Marconi_RevK.ppt by Barry K James April 2015
CANNOCK CHASE U3A
SCIENCE & T ECHNOLOGY GROUP
Guglielmo Marconi et al, and Radio Transmission April 2015 MARCONI ’S CLAIM TO FAME & A SPIRATIONS
Credited with being the father or inventor of radio. He wanted to use radio waves to create a practical system of “wireless telegraphy”. He was convinced communication among people was possible via wireless radio signalling. Was very commercially aware of the potential. What he didn’t realise, was what he started…..
Remember, Radio didn’t exist when Marconi was born SO, W HAT IS RADIO ? • A Radio communication link needs a Transmitter and a Receiver. • A Transmitter will emit electro-magnetic (EM) waves into the air. • The Transmitter EM wave will be at a specific Frequency (Hertz). • The Frequency can range from Long Wave (kHz) to UHF (MHz). • The Frequency must be “tuned” so that transmissions do not interfere. • The audio signal is “modulated” onto the EM carrier frequency. • The Receiver must pick up very small signals and recover the audio.
The Electromagnetic Radio Spectrum
Frequency = Speed of light ------Wavelength MARCONI WAS NOT ON HIS OWN
We associate radio with Marconi,
but Heinrich Hertz, Hertzian waves First transmission
Edouard Branley Coherer receiver
Sir Oliver Lodge FRS Transmitted before Marconi
Were also radio pioneers. MARCONI , T HE EARLY YEARS
Marconi born 1874, son of an Italian aristocratic landowner from Porretta Terme and an Irish/Scots wife, Annie Jameson. Lived in Bedford for 4 years.
Marconi had an interest in science and electricity. In particular Heinrich Hertz’s 1888 electromagnetic radiation (radio waves) work.
Marconi began to conduct experiments, building much of his own equipment in the attic of his home in Italy using spark producing equipment. MARCONI ’S FIRST EQUIPMENT
Marconi’s early spark transmitters
Marconi’s early coherer receiver
Antenna MARCONI ’S MAJOR ACHIEVEMENTS
When 20 , (1894) Marconi constructed a spark generator and receiver in his bedroom. The Italian government were not interested, so moved to the UK to gain interest, and demonstrated transmission to the Post Office, Army & Navy. By 23 (1897) he had sent a radio telegraph message 30km from Isle of Wight to a ship with a 40m antenna. By 25 (1899) he transmitted across the English Channel to Boulogne. By 27 (1901) he allegedly sent a signal across the Atlantic to Newfoundland from Cornwall. By 1902 , several ships were equipped with Marconi equipment for distress communication. By 1902-6, changed from spark to Continuous Wave (CW) for speech after the invention of the thermionic valve. In 1909 , was awarded the Nobel Prize in Physics development for practical wireless telegraphy. HOW DID MARCONI TRANSMIT SIGNALS
Spark on and off control THE SPARK TRANSMITTER Antenna
Ground
Drawbacks: Sounds… "CQ DE BO" A spark transmitter is: • Either on or off, i.e. Must use morse code only. • Is a broadband Spark waveform representing the letter “E” transmission. HOW DID MARCONI RECEIVE SIGNALS
The Coherer Receiver:
The Coherer Metal particles would cling together activated a or "cohere" causing the device to telegraph become conductive at an EM register, putting impulse. dots and dashes onto a roll of Later Magnetic Detector: paper tape, but needed resetting Fed an earpiece after each directly, for on impulse by a board ships. de-coherer. RADIO PROPOGATION
Marconi believed signals were unaffected by the curvature of the earth.
Marconi eventually found out about night/day transmission differences due to the ionosphere. Multi-path fading due to ground and reflected waves TYPES OF TRANSMISSION
Spark is Broadband interference!
Spark + Tuned circuit Uses an Inductor (L) and Capacitor (C) Lodge patented “Syntonic tuning” in 1898 Enabled tuned transmission and reception.
