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[Door opens] [Footsteps]

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[Jazzy music: 'The Russians Are Coming' - Val Bennett]

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Tim: There's something rather magical about radio waves.  They're actually a sort of invisible energy.

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This aerial can actually pick up enough of this energy to power this primitive receiver I made.

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It has no battery.  It relies entriely on harnessing the energy of the radio waves in the air.

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It's not very loud, so I'll have to put it straight on the microphone so you can hear it...

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[Indistinct voice drowned out by radio whistling]

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I managed to pick up Radio Israel broadcasting from Jerusalem on this one night.

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Although there's something quite wonderful about this little thing

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radio sets have been around for so long now that they've become rather ordinary, unglamorous contraptions.

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Even the electronics inside now look rather familiar.

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In this programme, I'm going to look at how these mysterious radio waves were discovered,

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and how radio receivers manage to pick them up.

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Creating radio waves is actually very simple: Any electric spark emits them.

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[Sparking]
Each of these sparks is sending out radio waves.

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You hear them on the radio as interference...
[Turns on radio - poorly tuned whistle]

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[Loud crackle from radio in time with sparks]

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That's why lightning makes radios crackle, and even the tiny spark inside a lightswitch is enough to produce a little 'pop'

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[Radio pops as light switches on and off]

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[Radio off]
But without a radio set though, it's not easy to detect these waves,

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and most scientists didn't believe they existed until just over 100 years ago.

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What finally convinced them was an experiment performed by the physicist Henirich Hertz in 1887.

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It was first demonstrated in Britain by a scientist called Oliver Lodge, here in the Royal Institution.

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Hertz used very big sparks, created by a machine like this, called an induction coil.

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Would you turn it on, Bill?
[Loud crackling from sparks]

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[Sparks stop]
This was connected to these metal plates, with another spark gap in the middle.

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And this acted as a sort of aerial.

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This was Hertz's receiver; it's simply a loop of copper wire.

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Well the big spark, er,  creates radio waves with enough energy to make a tiny spark jump

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across the gap between these balls in the receiver, when they're held very close together.

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So, um, if I hold these in position...

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Okay, Bill...
[Loud crackling from transmitter spark-gap]

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[quieter crackling]
If you look carefully, you can just see the spark jumping across the gap.

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[crackling stops]

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These sparks are so tiny, that Hertz had to let his eyes get accustomed to the dark for 15 minutes

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and then watch the sparks through a magnifying glass.

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His apparatus only had a range of a few metres, and he had no interest in finding any practial uses for it.

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The first person to use radio waves for signalling was Guglielmo Marconi.

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Marconi had been a difficult child.

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His mother was a Jameson, from the Irsish whisky distillers, who'd run away to become an opera singer

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and married an Italian landowner.  She quickly got bored on his estate.

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Anne Jameson: There's not much going on here, I think we'll go for a little jaunt.

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Tim: The infant Marconi spent much of his childhood being dragged around Europe by his mother.

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Marconi: Where are we going mama?
Anne: Barcelona.  Or perhaps, Boulogne...

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[Marconi sings in Italian]
[Clanking of plates]

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Tim: He showed little interest at school, and constantly annoyed his father with ridiculous 'scientific experiments'.

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Marconi: Eh...oh....la....eh...ah.... Vavoom!
[Bang!] [Plates shatter]

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Giuseppe Marconi:  You breaka my plate!  I smasha your face!

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Tim:  Shortly after failing to get into university, he happened to read an article about Hertz's work.

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Marconi: Oh!
Tim: He immediately started obsessively experimenting...

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...and had soon managed to transmit the signals over a mile.
[Muffled sparking and explosion sounds]

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Still aged only 20, he arrived in England to try and sell his ideas.

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[Rustling of kite]

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Marconi had found that fixing on side of the spark gap to a long vertical wire made a much better aerial than Hertz's.

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This was further improved by connecting the other side of the spark gap to earth.

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Apart from that, the transmitter was basically the same as Hertz's.

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Any electrical spark will do: here it's being provided by the ignition circuit of Rex's pickup truck.

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This primitive transmitter has a surprisingly long range.

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Marconi also used a much more sensitive receiver, called a coherer.

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This is based on a design by oliver lodge - this is my home-made version.

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It's just a tube of nickel filings.  I made it by filing down a coin.

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You fix one end to the aerial; another kite, and the other end to the earth.

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And what happens is when it detects the radio waves, its electrical resistance falls dramatically

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so it acts as a sort of switch, and turns on a circuit.

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The theory behind it's very complicated, and wasn't worked out for... till many years later.

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But it's quite simple to make it work.  The only slightly complicated thing is

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that you have to have something to shake it to restore its high resistance at the end of each signal.

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So now if I signal to Rex...

