International Morse Code is the earliest digital mode and is referred to as ‘CW’ in Amateur Radio jargon because a continuous wave is turned on and off to form the elements of the Morse Code characters. Standardized sequences of short and long elements are used to represent the letters, numerals, punctuation and special characters of a given message in a rhythmic manner designed to be read by humans without the need for decoding devices.
This was the original method of sending radio messages. However the United States Coast Guard ended the use of Morse Code transmissions in its maritime communications service in 1995, and UK radio amateurs haven’t had to learn Morse Code to obtain their license since July 2003. Despite this Morse Code has refused to die away for the following reasons:
As A Distress Signal – Western nations held a convention in 1906 to agree upon a single signal to ask for help that could be used anywhere in the world. Germany’s idea won, a simple and elegant string of three dots, followed by three dashes, followed by three dots. All of the acronyms attributed to the letters, including Save Our Souls or Save Our Ship, were made up after the distress signal came into use to fit the SOS letter arrangement, making them what have come to be called backronyms. The distress signal “…—…” can be sent quickly and easily and is hard to misinterpret, and went into effect on July 1, 1908.
In emergencies it can be sent by any means that can be turned on and off such as horns, whistles, torches, mirrors flashing sun light, tapping on pipes etc. The SOS letters can even be marked out on the ground.
As A Fault Finding Aid – Engineers often use Morse as an enhanced form of beep code built into their equipment to aid fault finding. Many Nokia cellphones even have an option to beep either “SMS” standing for Short Messaging System or “CONNECTING PEOPLE” in Morse Code as an audible alert for the reception of a text message.
In Amateur Radio – Many radio amateurs still use Morse Code because it only requires simple transmitters/receivers which are cheap and easy to build. The transmissions occupy very little bandwidth making them relatively easy to filter out from the background noise on reception so that inter-continental communication can be achieved with very little power (e.g. 10 Watts). Also in the Morse Code world there are many standard abbreviations which make it possible to exchange basic information between operators who do not speak the same language.
Morse Code also remains popular because it presents a challenge. Fortunately there are various software programs and apps. freely available to assist in the learning process. The speed of Morse Code is measured in words per minute (WPM), while fixed-length data forms of telecommunication transmission are usually measured in baud or bits per second (bps). The North Cheshire Radio Club can give advice and practice, and even provide certificates of proficiency starting at 5 WPM.
There are a number of programs and apps. available that can translate strong Morse Code signals under favourable conditions. The human ear is very good at filtering out the pulses but it is more problematic for devices to distinguish the spaces between the pulses from the variable background noise. The digitised signals designed for machines usually get over this problem by using one tone for a mark and another for a space, and have evolved to include additional coding to allow a degree of error correction on reception. This renders them unintelligible to the human ear.