Projects:2015s1-46 Channel Measurements for Search & Rescue

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Project Description

Project title: Channel Measurements for Search & Rescue

Project Description:

The Cospas-Sarsat group is currently developing a second generation search and rescue system. Emergency distress beacons are used to transmit a signal to satellites. The satellites relay the signal to ground stations and the time of flight is used to localize the beacon. First generation systems use low earth orbit satellites and a narrow band waveform while second generation systems use medium earth orbit satellites and a wide band waveform.

The purpose of this project is to characterise the channel for the uplink, i.e. the UHF channel from the beacon to the satellite. Initial measurement by ITR showed strong variations in signal strength that could be caused by antenna patterns, multi path fading, or atmospheric effects from the ionosphere. The student(s) is/are expected to work with software defined radios and our satellite ground station to conduct field trials and process the results.

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Field Trials High level plan

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Stage 1: Initial trials At this early stage, the goal is to confirm the viability of proposed field trial approach and that the existing software & hardware resources available for field trials are functional. It is also meant to allow the project team to familiarise themselves with the trial process and procedure.

Stage 2: Reproduce previously observed issues Project will replicate the field trial setup and attempt to reproduce the results observed in the previous ITR study including the signal strength variation.

Stage 3: Further trials At this stage, different field trial conditions and experiment parameters will be designed in a way that each proposed hypothesis can be individually explored. A high-level plan for experimenting with each hypothesis is as the following.

• Different antenna types and placement will be considered in trial condition explore antenna radiation patterns. The effect of varying satellite elevation angles along beacon antennas will also be examined

• Trials with test beacons placed in surrounding environments that cause multi-path propagation will be conducted to explore its impact.

• Ionospheric measurements in terms of signal strength attenuation and polarisation will be attempted to quantify its effect on SAR channel. Such measurement performed concurrently with the SAR channel measurements will be considered to examine any correlation between each other.

Controllable parameters

Variable How to monitor in practical Types of antenna Vary types of antennas Satellite elevation angles Recording of downlink signal from satellites at different elevation angles Beacon location Short distance adjustment to experiment multi-path propagation Long distance variation of transmitters ITR - Magill Faraday effects (TBD, considering use of ionospheric measurement)