International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, California / Several test programs have reported degraded Global Positioning System (GPS) performance when L-band (1435-1535 MHz) telemetry is used while other test programs have had acceptable GPS performance with L-band telemetry. Most test programs seem to have minimal problems with S-band telemetry interfering with GPS performance if a bandpass filter is used between the GPS antenna and the low noise amplifier (LNA). This paper will present measured data on GPS performance with L- and S-band telemetry and explain what must be done to minimize interference to GPS. The paper will present both GPS signal-to-noise ratio (S/N) values as well as measured spectra from telemetry transmitters. System design guidelines for compatible operation will be presented.

The Global Positioning System (GPS) signal simulator plays a critical role in developing and testing GPS receivers. Unfortunately, very few commercial GPS signal simulators are user-friendly for security researchers because they fail to generate abnormal GPS signals, which are fundamentally important. In this thesis, we develop a cost efficient software defined GPS signal simulator. To reduce the design complexity, we make some reasonable assumptions about the GPS system. This simulator is able to generate clean GPS signals, as well as polluted GPS signals by jamming, multi-path, and spoofing interferences. In addition to simulating GPS signals for a single stand alone antenna, our simulator is also able to simulate GPS signals for multiple antennas, simultaneously. These features of the simulator will immensely help the security researchers in the GPS community. / Master of Science

Diploma thesis describes direction finding principles for passive localization of emitting source. Direction finding system with one rotating antenna was chosen with triangulation calculation of emitter position. Input parameters are position of measurement point and direction of maximum signal receiving level. A suitable digital compass module and GPS receiver module for this measurement was chosen. For this purpose was created a graphic user interface, which allow user to communicate with external devices and control spectrum analyzer. Results of measurements are displayed at map, together with area of possible positions of transmitter. Receiving Yagi antenna is placed on rotator and whole system is placed on roof of car. Whole system was construct and results of measurement are discuss here.

Målsättningen med examensarbetet är att utvärdera en metod för att upprätta en kommunikationslänk från en mobil satellitterminal till en geostationär kommunikationssatellit utan kännedom om satellitterminalens position på jordytan. Målsättningen är intressant då GNSS-operatörer (främst i det allmänna USA-drivna GPS-systemet men möjligen även i de tillkommande franska, kinesiska, ryska och europeiska systemen) begränsar den allmänna tillgängligheten av taktiska/strategiska skäl vid konflikter och kriser. Därtill att allmänna globala navigationssatellittjänster, GNSS-system, ofta bygger på mottagningsantenner med låg riktverkan vilka kan störas ut av lokala störningskällor. En mobil satellitterminal blir därmed beroende av manuell inmatning av riktningsvinklar för att upprätta nya satellitkommunikationslänkar. Systemet blir då mycket sårbart. I denna rapport återges resultat från mätserier inhämtade vid satellitterminalinstallationer utförda i Frankrike, Indonesien, Kanada, Polen, Sverige och USA. / The objective of the thesis is to evaluate a method for establishing a communication link from a mobile earth station to a geostationary communication satellite without prior knowledge of the position of the earth station. The objective is interesting as the GNSS-operators (mainly in the United States-run GPS-system, but possibly also in the French, Chinese, Russian and European systems) limits the general availability of tactical/strategic reasons during conflicts and crises. Furthermore, general GNSS-systems are based on receiving antennas with low directivity which can be disrupted by a local opponent or by other local sources of interference. A mobile earth station, lacking proper positioning information, depends on manual entry of directional angles to establish new satellite communication links. The system then becomes very vulnerable. This report evaluates measurement data gathered from deployed satellite terminal installations in Canada, France, Indonesia, Poland, Sweden and the U.S.