A space diversity receiving system for the central station of a multi-direction time division multiplex communication network having a plurality of satellite stations, and one central station. Each satellite station transmits signals to the central station during an assigned time slot. The central station receives burst signals from the satellite stations. A first receiver has a main antenna. A second receiver has a supplementary antenna. Both receivers include a demodulator coupled to the corresponding antenna and a detector for detecting bit errors in the resulting demodulated signals, and for providing error pulses when appropriate. Each satellite station, needing space diversity, has a counter for competitively counting the error pulses from the receivers. A signal switcher responds to the demodulated signals and the counter for selecting a demodulated signal having a lower bit error rate.
A signal quality detector circuit which detects an error signal of an input signal, used for detecting transmission quality of a transmission line. The detector circuit equalizes the input baseband signal, analog-to-digital-converts the equalized signal to a digital bit signal, analog-to-digital converts the input baseband signal to a digital bit signal, compares the two analog-to-digital converted signals on a bit-by-bit basis and detects an error signal accumulates the error signal in a unit time, and detects transmission quality of a transmission line.
An antenna selection decision system detects the level of the TDM burst immediately preceding to the TDM burst of the user's own channel and decides, on the basis of the detected level, to use the antenna selection diversity method or another selection criterion. When the other selection criterion is selected, the antenna which should receive the next TDM burst of the user's own channel is selected depending on the level of TDM burst of the user's own channel.
Channel propagation characteristics in a wireless communication system, wherein plural communication links or channels are defined between multiple transmit antenna elements and multiple receive antenna elements, are determined by selecting a matrix of training signals for transmission from the transmit antenna elements, and providing information concerning the selected training signal matrix to a system receiver. The training signals are transmitted from the transmit antenna elements to the receive antenna elements in a determined sequence during a defined training signal time interval, and signals corresponding to the training signals are received via the receive antenna elements. Components of a propagation characteristic matrix for use in discriminating signals transmitted at times other than the training signal time interval, are determined at the receiver as a function of signals received during the training signal time interval and the information concerning the matrix of training signals.
A circuit and technique for directing an adaptable antenna system is described. The invention is coupled to the output of an RF receiver configured to provide a data signal output, and evaluates the quality of the receiver data signal. The invention switches antennas when the signal quality deteriorates below a predetermined level.
A diversity system of the selection type for correcting phase ambiguities among a plurality of differentially encoded digital signals while retaining the digital encoding of those signals. With this system, no differential decoding/encoding means are needed in relay units of the system. Thus, differentially encoded digital signals may be sent through relay systems containing error correcting MODEMs without the additional complication of differential decoding/encoding circuitry.
