In this paper a modification of the DCSK (Direct chaos shift keying) is considered. This modification, instead of using the reference signal part as in DCSK, transmits the information bit without it. The receiver then uses a unique key, known only to it and the sender, to decode the bit. The effectiveness of the system and two ways of its realization are tried, with this paper describing the experiments that are held. The effectiveness is defined by systems capability to transmit data. The theoretical experiments include testing five different keys and testing noise resistibility. The practical experiments include production of two models of the system, their comparison in functional and synthesis levels. The experiments are successful if the system model can be implemented in both ways that are tried, it is implemented in both ways, and the synthesis results are comparable.

Tikslas: FreeBSD serveryje konfigūruoti SMS žinučių siuntimą administratoriui, įvykus serverio sutrikimui. Analitinėje dalyje nagrinėjami aspektai: Programinės įrangos skirtos SMS žinučių siuntimui palyginimas; Techninių priemonių palyginimas; Internetinių sąsajų realizavimo būdai. Kuriamo produkto prototipai: FreeBSD serveris + GSM modemas - serveris sujungiamas su GSM modemu arba GSM telefonu ir SIM kortele. SMS žinutės siunčiamos naudojant GSM modemą; FreeBSD serveris + SMSC - serveryje įdiegiama speciali programa ir nustatoma darbui su SMSC serveriu, pvz., OMNITEL, per kurį bus siunčiamos SMS žinutės; FreeBSD serveris + SMS Gateway – naudojama komercinė SMS Gateway platforma, pasipildžius kreditus galima siųsti SMS žinutes. Technologinis sprendimas: Programavimui naudojama PHP kalba, HTML kalba, shell kalba. Panaudota programinė įranga: Gammu - programa SMS siuntimui ir įrašymui į duomenų bazę; Nagios - programa skirta pavojų nustatymams sutrikus serverio darbui; Macromedia Dreamweaver 8 – PHP ir HTML kalbos kodo rašymui; Apache – tinklo serverio kūrimui; MySQL – Gammu naudoja SMS žinučių laikymui ir gavimui. Naudotos UML diagramos: Administratoriaus panaudojimo atvejų diagrama; Sistemos procesų veikimo veiklos diagrama; Telefono numerio nustatymo veiklos diagrama; Sutrikimo atvejo nustatymo veiklos diagrama; Gaunamo SMS žinutės teksto nustatymo veiklos diagrama; Visų įrašų pažymėjimo veiklos diagrama; Įrašų šalinimo veiklos diagrama; Įrašų paieškos veiklos diagrama... [toliau žr. visą tekstą] / Project has been designed to alert administrators of disruption of the system, that he can get SMS messages every moment and to be able to know exactly what problems occurred in the system. On this project I analyzed and compared different software for sending SMS, analyzed the technical means for sending SMS. I choose Gammu and Nagios software which I make to interact with each other as one. To interact two different software helps shell script that uses configured SMS daemon. First software is Gammu which encompasses applications, scripts and drivers for managing various functions on cellular phones and similar devices. Second software is Nagios which in the event of a failure can alert administrator of the problem, allowing him to begin remediation processes before outages affect server processes. For sending SMS messages I used a device that can send SMS messages. Was chosen mobile phone SE W810i which is connected to the computer via a USB cable and seen directly in FreeBSD. MySQL relational database system - this Gammu uses to store/retrieve the SMS messages. Created web site where I can set phone numbers, several phones or just manage SMS storage. On SMS storage I can delete messages, or search for messages which I need. Web site is protected with password so on this web site can get in only administrator.