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[Engine starts]
[click-click-click of spark]

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[buzz-buzz-buzz in time with ignition spark]

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[Engine revs up, drowns out noise of sparks]

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[continuous buzzing]

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[tick-tick-tick of engine fades out]

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[continuous buzzy sparking noise]
This is marconi's original equipment that he brought to England with him.

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This is his transmitter, with an induction coil like Hertz's.

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And these balls that concentrated the energy of the spark - one end would have been connected to the aerial.

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[sparking]
This is his receiver; the aerial went on here.

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This is his coherer, inside the glass tube - the filings are actually in the gap in the middle.

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And this is the device to tap it.
[tap-tap-tap]

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Marconi would have been sending a combination of long pulses and short pulses, sending messages in morse code.

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Well this original apparatus only had a range of about 3 miles.

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But Marconi gradually increased the sensitivity of his coherers, and the size of his transmitters

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till he was sending messages hundreds of miles.

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The larger transmitters had much larger spark gaps, which got very noisy.

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So he had to take to putting them in enclosed boxes.

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[Very loud buzzy sparking]

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Marconi's early systems had a big disadvantage: They couldn't be tuned.
[buzzing of spark transmitter]

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You can hear the signal from our spark transmitter all across the short, medium and long wavebands.
[buzzing continues]

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The reason is that sparks create chaotic waves of all sorts of different wavelengths.
[buzzing continues]

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[spark transmitter off]
What was needed was a more precise transmitter than a spark.

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This was the solution: The tuned circuit.

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It suddenly starts to look like a proper radio, but the basic parts are still quite simple.

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There's a coil of wire here called an inductor, and a series of overlapping metal plates here called a capacitor.

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The electricity whizzes backwards and forwards from one to the other.

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Oscillating thousands of times a second.

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The valve acts as a sort of pump, keeping the whole thing going.

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You can see a picture of the radio waves this tuned circuit is transmitting, on this oscilloscope that I've hooked up to a short aerial.

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If I hold it near the tuned circuit and switch on...

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You can see how regular the oscillations, or waves that it's transmitting, are.

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Now if I compare this, er, with the spark machine...

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[buzzing of spark transmitter]
You can see just how chaotic its radio waves are.

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[buzzing of spark transmitter]

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Once the tuned transmitter had been perfected, spark transmitters were quickly banned for polluting the airwaves.

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With the problem of interference solved, radio seemed so miraculous that it could be capable of almost anything.

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[morse code beeping over whistly radio noise]

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Early radios did still have one limitation: They couldn't transmit speech.

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Only the simple pusles of morse code.

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Morse code is still used for messages on the shortwave band, and pulse codes are also used for radio-controlled models.

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[Brum whirrs and clicks pneumatically]

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[loud pneumatic clicking]
Rex: I built this little car for a children's television series.

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I've hooked the oscilloscope up to the transmitter, so you can actually see the stream of pulses

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that the car receives.  Er, If I work this switch...

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That's the one that moves the headlights, you can see it just moves one pulse.

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If I shift that one, which moves two pulses, which actually opens the door.

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This one works the steering, from left to right.  You see it's moving four pulses.

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This one is shifting five pulses, and that's the speed control, for forwards/backwards control.

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Erm, and so forth.  Each series of pulses work a different function inside the car.

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Tim: To transmit speech and music instead of simple pulses, you first have to convert the sound to an electrical signal

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with a microphone, and then combine it with, er,  the radio waves.

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In the radio receiver, it all gets seperated out again.

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You can see this very clearly on an oscilloscope...

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If I turn on this little radio...
Radio: (tinny voice) ...alternatives....

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Tim: ...and I now plug the oscilloscope in, to the loudspeaker.....that's a bit large...
[radio voice continues]

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This is giving a picture of the sound signal, and you can see it roughly matches the sound that's coming out of the loudspeaker.

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Radio: ...but if these countries...
Tim: Now if I plug it in further back on the circuit...

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Radio: ...remained, largely, not entirely fulfilled...
Tim: This is the sound signal combined with the radio waves.

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You can see the peaks still roughly match the sound that it's making

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and the radio waves are actually going rapidly up and down in the middle.

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Now if I stretch this out a bit...
Radio: ...which nations make any firm new committments...

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These are the actual radio waves, and you can see that what's happening is

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that that sound is constantly changing their size, or their amplitude.

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And that's why this is called Amplitude Modulation, or AM, radio.

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Radio: ...was the most important issues...

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The man who designed much of the practical circuitry for AM radio, was an American called Edwin Howard Armstrong.

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While in France during WW1, he invented the SuperHet circuit, which has been used ever since.

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He then sold a patent to RCA, back in America.

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Armstrong: I have an appointment to see Mr Sarnoff
Secretary: He's expecting you, Mr Armstrong.

