Design and implementation of an oblique ionosonde receiver. For studies of spatial and temporal ionospheric structures
Permanent lenke
https://hdl.handle.net/10037/25828Dato
2022-05-27Type
MastergradsoppgaveMaster thesis
Forfatter
Floberg, JensSammendrag
The study of the ionosphere has been of central interest since its discovery in the
early 20th century. In later decades there has been an increasing appreciation
and need for understanding the spatial and temporal structure of the ionosphere
and how the structure is affected by various processes in the atmosphere. An
important process in this context is that of atmospheric gravity waves (AGWs).
AGWs in the lower region of the atmosphere instigate propagating fluctuations
of the electron density in the ionosphere, the signatures of which are called
travelling ionospheric disturbances (TIDs). A series of methods that can be
used for investigating TIDs are already in existence, but between complex
techniques and expensive hardware there is still a need for access to simple
and inexpensive methods of inquiry. Oblique ionosonde receivers that work
with existing transmission infrastructure are a simple and inexpensive way to
address this need. In this project, we developed an oblique ionosonde receiver
using commercially available and/or easily manufactured components. The
receiver is based on software defined radio technology and utilizes a magnetic
loop antenna as the driven element operating with frequencies 1-30 MHz.
The receiver system is designed to be a sub-system in a network of oblique
ionosonde receivers that are synchronized using GPS. Four receiver systems
were built according to the design and deployed in a geographically distributed
network around an existing transmitter at Sodankylä Geophysical Observatory.
The fluctuation period of TIDs is governed by the buoyancy period defined by
the Brunt-Väisälä frequency. The buoyancy period varies with altitude but is
rarely below 5 minutes. The radar receivers built in this project are capable of
operating with a better temporal resolution than 1 minute, but the resolution
is limited by the transmitter antenna in Sodankylä as it performs a sweep once
every minute. A temporal resolution of 1 minute allows for Nyquist sampling
the Brunt-Väisälä frequency, meaning that operating the receivers in a network
makes for a suitable tool to resolve the signatures of TIDs. Both the receiver
design and the software used for operating the receiver are made available to
the public.
Forlag
UiT Norges arktiske universitetUiT The Arctic University of Norway
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