From a HF propagation point of view, the ionospheric layers act as partially conducting media (plasma) in which a transmitted radio wave can reflect upon.A way of determining whether a radio wave with a given frequency will reflect from the ionosphere or completely penetrate is to utilize special radar instruments know as ionosondes or chirp sounders. The technique is widely used by amateur enthusiasts and military radio users for monitoring available radio channel links between two remote locations and can often serve as a base for HF radio prognoses.The objective of this Bachelor’s Thesis was to explore, implement and test a single channel receiver for monitoring ionospheric sounders. The implementation is based on Software Defined Radio (SDR) technology and relies on the GNU Chirp Sounder (gcs) open source script program.

Submitted by Jean Medeiros (jeanletras@uepb.edu.br) on 2018-04-03T16:10:37Z No. of bitstreams: 1 PDF - Vera Yesutor Tsali-Brown.pdf: 30843412 bytes, checksum: 59e10df34146975cb54cee13f06cba2b (MD5) / Made available in DSpace on 2018-04-03T16:10:37Z (GMT). No. of bitstreams: 1 PDF - Vera Yesutor Tsali-Brown.pdf: 30843412 bytes, checksum: 59e10df34146975cb54cee13f06cba2b (MD5) Previous issue date: 2018-02-28 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The effects of the lunar tide in the F region of the ionosphere are studied in this work using measurements provided by the ionosonde installed in Cachoeira Paulista (22 ° S, 45 ° W) between 2009 and 2011. To identify the variations associated with the lunar tides, the following parameters are used: peak height of electronic density of the F region (hmF2) and the critical frequency of the F (foF2) region. The influence of the lunar tide in the Brazilian ionosphere was obtained using the residual measurements which was without the influence of the solar tide for each day, owing that all the months were converted to the lunar time and submitted to harmonic analysis to obtain monthly amplitudes and phases for the period of study. The maximum diurnal amplitude in foF2 determined was 0.41MHz and 0.42MHz in the semidiurnal component. Also the maximum diurnal amplitude in hmF2 determined was 6.25km and semidiurnal 7.76km. The seasonal variations in the amplitudes in foF2 and hmF2 were sometimes annual and semiannual in nature. / Os efeitos da maré lunar na região F da ionosfera são estudados neste trabalho utilizando medidas fornecidas pela ionossonda instalada em Cachoeira Paulista (22° S; 45° W) entre os anos de 2009 e 2011. Para identificar as variações associadas às marés lunares são utilizados os seguintes parâmetros: altura do pico de densidade eletrônica da região F (hmF2) e a freqüência crítica da região F (foF2). A influência da maré lunar na ionosfera brasileira foi obtida utilizando as medidas residuais sem a influência da maré solar. As medidas foram convertidas para o tempo lunar e submetidas à análise harmônica para obter amplitudes e fases mensais para o período de estudo. A variação sazonal das amplitudes nos parâmetros foF2 e hmF2 foi geralmente geralmente semestral. Também eram às vezes anual

The ionosphere is a constantly changing medium. From the sun to cosmic rays, the ionosphere proves to be a continually interesting area of study. The most notable change that occurs in the ionosphere is the day and night cycle. The ionosphere is not a singular medium, but rather made up of different sections. The day side of the ionosphere consists of a D, E, F1, and F2 layer. The night day of the ionosphere consists of an E and F layer. These layers all have different properties and characteristics associated with them. A notable interaction is how radio waves propagate through the ionosphere. A radio wave can either reflect, refract, or pass through a layer of the ionosphere depending on the frequency of the signal, among other sources of disturbance. The ability to have a radio wave reflected back downwards is a core principle of an ionosonde, which measures the height of the ionosphere. A solar eclipse presents a night side ionosphere condition during the day. The change in the ionosphere that the eclipse will cause is something not a lot of research has gone into. This thesis aims to elaborate on the design and development of an ionosonde along with eventual ionosphere readings during the August 2017 total solar eclipse. / Master of Science / The atmosphere that surrounds the earth is made up of various unique regions. The region of interest for this thesis is the ionosphere. The ionosphere plays an important role in wireless communication of radio waves. It follows that changes in the ionosphere are something of great interest and study. A notable change that the ionosphere undergoes on a daily basis is the shift from the day side to the night side. A solar eclipse serves not only as a spectacular sight, but also to bring a night side condition to the day side. This thesis aims to uncover the changes that will occur to the ionosphere during the August 2017 total solar eclipse.

This thesis has two major objectives. The first objective is to investigate the seasonal and diurnal variations in occurrence of HF coherent echoes. We assess F-region echo occurrence rates for the PolarDARN HF radars at Inuvik (INV) and Rankin Inlet (RKN) and the auroral zone SuperDARN radars at Saskatoon (SAS) and Prince George (PGR) for the period of 2007-2010. We show that the INV and RKN PolarDARN radars show comparable rates of echo occurrence all the time and they detect 1.5-2.5 times more echoes through ½-hop propagation mode (MLATs=80°-85°) than the SAS and PGR SuperDARN radars through 1½-hope propagation mode (MLATs=75°-80°). For all four radars, the winter occurrence rates are about ~2 times higher than the summer rates. For observations in the dusk, midnight and dawn sectors, equinoctial maxima are evident. The pattern of echo occurrence in terms of MLT/season is about the same for all radars with clear maxima near noon during winters and summers and enhanced (as compared to other time of the day) occurrence rates during equinoctial dusk and dawn hours. Additionally, to investigate the effect of solar cycle on occurrence of F-region echoes, we consider the near noon and near midnight echo occurrence rates for the Saskatoon radar over the period of 1994-2010. We show that there is a strong, by a factor of ~10, increase in SAS night-side echo occurrence towards solar maximum. The effect does not exist for the dayside echoes; moreover, a decrease in number of echoes, by a factor of ~2, was discovered for the declining phase of the solar cycle. The second objective is to evaluate the electron density and the electric field as factors controlling the occurrence of F-region echoes. We use observations of these two ionospheric parameters measured by CADI ionosonde and RKN observations of echo occurrence rates over Resolute Bay (MLAT=83°). We show that there is a correlation in changes of echo occurrence and electron density changes for 3 years of radar-ionosonde joint operation (2008-2010). The comparison of radar-ionosonde data shows that the enhanced echo occurrence at near noon hours during summer months correlate with the enhanced electric field during these periods.