Abstract: A low frequency signal generating portion 1 generates a first discrete signal (a signal sampled at a first sampling rate f1). A band pass portion 2 operates at a second sampling rate f2, performs a frequency selecting operation to a second discrete signal generated when the first discrete signal generated by the low frequency signal generating portion 1 is inputted, and generates a modulated signal with a prescribed center frequency.

Abstract: An adaptive antenna includes a buffer for storing sample data obtained by sampling a receive signal, an information storage part for storing a plurality of sets of coefficients, an evaluation part for calculating an evaluation value of the result obtained by the coefficient and the sample data, a selection part for selecting two or more sets of coefficients in order of decreasing evaluation, an exchanging part for exchanging a part of coefficients between the selected sets of coefficients to generate a new set of coefficients, a changing part for changing a part of coefficients of the selected sets with random numbers to generate a new sets of coefficients, a reproduction part for reproducing the selected sets of coefficients as they are, and a determination part for outputting the result obtained by the set of coefficients with the highest evaluation value after the information storage part, the evaluation part, the selection part, the exchanging part, the changing part, and the reproduction part repeats res

Abstract: A down-link frame generating/transferring portion 12 detects a free channel from among a plurality of previously assigned up-link channels. The down-link frame generating/transferring portion 12 selects a secondary station 2 to which the free channel is to be assigned by referring to an address table 11 every time it detects a free channel. Then the down-link frame generating/transferring portion 12 sends out onto a down-link channel a down-link frame in which the secondary station address of the selected secondary station is set in an address slot corresponding to the free channel.

Abstract: A complex multiplier 5 complex-multiplies base band signals x and y obtained from a receive signal by local oscillation signals c and s, to output complex detection signals p and q. A phase difference detecting portion 7 outputs the amount of the detected phase difference corresponding to the phase difference between the phase of the receive signal and the phase of the local oscillation signals. A loop filter 8 emphasizes its DC component. A local oscillation portion 6 outputs local oscillation signals having a frequency corresponding to the amount of the detected phase difference. A region judging portion 9 judges which of regions on a complex plane is one to which the base band signals belong, and outputs a region signal. A most frequent region judging portion 10 judges which of the regions is one in which the base band signals are concentrated most frequently upon input of the region signal a predetermined number of times.

Abstract: An orthogonal frequency division multiplexing signal transmitted from the transmitting end to the receiving end intermittently includes a particular symbol S0 having a predetermined particular pattern in addition to a symbol Sm including data to be transmitted. At the receiving end, the variation in the receiving level and/or the variation in the frequency band of a received signal are detected and corrected on the basis of the received particular symbol S0. Since the particular symbol S0 has a particular pattern, the variation in the level and/or the variation in the frequency are strongly correlated with the variation in the receiving level and/or the variation in the frequency band of the received signal. Consequently, the variation in the receiving level and/or the variation in the frequency band of the received signal can be accurately detected from the particular symbol S0 and consequently high-precision correction can be made.

Abstract: A complex multiplier complex-multiplies a carrier modulation signal group for decoding the phases and amplitudes of a plurality of carriers which are orthogonal to each other on the frequency axis by a complex signal group having a predetermined specific pattern which varies in phase at random. An inverse Fourier transformer performs inverse Fourier transformation on an output of the complex multiplier, for transforming a digital signal which is multiplexed on the frequency axis to an OFDM signal on the time axis. A guard interval insertion part adds front and rear guard intervals to front and rear parts of each symbol of the OFDM signal respectively. The front and rear guard intervals include data which are identical to those of rear and front end parts of the corresponding symbol respectively. Arithmetic processing which is reverse to that on a transmission side is performed on a receiving side, whereby distortion of received data is removed.