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Polyspectral methods as tools for uncovering the statistics of pulsar radio signals.
Thesis (PhD)--Stellenbosch University, 2023.
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| Format: | Thesis |
| Language: | en_ZA en_ZA |
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Stellenbosch : Stellenbosch University
2023
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| _version_ | 1867614136359190528 |
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| access_status_str | Open Access |
| author | Alexander, Faustmann |
| author2 | Gilmore, Jacki |
| author_browse | Alexander, Faustmann Gilmore, Jacki |
| author_facet | Gilmore, Jacki Alexander, Faustmann |
| author_sort | Alexander, Faustmann |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (PhD)--Stellenbosch University, 2023. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/127081 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA en_ZA |
| last_indexed | 2026-06-10T12:47:14.760Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2023 |
| publishDateRange | 2023 |
| publishDateSort | 2023 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/127081 Polyspectral methods as tools for uncovering the statistics of pulsar radio signals. Alexander, Faustmann Gilmore, Jacki Schwardt, Ludwig Stellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering. Pulsars Signal detection Random noise theory Thesis (PhD)--Stellenbosch University, 2023. ENGLISH ABSTRACT: Although the first r adio p ulsar w as d iscovered 5 5 y ears a go, t here i s s till a l ack o f consensus concerning the mechanism responsible for the observed radio emissions. Additionally, the improvement in observing instrumentation has achieved a poorer improvement in timing precision than anticipated. The number of catalogued pulsars to date is also far below the theoretical and observable galactic population. These issues have motivated this study, which applies novel signal processing techniques to pulsar radio signals. The higher-order stationary moment spectra are the Fourier companions of the higher-order stationary moment functions. They offer a host o f p owerful statistical tools and are useful for system identification a nd n on-Gaussian p rocess c haracterization. T he p olyspectra g eneralize t he stationary moment spectra to the non-stationary case and are intimately linked to correlations of spectral processes. The noise spectrum comprises the variances and covariances between channels of the power spectrum; it is related to the polyspectrum and its inverse Fourier transform yields the estimation error of the autocorrelation function. This estimation-error function is able to discriminate an intermittent process from a Gaussian one and also to estimate the statistics of the intermittency. The work presented here applies methods based on the higher-order spectra, polyspectra, and noise spectra to pulsar radio signals. The experiments performed over the course of the investigation are unique in the field of radio pulsar a stronomy. The primary contribution of the work is the extension of the noise spectra technique to a Bernoulli-sampled Gaussian process and the application of the method to radio signals from six pulsars. The final result i s evidence in support o f a signal model for pulsar radio signals that is sparse and impulsive. If this is indeed the case, then it explains the excess timing noise, provides observational evidence for constraining the emission mechanism and also provides a possible feature for advanced detection algorithms. AFRIKAANS OPSOMMING: Die eerste radiopulsar is meer as veertig jaar gelede ontdek, maar daar is steeds ’n gebrek aan konsensus oor die meganisme wat verantwoordelik is vir die waargenome radio-emissies. Boonop het die verbetering in waarnemingsinstrumentasie ’n swakker verbetering in tydsberekeningspresisie behaal as wat verwag is. Die aantal katalogiseerde pulsars, tot op datum, is ook ver onder die teoretiese en waarneembare galaktiese bevolking. Hierdie kwessies het die studie van nuwe seinverwerkingstegnieke toegepas op pulsarradioseine gemotiveer. Die ho¨er-orde stilstaande momentspektra is die Fourier-metgeselle van die hoe¨r-orde stasionˆere momentfunksies. Hulle bied ’n magdom kragtige statistiese instrumente en is nuttig vir stelselidentifikasie e n n ie-Gaussiese p roseskarakterisering. D ie p olispektra v eralgemeen d ie stilstaande momentspektra na die nie-stasionˆere geval en is intiem gekoppel aan korrelasies van spektrale prosesse. Die geraasspektrum bestaan uit die variansies en kovariansies tussen kanale van die drywingspektrum; dit is verwant aan die polispektrum en sy inverse Fourier-transformasie lewer die skattingsfout van die outokorrelasiefunksie. Hierdie skattingsfoutfunksie is in staat om ’n onderbroke proses van ’n Gaussiese een te onderskei en ook om die statistieke van die onderbrekings af te skat. Die werk wat hier aangebied word, pas metodes gebaseer op die ho¨er-orde spektra, polispektra en ruisspektra toe op pulsarradioseine. Die eksperimente wat deur die loop van die ondersoek uitgevoer is, is uniek op die gebied van radiopulsar-astronomie. Die primˆere bydrae van die werk is die uitbreiding van die ruisspektra-tegniek tot ’n Bernoulli-gemonsterde Gaussiese proses en die toepassing van hierdie metode op radioseine vanaf ses pulsars. Die finale r esultaat i s b ewyse ter ondersteuning van ’n seinmodel vir pulsarradioseine wat yl en impulsief is. As dit wel die geval is, verduidelik dit die oormaat tydsberekeningfoute, verskaf aarnemingsbewyse vir die limiete van die emissiemeganisme en bied ook ’n moontlike kenmerk vir gevorderde opsporingsalgoritmes. Doctoral 2023-03-03T09:22:35Z 2023-05-18T07:03:20Z 2023-03-03T09:22:35Z 2023-05-18T07:03:20Z 2023-03 Thesis http://hdl.handle.net/10019.1/127081 en_ZA en_ZA Stellenbosch University vi, 57, 13 pages : illustrations application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Pulsars Signal detection Random noise theory Alexander, Faustmann Polyspectral methods as tools for uncovering the statistics of pulsar radio signals. |
| title | Polyspectral methods as tools for uncovering the statistics of pulsar radio signals. |
| title_full | Polyspectral methods as tools for uncovering the statistics of pulsar radio signals. |
| title_fullStr | Polyspectral methods as tools for uncovering the statistics of pulsar radio signals. |
| title_full_unstemmed | Polyspectral methods as tools for uncovering the statistics of pulsar radio signals. |
| title_short | Polyspectral methods as tools for uncovering the statistics of pulsar radio signals. |
| title_sort | polyspectral methods as tools for uncovering the statistics of pulsar radio signals |
| topic | Pulsars Signal detection Random noise theory |
| url | http://hdl.handle.net/10019.1/127081 |
| work_keys_str_mv | AT alexanderfaustmann polyspectralmethodsastoolsforuncoveringthestatisticsofpulsarradiosignals |