Full Text Available
Note: Clicking the button above will open the full text document at the original institutional repository in a new window.
Aspects of small airborne passive millimetre-wave imaging systems
Thesis (PhD (Electrical and Electronic Engineering))--University of Stellenbosch, 2010.
Saved in:
| Main Author: | |
|---|---|
| Other Authors: | |
| Format: | Thesis |
| Language: | English |
| Published: |
Stellenbosch : University of Stellenbosch
2010
|
| Subjects: | |
| Tags: |
No Tags, Be the first to tag this record!
|
| _version_ | 1867614070434168832 |
|---|---|
| access_status_str | Open Access |
| author | Smith, David Michael Patrick |
| author2 | Meyer, P. |
| author_browse | Meyer, P. Smith, David Michael Patrick |
| author_facet | Meyer, P. Smith, David Michael Patrick |
| author_sort | Smith, David Michael Patrick |
| collection | Thesis |
| dc_rights_str_mv | University of Stellenbosch |
| description | Thesis (PhD (Electrical and Electronic Engineering))--University of Stellenbosch, 2010. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/3979 |
| institution | Stellenbosch University (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:46:11.731Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2010 |
| publishDateRange | 2010 |
| publishDateSort | 2010 |
| publisher | Stellenbosch : University of Stellenbosch |
| publisherStr | Stellenbosch : University of Stellenbosch |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/3979 Aspects of small airborne passive millimetre-wave imaging systems Smith, David Michael Patrick Meyer, P. University of Stellenbosch. Faculty of Engineering. Dept. of Electrical and Electronic Engineering. Passive millimetre-wave imaging Image reconstruction Kalman filter Multi-octave stripline multiplexer Dissertations -- Electronic engineering Theses -- Electronic engineering Infrared imaging Airborne surveillance Images -- Reconstruction Thesis (PhD (Electrical and Electronic Engineering))--University of Stellenbosch, 2010. ENGLISH ABSTRACT: Passive millimetre-wave (PMMW) imaging is a technique that uses radiometers to detect thermal radiation emitted and reflected by metallic and non-metallic objects. While visual and infra-red emissions are attenuated by atmospheric constituents, PMMW emissions are transmitted, resulting in consistent contrast between different objects from day to night in clear weather and in low-visibility conditions to form images for a range of security and inclement weather applications. The use of a PMMW imaging system on a small unmanned aerial vehicle (UAV) offers extremely attractive possibilities for applications such as airborne surveillance for search and rescue operations, which are often hindered by inclement weather making visibility poor and endangering the rescuers as the search vehicle flies through the bad weather zone. The UAV would fly above the bad weather zone, with the PMMW imaging system detecting the thermal radiation emitted and reflected by objects in the MMW spectrum through the inclement weather. The 35GHz propagation window is chosen for the greater transmission through atmospheric constituents. The design of the PMMW imaging system is severely limited by the size of the UAV, particularly in the inability to incorporate any form of optical or mechanical scanning antenna. A possible solution is a long, thin antenna array fitted under the wings of the UAV. Such an antenna has a narrow, high gain, frequency-scanned beam along the plane perpendicular to the flight path, but a very broad beam along the plane of the flight path blurs the image, making it difficult to accurately determine the position of an object or to differentiate between objects situated along the plane of the flight path. This dissertation proposes a technique of image reconstruction based on the Kalman filter, a recursive filter that uses feedback control to estimate the state of a partially observed non-stationary stochastic process, to reconstruct an accurate image of the target area from such a detected signal. It is shown that given a