| 1. |
- Ahlström, Per
(författare)
-
Signalprediktering i vitt gaussiskt brus med hjälp av ett adaptivt signalanpassat filter
- 1976
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Ett signalanpassat filter har ett impulssvar som är den exiterandesignalens spegelbild . Ett dylikt filter maximerar vid en viss tidpunkt signalbrusförhållandet på utgången.Ett adaptivt transversalfilter styrt av en gradientkännande algoritm, vilken maximerar signalbrusförhållandet på filterutgången, har studerats. Det spegelvända impulssvaret har använts som prediktion av signalen. Denna prediktion har, vid simulering gjord på dator, ej visat sig vara bättre än en klassisk prediktion med en ren summering av brusstörda upplagor av signalen. Inte ens då dylika summerade upplagor av den brusstörda signalenanvänts som insignal till filtret har signalprediktionen via filtrets impulssvar uppvisat ett lägre kvadratiskt medelfel än d en klassiska.
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| 2. |
- Andersson, Ulf
(författare)
-
Betalkort : Slutrapport
- 1980
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Idén till Universalkort uppkom för cirka tre år sedan, som en följd av ett examensarbete med namnet "ID- kort med minne". Där undersöktes möjligheten att placera ett nonvolatilt minne på ett kort. Fortsättningen på det projektet beskrivs kort under rubriken ”Existerande hårdvarusystem”.Utvecklingen av Betal- och Universalkortsidén har sedan dess bedrivits i samarbete med personal på Institutionen för Systemteknik inom ämnesområdet informationsteori vid LiTH. Jag vill rikta ett varmt tack till dessa och speciellt till Rolf Blom , Robert Forchheimer och Ingemar Ingemarsson för deras bidrag till arbetet.
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| 3. |
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| 4. |
- Blom, Rolf, et al.
(författare)
-
Data Network Security : Part I Problem Survey and Model
- 1977
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Data encryption and related methods may be used to preserve information security i n a data network. Here information security is defined as the degree to which the destruction, change or loss of information is presented. Information is defined as the content of the message represented by the data. The information in a block of data is unchanged if the intended result of the transmission of the block is obtained. This means for example that the original message reaches the correct destination where it is interpreted as intended. Undisturbed information does not, in general, require un disturbed data.The network is supposed to be a public network, accessed by many different users. We are interested in a well defined group of users who are communicating mainly among themselves. Different groups, however, are also allowed to communicate in a well defined manner. The logical structure of the communication within a group is star-shaped. The information communicated within the groups hall be protected against threats from other users of the network, from illegitimate users (wiretappers etc) and from members in the group. The structure of the threats is described in section 3 of this paper.The network itself and the requirement it imposes are supposed to be unchanged. Encryption and decryption are taking place outside the network. The encrypted data shall comply with the requirements of the network. The communication process in the group consists of time-limited messages which are essentially transmitted from one point to another in the network. This is the basis for the model of the communication which is described in section 4. The model, although simple, enables us to structure the problems in connection with encryption/decryption. This is done in section 5 and 6. The purpose of the paper is to form a basis for synthesis of security measures by means on cryptological methods. The analysis is general enough to be applied to any data network and any type of user group.
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| 5. |
- Blom, Rolf
(författare)
-
On Pure and Related Ciphers
- 1981
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- It is possible to formulate several properties of a cipher that can be said to make the cipher homogeneous with respect to the key, i.e. whatever key used different aspects of the enciphering, deciphering and decrypting processes will be independent of the key choice. We investigate such properties and define a property called key homogeneity. The class of key homogeneous ciphers is shown to include the class of pure ciphers. The algebraic properties of pure ciphers are analyzed in detail. Finally the connection between pure ciphers and key homogeneous ciphers is investigated.
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| 6. |
- Blom, Rolf
(författare)
-
On Pure Ciphers
- 1979
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The algebraic structure of the set of enciphering trans formations of a pure cipher is analysed. An alternative definition of pure ciphers is given and necessary and sufficient conditions for the product of two pure ciphers to be pure is found.
