My grandmother told me how the whole family would gather after dinner around the radio to hear the evening news. I guess if you didn't grow up with information being always available everywhere, this must have been quite exciting to hear in your own living room what has happenend in some other part of the world! Best,
B.
3:12 PM, December 24, 2006
Anonymous said...
Hi,
-but the signals used a very broad spectral range -
That would imply an awful lot of energy, wouldn't it ?
at each frequency at least enough of photons to be detected by a reciever...
greetings
Klaus
6:23 AM, December 25, 2006
Cynthia said...
Klaus,
Sounds as though you're bordering on blackbody ultraviolet catastrophe!;) Hence, take utmost care traversing the planet's atmosphere...
I am not an expert on radio technology... If you are interested in more details, the online paper of John S. Belrose may be a good starting point. Anyway, if I understand it correctly, the frequency of radio waves transmitted in the Marconi technology depends only on the size and damping of the antenna system, which works as a resonator and filters a band of frequencies from for the very broad radio spectrum created in the spark decharge. This band is broad compared to bandwidths used in modern radio, and compared to the Fessenden technology, so my wording very broad may be misleading... As for power consumption: The Marconi transatlantic link opened in 1907 worked at about 70 kHz, and the sender consumed 100 to 300 kW... that's quote a lot compared to modern LF radio...
Best, stefan
7:16 AM, December 27, 2006
Whatever Bee may think about the German public radio Deutschlandfunk, it is indeed my favourite radio station, with lots of interesting programmes. One special gem is the daily Kalenderblatt, a five-minute feature about some historical event related to the current date. This morning, the programme looked back on the first radio broadcast, 100 year ago on Christmas Eve 1906. You can listen to the programme (in German) here.
The early wireless communication technology invented and pushed by Guglielmo Marconi was based on electrical sparks creating bursts of radio waves. This was fine for transmitting Morse codes, but the signals used a very broad spectral range - it was not possible to tune in to a specific station as we are used to today - and could not be modulated to carry music or voice. The German word Rundfunk for radio broadcasting goes back to this technology: Funken is the German word for spark.
[Image] Reginald Fessenden, Radio Pioneer and Christmas Broadcaster (source)
The Canadian engineer Reginald Fessenden had the idea to use a continuous radio wave of a specific frequency as a carrier to transmit a signal. He constructed a high-frequency alternator that produced frequencies up to about 100 kHz, and experimented with this technology in 1905/06. His original idea was to build a wireless telephony system, to offer some alternative to the monopoly of the dominating telephone companies. He had to cope with some problems and drawbacks, but then, to cite from this paper:
Fessenden's greatest success took place on Christmas Eve 1906, when he and his colleagues presented the world's first wireless broadcast. The transmission included a speech by Fessenden and selected music for Christmas. Fessenden played Händel's Largo on the violin. That first broadcast, from his transmitter at Brant Rock, MA was heard by radio operators on board US Navy and United Fruit Company ships equipped with Fessenden's wireless receivers at various distances over the South and North Atlantic, and in the West Indies. Fessenden and Marconi: Their Differing Technologies and Transatlantic Experiments During the First Decade of this Century, by John S. Belrose; International Conference on 100 Years of Radio, September 1995.
100 years is a long time ago, and for me today, used to sit comfortably on a sofa with my notebook and connected to the internet via WLAN, its is hard to imagine the world before radio broadcasting. But then, I remember my grandparents, my father's parents, who were just kids in 1906. They grew up in a world very different from today, to see so many things happen and change. What will be in 100 years from now?
"Christmas Broadcast"
4 Comments -
My grandmother told me how the whole family would gather after dinner around the radio to hear the evening news. I guess if you didn't grow up with information being always available everywhere, this must have been quite exciting to hear in your own living room what has happenend in some other part of the world! Best,
B.
3:12 PM, December 24, 2006
Hi,
-but the signals used a very broad spectral range -
That would imply an awful lot of energy, wouldn't it ?
at each frequency at least enough of photons to be detected by a reciever...
greetings
Klaus
6:23 AM, December 25, 2006
Klaus,
Sounds as though you're bordering on blackbody ultraviolet catastrophe!;) Hence, take utmost care traversing the planet's atmosphere...
Best wishes,
Cynthia
12:16 PM, December 25, 2006
Dear Klaus,
I am not an expert on radio technology... If you are interested in more details, the online paper of John S. Belrose may be a good starting point. Anyway, if I understand it correctly, the frequency of radio waves transmitted in the Marconi technology depends only on the size and damping of the antenna system, which works as a resonator and filters a band of frequencies from for the very broad radio spectrum created in the spark decharge. This band is broad compared to bandwidths used in modern radio, and compared to the Fessenden technology, so my wording very broad may be misleading... As for power consumption: The Marconi transatlantic link opened in 1907 worked at about 70 kHz, and the sender consumed 100 to 300 kW... that's quote a lot compared to modern LF radio...
Best, stefan
7:16 AM, December 27, 2006