Some people are very concerned that radio wave power coming from radio transmitters’ antennas will harm people. In particular people are troubled by mobile phone masts causing long term health problems when they are near to their homes.
I just want to make it clear how much a transmitter’s power diminishes as it spreads out from a transmitter. I’m sure some feel it must follow a simple linear law such as:
double the distance and get half the power,
triple the distance and get a third of the power,
quadruple the distance and get a quarter of the power.
When in fact it follows an inverse square law which is nonlinear and gives this type of result:
double the distance and get a quarter of the power,
triple the distance and get a ninth of the power,
quadruple the distance and get a sixteenth of the power.
This means the power (and damaging energy) is much lower than might be expected at any particular distance. Even within a short distance the power can drop considerably.
Morse Code was devised by Samuel Finley Breese Morse, an American artist and inventor, in the 19th century. It is made up of a series of dots and dashes when written down.
Speaking Morse Code
When spoken a dot is pronounced “dit” if it is the final element of a character, else it’s pronounced “di”, and a dash is pronounced “dah”. e.g. “C” [ — · — ·] = “dah-di-dah-dit”.
Transmitting Morse Code
1. By Interupting A Light Beam
If Morse Code is transmitted as a beam of light then the transmitting light often has a shutter in front of it which is opened by means of a lever to let the light out. Historically this is because the persistence of electric lights is too long if they are turned on and off by electrical means.
2. By Using An Electrical or Radio Signal
If Morse Code is transmitted as a radio signal, or current down a wire, then the signal is controlled by a special electrical switch known as a Morse Key or Telegraph Key. In its simple form this is an ON/OFF switch, but in its more complex form it is a changeover switch. With the changeover switch in one position it sends a series of dots and in the other position it sends a series of dashes. The timing of these is electronically generated. The operator leaves the key in the central position (the default) when not transmitting and moves the key from side to side to send the necessary dots and dashes while listening to his output on headphones. By this means the operator can send a fast signal with fewer movements of the wrist.
When transmitted as a radio carrier wave, light or electrical current a dot is a short burst of radio carrier wave, light or current, and a dash as a burst of radio carrier wave, light or current with a period three times as long as a dot.
The period between a dot/dash and the next dot/dash within the same character is equal to the period of a dot.
The period between characters is equal to the period of a dash.
The period between words is the same as seven dots.