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| 7. |
- Danielsson, Per-Erik
(författare)
-
Implementations of the Convolution Operation
- 1982
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The first part of this article surveys a large number of implementations of the convolution operation (which is also known as the sum-of-products, the inner product) based on a systematic exploration of index permutations. First we assume a limited amount of parallelism in the form of an adder. Next, multipliers and RAM:s are utilized. The so called distributed arithmetic follows naturally from this approach.The second part brings in the concept of pipelining on the bitlevel to obtain high throughput convolvers adapted for VLSI-design (systolic arrays). The serial/parallel multiplier is analyzed in a way that unravels a vast amount new variations. Even more interesting, all these new variations can be carried over to serial/parallel convolvers. These novel devices can be implemented as linear structures of identical cells where the multipliers are embedded at equidistant intervals.
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| 8. |
- Ericson, Thomas
(författare)
-
A Converse to the Sampling Theorem
- 1982
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Various forms of the sampling theorem assure that any signal x(t) which satisfies a certain bandwidth limitation can be uniquely reconstructed from its values at equally spaced sample points. Inherent in all these results is that the reconstruction is invariant under timeshifts. Our present result is that if such a time shift invariance is required, a certain bandwidth limitation is not only a sufficient but also a necessary condition for reconstruction of a signal from its sample values.
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| 9. |
- Eriksson, T., et al.
(författare)
-
Successive Encoding of Correlated Sources
- 1982
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The encoding of a discrete memoryless multiple source for reconstruction of a sequence with is considered. We require that the encoding should be such that is encoded first without any consideration of , while in a seeond part of the encoding this latter sequence is encoded based on knowledge of the outcome of the first encoding. The resulting scheme is called successive encoding. We find general outer and inner bounds for the corresponding set of achievable rates along with a complete single letter characterization for the special case . Comparisons with the Slepian-Wolf problem [3] and the Ahlswede-Körner-Wyner side information problem [2 ], [9) are carried out.
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| 10. |
- Fahlander, Olov
(författare)
-
Hemligheten bakom datorgenererad musik
- 1980
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Föredraget kommer av utrymmesskäl att ganska summariskt behandla möjligheterna till musikalisk ljudsyntes med digitala metoder främst med tanke på ”personal computing”. Vissa utvikningar utöver detta är oundvikliga och föredraget har därför mer karaktären av översikt snarare än en mer detaljerad genomgång av speciella metoder. Några konkreta exempel på hårdvarulösningar har dock redovisats och därutöver hänvisas till ett antal referenser som för den intresserade kan ge en mer detaljerad förståelse .Föredraget är uppdelat på tre huvudgrupper: Klang syntes, interaktion och komposition, där det förstnämnda ges mest utrymme. Enligt min personliga uppfattning ligger dock dom intressanta spörsmålen inom det sistnämnda området och det är antagligen här de största in satserna i framtiden kommer att göras, när väl hårdvaruutvecklingen mognat tillräckligt.Det kan nämnas i detta sammanhang att forskningen inom områden som dessa för ett mycket tynande liv, trots att musikindustrin, framtidens stora avnämare för dess resultat, omsätter svindlande summor över hela världen . I Europa är det främst i Paris vid IRCAM som en satsning av betydelse sker. De amerikanska universiteten har annars svarat för den främsta utvecklingen. Detta områdes stora popularitet ]land hobbymänniskor bevisas av att det numera utkommer en specialtidskrift ”Computer music journal” med fyra nummer per år samt att artiklar inom området är mycket vanliga i hobbytidskrifter som ”Byte” och liknande.
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| 11. |
- Fahlander, Olov, et al.
(författare)
-
Linear Codes for Real-Time Colour Graphics
- 1980
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In this paper, the problem of 'hidden - surface' elimination is considered. It is shown that a new linear surface- filling algorithm leads to some simple techniques for hidden-surface removal. Necessary conditions are established for three such methods to work and hard ware to implement these solutions is shown to be practicable. Each of the three proposed methods is seen to have advantages in certain circumstances - the choice between them depends very much on the nature of the graphics system in which they might be used.
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| 12. |
- Fåk, Viiveke, et al.
