Abstract: In OFDM transmission use of an FFT is made for demodulating all carriers simultaneously. In order to prevent adverse influence of intersymbol interference due to multi-path propagation, it is known to determine the impulse response of the transmission medium and to adapt the FFT window accordingly. The center of gravity of the impulse response is now used rather than the first significant value of the impulse response. This has the advantage that the influence of deep fading has less influence on the selection of the FFT window, resulting in an improved performance.

Abstract: System for broadcasting and receiving digital data within time divisional multiplexed channels, grouped in frames, each frame comprising multicarrier symbols, including data symbols and system symbols, each symbol comprising a set of orthogonal frequency division multiplexed carriers at carrier positions within a frequency raster with regular carrier spacing. To provide in such system the possibility for a dynamic and accurate synchronization of the local oscillator of the receiver with that of the transmitter while allowing the free running tolerance range of the receiver's local oscillator to be much wider than that of the known receiver, the frames include frequency reference symbols, each carrying information to generate a peak value at at least one reference peak position within the frequency raster separated by at least one carrier position from each of the edges of the frequency raster and by at least two carrier positions from an eventual subsequent reference peak position.

Abstract: A class-G amplifier comprises first, second and third terminals connected to a load, first supply voltage (V.sub.1) and second supply voltage (V.sub.2), respectively, where V.sub.2 >V.sub.1. First (T.sub.1) and second (T.sub.2) transistors are series-connected between the first and third terminals with the collector of T.sub.1 coupled via first diode (D.sub.1) to the second terminal. A third emitter follower transistor (T.sub.3) has a B/E junction coupled between a signal input terminal and base of T.sub.1. A first current source (5) couples the third terminal and third transistor. A driver circuit includes a first current path between the third terminal and emitter of T.sub.3 comprising, in series, a second current source (7), a fourth transistor (T.sub.5) and second diode (D.sub.4). A second current path between a junction point (3) and common point (11) comprises, in series, third (D.sub.2) and fourth (D.sub.3) diodes and a third current source (8).

Abstract: A high-efficiency class-G type amplifier comprises a first transistor (T.sub.1), having its collector connected to a first supply voltage (V.sub.1) via a first diode (D.sub.1) and a second transistor (T.sub.2), connected in series with the first transistor and which has its collector connected to a second supply voltage (V.sub.2). The series arrangement of a second (D.sub.2), a third (D.sub.3) and a fourth diode (D.sub.4) is connected between the bases of the first and the second transistor (T.sub.1, T.sub.2) the fourth diode (D.sub.4) is poled in a direction opposite to that of the second (D.sub.2) and the third diode (D.sub.3). The series arrangement of a first resistor (R.sub.1) and the emitter-collector path of a first current-source transistor (T.sub.4) connects the second supply voltage to the anode of the fourth diode (D.sub.4). The junction point (5) between the first resistor (R.sub.1) and the current-source transistor (T.sub.4) is connected to the output (2) by means of a capacitor (C.sub.1).

Abstract: A high efficiency class-G amplifier comprises first (2), second (4) and third (10) terminals connected to a load, a first (V.sub.1) and second (V.sub.2) supply voltage, respectively, where voltage V.sub.2 >V.sub.1. First (T.sub.1) and second (T.sub.2) transistors are serially connected between the first and third terminals. A third transistor (T.sub.3, emitter-follower) couples a signal input terminal (6) to the base of the first transistor. A first diode (D.sub.1) connects the collector of T.sub.1 to the second terminal. A driver circuit includes a current path between the third terminal and a common terminal (11) having, in series, a first current source (7), second (D.sub.2) and third (D.sub.3) diodes and a second current source (8). A fourth diode (D.sub.4) connects junction point 3 to junction point 9. A fifth diode (D.sub.5) connects the emitter of the third transistor to the second current source.