combination of electron tubes and semiconductor switches. The keying ratio of the amplifier is improved by associating the pulse trains in pairs, the two members of each pair being phase shifted 180.degree. relative to each other. The amplified pulse trains are superimposed to form a single combined amplified pulse train.

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Unterbozberg, Switzerland

Bohumil Kyrian