Now we use a continuous wave Audio Signal (CW) for voice with AM and FM modulation. MARCONI ’S LATER ACHIEVEMENTS
Titanic 1912 had Marconi spark equipment. Carpathia distress signals enabled 700 lives to be saved. Made a requirement for shipping after 1912 above a certain weight.
He established the Wireless Telegraph & Signal Company Limited in July 1897
Established the first “short wave” (HF) transmission system with a directional “beam” antenna connecting the UK with USA, Japan and Brazil.
Established the world’s first microwave radiotelephone link (UHF) in 1932 in the Vatican area. THE DEMISE OF MARCONI
Marconi died in Rome on 20 July 1937 at age 63, following a series of heart attacks, and Italy held a state funeral for him.
As a tribute, at 6 pm the next day, the time designated for the funeral, all BBC transmitters and wireless Post Office transmitters in the British Isles observed two minutes of silence in his honour.
The Marconi Society was established in 1974 by his daughter Gioia. AND THE LOCAL TWIST - OLIVER LODGE FRS
Sir Oliver Lodge, born in Penkhull, Staffordshire 1851 – 1940. Demonstrated radio a year before Marconi.
Lodge patented “Syntonic tuning” in 1898. Contested by Marconi in court. Lodge won. Formed Lodge spark plug company. Invented the loudspeaker.
Founded Lodge Fume Co Ltd, Birmingham B3, in May 1913 for Electrostatic Precipitation. Became: SIR OLIVER LODGE FRS
Invented moving coil loudspeaker
Invented the Precipitator (Willesden 1929)
Lab LODGE ’S ELECTROSTATIC PRECIPITATOR NEXT
TEA ANYONE?
ANY QUESTIONS?
Simulating an Early Spark Transmitter SIMULATING AN EARLY SPARK TRANSMITTER
Set up kit radios to receive the sparks transmission.
Transmit a short message SIMULATED SPARK TRANSMITTER CIRCUIT MORSE CODE
Letter Morse Letter Morse Digit Morse A .- N -. 0 ----- B -... O --- 1 .---- C -.-. P .--. 2 ..--- D -.. Q --.- 3 ...-- E . R .-. 4 ....- F ..-. S ... 5 ..... G --. T - 6 -.... H .... U ..- 7 --... I .. V ...- 8 ---.. J .--- W .-- 9 ----. K -.- X -..-
Love and L .-.. Y -.-- kisses 88 M -- Z --.. THAT’S IT….
Hope you received the message. COMMERCIAL SPARK TRANSMITTER
Telefunken spark transmitter 6 spark tubes, tuned. Audio modulated by Trumpet microphone in antenna lead. OLIVER LODGE HISTORY
Sir Oliver Joseph Lodge, (born June 12, 1851, Penkhull, Staffordshire , Eng.—died Aug. 22, 1940, Lake, near Salisbury , Wiltshire ), British physicist who perfected the coherer , a radio-wave detector and the heart of the early radiotelegraph receiver.
