Information Systems 12 (E238) Data Communications: Noise 2008

Noise is any interference with the transmission of a message. The result is that the message received is NOT the same as the message that was transmitted (sent).

The mis-hearing or misinterpretation of a message is a common humour device used in television and film comedy.

In the real world, noise is often just, simply, noise.
In the electronic world, common sources of noise are electrical interference or magnetic interference (or electromagnetic interference).

Noise also affects the speed of data transmission. Update: 11 November 2007: Aussie Scientist Supercharges ADSL

“On his homepage, Papandriopoulos notes that ADSL technology is hampered by two big limitations, namely the length of a line from the exchange, and electromagnetic crosstalk, or line interference. Couple the two, and usable bandwidth often plummets from theoretical maximums on ADSL, ADSL2+ and VDSL2, leaving the average user struggling with well under 10Mbits/s.”

Using your knowledge of computing, you should be able to state that “the length of a line from the exchange” would result in attenuation. You should also be able to state that “electromagnetic crosstalk, or line interference” is referred to as noise.

Example 1: Chinese Whispers

In the real world, “Chinese Whispers” are an example of how noise interferes with the transmission of the exact message. A classic example of Chinese Whispers is this one-liner.

The message sent from the front (where the fighting is occurring) is, “Send reinforcements! We’re going to advance.” By the time the message has been relayed (passed from person to person) to headquarters (HQ), the message they receive is, “Send three and four pence. We’re going to a dance.”

OK! So, the message is dated. In fact, it’s way out of date. The phrase “three and four pence” is a reference to English and Australian currency as used during World War II. It refers to three shillings and four pence. The currency has changed. (In Australia, the currency changed way back in 1966.) Most young Australians (in our school!) don’t have English (or Australian English) as a common background.

Example 2: Chinese Whispers

Here’s a similar example, but not a one-liner. It is still a military example, with the message being transmitted down through the hierarchy of command. It is still outdated, because Comet Halley appeared in 1985-86, before all current school students were born. (Most current students will get a chance to see Comet Halley in 2061-2062. You will be only 71 or 72 by then.)

Communication

The ART of communicating from an ARMY plan to allow the men to watch Halley’s Comet.

The Commanding Officer (CO) issued the following directive to his Operations Officer (OPSO).

CO to OPSO: “Tomorrow evening at approximately 2000 hours Halley’s Comet will be visible in this area, an event which occurs only once every 75 years. Have the men fall out in the battalion area and I will explain this rare phenomenon to them. In case of rain, we will not be able to see anything, so assemble the men in the theatre and I will show them films of it.”

OPSO to OC: “By order of the Commanding Officer, tomorrow at 2000 hours, Halley’s Comet will appear above the battalion area. If it rains, fall the men out, then march them to the theatre where this rare phenomenon will take place, something which occurs every 75 years.”

OC to 2IC: “By order of the Commanding Officer, at 2000 hours tomorrow morning the phenomenal Halley’s Comet will appear in the theatre. In case of rain, in the battalion area, the Commanding Officer will give another order, something which occurs once every 75 years.”

2IC to CSM: “Tomorrow at 2000 hours, the Commanding Officer will appear in the theatre with Halley’s Comet, something which happens every 75 years. If it rains, the Commanding Officer will order the comet into the battalion area.”

CSM to Platoons: “When it rains tomorrow at 2000 hours, the phenomenal 75 year old General Halley, accompanied by the Commanding Officer, will drive his comet through the battalion area theatre.”

Such jokes are not really about “data communications” or “noise”, but are intended to show that people at all levels of command in the army are foolish. It suggests that they have no real understanding of things they are told, and they also have no understanding of what they are saying. In this respect, they are very much like DCE (Data Communications Equipment).

OC: Officer in Charge.
2IC: Second in Charge.
CSM: Company Sergeant Major.
Platoon: a group of Privates under command of the next-ranking officer.

Example 3:

In the real world, very loud music makes it difficult to hold a conversation. Here is an example of how noise interferes with the transmission of the exact message.