simulated target area, populated with an arbitrary number of objects, the Kalman filter is able to successfully reconstruct the image using the measured antenna pattern to model the scanning process and reverse the blurring effect AFRIKAANSE OPSOMMING: Passiewe millimetergolf (PMMG) beeldvorming is ’n tegniek wat van radiometers gebruik maak om termiese straling waar te neem vanaf beide metaal en nie-metaal voorwerpe. Waar optiese en infra-rooi straling attenueer word deur atmosferiese bestanddele, plant PMMG strale ongehinderd voort. Dit lei tot konstante kontras tussen verskillende voorwerpe in daglig of snags, mooi of bewolkte weer, en in ander lae-sigbaarheid toestande om beelde te vorm vir ’n wye reeks sekuriteits- of weertoepassings. Die gebruik van PMMG beeldvorming op ’n klein onbemande lugtuig (OLT) bied aantreklike moontlikhede vir toepassings in observasie en reddingsoperasies, wat dikwels verhinder word deur bewolke weer wat reddingswerkers in gevaar stel as hul moet vlieg in toestande van lae sigbaarheid. Die OLT kan bokant die onweer vlieg, met die PMMG beeldvormer wat termiese straling in die millimetergolf spektrum vanaf voorwerpe kan waarneem in swaks weerstoestande. Vir verbeterde golfvoortplanting deur atmosferiese bestanddele, word die 35GHz band gekies. Die ontwerp van die PMMG stelsel word geweldig beperk deur die grootte van die OLT, spesifiek deur die tuig se onvermoë om ’n antenne te huisves wat opties of meganies kan skandeer. ’n Moontlike oplossing is om gebruik te maak van ’n lang, dun antenne samestelling wat onder die OLT se vlerke geplaas word. So ’n antenne het ’n nou, hoë-aanwins bundel wat met frekwensie skandeer langs ’n vlak loodreg tot die vlugtrajek. So ’n antenne het egter ’n baie wye bundel langs die vlugtrajek, wat beeldkwaliteit verlaag en dit moeilik maak om die posisie van ’n voorwerp langs die vlugtrajek te bepaal, of om tussen veelvuldige voorwerpe te onderskei. Hierdie proefskrif bied ’n tegniek van beeldherwinning gebaseer op die Kalman filter, ’n rekursiewe filter wat terugvoerbeheer gebruik om die toestand van ’n nie-stasionêre stochastiese proses af te skat wat slegs gedeeltelik waargeneem is, om soedoende ’n akkurate beeld van die teikenarea te herkonstrueer vanuit ’n verwronge beeld. Dit word getoon dat, gegewe ’n gesimuleerde teikenomgewing met ’n arbitrêre hoeveelheid voorwerpe, die Kalman filter suksesvol ’n beeld kan herkonstrueer deur gebruik te maak van die antenne se gemete stralingspatroon om die skanderingsproses na te boots, om sodoende die beeldkwaliteit te verhoog Doctoral 2010-02-18T14:14:56Z 2010-08-13T13:10:43Z 2010-02-18T14:14:56Z 2010-08-13T13:10:43Z 2010-03 Thesis http://hdl.handle.net/10019.1/3979 en University of Stellenbosch 121 p. : ill. application/pdf Stellenbosch : University of Stellenbosch |
| spellingShingle | Passive millimetre-wave imaging Image reconstruction Kalman filter Multi-octave stripline multiplexer Dissertations -- Electronic engineering Theses -- Electronic engineering Infrared imaging Airborne surveillance Images -- Reconstruction Smith, David Michael Patrick Aspects of small airborne passive millimetre-wave imaging systems |
| title | Aspects of small airborne passive millimetre-wave imaging systems |
| title_full | Aspects of small airborne passive millimetre-wave imaging systems |
| title_fullStr | Aspects of small airborne passive millimetre-wave imaging systems |
| title_full_unstemmed | Aspects of small airborne passive millimetre-wave imaging systems |
| title_short | Aspects of small airborne passive millimetre-wave imaging systems |
| title_sort | aspects of small airborne passive millimetre wave imaging systems |
| topic | Passive millimetre-wave imaging Image reconstruction Kalman filter Multi-octave stripline multiplexer Dissertations -- Electronic engineering Theses -- Electronic engineering Infrared imaging Airborne surveillance Images -- Reconstruction |
| url | http://hdl.handle.net/10019.1/3979 |
| work_keys_str_mv | AT smithdavidmichaelpatrick aspectsofsmallairbornepassivemillimetrewaveimagingsystems |