As mentioned, hams use various modes of transmission to communicate.
Radio waves are transmitted via communication satellites (known as OSCARs which stands for Orbiting Satellite Carrying Amateur Radio), hand-held transceivers and even the factory “rubber duck” antenna. As well, hams use the moon, the aurora borealis, and the ionized trails of meteors for reflectors of radio waves. Sometimes, hobbyists also make contact with the International Space Station (ISS), since many astronauts and cosmonauts are licensed as amateur radio operators. NASA even has a team of former classroom teachers devoted to helping educators make science, technology, engineering and mathematics, or STEM, come alive for young learners. The experiences and resources offered through Teaching From Space are intended to be unique and accessible and to provide real-life connections to the world of STEM. The Teaching From Space Office is located at NASA’s Johnson Space Center in Houston, Texas if you are interested in contacting them. There is an ARISS Proposal Form you will have to fill out to apply. The ARISS program is a cooperative venture among the NASA, the ARRL and AMSAT and other international space agencies that organizes scheduled contacts via Amateur Radio between cosmonauts and astronauts aboard the ISS and classrooms and educational organizations.
I remember when my wife’s class (she teaches seventh grade science) learned what’s involved in tracking a satellite to communicate by amateur radio. The day she received acceptance of her application, the PTA of her school sent her and the other teachers involved champagne gift baskets to celebrate. Needless to say my sister and her cohorts were surprised and pleased. Also included in the champagne gift basket were savory and sweet treats: Moravian cranberry orange cookies, roasted almonds with sea salt, a deluxe assortment of chocolate truffles along with crispy pretzels that were covered in luscious Godiva milk chocolate, raspberry tea cookies, and seasoned popcorn. She brought some of cookies from the gift basket to class so all her students could share in the congratulatory gift basket. We drank the champagne after school was over. However the neatest thing my sister did was finding a memento she gave each student at the end of the year: little sterling silver pins with different electronic schematic symbols engraved on them. I couldn’t believe it. Where did she find such pins? Online, of course. The first time I did a search on line for sterling silver jewelry was when I was looking for an engagement ring for my future wife. I found a great online site called sterlingforever.com that offered loads of great sterling silver rings styles and other jewelry. Their sterling silver engagement rings had cubic zirconia as the gemstone rather than real diamonds. Cubic zirconia is a synthetic gemstone that really rivals the look of a diamond. Dazzling and brilliantly white, like the perfect diamond, the cubic zirconia along with the sterling silver band made a striking engagement ring that was affordable. Well, the students’ sterling silver pins didn’t have a sparkling cubic zirconia gemstone, but the little electronic schematic symbols were really very cool. She told me that several of the students converted the pins to earrings which became the rage the next school year. Needless to say, her science class was very popular with the students and a number of her students became ham radio enthusiasts.
Anyway, the most common mode of transmission is via voice. Frequency modulation (FM) offers high quality audio, and others, whereas single sideband (SSB) – though has less audio quality – offers more reliable communications, which is often preferred for communication across long distances, where signals can be marginal and bandwidth may be restricted.
Another method is radiotelegraphy, which uses Morse code. Left over from the earliest days of radio, some hams still use and enjoy this form of transmission, which is also known as “CW” from “continuous wave”.
Personal computers, employing protocols such as TCP/IP is another popular method of broadcasting radioteletype communication.
By adapting consumer video electronics (camcorders / video cards) in PCs, hobbyists have created a new, popular form of broadcasting via scan amateur television.