(författare)
-
Inslag av teknik i humanistisk universitetsutbildning : Ett försök, en utredning och ett förslag
- 1981
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Sedan några år ger vi en kurs i Telekommunikationsteknikens utveckling för elever vid Kulturkommunikationslinjen vid Linköpings Universitet. Syftet med denna kurs var att ge även humaniorastuderande en grundläggande kunskap i för dem relevant teknik. Erfarenheterna av den kursen ledde oss till att. diskutera hur humanister skulle bibringas kunskap om teknik i allmänhet. Dessa diskussioner vidgades till den här rapporterade utredningen, där vi dels berättar om våra erfarenheter av den nämnda kursen, redogör för resultaten av en enkätundersökning bland eleverna som genomgått kursen och diskuterar vilka inslag av teknik som bör finnas i humanistisk universitetsutbildning och hur dessa inslag bör utformas. För den senare delen har vi också diskuterat med åtskilliga företrädare för utländska universitet, främst amerikanska, om deras erfarenhet av att undervisa i tekniska ämnen för humanister.
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| 13. |
- Granlund, Gösta H.
(författare)
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A Nonlinear, Image-content Dependent Measure of Image Quality
- 1977
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In recent years, considerable research effort has been devoted to the development of useful descriptors for image quality. The attempts have been hampered by i n complete understanding of the operation of the human visual system. This has made it difficult to relate physical measures and perceptual traits.A new model for determination of image quality is proposed. Its main feature is that it tries to invoke image content into consideration. The model builds upon a theory of image linearization, which means that the information in an image can well enough be represented using linear segments or structures within local spatial regions and frequency ranges. This implies a l so a suggestion that information in an image has to do with one- dimensional correlations. This gives a possibility to separate image content from noise in images, and measure them both.Also a hypothesis is proposed that the visual system of humans does in fact perform such a linearization.
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| 14. |
- Ingemarsson, Ingemar, et al.
(författare)
-
Computer Security 1981
- 1976
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The goal of COMPUTER SECURITY 1981 is to prediet the demand for protection of eleetronic data processing (EDP) and for the information processed. To predict the future demands on computer security we have discussed the issue with several people involved in one way or another with EDP. These discussions, our own knowledge other background material have been the material for discussions amongst the authors. The results are divided into two parts. In the first part (section 4) we have been as objective as possible. In the latter part (section 5) we have discussed the differences between the results in section 4 and our own opinion as proffessional researchers.In addition the report covers a summary of how EDP is used 1981 and a section describing the structure of the security field (which we have used in the interviews) and an outline of the investigation.
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| 15. |
- Ingemarsson, Ingemar
(författare)
-
Encryption in Data Networks with Application to Teletex
- 1978
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- TELETEX is a new international telecommunication service for text communication between terminals capable of data storage and possibly integrated in a information processing system, [l]. The new service is intended to fill the same needs as does business mail. With regard to information security this means that the information handled by the TELETEX system shall not be unintentionally changed or destroyed or lost to an unintended receiver. Measures to prevent this are called information protection. (We prefer to use the terms information security and information protection rather than data security and data protection. The reason is that "data " in the sense of a string of symbol s may be lost without revealing the information represented by the data. This is for example the case when the data consists of encrypted information).One of the most efficient methods for information protection is to use encryption. This means that the information is transmitted using a ''language" which i s not understood by is efficiently protected against loss and in most cases also against undetected change. Cryptological methods can also be used to detect information destruction. In Section 2 of this report we discuss the basic problems involved with the use of encryption in data networks in general.In a separate report we discuss the possible threats to the information security in TELETEX. This leads to suggestions regarding suitable protection methods. Our standpoint is that TELETEX shall offer at least the same level of information security as does the established mail distribution system.
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| 16. |
- Ingemarsson, Ingemar
(författare)
-
Encryption in Telefax
- 1978
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Our standpoint is that the basic need for information security in TELETEX is provided by the data network used together with the possibility to encrypt the messages in the terminals, thereby protecting the messages from information loss. Means for detection of information destruction or change and f or verification at unencrypted data may then be provided for by the user of the TELETEX system.
