Abstract:
The invention relates to a receiving device for angle-modulated signals. Channels are not selected in an analogue but a digital manner (10, 11). To this end, a receiving signal is preferably converted to an intermediate frequency band ( omega ZF), filtered and A/D converted. The receiving signal is subsequently converted to the baseband and channels are selected in a digital manner by means of a digital complex multiplier (9) before the receiving signal portion of the selected transmission channel is demodulated and the corresponding signals are detected by means of a differential demodulator (12).
Abstract:
According to the inventive method, a channel selection of a received signal is carried out by an analogue channel selection filter (KSF), the signal is then converted into a digital time-discrete and value-discrete signal, and the continuous-time and continuous-value course of the signal is determined by a mathematical reconstruction using zero crossings {ti} and phase values { phi (ti)=ki • pi / 2,ki ∈ N0} by means of a mathematical reconstruction algorithm, using a function system { phi (t - k)}.
Abstract:
The invention relates to a data transmission system comprising means for the radio transmission of first data bursts from a base station (B) to mobile stations (Mi). Said first data bursts contain, at least in part, a plurality of data blocks for various mobile stations (Mi). The inventive data transmission system also comprises means for transmitting second data bursts from at least one of the mobile stations (Mi) to the base station (B), and means for generating protection intervals ( DELTA T2) between successive data bursts.
Abstract:
The invention relates to a data transmission system comprising at least two stations (B, Mi) between which data bursts are exchanged via radio. A frequency hop is provided between the first channel mid-frequency (f>2n 2n+1
Abstract:
The invention relates to a method for calculating zero crossing reference sequences ({ti}) for carrying out the data detection of a sequence of zero crossings (formula (I)) of a received signal (2), said sequence being determined in a receiver. A data symbol sequence ({dk}), which is angle-modulated on the side of the transmitter and which is transmitted to the receiver, is based on the received signal. According to the invention, zero crossing reference sequences ({ti}) are calculated according to an equation that specifies the output of a linear status machine (FSM, 12). The linear status machine (FSM, 12) describes, at least approximately, the signal generation in the transmitter.
Abstract:
The zero crossings of a reception signal or an intermediate frequency signal produced from a reception signal are determined by a zero-crossing detector (1,10). Since the number of zero crossings per symbol interval in frequency-modulated signals is not constant by nature, the sequence of zero crossings is represented by means of a mathematical, especially non-linear representation on a sequence{zi} of temporally equidistant parameter values zi. The representation can be based upon the formation of average values for zero-crossing differences or a determination of the number of zero crossings. The chronologically equidistant sequence of parameter values zi can be added to a conventional detection algorithm such as a Viterbi detection algorithm.
Abstract:
A receiver circuit in a wireless communication system, comprising an analog signal processing section with a channel selection filter (KSF) and a digital signal processing section (DIG) which is arranged downstream therefrom and provided with a group delay equalizer (AP1, AP2). The group delay equalizer (AP1, AP2) is used to eliminate signal distortion caused by the channel selection filter (KSF).
Abstract:
For the purpose of estimating the frequency shift of a CPFSK signal (x(t)), a variable, integer delay parameter D is introduced. The respective CPFSK signal (x(t)) is scanned at intervals k•T+&tgr;, T being the scanning period, k a scanning index and &tgr; a delay constant. For the intervals k•T+&tgr;, intermediate signal values (z(k)) are determined from the scanning values (x(k)) of the CPFSK signal (x(t)) obtained for the intervals k•D•T+&tgr; and [k-1]D•T+&tgr; depending on said parameters. The estimated value (&ngr;) for the frequency shift is then obtained from a number of L0 intermediate signal values (z(k)) that have previously been determined for the intervals i•D•T+&tgr; (i = 0...L0-1).
Abstract:
The invention relates to a receiver circuit for a mobile radio receiver, comprising a programmable gain control (PGC) with variable amplification, an analogue to digital converter stage (3), a digital filter arrangement (KS1, KS2), for channel selection and a signal strength estimator (PE), arranged after the above in the signal path for determination of the signal strength in selected applied signals. Control of the amplifier (PGC) is carried out depending upon the applied channel signal strength as determined by the signal strength estimator (PE).
Abstract:
The aim of the invention is the offset compensation of a digital signal (r), especially a communications signal that is transmitted in a cordless digital communications system. According to the invention, a recursive digital filter is used. At least one filter coefficient ( gamma , nu ) thereof is modified in a time-dependent manner. The filter can thus be adapted for the access information and the actual useful information of a burst in different manners, whereby said burst pertains to the communications signal (r).