In
telecommunications
Telecommunication, often used in its plural form or abbreviated as telecom, is the transmission of information over a distance using electronic means, typically through cables, radio waves, or other communication technologies. These means of ...
and
radio science
One way of outlining the subject of ''radio science'' is listing the topics associated with it by authoritative bodies.
Union of Radio Science International (URSI)
The International Union of Radio Science has several commissions corresponding t ...
, an ionospheric sounding is a technique that provides real-time
data
Data ( , ) are a collection of discrete or continuous values that convey information, describing the quantity, quality, fact, statistics, other basic units of meaning, or simply sequences of symbols that may be further interpreted for ...
on
high-frequency
High frequency (HF) is the International Telecommunication Union, ITU designation for the radio band, band of radio waves with frequency between 3 and 30 megahertz (MHz). It is also known as the decameter band or decameter wave as its wavelengt ...
ionospheric-dependent
radio propagation
Radio propagation is the behavior of radio waves as they travel, or are wave propagation, propagated, from one point to another in vacuum, or into various parts of the atmosphere.
As a form of electromagnetic radiation, like light waves, radio w ...
, using a basic
system
A system is a group of interacting or interrelated elements that act according to a set of rules to form a unified whole. A system, surrounded and influenced by its open system (systems theory), environment, is described by its boundaries, str ...
consisting of a synchronized transmitter and receiver.
The time
delay
Delay or DeLay may refer to:
People
* B. H. DeLay (1891–1923), American aviator and movie stunt pilot
* Dorothy DeLay (1917–2002), American violin instructor
* Florence Delay (born 1941), French academician and actor
* Jan Delay, stage name ...
between
transmission
Transmission or transmit may refer to:
Science and technology
* Power transmission
** Electric power transmission
** Transmission (mechanical device), technology that allows controlled application of power
*** Automatic transmission
*** Manual tra ...
and reception is translated into effective
ionospheric layer
The ionosphere () is the ionized part of the upper atmosphere of Earth, from about to above sea level, a region that includes the thermosphere and parts of the mesosphere and exosphere. The ionosphere is ionized by solar radiation. It plays an ...
altitude. Vertical incident sounding uses a collocated transmitter and receiver and involves directing a range of frequencies vertically to the
ionosphere
The ionosphere () is the ionized part of the upper atmosphere of Earth, from about to above sea level, a region that includes the thermosphere and parts of the mesosphere and exosphere. The ionosphere is ionized by solar radiation. It plays ...
and measuring the values of the reflected returned signals to determine the effective ionosphere layer altitude. This technique is also used to determine the
critical frequency
Critical or Critically may refer to:
*Critical, or critical but stable, medical states
**Critical, or intensive care medicine
*Critical juncture, a discontinuous change studied in the social sciences.
*Critical Software, a company specializing in ...
. Oblique sounders use a transmitter at one end of a given propagation path, and a synchronized receiver, usually with an oscilloscope-type display (
ionogram
An ionosonde, or chirpsounder, is a special radar for the examination of the ionosphere. The basic ionosonde technology was invented in 1925 by Gregory Breit and Merle A. Tuve and further developed in the late 1920s by a number of prominent phys ...
), at the other end. The transmitter emits a stepped- or swept-
frequency
Frequency is the number of occurrences of a repeating event per unit of time. Frequency is an important parameter used in science and engineering to specify the rate of oscillatory and vibratory phenomena, such as mechanical vibrations, audio ...
signal
A signal is both the process and the result of transmission of data over some media accomplished by embedding some variation. Signals are important in multiple subject fields including signal processing, information theory and biology.
In ...
which is displayed or measured at the receiver. The measurement converts
time
Time is the continuous progression of existence that occurs in an apparently irreversible process, irreversible succession from the past, through the present, and into the future. It is a component quantity of various measurements used to sequ ...
delay to effective altitude of the ionospheric layer. The ionogram display shows the effective altitude of the ionospheric layer as a function of frequency.
See also
*
Kennelly–Heaviside layer
The Heaviside layer, sometimes called the Kennelly–Heaviside layer, named after Arthur E. Kennelly and Oliver Heaviside, is a layer of ionised gas occurring roughly between above the ground — one of several layers in the Earth's ion ...
*
Edward V. Appleton
References
*
Ionosphere
Radio frequency propagation
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