I study little things. I sweat the little things in life. So many people around me rush to accomplish something truly big with their careers, their relationships, and their lives not realising that life itself is made up of little things. It is the littlest of details that are vital to me after all little things make big things happen. I study Lepidoptera and Hymenoptera and all these little insects and creatures as a hobby but I also study things so small they are invisible to the human eye. Of all the little things I study and attempt to understand, as a radio scientist and radio astronomer, it is the electron that takes most of my attention. In physics they say the electron has no size at all, it is for all intents and purposes, infinitely small. Whatever the theorists and experimentalists say, these things are really, really, really little. I mean they are small, can’t emphasise that enough here. I sit and think about the theories revolving around the tiny electron, and the continued discoveries relative to this little particle. When someone flips a light switch, or turns on the headlights of their automobile, or dials through the stations on their car radio, my mind drifts to the electron. Such a tiny particle that, with other tiny particles, makes some really big things happen or prevents some big things from happening as is the case from time to time.
I sit on my balcony here at my Sanctum Sanctorum in Grid Square EL98gm (yeah I love the Maidenhead Locator System), I light a cigarette and sip my coffee and find myself staring off at the bluebird sky, and the soft cirrostratus clouds drifting overhead. Here in the Sunshine State, and most days we truly live up to that name, the Sun’s rays beat down creating amazing heat and humidity, but also creating some of the most scenic views and skylines I’ve ever seen in all my travels around the world. No skies like these anywhere, no matter what you think. I stare deeper, past the beautiful clouds, past the endless sea of azure sky, and I imagine myself seeing countless trillions of electrons buzzing around before my eyes. The sky disappears altogether, the skies turn black and I think of electrons. I think of the tiniest of tiny things that are the building blocks of the universe. My mind drifts, as if in a state of Zen, and I think of languages, communication, radio science, radio propagation, and all my studies over the last decade and a half. It is all in thanks to the Sun, the almighty, glowing, fiery orb that grants me and every person on this giant football called planet Earth life.
As I stare off into space, I clear my mind, focusing on my concept of electrons, and I try to imagine a tube of sorts between two points in the sky. I look to the east and imagine myself being able to run through this tube straight across the Atlantic to the Canary Islands from my little spot here in Florida. Then I shrink this tube and all in my mind I cross section it to a size of one metre squared. I picture this tube now filled with electrons, and begin picturing what scientists would refer to as the TEC or total electron content, which is a descriptive quantity in ionospheric studies here on Earth. TEC being the total number of electrons integrated, as stated above, between two points along a cross section tube of one metre squared, id est, the electron columnar number density. For those of you not understanding columnar number density it is simply a number density of quantity, the number or count of a substance as opposed to the mass, per unit area integrated along a path: N = ∫ n d s. Picture an ant colony in a cross sectioned tube if you will. Total Electron Content is reported generally in multiples of a TEC unit, also known as TECU, which is defined as TECU = 1016electrons/m². Have I lost you yet? Bored to tears yet? Well stick with me, because it gets a little more interesting, at least I think so anyway.
So TEC is reported in multiples of TECU and vertical TEC values can range from a couple to several hundred TECU. So what is TEC and why do I care so much about it that I sit and daydream about imaginary cross-sectioned tubes filled with electrons? Well as I stated above, I’m a bit of a radio scientist, and I deal on a day to day basis with radio propagation, whether I’m studying it, or teaching its principles to others. I work in electronics consultations and sales and I deal with a good amount of GNSS (Global Navigational Satellite Systems) technology, satellite communications, and UHF and VHF radio communications equipment. Understanding TEC as it pertains to satellite communication and satellite navigation equipment helps me understand the phenomena that can both promote and degrade the systems we use everyday in the commercial, military and private sector. So TEC is simply the total number of electrons existing along a pathway between say a radio transmitter and a radio receiver. Radio waves are affected by the presence of electrons, always, so it stands to reason the more electrons in the path of a radio wave or radio waves, the more the signal will be affected. So more or less electrons concentrated in the Earth’s ionosphere play an important role on radio propagation and any impedance or promotion thereof.
