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Adaptive remote sensing
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Steering your station’s receiving capabilities based on other data from other sources. Hams have been pioneers in this area with the DX spotting networks reaching back to the early days of packet radio networks!
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AE index
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Auroral Electrojet Index. Measure of strength of currents flowing in the E region of the ionosphere near the auroral zone, driven by closure currents along magnetic field lines when aurora is active. Much more about aurora in tomorrow’s tutorials.
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AGU
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American Geophysical Union
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AGW
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Atmospheric Gravity Wave. Not to be confused with gravitational waves.
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AMISR
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Advanced Modular Incoherent Scatter Radar. Phased-array ISR designed by SRI International and deployed at Poker Flat (PFISR), Resolute Bay (RISR-C, RISR-N), and a smaller version at Jicamarca, Perú.
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AU
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Astronomical Unit : 149.6 million kilometers, the mean distance from the center of the earth to the center of the sun
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CW
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Continuous Wave. Typically called Morse code, a communications mode using dots and dashes to represent letters, numbers and punctuation.
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Decimation
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Keep only 1 out of N samples. Effectively reduces the time rate of the signal (but is subject to aliasing of higher frequencies if you haven’t filtered the signal first). Standard signal processing technique.
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Digital modes
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FT8, PSK31, WSPRNet, Olivia, RTTY - all examples of coded transmissions for digital communications used by amateurs. (FCC Part 97, which licenses amateurs, requires though that all digital comms be easily unencrypted by all on the ham bands - no public/private key pairs, for instance)
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DOA
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Direction of Arrival (within the context of radio direction finding)
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DOI
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Digital Object Identifier. A “one-stop shop” to find a particular scientific dataset or article. See http://dx.doi.org for a lookup tool. DOI is a way to get cited for your data & contributions as well. Looks good on a CV (especially for the early career folks).
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Doppler Effect
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Doppler Effect is the change in the frequency of a wave in relation to an observer who is moving relative to the source of the wave.
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Dst
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Measure of magnetic field depression at several stations around the earth’s equator. This is due to a current out in space called the ring current, which gets enhanced during geomagnetic storm activity. Think of it as a fine grained index that tells us more and different things about activity levels.
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DX
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Long distance contacts or long distance reception (usually, between countries, but often between continents)
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Epoch
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A reference time that data is aligned to, defined by the study under question. It’s a way to make different data taken at different times line up to e.g. test a hypothesis on a particular phenomenon.
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FAC
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Ffield Aligned Currents. Phenomena resulting from electron precipitation that directly drive the large voltage drops and particle impacts that cause the visible (and radio) aurora. (defined by Kristian Birkeland)
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FD
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Field Day. It is an annual amateur radio exercise that serves emergency preparedness, competitive, social, educational and public relations goals. It happens on the fourth weekend in June and participants are from the US and Canada. Contacts take place at a very rapid rate. Hams use Morse code, voice and digital modes to make contacts. An estimated 30,000 hams participate in this activity every year. It is sponsored by the American Radio Relay League (ARRL), the National Association for Amateur Radio.
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FPGA
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Field Programmanble gate array. A highly complex, highly flexible type of integrated circuit
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Geospace
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Processes and features in near-Earth space, including the magnetosphere (place where the Earth’s magnetic field is a dominant force)
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GNSS
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Global Navigation Satellite Systems (GPS is one. Others are GLONASS, GALILEO, COMPASS/BEIDOU)
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GPSDO
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GPS-Disciplined Oscillator. An oscillator (used to provide a reference frequency for making measurements) that is adjusted based on timing signals from the GPS constellation. Once adjusted, can provide very accurate reference frequencies.
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Ham radio
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Not an acronym for anything. No one really knows why amateur radio operators became known as "hams" - there are competing theories - but it's just a slang reference. Should be styled "ham radio," never "HAM radio." Or you can always say "amateur radio" to err on the side of formality.
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Heliophysics
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The science of the Sun and the physical connections between the Sun and the rest of the solar system.
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IS radar
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Incoherent scatter radar. Also called Thomson scatter radar, from JJ Thomson (discoverer of the electron). Uses very weak backscatter from thermal electrons in the ionosphere, electrostatically modified by the presence of ions. Technique remotely senses plasma state properties: electron density, electron and ion temperature, ion velocity, ion composition. Makes full altitude profiles due to the weak nature of the scatter (Born approximation), but requires a megawatt pulsed radar combined with large antennas (30 meter diameter or bigger, or phased arrays), typically at UHF frequencies. Perhaps 12+ IS radar systems worldwide are operated for ionospheric diagnostics - US equals NSF Geospace Facilities program (Geosciences Directorate), Europe eq EISCAT (European Incoherent Scatter Scientific Association). EISCAT operates the only truly tri-static ISR capable of measuring ionospheric plasma flow in 3D within a “common volume” of overlapping beams. In 2023, the phased-array EISCAT_3D is expected to be operational, which will be able to measure vector velocities at all relevant altitudes along the transmitter beam simultaneously.
