US5265128A — Method and device for the digital transmission of…

Claim 1

Independent Claim 228 words

Method for the digital transmission of information in short-wave radio networks having a plurality of stations with a transmitter and/or a receiver to enable robust, efficient data communications, comprising the steps of: adding at the transmitter a predetermined reference signal to a data signal containing actual information for estimating channel state at the receiver end, addition of the reference signal to the data signal being effected by a quadrature modulation with the reference signal on a Q-axis and with the data signal on an I-axis, envelopes of the reference signal and the data signal being selected so that the magnitude of a complex envelope of the quadrature modulated signal is constant; transmitting the added reference and data signals; and, processing the quadrature modulated signal as a receiver input signal by detecting a received signal vector element-by-element, each element of said signal vector representing a complex value of a quadrature detection of an ith receiver input signal time interval and the complex value consisting of an ith data signal element and reference signal element, the quadrature detection being realized by correlation, said correlation being implemented by applying fast Fourier transforms (FFT0 of mutually overlapping time intervals of the receiver input signal and by alternatingly associating each FFT-processed interval with the ith data signal element and reference signal element; and, processing further said signal vector for channel adaptive data detection.

Claim 2

Dependent Claim 228 words

Method for the digital transmission of information in short-wave radio networks having a plurality of stations with a transmitter and/or a receiver to enable robust, efficient data communications, comprising the steps of: adding at the transmitter a predetermined reference signal to a data signal containing actual information for estimating channel state at the receiver end, addition of the reference signal to the data signal being effected by a quadrature modulation with the reference signal on a Q-axis and with the data signal on an I-axis, envelopes of the reference signal and the data signal being selected so that the magnitude of a complex envelope of the quadrature modulated signal is constant; transmitting the added reference and data signals; and, processing the quadrature modulated signal as a receiver input signal by detecting a received signal vector element-by-element, each element of said signal vector representing a complex value of a quadrature detection of an ith receiver input signal time interval and the complex value consisting of an ith data signal element and reference signal element, the quadrature detection being realized by correlation, said correlation being implemented by applying fast Fourier transforms (FFT0 of mutually overlapping time intervals of the receiver input signal and by alternatingly associating each FFT-processed interval with the ith data signal element and reference signal element; and, processing further said signal vector for channel adaptive data detection.

Claim 3

Dependent Claim 41 words

Method according to claim 1, wherein said step of transmitting further includes a step of splitting a transmitted signal into several partial signals with different frequencies, and a sub-channel frequency is selected pseudo-randomly or in step-like manner for each data sequence.

Claim 4

Dependent Claim 43 words

Method according to claim 2, wherein said step of transmitting the data signal and the reference signal further includes transmitting channel quality data and commands on the data signal for system adaptation to the channel state by altering code-rate, baud-rate and/or sub-channel frequency.

Claim 5

Dependent Claim 67 words

Method according to claim 3, wherein before applying the Fourier transforms of the receiver input signal, said step of processing the quadrature-modulated signal further includes the steps of executing a short duration burst noise filtering, a frequency shift of the received signal by the difference between discrete frequency points of the fast Fourier transform and an estimated frequency from the radio link establishment, and a window weighting.

Claim 6

Dependent Claim 24 words

Method according to claim 4, further comprising a step of selecting three frequency domain samples after the FFT for further processing as detection values.

Claim 7

Dependent Claim 28 words

Method according to claim 5, further comprising a step of effecting, after the selection of the detection values, a long duration burst noise filtering and a standard scaling.

Claim 8

Dependent Claim 39 words

Method according to claim 6, further comprising a step of selecting the combined data/reference signal on the basis of an index of the detection values, the detection values containing the reference signal with the corresponding index being split off.

Claim 9

Dependent Claim 82 words

Method according to claim 7, further comprising a step of estimating channel state information by autoadaptive filtering of the reference signal in the frequency domain, a system vector being first generated from the reference signal vector by a superordinate FFT, said system vector, in order to obtain the estimation of the channel state vector forming together with a noise term the additive components of the reference signal vector, being weighted with a weighting matrix and subsequently subject to an inverse Fourier transform.

Claim 10

Dependent Claim 27 words

Method according to claim 8, further comprising a step of effecting, following the inverse Fourier transform, a demodulation and then a decoding/accumulation and a time slip estimation.

Claim 11

Dependent Claim 90 words

Device for the digital transmission of information in short-wave radio networks having a plurality of stations with a transmitter and/or a receiver, comprising: a receiver for providing real-time processing of received data and including; a preprocessor function stage for preprocessing a receive signal; a quadrature detector function stage for quadrature detection of preprocessed receive signal elements, including data and reference signal elements; a selector function stage for separation of data/reference signals; and an estimator function stage for estimating the channel state using at least a portion of said receive signal.

Claim 12

Dependent Claim 90 words

Device for the digital transmission of information in short-wave radio networks having a plurality of stations with a transmitter and/or a receiver, comprising: a receiver for providing real-time processing of received data and including; a preprocessor function stage for preprocessing a receive signal; a quadrature detector function stage for quadrature detection of preprocessed receive signal elements, including data and reference signal elements; a selector function stage for separation of data/reference signals; and an estimator function stage for estimating the channel state using at least a portion of said receive signal.

Claim 13

Dependent Claim 42 words

Device according to claim 10, wherein the preprocessor function stage for preprocessing the receive signal includes an input filter, a first mixer, an IF filter, an AGC circuit, a second mixer, an image-frequency filter and an A/D converter, respectively arranged in series.

Claim 14

Dependent Claim 43 words

Device according to claim 10, wherein for quadrature detection of the receive signal elements the quadrature detector function stage for quadrature detection has a bank of detectors which work simultaneously on different frequencies with the aid of a first fast Fourier transform FFT.

Claim 15

Dependent Claim 25 words

Device according to claim 12, wherein upstream of the FFT a first burst filter, a first frequency shifter and a 4-term Harris window are interconnected.

Claim 16

Dependent Claim 68 words

Device according to claim 10, wherein the selector function stage for the selection of the data/reference signal includes a frequency selector, a second burst filter and a data/reference signal selector, and said function stage for the selection of the data/reference signal further includes two sign changers, two second frequency shifters and two buffers memories, in each case one for the data signal and one for the reference signal.

Claim 17

Dependent Claim 39 words

Device according to claim 10, wherein the estimator function stage for estimating the channel condition has an autoadaptive filter which includes a second fast Fourier transform performing a condition output vector, a weighting matrix and an inverse Fourier transform.

Claim 18

Dependent Claim 34 words

Device according to claim 15, wherein after the inverse Fourier transform, receive vectors corresponding to the data signal are multiplied by a conjugated complex value of the condition output vectors of the autoadaptive filter.

Claim 19

Dependent Claim 29 words

Device according to claim 16, wherein a real part and an imaginary part resulting from said multiplication are used for decoding the transmitting information and for time slip estimation.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1996-11-22	1997-05-24	1997-11-23	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2000-11-22	2001-05-24	2001-11-23	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2004-11-22	2005-05-24	2005-11-23	$7700.00	Window Closed / Lapsed

Method and device for the digital transmission of information in short-wave radio networks

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