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| 17. |
- Ingemarsson, Ingemar
(författare)
-
Några reflektioner kring elektroniska betalningsmedel
- 1979
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- De här nedskrivna tankarna är en frukt av diskussioner med bankfolk och datasäkerhetsforskare rörande olika problem med elektroniska betalningsmedel. De utgör ett försök att formulera de mest grundläggande egenskaperna i viss mån för betalningsmedel i allmänhet och för elektroniska i synnerhet. Syftet är att skapa diskussion kring de problem (främst säkerhetsproblem) som en allmän användning av elektroniska betalningsmedel kan ge upphov till.
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| 18. |
- Kornfeldt, Eva, et al.
(författare)
-
Studium av två endimensionella koder för faksimil överföring
- 1978
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Två endimensionella koder för faksimil överföring av dokument har studerats, Modified Huffman Code (MHC} och Intermediate Ternary Code (ITC}. Båda koderna är föreslagna till CCITT för standardisering. Vi har beräknat hur bra kompression man får med de båda koderna på CCITT:s 8 testdokument. skillnaderna är inte så stora men MHC har en något bättre kompressionsförmåga.
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| 19. |
- Kunt, Murat
(författare)
-
Picture Coding wiht the General Operator Processor (GOP)
- 1980
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Basically, this report gives guidelines for picture coding within the framework of GOP. Two general methods are suggested, exploiting the structures of this general, versatile and elegant operator. The first one is based on the convolutional aspects (sub band coding) whereas the second uses contour and texture description. Alternatives of these two techniques are also indicated. Because GOP has close similarities with the human visual system, super compression in picture coding can be expected. Obtainable efficiencies are indicated in a rather speculative way.
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| 20. |
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| 21. |
- Lawson Jr., Harold W.
(författare)
-
Micro- and System Architectures in the 1980's
- 1980
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- After approxirnate1y 30 years experience with microprogrammed control concepts, we find ourselves at an interesting turning point leading into the 1980's. Experience with various microprogrammed contro1 techniques has been obtained, some experience has been obtained in recent years in the redistribution of functions between various software and microarchitectureal levels and we have a better idea of methods of timing and synchronization. This know1ed~e together with the possibilities brought on by VLSI will meet in the 1980's and have several interesting effects upon system architecture at microarchitecture and higher architectural levels.We shall consider some of the opportunities and limitations of VLSI and their potential effects upon microarchitecture followed by a view of the future utilization of "programmed logic". More specifically, we shall be considering the structuring of logic, synchronization, microarchitecture characteristics, target machine properties and special purpose microprogrammed machines. Further, we shall touch upon relationships to function distribution, computer aided design and the possibilities for architectural synthesis.
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| 22. |
- Magnhagen, Bengt, et al.
(författare)
-
CAD & VLSI Course in Linköping, 1981
- 1981
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- On July 6 - 11, 1981, the LSI Design Center and the DIGSIM team at Linköping Institute of Technology arranged a CAD & VLSI Course. 60% of the 75 attendants represented different European industries. The aim of the course was to present current and future directions in techniques, methods and CAD-tools for development of LSI and VLSI designs. 6 of the 11 lecturers represented industries as IBM, WANG, DEC, ASEA-HAFO and Electric Bureau. The course attendants had access to DEC-10 and· VAX-11 / 78 computers from graphic terminals. Among the offered software packages were CIFPLOT, DIGSIM, GAELIC, ISPS, NAP2, SPICE and CALMOS.
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| 23. |
- Mårtensson, Anders
(författare)
-
The Controller for Parallel Transfer Disk Drivers in the Picap II System
- 2016
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This document describes the physical and functional characteristics of the disk drive control unit used in the PICAP system. To read the document some knowledge of the PICAP II system is necessary. It is also recommended to get acquainted with the AMPEX PTD-9309, Parallel Transfer Drive.
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| 24. |
- Nygren, Sven
(författare)
-
En studie av kryptering vid satellitkommunikation
- 1982
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Stormakterna övervakar varandra och den övriga världen med hjälp av ett stort antal spionsatelliter. Det finns många olika typer av rent militära satelliter, men även alla . .normalt civila satelliter som lämnar information som kan vara av taktisk eller strategisk betydelse och måste betraktas som militära i en konfliktsituation. Som exempel på dessa "halvmilitära" satelliter kan nämnas; vädersatelliter, telesatelliter, navigationssatelliter och fjärranalyserande satelliter typ LANDSAT….
