Development of an RFI signal strength detector

Thesis (MEng)--Stellenbosch University, 2022.ENGLISH ABSTRACT: The integrity of the SKA telescopes’ measurements is dependent on sufficient detection and elimination of Radio Frequency Interference (RFI). This is for both within the SKA premises and surrounding farms. A system to detect and log the various RFI sources is imperative to achieving radio quiet zones. In this thesis, a hand-held/portable RFI signal strength detector is developed to aid the existing system of eliminating the RFI sources. The focus of this thesis is the design of a receiver that detects the major culprits namely Wi-Fi, Bluetooth and cellular networks. The detected levels are displayed visually on the device while logging the data simulta neously. Furthermore, this thesis includes the design of a signal processing system that processes the measurements that are logged along with their timestamp and positioning data to generate graphical feedback to the end-user. To test the device in a controlled environment, measurements were acquired in a reverberation chamber. The performance of the receiver was tested separately and showed a sensitivity of approximately -50 dBm which is well above the -75 dBm the system was designed for. This performance was carried through into the measurements taken with the full system implemented. The signal processing operated as desired, and graphs can be used to inspect the maximum power, time occupancy over a set time frame.AFRIKAANSE OPSOMMING: Die integriteit van die SKA-teleskope se metings is afhanklik van voldoende opsporing en uitskakeling van Radiofrekwensie-interferensie (RFI). Dit geld vir beide binne die SKA perseel en omliggende plase. ’n Stelsel om die verskillende RFI-bronne op te spoor en aan te teken is noodsaaklik om radiostil sones te bereik. In hierdie tesis word ’n draagbare RFI-seinsterkteverklikker ontwikkel om die bestaande stelsel te help om die RFI-bronne uit te skakel. Die fokus van hierdie tesis is op die ontwerp van ’n ontvanger wat die hoof oorsake van RFI, naamlik Wi-Fi, Bluetooth en sellulˆere netwerke, opspoor. Die bespeurde vlakke word visueel op die toestel vertoon terwyl die data gelyktydig aangeteken word. Verder sluit hierdie tesis die ontwerp van ’n seinver werkingstelsel in wat die metings wat saam met hul tydstempel en posisioneringsdata aangeteken word verwerk om grafiese terugvoer aan die eindgebruiker te genereer. Om die toestel in ’n beheerde omgewing te toets, is metings in ’n nagalmkamer verkry. Die werkverrigting van die ontvanger is afsonderlik getoets en het ’n sensitiwiteit van ongeveer -50 dBm getoon wat ver bo die -75 dBm is waarvoor ontwerp is. Hierdie prestasie is deurgevoer in die metings wat geneem is met die volledige stelsel ge¨ımplementeer. Die seinverwerking werk soos verlang, en grafieke kan gebruik word om die maksimum krag, tydbesetting oor ’n vasgestelde tydraamwerk te inspekteer.Master