Siemens Aktiengesellschaft

Alexander Starck

Wolfgang Postl

Hans-Joachim Grallert

Carsten Ball

A method for influencing the level of a radio-frequency transmitted signal in a base station in a fixed radio network wherein the level of the radio-frequency transmitted signal is measured, and the level difference from the measured levels is determined in a transmitting/receiving unit and in an antenna transmitting/receiving unit which is connected to the transmitting/receiving unit via a cable. The level of the transmitted signal is influenced in such a manner that the level difference which is determined is maintained approximately at a predetermined level difference so as to compensate for level fluctuations in the transmitted signal caused by different cables and environmental influences.

Method for influencing the level of a radio-frequency transmitted signal in a base station in a fixed radio network

An arrangement for differential pulse code modulation coding comprises a controllable quantizer and a quantizer controller and is dependent on picture signal values. The quantizer controller contains a plurality of series-connected registers which store adjacent picture element signal values. A comparison device provides a differential formation between all picture signal values and a control is provided to which all results of the difference formations are supplied and which controls a multiplexer such that only the respectively highest and lowest picture signal values, the extrema, are through-connected for further processing. A subtractor, wherein the difference between the last picture element signal value and the extrema, as well as between the extrema themselves are identified is also provided. A difference selection control through-connects the maximum difference to a threshold logic which controls the quantizer in accordance with the amount of the maximum difference.

Arrangement for two-dimensional DPCM coding

A method and apparatus for transmitting digital luminance and chrominance television signals utilize unchanged PCM codewords and PCM codewords which have been converted into DPCM codewords. The DPCM codewords each contain the difference between the scan values to which they are allocated and the scan values for the adjacent, unchanged PCM codewords. If the amplitude value of an unchanged PCM codeword is B and if the amplitude values of the adjacent PCM codewords are A and C, inverting registers are employed to invert the amplitude value B in relation to the other amplitude values. Adders then form different codewords with the amplitude values A-B and C-B which are encoded in DPCM coders. At the correct time a parallel-series register converts the unchanged PCM codeword and the newly formed DPCM codewords into a time division multiplex signal. Corresponding reconversion is undertaken at the receiving side.

Method and apparatus for transmitting digital luminance and chrominance

A method for clock rate conversion of digitized television signals for the acquisition of a television signal having a prescribed processing clock rate is provided wherein the digitized television signal is band-limited, a clock rate conversion being subsequently undertaken. The television signal having a second clock rate is written into a memory 6 and is, in turn, read with the prescribed processing clock rate, whereby an unaltering plurality of data words corresponding to picture points is not output in every television line.

Method for clock rate conversion

A method for improving picture quality given DPCM coded television signals provides for the determination of an activity criterion from the video values of the same television field which surround a current sample and the video signal values of the preceding television field by calculation of the intensity differences between the video signal values. The estimated value is determined from the video signal values of the most recent television field, from the video signal values of the most recent and current television fields, or only from the video signal values of the current television fields, as a function of two thresholds.

Method and circuit arrangement for the improvement of the picture

A process for facsimile coding in which the items of information contained on a two-color original are scanned line-by-line for the purpose of transmission, in which the length of sequences of a first of these colors is represented by first code words consisting of a given first number of binary characters, and the lengths of sequences of the second color are represented by second code words consisting of a second number of binary characters, and in which the first and second code words are followed by third code words when the binary characters are not sufficient for coding the corresponding sequences, provides that the number of binary characters in the third code words is equal to the sum of the number of binary characters of the first code words and the number of the binary characters of the second code words. In a transmitter a coder is provided for the production of the code words, and in a receiver a decoder is provided for decoding the code words. A code word generator is provided in the coder and contains a counter which serves to establish the sequence length of the sequences to be coded and contains a shift register into which the contents of the counter are transferred at stipulated times, in each case after a number of emitted binary characters which is equal to the number of binary characters in the particular transmitted code words and from which the code words are emitted to a transmission unit. A code word decoder is provided in the decoder and contains first and second registers into which the first and second code words are input. The first and second code words being assigned to the sequences with the first and second color respectively, a third register into which the third code words are input, and a transfer switch by way of which the code words are read-out from the first, second or third registers.

Process and arrangement for facsimile coding

In facsimile coding in which the items of information contained on a two-color original consisting of individual surface elements are scanned for transmission, and in which sequence lengths are represented in lines by code words composed of binary characters, and in which a line synchronizing word is produced at the beginning of the coding of each line, address words are inserted after the line synchronizing word after a given number of transmitted binary characters, each address word indicating an address of a specific surface element of a sequence. A coder is provided in a transmitter for producing the code words and a decoder is provided in a receiver for decoding the code words. A first address unit is arranged in the coder which, after each line synchronizing word and after the particular given number of binary characters of the code words, receives the address of the particular next sequence as an address word from a first storage unit which serves to store the sequences assigned to a line and operates to emit the address at the output of the coder. A second address unit is arranged in the decoder which, after each line synchronizing word and after the particular given number of binary characters recognizes the address words and feeds them, as addresses of the particular next sequence, to a second storage unit which contains the colors of the sequences.

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Munich, Germany

Alexander Starck