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JGR
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Journal of Geophysical Research (major journal for upper atmospheric physics among other things)
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Kp
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planetary K index<> average of magnetometers at ~12 stations around the world<> quasi-logarithmic indication of currents flowing in the upper atmosphere caused by geomagnetic disturbances. See https://aurorasaurusbl.wpengine.com/?p=187. The Kp index is calculated using measurements from ground magnetometers.
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L1
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About 1.5 million kilometers from Earth, or 0.01 au, 1/100th the distance to the Sun (according to Wikipedia)
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Laminar
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A smooth flow, as opposed to highly structured (or turbulent) flow
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Leo Bodnar GPSDO
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Low cost yet high performance GPS disciplined oscillator from Leo Bodnar Electronics - programmable, usually used to provide 10 MHz and 1 PPS outputs. See leobodnar.com
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Meridional
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North-South
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MLT
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Magnetic Local Time. Midnight is when your location is opposite the sun
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NCJ
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National Contest Journal (www.ncjweb.com). Magazine covering competitive aspects of ham radio.
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NSPIRES
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NASA system for people who write proposals, manage grants, and write reviews.
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NVIS
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Near-Vertical Incidence Skywave
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Ovation Prime
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Operational model for where auroral boundaries are in a rough sense based on historical data - but it’s only a model.
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PCA
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Polar Cap Absorption
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| Phase noise |
Phase noise is the term used to describe short term variations in phase or frequency stability, with "short term" referring to time intervals on the order of seconds or less. Another way of defining or describing phase noise is as random or unintentional phase modulation. Short term stability or "good phase noise performance" is very important in a wide variety of RF applications, but this short term stability can be difficult to obtain, with a substantial cost and complexity often associated with even modest increases in phase noise performance.
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Plasma
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4th state of matter - in which both negative and positive charged particles which are to zeroth order balanced (no net charge) but at the 1st order and above, lots of dynamics and therefore electrodynamics going on. Coined by Irving Langmuir (physical chemist <> Nobel laureate <> GE R+D leader) in the early 20th century. 99% of the universe (probably more) is in the plasma state.
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PMSE
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Polar Mesospheric Summer Echoes <> very bright scatter from probably charged ice particles in the mesosphere <> VHF and up.
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QAM
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Quadrature Amplitude Modulation, a digital transmission method that was shown off here.
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QEX
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An ARRL publication for experimenters and those intrested in new radio technology. http://www.arrl.org/qex
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QRZ
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“https://qrz.com”, a go-to site to look up ham information by call sign, along with forums, etc. etc.). “The facebook of amateur radio.”
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QSO
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Two-way contact made over amateur radio
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RF
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Radio Frequency
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RIOMETER
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Relative Ionospheric Opacity Meter for Extra-Terrestrial Emissions of Radio noise. Developed in the 1950s at U Alaska, it measures radio noise power using simple yagi antennas. Typically, the measured noise power is compared to the “Quiet Day Curve”, i.e. the received noise power on a day without ionospheric disturbances. It thereby measures the opacity of the ionosphere for radio waves. Riometers have been operated between 20 MHz and 50 MHz, most commonly around 30 MHz. Nowadays, spectral riometers are used, which can measure many frequencies simultaneously and use, e.g., inverted-V or log-periodic antennas. Spectral riometers have been developed in Finland and Norway. The shape of the profile of differential absorption, i.e. the part of the radio noise absorbed at a specific altitude, does depend on frequency. The effect is slight, but allows for getting D-region electron density profiles from this otherwise integrated measurement.
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RTTY
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Radio Teletype. Long standing amateur radio digital mode, back to the days of physical teletypes (pre-WWII)
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Scintillation
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Rapid variation of signal strength and phase caused by small-scale irregularities in the ionospheric plasma density along the propagation path. The size of the irregularities causing scintillation on a particular signal are a function of the radio frequency, but are typically on the order of meters to kilometers, with smaller scales having smaller density variations than the larger scales (a “red” spectrum). Scintillation will affect frequencies from HF to tens of GHz.
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SDR
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Software Defined Radio, in which a good portion of the RF processing (sometimes all) takes place in software.
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Simplex
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Direct stations to station communication (as opposed to going thru a repeater or any sort of intermediary rebroadcasting device)
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Sonification
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Process of creating audio from (in our case) radio frequency signals. In any given measurement, the range of frequencies and the length in time of recorded may not be the frequencies or durations humans are capable of (or willing to put up with) listening to, so there are a number of choices to make when converting a measurement to audio.
