Analog Operating Modes
CW is one of the oldest telecommunication modes, and it is in a
class that can be described as an analog modulation,
whereby a radio frequency is turned on and off to impress a code. Some
may say this is a form of digital communication. So it might be considered a hybrid.
Voice communication, such as the telephone, was implemented using analog technology.
Here is a wav file that has a recoding of 40 Meter SSB.
Note the two different stations and the different signal strength each has.
My primary use of SSB is to coordinate
the transmission and reception of analog or digital images, or slow scan television (SSTV).
RTTY
Radio TeleTYpe (RTTY) was a fairly complex, and expensive, operation when I first received my license. About 1976 I was given a Model 19 Teletype machine from Voice of America, that had become surplus. When I went to pick it up I was shocked to find it was new, or at least very lightly used. Shortly after that the personal computer made operation of RTTY a more accessable capability for all. RTTY uses two alternating tones that are encoded in one of two codes (Baudot or ASCII). The picure at the right shows how a Baudot RTTY code looks when it is decoded. This station was operating in a contest and calling CQ (a general call for someone to respond).
Note that this was a screen shot from my computer running a application to decode RTTY. Look at the map and you can see the bearing from my station to the station in the Netherlands. This software will also automatically turn my beam antenna in that direction.
RTTY Tuning is achieved by placing the mark and space tones precisely
within the limits of the decoder. This 20 Meter station being decoded was from the Netherlands.
Slow Scan Television - Analog
Slow Scan Television (SSTV) on the amateur bands uses different tones in a voice bandwidth of approximently 3 kHz to transmit images. In the early days SSTV was limited to black and white images, frequently displayed on a long persistance cathode ray tube. My first SSTV operation in the 1970s used such an approach.
The advent of the personal computer and speciality media cards (soundcards, video cards, camera interfaces, and the like) made the process cheaper and enabled color transmission and reception. Today there are both analog and digital SSTV operations, although the quality and popularity of analog SSTV is begining to be overtaken by digital SSTV.
My operation on analog SSTV these days is limited since digital SSTV offers nearly perfect pictures. The picture on the right is of rare quality for analog SSTV.
Example of An Excellent Quality SSTV Picture This is an exceptionally
high quality analog SSTV picture received at my station.