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Secretary: You're welcome.
Tim: he became a millionaire overnight, and fell in love with the chairman's secretary.

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Armstrong: How about you come for a spin in my motor?
Secretary: Okay...

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Armstrong: Hop in there.
Secretary: Oh!  It sure is a big one!

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Tim: He bought a huge Hispano-Suiza and climbed his tallest aerial to impress her.

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They were married soon afterwards...
Armstrong: WILL YOU MARRY ME?

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Secretary: Oh, Howard, my hero!

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Tim: The fundamental principles of radio have remained unchanged.

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This is the BBC transmitter at Brookman's Park, broadcasting medium-wave radio to SE England.

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Inside, the engineers have restored the BBC's very first transmitter; built by the Marconi company in about 1920.

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This end of it actually creates the radio waves.....and this end of it combines them with the sound signal, the amplitude modulation.

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It's basically a series of giant tuned circuits.

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With the valves, the coils of wire of the inductors, and the overlapping metal plates of the capacitors.

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Well, this generates about 2 kilowatts.  This may sound a lot, but...

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...this modern transmitter is rated 150kW, and it's all much more sophisticated.

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This one's actually broadcasting Radio 3 on AM, all over south-east England.
[opera plays from monitor speaker]

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Inside though, the basic components are sill remarkably similar.

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The inductors have remained exactly the same, and the valves and capacitors, although they're now more enclosed

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still work on the same principles as well.

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Transmitters like these, broadcasting sound, first appeared in WW1.

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They were used for sending messages, by radio telephony.

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Broadcasting radio to entertain people was first started after the war by enthusiastic Marconi engineers.

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[silent film]

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The BBC was then set up by the government in 1922, and listening to the radio rapidly became very popular.

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[silent film]

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At first, most listeners had very simple receivers, crystal sets like the Rexophone.

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They needed enormous aerials, because, like my radio at the start of the programme

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they had no battery, and relied entriely on the energy of the radio waves in the air.

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Radio: (whistly) ...on the literature they've been taught in these academic institutions, they found it wasn't their literature.

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Tim: It' easier to see how they worked on this home-made version.

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Radio: ...century... [loud crackling]
Tim: Instead of a coherer, it has a lump of crystal, and a fine wire called a cat's whisker.

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Electricity will only flow one way through the contact between the fine wire and the crystal.
[crackling]

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And this has the effect of seperating out the sound from the radio waves.
[whistling]

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Like the coherer, the theory behind the cat's whisker is very complicated, but it's quite simple to make it work.

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The imperfect contact between teeth and fillings can occasionally have the same effect.

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Causing a few unfortunate people to hear the radio inside their head all the time.

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This is the modern equivilant of the cat's whisker; the germanium diode.

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If i put it under a magnifying glass, you can see it's an enclosed version of the same thing.

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You can see the whisker jus touching the lump of germanium.

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The primitive radio I had at the beginning of the programme worked with one of these.

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And in fact most modern transistor radios use them as well.

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Much of the radio's evolution has been preserved by Gerald Wells at the Vintage Wireless Museum.

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Tim: If you wanted something better than a crystal set, what sort of thing would you have had?

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Gerald: Well, you'd have had something like this, which is three seperate units,

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hence it was called a wireless, or radio, set - because it was a set of parts.

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It would have consisted of a tuned circuit and RF amplifier

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detector stage, and a power output stage.

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And that would have got you most of the local stations with earphones or a modest loudspeaker.

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Tim: What happened after that, was the next stage...

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Gerald: Well the enxt stage was they decided to stick it all in one box, to make it less wires and make it neater.

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And this was a bit more elaborate as well.  More stations were coming onto the airwaves

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so more elaborate tuning was needed. So they brought in series-parallel switching

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for the aerials and tuned circuits, variable condensor, reaction condensor.

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An RF stage to amplify the signal.

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A detector stage to take the place of the old-fashioned cat's whisker, and two stages of LF amplification.

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That would be quite an elaborate set.  But you could, by moving these bars around

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do away with those stages, and listen with earphones on there, and save a lot of battery power.

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Tim: When did they start enclosing all the working parts of the radios?

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Gerald: Well certainly by the mid 20s, when they decided that this wasn't really very nice in the living room

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and they started building them into familiar objects, like the medicine chest, for instance.

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Where it could be easily disguised, and that wouldn't disgrace any respectable home.

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Tim: What other shapes...
Gerald: Well the most famous of all, is the smokers' cabinet.

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Every home had a smokers' cabinet. You'd have your pipe-racks and your bits at the top

200
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- smoking was a big industry - you'd have your drawer at the bottom

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where you'd have your pipe-cleaners, your matches and your tobacco.

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And it would all fold away and look innocent.  It didn't scream 'Wireless!' at you.

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Tim: Of course all these early radios were powered by batteries, weren't they?

