Different types of signals sent over radio waves are called MODES. SSB is a mode. AM is a mode. FM is a mode. CW (Continuous Waveform aka Morse Code) is a mode. RTTY (radio teletype) is a mode. And there are also many, many digital modes used to send text, pictures, telemetry and more over radio such as PSK31 and JT-65.
It is possible to use ANY mode (AM, FM, SSB, CW, RTTY, DIGITAL) on ANY band or frequency. In actual practice, different modes work better on different bands. "FM" broadcasting takes up a lot of space in the radio spectrum (it's quite wide so that music can sound good), so it is located where there is lots of room for these wide-band frequencies on the VHF (very high frequency) band.
SSB actually came from the AM mode. It is about 1/4 of the AM signal (one of the TWO side-bands that make up an AM transmission), minus the "carrier" (the raw radio signal that "carries" the voice or other modulation). So, you get rid of one side-band along with the carrier and you have, single side-band!
It is also possible to receive many kinds of digital signals using the Skywave SSB. You can send the audio to your computer or other device for decoding with the appropriate software using a simple audio patch cable. The JT-65HF digital mode is particularly useful and popular because it can receive very weak signals very well. The original version of JT-65 was actually used by hams to make contacts by bouncing signals off the moon with minimal antennas and power.
If you've learned Morse Code, (160-year-old digital format), you can use the Skywave SSB to listen to CW signals, too. Just remember that due to the nature of receiving CW transmissions, the indicated frequency will be offset from the actual frequency 500-700Hz or so depending on how you tune the signal for a tone that is comfortable for your ear.
The 6-meter band is the lowest portion of the very high frequency (VHF) radio spectrum internationally allocated to amateur radio use. The term refers to the average signal wavelength of 6 meters.
Although located in the lower portion of the VHF band, it nonetheless occasionally displays propagation mechanisms characteristic of the high frequency (HF) bands. This normally occurs close to sunspot maximum, when solar activity increases ionization levels in the upper atmosphere. Worldwide 6 meter propagation occurred during the sunspot maximum of 2005, making 6 meter communications as good as or, in some cases and locations, better than HF frequencies. The prevalence of HF characteristics on this VHF band has inspired amateur operators to dub it the "magic band".
In the northern hemisphere, activity peaks from May through early August, when regular sporadic E propagation enables long-distance contacts spanning up to 2,500 kilometres (1,600 mi) for single-hop propagation. Multiple-hop sporadic E propagation allows intercontinental communications at distances of up to 10,000 kilometres (6,200 mi). In the southern hemisphere, sporadic E propagation is most common from November through early February.
The 6-meter band shares many characteristics with the neighboring 8-meter band, but it is somewhat higher in frequency.
You can do almost anything on six meters that you would do on any other HF band. Hams have earned WAS, WAC and DXCC awards on six. At times, six meters can sound like a contest weekend on 20 meters, filled with signals and pileups galore. What makes it so different from the HF bands is that you never know when this excitement will come.
On six meters you are traveling through another dimension, a journey into a wondrous land whose boundaries are that of 50-54 MHz. It’s on the edge of HF and VHF, and can behave like either at any moment. This band includes all modes of amateur communications: phone, CW, SSTV, digital, remote control, beacons and repeaters. It’s divided into segments, according to a band plan, for minimal interference between the different modes and uses.
Many of the newer HF rigs come with six-meter capability built in, something that has become common in the last two decades. Why? One answer might be to provide an on-ramp to more serious participation in VHF operation. Another is to attract those with Technician licenses who can use the entire band and all its modes
–with the possibility of working some DX as well.