Abstract: The invention relates to a method and a device for image coding having a particular, but not necessarily an exclusive, application in the transmission of video signals. The video signal is converted to a bit stream by coding and quantising and stored in a buffer store before it is transmitted on a transmission line at a constant bit rate. Problems experienced with the known technology have been the prevention of overflow in the buffer store and the buffer store being emptied prematurely. Both of these problems give rise to a deterioration in image quality. At the same time, the content of the buffer store should be as small as possible. According to the invention, not all the frames are coded and transmitted, but a certain number (k) of frames are skipped between each coded frame. The number k is based on the transmission rate R, the frame rate fo of the video signal and minimum value (bR/fo) set for the content of the buffer store.

Abstract: The invention relates to a method and an arrangement for radiocommunication between a transmitter and a receiver, especially transmission of information between mobile units and/or fixed units in connection with monitoring and controlling traffic. A problem with this type of communication arises when a single wave is reflected from the roadway or ground and this wave is of approximately the same strength as the direct wave between transmitter and receiver. According to the invention, the problem is overcome by using communication at high frequencies, the GHz range, and using a spread-spectrum technique. By utilizing a spread-spectrum technique, the relative distance and relative speed between transmitter and receiver can also be calculated by simple means, which is a special advantage in this application (FIG. 2 a).

Abstract: The present invention relates to a method for resource allocation in a radio system comprising base stations with respective coverage areas and mobile units. The interaction between the stations in the system is defined with the aid of measured and/or calculated field strengths from all base stations on relevant traffic routes in the geographic area of the radio system, preferably in the form of an exclusion matrix. An allocating matrix is formed by compressing the exclusion matrix by means of an allocating algorithm. The algorithm utilizes figures of merit which are on the one hand calculated by mathematical/logical means to form possible combinations of stations and utilizes on the other hand a random technique for selecting one of these combinations. The algorithm is iterated a number of times and different allocations are obtained thanks to the random technique. The best one of the allocations from any point of view is selected.

Abstract: The invention relates to a method for making handover decisions in a radio communication network comprising a number of fixed base stations and a number of mobile units. The method utilizes an artificial neural network which is an image of the real network of a respective base station and which exhibit a behavior pattern learned through the acquisition of information from the network. Thereafter, simulation is carried out in the neural network through the generation of a list of eligible base stations to which handover can be effected, every one of the eligible stations being given points. Thereafter, a decision is made whether, or not, a handover will be effected by the network.

Abstract: A method is employed for estimating traffic density in a mobile telephone network. A specialized measuring mobile unit which is capable of determining its own position independently of the system is allowed to pass through relevant traffic routes during which time the measuring mobile station transmits a radius signal as well as its position to the various fixed measuring stations. The signal strength received from the measuring mobile station is recorded synchronously with the aid of a number of suitably cited measuring base stations. The measuring values from the measuring stations are compiled with the respective registered positions so that an unambiguous relationship between the signal strength values and the position of a mobile station passing through the entire system is obtained. An actual traffic is then measured with the aid of the measuring station and the measurement results thereof are related to the geographic positions so that a topographic distribution of the traffic density is obtained.

Abstract: The invention relates to a way for subjective, graphical measurement of picture sharpness/picture quality. Measuring and assessing picture quality have so far been a time-consuming chore for laboratory engineers having access to expensive and complicated electro-optical measuring equipments. The way described enables an unknown text object to be measured with respect to objective and subjective picture quality using for example a series of previously measured paper pictures in a simple and reliable way.

Abstract: The invention relates to a method and an arrangement for splicing optical waveguides and, more specifically, for effecting such splicing under field conditions i.e. directly in cable pits where the waveguides requiring splicing are housed. In accordance with the invention, a solidifiable refractive-index matching means is used to effect the splicing. The index-matching means is applied between the ends of the two waveguides in a support arrangement and is then solidified to form a splice having optical, ageing and temperature characteristics substantially corresponding to those of the waveguides. The temperature at which solidification is effected can be such that the refractive index-matching means is sintered to form a glass splice. The index-matching means is preferably a silica gel which can be solidified either chemically or by the application of heat.

Abstract: The present invention provides a method for checking the degree of coverage in a mobile radio system. According to the method, field strengths are utilized which have been measured from all base stations for all important traffic routes in the mobile radio system. The field strength values are related to geographical coordinates in a respective coverage area and the highest value for each coordinate is stored. The values noted are then compared with a predetermined coverage limit value. With the aid of the method, a graph can be produced using the field strength values stored for each coordinate, the coordinates which are lower or higher than the coverage limit value being marked in the graph.

Abstract: The invention relates to a means for identification and exchange of encryption keys between communicating apparatuses for encrypted transmissions. The means comprises a card reader for smart cards connected to the communication apparatus which may be a telecommunication apparatus, e.g. of telephone or facsimile type. The reader can communicate with another reader at a called telecommunication apparatus. For identification and exchange of encryption keys the required calculations are performed by the reader or the smart card using data stored on the smart card in a protected field with limited access. The means enable intercommunication between products of different makes owing to a standard identification procedure and exchange of encryption keys.

Abstract: The present invention relates to a method for planning radio cells. The method utilizes an exclusion matrix calculated on the basis of measured field strengths and an iterative allocating algorithm, which allows an adaptation of the cell planning to prevailing traffic demand.

Abstract: The present invention relates to methods and apparatus for encryption and decryption, respectively, of digital sound in television. The decryption takes place in two steps. The first step, encryption with running key, is achieved by adding modulo 2 a pseudo random sequence to the digital signal containing a sound information. The pseudo random sequence is preferably generated by a non-linear feedback register initialized by the control word. The second step involves encryption of the control word, thereby being transmitted to the receiver in ciphered form. The encryption is preferably achieved by a microprocessor also performing coding of the control word for forward error correction. The control word in turn is generated by a true random sequence generator. The invention enables an encryption that is secure against breaking without deteriorating the sound quality and also enables efficient handling of the key of the encryption.

Abstract: The present invention provides a method for simulating the effect of alternative antenna patterns on the coverage and interference pattern of a mobile radio system. The method is mainly characterized by the fact that signal strength values of an existing antenna are measured for relevant coordinates, the ideal difference in antenna gain is formed by "reducing" the ideal radiation pattern of the antenna which is to be simulated with the ideal radiation pattern of the existing antenna, and the measured field strength values are "weighted" with the ideal antenna gain difference to form a set of simulated field strength values.

Abstract: A method and a device are disclosed for variable length coding and decoding of an information block of input signals, with the information being concentrated at the beginning of the block and the block being terminated by a continuous succession of zero words. Two code trees are utilized for coding and decoding the block. The first of the code trees is utilized for coding and decoding the first part of the block up to and including the word before the last non-zero and an end of the block character EOB, and the second code tree is specially designed for coding and decoding the last non-zero word. A switching device provides for switching between the two code trees and associated devices after the character EOB and before the last non-zero word.

Abstract: A method and apparatus for coding and decoding picture information is described. According to prior art two modes, are utilized for transmitting picture information, respectively. According to the present invention advantages are obtained in using a mixed mode, i.e. certain frequency components are transmitted with prediction and the remaining components without. In the invention two channels, with and without prediction, are utilized respectively. These channels are selectively connected by means of switches, which are controlled by a control means.

Abstract: A switch for use in a printed circuit board having printed circuits on a surface (1a) thereof. One or several contact rollers (6, 7, 8) are adapted in a slider (4) for movement relative to the surface (1a) in such a way that the rollers interact with the printed circuit strips for closing and interrupting electrical circuitry connected to the printed circuit strips in dependence of the position of the slider.