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| Spectral Spreading |
Spectral spreading, also referred to as frequency spreading or Doppler spreading, is a broadening of the frequency spectrum of a transmitted signal that may arise from a number of causes. Phase noise, also known as frequency jitter, within the oscillators of the transmitter and receiver can give rise to spectral spreading. When a signal is propagated via the ionosphere small-scale turbulent motions cause variations in phase path, hence in Doppler shift, which contributes to spectral spreading. Turbulent motions may be much stronger during geomagnetic storms and at auroral latitude, hence spectral spread may be higher under those conditions. Multipath and multihop propagation, spread-F propagation, and two-hop sidescatter propagation can lead to substantially greater spectral spread than on simple one-hop paths. The spectral spread of a simple crystal oscillator and synthesiser, for example in a WSPR transmitter, can be greater than from one-hop propagation. If spectral spread approaches the tone spacing of a digital mode the probability of decode will be reduced, despite adequate signal to noise ratio. Care is needed when comparing values as different width criteria are used, for example the frequency span that contains 50% or 90% of the total power. |
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STEVE
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Strong Thermal Emission Velocity Enhancement. Newly discovered sub-auroral sky glow in the upper atmosphere, which looks like a purple-white narrow auroral arc. While aurora is created by particle precipitation, STEVE is mostly due to very fast plasma streams in a very narrow and very long area in the F region, i.e. above the typical auroral altitudes. However, involvement of some particle precipitation hasn’t been completely ruled out. STEVE was discovered by citizen scientist photographers!
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Substorms
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An increase in magnetic field reconfiguration and activity in the magnetosphere that can end up injecting lots of energy and particles into the upper atmosphere.
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SuperDARN
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Super Dual Auroral Radar Network. A network of paired HF radars from ~2 - 16 MHz approximately, with beams steered electronically. It typically sweeps at 2 minute cadence across a wide field of view, measuring ionospheric velocity by tracking 10s of meter scale irregularities embedded in the ionospheric flow. SuperDARN is an international collaboration and was started in the mid 1980s by pioneers including Dr. Ray Greenwald at Johns Hopkins Applied Physics Laboratory
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SWPC
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Space Weather Prediction Center at NOAA.
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SYM-H
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A higher time resolution version of Dst (defined above as being caused by the ring current). Yet another measure of geomagnetic activity. SYM-H , Dst, and other indices are calculated by the World Data Center in Kyoto Japan and provided free on the web to the community.
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TAPR
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Tucson Amateur Packet Radio Association. Group of technically minded amateur radio entrepreneurs, currently leading the technical implementation of the Personal Space Weather Station.
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TEC
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Total Electron Content. Defined as the total number of electrons along a specified path (units electrons/m**2). There are two forms of TEC: slant TEC (sTEC), the TEC along a ray path between a ground location (typically a receiver) and a satellite (typically a transmitter)<> and equivalent-vertical TEC (evTEC), the TEC along a vertical path from a ground location to overhead (also vertical TEC (vTEC), or simply “TEC”). Except when from a model, vTEC is almost always a converted sTEC, with a variety of methods used for the conversion process. A couple of things to think about regarding TEC: 1) It is a beautiful way to get a large-scale measurement of the ionosphere 2) Even so, it does not tell the whole story. TEC is an integrated measurement.
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TIDs
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Traveling Ionospheric Disturbances. On HF/shortwave, it can cause fades that last 15 to 60 minutes. Just like waves on a beach, TIDs come in different spatial wavelengths too (hundreds of km to 1000s of km long) and wave periods (as said above, 10-15 minute to 60 minutes). Anything longer than 1 hour or so gets studied separately as tidal motions (i.e. 6 hour tide, 12 hour tide, 24 hour tide, multi-day tides). (Also, MSTIDs (medium-scale TIDs and LSTIDs, large scale TIDs)
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ULF
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Ultra-Low Frequency. Oscillations in the few milliHertz corresponding to periods of a few minutes. ULF oscillations are often a result of magnetic field line oscillations out in the magnetosphere or traveling Alfven waves (think plucking a bass string)
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USRP
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Universal Software Radio Peripheral. Essentially an Ethernet connected SDR with high bandwidth and the ability to generate as well as receive signals. USRP generates 10 mW or so maximum - then must have a power amplifier afterwards (with low pass filters, etc.) Manufactured by Ettus Research, now a part of National Instruments.
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Zonal
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East-West
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Credits:
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This glossary was developed during the 2020 HamSCI Workshop. Thanks to the Workshop participants for their suggestions, and especially to Phil Erickson, W1PJE for his many contributions and to Aidan Montare, KB3UMD for authoring the original version.
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