At a party in the 1970s (yes, all of my examples are dated), the music being played was “Fugue and Tocata” by J.S. Bach. It was being played in an uptempo style popular at the time (“Switched on Bach”) very much in the same way as classical music is popularised today by groups such as “Il Divo”, “Bond”, and “Flamingo”, or by individuals such as Vanessa Mae. Sitting next to the amplifier was a certain Brian Carter, known by all to be a bit of a bastard in his treatment of women. As soon as the Fugue and Tocata started, Brian turned up the volume, as it was something appreciated by everyone present.

Sitting on the opposite side of the room was Brian Carter’s partner for the evening. She was busy in conversation with another person. When the volume was turned up, the speaker nodded towards the amplifier and said, “It’s the Bach’s Tocata!”, but what she heard was, “It’s the bastard Carter!” From that time onwards, Brian Carter was referred to as The Bastard Carter.

Example 4:

Maybe in the real world, young children make their own words based on their understanding—which doesn’t necessarily match the understanding of the adults listening.

Example 5: Chinese Whispers

Janus Episode 1, 1 September 1994

Judge: "He’s the paragon of virtue."

Transcript: "He's the parrot on a perch."

Example 6: Lost in Translation

This is a variation on the Chinese Whispers theme from above. Interference in the form of “noise” occurs for people who don’t have English (or Australian English) as a common background. There are variations in the pronunciation of common words, which leads to the wrong message being received. It sometimes results in bizarre conversations. Unfortunately, students also use it as a pretended “excuse” that they can’t understand a word that the teacher says.

AJS in Biology Class 1989

AJS: “Corellas at the Gascoyne River (1987) were in flocks of 400. Dr. D.L. Serventy records them in flocks of up to 70,000, and when they land, the trees appear to be full of white blossom.”

Skhumbuzo “Homeboy” Madikiza (student 1990): “Gorillas are black, not white.”

Example 7: Lost in Translation

AJS in Human Biology 1978

Mrs Cathy Broughton, Human Biology teacher at Mount Lawley 1974-1985: (Chinese Malay, with clipped vowel sounds) says to class: “Take out a piece of paper.” Class always laughed when she said this because what they heard is not what she said, that is, the message received was not identical to the message that was transmitted. So she changed it to: “Take out a sheet of paper.” The class still laughed, but louder and longer.

Example 8: Lost in Translation

AJS in St. John of God Hospital 1993

Nurse (maybe Chinese Malay, with clipped vowel sounds) to patient in adjacent bed: “Have you been to toilet?”

Patient, puzzled: “No! Are you from there?”

Australians do not pronounce vowels the way they should. When we hear Europeans pronouncing vowels correctly, it sounds funny to us. Unfortunately, a change in the sound of the vowels also causes a change in the interpreted meaning. We had a Dutch Professor visiting Perth, telling us about fungi in Holland. He said:

“There are very many different and exciting mushrooms growing in a Pinus plantation.”

As we were visitors in MB’s house, all we could do was smile broadly and nod knowingly.

Example 10: Lost in Translation—late 1970s

People from other countries may put the emphasis on a different syllable (put the em-face-us on a different sill-ahhh-bl). When Madame de Gaulle, the wife of the French President Charles de Gaulle, was asked at his retirement function,

“What are you most looking forward to in those retirement years?”

She answered immediately, “Happiness!” but in the English with a French accent and emphasis.

You’ll have to ask me how it sounded (or you can read about it in the Urban Legends Reference Pages).

Example 11: Lost in Translation—early 1990s

My Cousin Vinnie (Nestor Carbonell) constantly used malapropisms

“What are you most looking forward to in those retirement years?”

She answered immediately, “Happiness!” but in the English with a French accent and emphasis.

You’ll have to ask me how it sounded (or you can read about it in the).

Example 12: Cake Inscriptions Gone Wrong

Instructions given over a telephone can have unexpected results.