Lodge became assistant professor of applied mathematics at University College, London, in 1879 and was appointed to the chair of physics at University College, Liverpool, in 1881. During his tenure in Liverpool, he conducted experiments in the propagation and reception of electromagnetic waves. In 1890 a French physicist, Édouard Branly , showed that loose iron filings in a glass tube coalesce, or “cohere,” under the influence of radiated electric waves. To this basic design Lodge added a “trembler,” a device that shook the filings loose between waves. Connected to a receiving circuit, this improved coherer detected Morse code signals transmitted by radio wave and enabled them to be transcribed on paper by an inker. Lodge’s device, first demonstrated before the Royal Institute in 1894, quickly became the standard detector in early wireless telegraph receivers. It was outmoded the following decade by magnetic, electrolytic, and crystal detectors. Lodge also obtained patents in 1897 for the use of inductors and capacitors to adjust the frequency of wireless transmitters and receivers. OLIVER LODGE HISTORY
Lodge set up a demonstration on the quasi optical nature of "Hertzian waves" (radio waves) and demonstrated their similarity to light and vision including reflection and transmission at distances up to 50 meters. [12] Lodge used a detector called a coherer (invented by Edouard Branly ), a glass tube containing metal filings between two electrodes. When the small electrical charge from waves from an antenna were applied to the electrodes, the metal particles would cling together or "cohere " causing the device to become conductive allowing the current from a battery to pass through it. In Lodge's setup the slight impulses from the coherer were picked up by a mirror galvanometer which would deflect a beam of light being projected on it, giving a visual signal that the impulse was received. After receiving a signal the metal filings in the coherer were broken apart or "decohered" by a manually operated vibrator or by the vibrations of a bell placed on the table near by that rang every time a transmission was received. [13] Since this was one year before Marconi 's 1895 demonstration of a system for radio wireless telegraphy and contained many of the basic elements that would be used in Marconi's later wireless systems, Lodge's lecture became the focus of priority disputes with the Marconi Company a little over a decade later over invention of wireless telegraphy (radio). At the time of the dispute some, including the physicist John Ambrose Fleming , pointed out that Lodge's lecture was a physics experiment, not a demonstration of telegraphic signaling. [14] Lodge would later work with Alexander Muirhead on the development of devices specifically for wireless telegraphy.
In January 1898 Lodge presented a paper on “syntonic” tuning [15] which he received a patent for that same year. [2] Syntonic tuning allowed specific frequencies to be used by the transmitter and receiver in a wireless communication system. The Marconi Company had a similar tuning system adding to the priority dispute over the invention of radio. When Lodge's syntonic patent was extended in 1911 for another 7 years Marconi agreed to settle the patent dispute, purchasing the syntonic patent in 1912 and giving Lodge an (honorific) position as "scientific adviser". [16] THE ELECTRO -MAGNETIC SPECTRUM TOPICS CALENDAR 2015
November: Using an Internet Browser and security for banking online.
December: No meeting
January: A Famous Scientist study. Leonardo DaVinci.
February: Energy. The practical truth about solar PV panels and power facts.
March: Practical Session 1. Soldering, Components, Kits construction; crystal radio, clock, solar car
April: Practical Session 2. Soldering, Components, Kits construction; crystal radio, clock, solar car
May: Cancelled
June: Using Microsoft PowerPoint
July: The Electric & Hybrid Car. The workings inside the engine and battery of pure electric and hybrid cars.
Aug: A Famous Scientist 2: Guglielmo Marconi and radio.
Sept: Introduction to 3D Graphics (movies) TOPICS IDEAS 2015
November: Using an Internet Browser and security for banking online.
December: No meeting
January: A Famous Scientist study. Leonardo DaVinci.
February: Energy. The practical truth about solar PV panels and power facts.
Practical session: Soldering and building of radio kits
A famous scientist: Guglielmo Marconi and radio transmission
The Electric and Hybrid Car. The workings inside the engine and battery of pure electric and hybrid cars.
Climate change
Microsoft Word fundamentals of document creation.
Microsoft Excel fundamentals of spreadsheet use.
Microsoft PowerPoint fundamentals of creating a presentation.
Energy Recovery: By surprising means
The History of Speech
Amateur Weatherstations FUTURE SESSION IDEAS
The use and benefit of technology (PC’s, Cameras/Photography, Tablets, Music MP3, etc) Scientific and Engineering achievements of interest.
Famous Scientists or Engineers (Brunel, Marconi, Faraday) DVDs of Railways, Industrial Age, Air transport, Road transport, Buildings (Eiffel, Bridges), Waterways. Own interests, diagrams, photos. Group visits (JCB, Jaguar, Jodrell Bank, BBC, Transport museum, Chasewater engine sheds, Space Centre, RAF Cosford?) Electronics practical projects and workshops (Soldering, Components, Raspberry Pie, Picaxe) PICAXE PROJECTS
Anyone look at the Picaxe or Revolution Education websites? Any project ideas?
How about 2 robot teams competing for the best obstacle course program? How about making a weather station or kit? Any more suggestions?