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| 25. |
- Persson, Iréne E, et al.
(författare)
-
Design Considerations of a Distributed Packet Radio Network Using the Radio Amateur Band
- 1980
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The paper outlines an experimental radio based data network to be used by radio amateurs and computer hobbyists. Various aspects of network design is discussed with the intention to provide a foundation on which a more detailed specification can be based. Underlaying principles and qualitative rather than quantitative results are stressed.
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| 26. |
- Rowa, Per, et al.
(författare)
-
Automated Malaria Parasite Detection
- 1977
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- A system for malaria parasite detection in thin blood-smears is presented. Sample slides prepared with standard methods are accepted. A low-cost TV-camera mounted on an ordinary microscope with a computer controlled stage is used as a picture sensor. Frames, digitized in windows of 64 x 64 pixels are fed into a special purpose picture processor at normal frame rate (25 frames/sec). In the picture processor measurements are made on the images at high speed. The classification problem is split into different levels each having different characteristics such as different sampling density. Four classes, three of which are different types of malaria parasites, are recognized. As a whole the classification is best labelled as a sequential pattern recognition procedure.In its preliminary version the system has been run at a speed comparable to that of a human operator, that is l 500 cells per minute. A test on 80 000 cells gave 25 false negatives out of 283 parasites (9%) and 41 false positives (0.05%).
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| 27. |
- Rowa, Per, et al.
(författare)
-
Datoriserad mätning av vita blodkroppars rörelse
- 1978
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Denna skrift redovisar försök att kvantitativt mäta rörelsen hos levande vita blodkroppar .Mätningarna sker helt automatiskt och i reell tid.Bilden av preparatet överförs via en TV-kamera på mikroskopet till en dator. Datorn utnyttjar en speciell bildprocessor för bildoperationer och mätvärdesextraktion .Cellernas individuella rörelser både i form av globala tyngdpunktsförflyttningar och lokala formförändringar uppmäts. För hela populationen beräknas en mängd statistiska uppgifter och resultatkurvor uppritas under mätningen .Praktiska och principiella svårigheter vid analysen av TV-bilden beskrivs utförligt.
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| 28. |
- Wallin, Lars, et al.
(författare)
-
Hierarkisk kodning för faksimilbilder
- 1980
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Här undersöks hierarkisk kodning av binära bilder och jämförs med en av CCITT standardiserad endimensionell kod. Resultaten visar att prestanda för de hierarkiska koderna uppfyller det mål man vanligtvis vill uppnå.
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| 29. |
- Zander, Jens
(författare)
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Multiple Access Schemes for Packet Switching in Radio Channels : An Overview
- 1981
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- For almost a century circuit switching has dominated communication / networks. It was not until the beginning of the 70's as switching cost dropped below communication (bandwidth) costs making packet switching networks feasable. For modern computer communications, circuit switching 1s very wasteful, especially over long distances. This is due to the fact that the datastream from computers and terminals is very bursty, with peak to average ratios up to 2000 to | [5]. If, in a circuit switching environment a high bandwidth channel is used to ensure low delay, this channel will be idle most of ~the time. If we instead use a channel with a bandwidth corresponding to the ~average transmission rate, we will get intolerable delays. The above dilemma arises because the users access the channels randomly. We have no way to tell when the channel will be used, so we assign one channel capable of handling peak rates all the time. This is of course wasteful.The packet-switching solution to the situation above is based on the law of large numbers, stating that the sum of all demands from a large number of users will fluctuate very little. around its average. This is usually called statistical load averaging. The implication is clear -we should use a single wideband channel, dynamically shared among the users. This has been utilized in packet-switched computer networks. The datastream is divided into packets. When a packet is ready for transmission, it is allocated some time-slot (possibly after some queuing delay) on the shared channel. The allocation of suitable time-slots is here done by the network facilities.In recent years the use of packet switching in radio channels has been proposed and implemented. 8oth ground radio and satellite channel s have been utilized for packet switching. The radio medium offers several advantages for these applications....
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