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Gerald: Well yes, there was very little electricity around.

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And the early radios required: A 2 Volt accumulator - sometimes 4 or 6, but usually 2

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- which had to be charged up every week, so that meant you had two of 'em, one being charged, one in use.

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And you'd need a high-tension battery... you'd need a grid-bias battery.

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Grid-bias battery lasted about a year, and cost 9 pence.

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That would last you about 3 months, and cost you 7 and sixpence.

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Tim: So it was quite expensive then.
Gerald: It was an expensive business.

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And it took a lot of rigging up - you had to have an elaborate aerial and earth system.

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And all the bother of getting the accumulator charged every week

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Admittedly it was only 3 pence, reasonably cheap, but it did mean you had to be careful.

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You had about 20 hours listening a week.  So when you went to your radio shop

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there was usually a Radio Times provided on the counter, that saved you buying one.

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With the aid of the bakelite fountain pen and a pad, you could make notes of what was worth listening to during the following week.

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You could pick your programmes and plan your meals around the wireless set.

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You didn't just hear it, you actually sat down and listened to it, and gave it all your attention.

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You had to, it had cost you so much to rig up.

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And of course, when you came in with your accumulator every week

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There was all the other old tearaways and ratbags in there as well, and you would discuss the programmes.

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So the reputation of wireless programmes was made and lost in the wireless shop.

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Tim: By the 30s, the appearance of radios had started to change dramatically

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with the introduction of the new material, Bakelite.

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Pioneered in Britain by the Ekco company, this could be moulded to almost any shape.

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It's one drawback was that it was easily breakable.

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Voiceover: See these two portable radios?  Well watch this.... let her go, Betsy!
[smash!]

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Sorry friend, you old-style portables have to go.

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But look at our new RCA-Victor portable radio!

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Man: Came through without a chip.
Voiceover: RCA-Victor's non-breakable impact case means

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[bang] No chipping...  [bang] No cracking... [bang] No breaking...

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And hear that tone!  It's RCA-Victor's great golden-throat sound.

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See the world's only portables with the non-breakable impact case, as low as $27.95 at your RCA-Victor dealer.

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Tim: The biggest change in broadcast radio since the war has been the introduction of FM.

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The great advantage is that it's much less susceptable to interference.

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[hum of untuned AM radio]
The spark which drowns out AM radio...

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[spark causes loud click on radio]
Is hardly audible on FM...

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FM Radio: ...Mrs Thatcher why she'd used the phrase 'geurilla warefare'...
[spark makes barely audible click on radio]

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Tim: FM stands for Frequency Modulation.

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The principle behind it's really quite simple:

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instead of the sound altering the amplitude of the radio waves, as in AM, it alters their frequency.

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FM radio was yet another invention of Howard Armstrong.

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He started in the early 30s, with a missionary zeal to produce true Hi-Fi radio.

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After encouraging tests with RCA, the company suddenly pulled out.

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Armstrong: Sarnoff!  ...Well why have you cancelled my project?

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[indistinct argument]
Sarnoff: Get off my back!  We never promised you nothin'! We're into TV now...

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When FM radio was becoming establised, Armstrong and RCA started a lengthy battle over the patents.

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"We invented this FM radio." "You have stolen my ideas!" "You did not!" "I was the inventor!" "Certainly not!"

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Tim: This had a disasterous effect on his health.  And on his marriage.

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Armstrong: God, I've had such a terrible day!
Wife: By the way, I'm leaving...

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[Door slams]
Armstrong: This is the last straw!  I can't take any more!

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AAAAaaaaaaaggggggh!

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[loud plane engine]
FM has now become firmly established, and is invaluable for radio communications, as well as broadcasting.

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Rex: When I fly my little aircraft, I use radio.  I personally wouldn't fly without one.

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This enables me to keep in touch with air traffic control, and other air users

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and also airfields, to tell them of your intentions.

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And if you do happen to get lost, air traffic control can help you find your way.

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And it also is a navigation radio: I can tune in to various fixed beacons throughout the country.

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I can fly directly to and from these beacons.

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And that helps immensely to find your way around the country.

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Tim: Domestic radios have also become much more sophisticated.

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Many now have automatic push-button tuning, and the sound quality can be very impressive, particularly in stereo FM.

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But despite this improvement, radio has really been eclipsed by television and other modern marvels.

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And radio sets aren't the important, prized posessions they once were.

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In fact, the whole idea of a seperate radio set is rather disappearing.

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Radios now tend to be combined with cassette tape recorders, or alarm clocks, or Hi-Fi systems.

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Radio is so taken for granted today, it's hard to think of it as magical any more

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but I hope in this programme I've managed to persuade you that it still is.

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[Jazzy music: 'Take 5' - Dave Brubeck]