Abstract: Non-linear intersymbol interference and noise in a received data signal are corrected through use of a Viterbi detector which estimates the most likely sequence of transmitted data symbols by keeping track of candidate data sequence that are recursively updated, based on likelihood measures which are determined by a signal processor which includes circuits for estimating hypothesized channel outputs in the absence of noise. Non-linear input-output relations are stored in one or more look-up tables which, in a preferred embodiment, are registers that store hypothesized channel output symbols in the absence of noise. The contents of the look-up tables may be modified in response to an error signal representative of the difference of the channel output signal and the look-up table output signal.

Abstract: In a system for transmitting a binary source signal from a data transmitter to a data receiver through a noisy dispersive channel, the data transmitter includes a sliding block encoder which converts the binary source signal at a given symbol rate 1/T into an encoded binary data signal at a symbol rate P/(NT), where P and N are positive integers such that N/P.ltoreq..sup.2 log(3)/2= 0.79248. Since the channel introduces intersymbol interference and noise into the encoded data signal, the data receiver is formed from the cascade of an equalizer, a sampler and a reconstruction circuit which serves to reconstruct the binary source signal at the symbol rate 1/T. The reconstruction circuit includes a detector in a cascade with a decoder having memory the equalizer, sampler and detector are arranged for the detection of a ternary data signal at the symbol rate P/(2NT).

Abstract: A system for transmitting an n-level data signal (d.sub.k) at a given symbol rate 1/T comprises a data transmitter (1), a transmission channel (2) and a data receiver (3) with an equalizer (30) of the decision feedback type. By arranging this equalizer (30) for forming an estimate (c.sub.k) of a virtual m-level data signal (c.sub.k) instead of the output signal (b.sub.k) of the data transmission (1) error propagation in the equalizer (30) is considerably reduced without thereby appreciably adding to the implementation-complexity of the system.

Abstract: Apparatus for combatting intersymbol interference and noise introduced into a data signal transmitted at a symbol rate l/T by a transmission channel having a memory span LT corresponding to a number of L consecutive data symbols, comprises a receive filter (RF), a first decision circuit (ID) for forming preliminary symbol decisions in response to the transmitted data signal, a second decision circuit (FD) for forming final symbol decisions, means (FFS and FBS) for compensating pre- and post-cursive intersymbol interference, and a combining circuit (AD) for forming the input signal for the second decision circuit (FD).

Abstract: An arrangement for combating intersymbol interference and noise, which are introduced into a data signal (a.sub.k) transmitted at a symbol rate 1/T by a dispersive transmission channel (CH), comprises an adaptive equalizer (EQ) with a symbol detector (ID) for forming tentative symbol decisions (a.sub.k) as well as a post-detector (PD) for forming final symbol decisions (a.sub.k-M) using an auxiliary signal which is derived from the transmitted data signal (r.sub.k) at the input of the arrangement. By using a priori knowledge of the main character of the transfer characteristic of the transmission channel (CH) and by using as an auxiliary signal for the post-detector (PD) the input signal (a.sub.k) of the symbol detector (ID) in lieu of the transmitted data signal (r.sub.k), this post-detector (PD) can be arranged in a non-adaptive and thus simpler way without a resulting noticeable loss of transmission quality. (FIG. 4).

Abstract: A system for transmitting a data signal (a.sub.k) at a given symbol rate 1/T comprises a data transmitter (1), a channel (3(1)) of a transmission facility (3) having a plurality of channels (3(1)-3(M), and a data receiver (2) with an equalizer (7) of the decision feedback type. This equalizer comprises a feedback filter (12) with a memory span NT and a feedforward filter (8) which includes a low-pass filter section having a substantially minimum-phase character and an amplitude-frequency characteristic .vertline.W(f).vertline. which has a pronounced maximum .vertline.W(f.sub.m).vertline. for a frequency f.sub.m near to the frequency f=1/((N+1)T) and which is decreasing for frequencies exceeding f.sub.m [FIG. 5A]. Consequently, with respect to conventional dimensionings of the equalizer (7), this achieves an improved transmission quality and/or a reduced complexity of the feedback filter (12).

Abstract: A system for transmitting an n-level data signal (d.sub.k) at a given symbol rate 1/T comprises a data transmitter (1), a transmission channel (2) and a data receiver (3) with an equalizer (30) of the decision feedback type. By arranging this equalizer (30) for forming an estimate (c.sub.k) of a virtual m-level data signal (c.sub.k) instead of the output signal (b.sub.k) of the data transmitter (1) error propagation in the equalizer (30) is considerably reduced without thereby appreciably adding to the implementation-complexity of the system.

Abstract: The transmitter (DTR) and the receiver (DRC) of a system for transmitting data signals at a given symbol rate 1/T comprise discrete-time smearing filters (SM and DSM) for combatting the effect of additive pulse-like disturbances (p'(t)) in the transmission channel (TCH). In many cases these disturbances (p'(t)) turn out to have a pronounced bandwidth-limited nature. By utilizing this feature the implementation of the smearing filters (SM and DSM) is simplfied and/or their performance level is improved in that the non-zero values of their impulse responses s(i) and d(j) only occur at the points of grids of the indices i and j recurring with a period of L, where L is an integer greater than 1 and where L is determined substantially by the ratio L.sub.0 of the symbol rate 1/T to twice the highest significant frequency f.sub.m of these disturbances (p'(t)).

Abstract: An arrangement for full-duplex data transmission over a two-wire circuit (1) comprises a transmit channel (2) connected to a baseband data transmitter (6) and including a smearing filter (18), a receive channel (3) connected to a baseband data receiver (9) and including a complementary smearing filter (19), a hybrid junction (4), an echo canceller (14) with an adaptive filter (15) and an adjusting circuit (16), and a combining circuit (17) inserted in the receive channel (3).