Bendigo Swap find

[motto]

On the topic of radio interference or static, I was intrigued to learn that this was exactly what the early Marconi radio signals consisted of. A Tesla coil and antenna was used to broadcast static that was interrupted with a Morse key to send the message. How stunningly simple is that?

David

[Richard Farrant]

I remember years ago when we used to suffer interference on radio and TV from unsuppressed vehicles, especially motorcycles and you could hear the gear changes as the note changed ........ usually right in the middle of what you were listening too!

[Phil Waterman]

Originally Posted by Richard Farrant

I remember years ago when we used to suffer interference on radio and TV from unsuppressed vehicles, especially motorcycles and you could hear the gear changes as the note changed ........ usually right in the middle of what you were listening too!

Hi Richard

Yup, I can remember the static on the radio and TV caused by bad ignition systems, my dad an electrical engineer and car guy would/could diagnose the car by the static signal, things like six cylinder with grounded spark lead, or V8 with loose spark lead. He also had a wonderful ear for music which is how I think he could sort out the sounds. I can remember him tuning the radio to a quiet spot on the dial to actually listen to and engine run.

Now if we can only figure out how to set our cars up to blank out cellphone signals we could end the problem of people driving and talking and/or texting instead of paying attention to the road.

Cheers and Seasons Greeting Phil

[Richard Farrant]

Originally Posted by Phil Waterman

Hi Richard

Yup, I can remember the static on the radio and TV caused by bad ignition systems, my dad an electrical engineer and car guy would/could diagnose the car by the static signal,

Good one Phil !

Know what you mean re. cellphones ......


Best wishes to you also.
regards, Richard

[Mike K]

Originally Posted by motto

On the topic of radio interference or static, I was intrigued to learn that this was exactly what the early Marconi radio signals consisted of. A Tesla coil and antenna was used to broadcast static that was interrupted with a Morse key to send the message. How stunningly simple is that?

David

Yes , they were known as spark transmitters , they used a gap ( usually two balls ) across which a spark jumped . There was a mechanism that continually interupted the current through the large primary coil , thus creating a buzzing effect , or a constant spark . The Titanic and all the early wireless gear on ships had this setup http://en.wikipedia.org/wiki/Spark-gap_transmitter

The transmitted signal was very broad and dirty , not clean , the signal radiated out on many frequencies apart from the theoretical resonant frequency of the antenna .

Before the use of valve detectors , the receivers were as deaf as a post . They used massive transmit power to get away with having to use the deaf receivers .

Some of the early modulalted transmitters ( voice ) used a weird arc system .

Mike .