The TEC in the Earth’s ionosphere is altered by various factors including EUV (Extreme Ultra-Violet) radiation, geomagnetic storms et cetera, with radiant energy always proportionate to frequency. Unfortunately there is not just one standard TEC report to be had. The TEC depends on your local time, your coordinates on Earth, the season you’re experiencing, the particular solar cycle we’re in the midst of, the current activity of the Sun and various other tropospheric conditions. Radio waves are affected by the ionosphere and the velocity of these radio waves changes when the signal passes through electrons in the ionosphere. Thus the importance of being knowledgeable of total electron content can not be understated in most radio scientific and engineering fields. However, this being said, the frequency of the radio waves will determine the amount of delay suffered passing through the ionosphere and any impedance to the signal or outright reflection. If you understand basic radio propagation, some radio wave frequencies pass quite easily through the ionosphere, whilst radio signals at other frequencies are either absorbed completely, scattered or reflected back down to the Earth.
In my day job, I stay up to date on any changes in GNSS technology, or changes to radio frequency allocation or new apparatus created for the functional use of GNSS whether it be in the American GPS constellation, or the Russian GLONASS or soon to come Beidou and Galileo constellations. Whilst dealing with clientele over the years I’ve heard odd reports of GNSS or GPS receiver malfunctions, bugs, quirks and general anomalies. Many can be disregarded as user error, others still as software-defined issues, but there have been many cases that puzzled me. We tend to forget that these cellular phones and GPS or satnav systems we use daily are radio equipment, but they most certainly are radio equipment and prone to the same pros and cons that come with all radio equipment and of course these pros and cons being dependent on the frequencies being transmitted and received from said devices. The ionosphere affects radio waves of any frequency, simple fact. To certain UHF (Ultra High Frequency) or SHF (Super High Frequency) signals there could be little to no effect, however to MF (Medium Frequency) and especially HF (High Frequency) signals there can be enormous effect. With the aforementioned GNSS equipment any alteration in the path and velocity of the radio waves at the corresponding frequencies in the ionosphere can have an impact on the accuracy of satellite navigation systems. If operators and technicians and engineers were to neglect changes in the Total Electron Content in the ionosphere it could result in tens of metres of error in positioning calculations. There is an empirical model known as the Klobuchar model, used in the Global Positioning System (GPS), the American part of GNSS, which calculates and removes part of the positioning errors that are caused by the ionosphere when single frequency GPS receivers are utilised. If conditions should deviate from those predicted by the Klobuchar model, GNSS systems could have larger positioning errors. This is just an example in a commercial, military and private sense where understanding and monitoring TEC is of importance to the radio community especially radio operators and the engineers designing and the technicians maintaining these systems. Of course TEC to the radio scientist is all too important in radio propagation and radiophysics studies.
So what does all this mean to you? Or to a radio operator? Well everything and nothing at all. It is what you want to make of it. Some key the mic on their transmitter and just hope for the best, others, like myself, obsess about the how, where, what, why and when of radio science. Maybe you don’t need to know how the jasmine rice is grown to enjoy its nutty flavour and rich aroma. In fact some have accused me of taking away the magic of radio technology and science through my constant studies and ramblings. But I can attest, that as I found out how the rice was cultivated, grown and promulgated and discovered the regions it originated from and the people who were involved in the entire process, I enjoy and cherish every bowl of that jasmine rice to this day, more so than before gaining this knowledge. As I dig deeper into the world of radio technology, radio science, electricity and heliophysics, it makes me appreciate my own little world so much more and the more I begin to understand it more, the more magical everything truly seems. There is no such thing as useless knowledge. I hope you enjoyed reading. If you did, share it on whatever social media. If not, I apologise, I really just type these blog posts for myself. The best way to learn is to teach, and I teach myself something new almost daily. Asante sana! – Packie, KY3I