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 Rediffusion and cable radio receivers
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 Return to top of page · Post #: 1 · Written at 1:50:00 PM on 9 September 2014.
Maven's avatar
 Location: Canberra, ACT
 Member since 23 August 2012
 Member #: 1208
 Postcount: 584

In the thread "Philips" in this forum, the subject came up of responses to crowded radio broadcasting spectrum.

I remembered seeing and hearing high-quality cable radio receivers in Europe in the late 1960s - Grundig, Philips and Telefunken. It was used in many countries where topography and population distribution justified it. It was also used in Nazi Germany and the Soviet Union (and in crude form in China) to provide government-controlled propaganda broadcasts.

This Wikipedia article gives a good potted history.

http://en.wikipedia.org/wiki/Linjesender.

Note the UK company Rediffusion began in this business, then later became a conglomerate with ITV franchise licenses and retail businesses. (off-topic - How many remember that global Vodafone began as Vodafax and then answering-machine operator, before competition was allowed to British Telecom?)

As far as I know there was no public cable radio in Australia before cableTV was introduced. Am I wrong?

I have never heard of any domestic cable radio receivers in Australian collections. Has anyone ever seen one here? The european ones I saw had a co-ax connector like a 75ohm TV antenna connection. They had pre-selector buttons for FM channels filtered from the broadband cable carrier signal. (probably not broadband by today's standards)

Maven


 
 Return to top of page · Post #: 2 · Written at 4:13:24 PM on 9 September 2014.
Brad's avatar
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 Location: Greenwich, NSW
 Member since 15 November 2005
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As far as I know there was no public cable radio in Australia before cable TV was introduced. Am I wrong?

I've never heard of any such installations. The output power of the transmitters and the relative scarcity of stations in a given listening area would negate the need for it I think.

I once owned a Thorn television with a badge "AWA Rediffusion" on it and at the time assumed it had something to do with some hidden feature inside the set, although I hadn't acquired it for that particular reason. Years later I saw the same badge on ex-rental sets from companies like Electronic Sales and Rentals, Visionhire and Canberra Television and yet still do not really comprehend the significance of it.


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A valve a day keeps the transistor away...

 
 Return to top of page · Post #: 3 · Written at 5:28:01 PM on 9 September 2014.
Maven's avatar
 Location: Canberra, ACT
 Member since 23 August 2012
 Member #: 1208
 Postcount: 584

Appliance rental was one of the businesses of the UK Rediffusion corporation. They may even have bought the Australian group Radio Rentals?? No relevance to their original transmission business.


 
 Return to top of page · Post #: 4 · Written at 6:06:12 PM on 9 September 2014.
Brad's avatar
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 Location: Greenwich, NSW
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Could well be the case. I know that Thorn (UK) owns Radio Rentals these days, except a non-related company also called Radio Rentals in South Australia - not sure how that works or why one hasn't sued the other over the use of the name but probably best for both that they just co-exist and not compete with each other I suppose.


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A valve a day keeps the transistor away...

 
 Return to top of page · Post #: 5 · Written at 8:26:51 PM on 9 September 2014.
Art's Gravatar
 Art
 Location: Somewhere, USA
 Member since 22 October 2013
 Member #: 1437
 Postcount: 895

They have run satellite radio for years.
That's how Big W, Woolworths, Supercheap Auto and many other companies get their background music.
If they were going to do it over cable I would expect it would be digital now.

The Jerrold Cable TV decoder (Optus) and Telstra Digital Cable Decoder which was actually analogue (Foxtel) were the last analogue pay TV set top boxes.

For a time the older UEC Foxtel boxes could be tricked up to receive all of the radio channels, and pay TV channels as well,
and so could the Optus Jerrold decoders.

The so called Telstra digital cable decoders could be plugged into a TV antenna and receive ABC with no modification at all.

The Jerrold decoder looked at a particular frequency for serial data from the provider's head end to read the entitlement packets.
Once that box was tricked up, there was nothing more available than extra TV channels which were originally received with a satellite decoder at the cable company and retransmitted.

If you had a sat decoder and a Jerrold cable TV box on the same channel there was about a second delay from the Jerrold decoder.


 
 Return to top of page · Post #: 6 · Written at 8:38:58 AM on 10 September 2014.
Wa2ise's avatar
 Location: Oradell, US
 Member since 2 April 2010
 Member #: 643
 Postcount: 766

This scheme sounds similar to "carrier current" systems used on some college campuses. To allow the existence of a college campus radio station in areas that are saturated with radio stations and have no empty RF spectrum. Some colleges had AM carrier current stations, using a somewhat empty frequency (but not empty enough to allow actual over the air broadcast use).
http://en.wikipedia.org/wiki/Carrier_current

Other systems using FM radio use leaky coax strung through a college dorm to provide an FM campus radio station. The coax from Radio Shack may be sufficiently leaky... Smile


 
 Return to top of page · Post #: 7 · Written at 9:57:40 AM on 10 September 2014.
Brad's avatar
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 Location: Greenwich, NSW
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They use leaky coax here to rebroadcast mobile phone and AM/FM radio in Sydney's rail and motorway tunnels.

Universities that run radio stations here such as Macquarie University's 2SER are pretty much just standard community radio stations - no commercial advertising and a lightweight transmitter.


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A valve a day keeps the transistor away...

 
 Return to top of page · Post #: 8 · Written at 12:39:34 PM on 10 September 2014.
Maven's avatar
 Location: Canberra, ACT
 Member since 23 August 2012
 Member #: 1208
 Postcount: 584

The Wikipedia item on Carrier Current is interesting but doesn't properly distinguish between closed campus systems using powerlines and the public rediffusion systems, mostly using the telephone lines but in some cases unique cable networks.

The telephone-line systems that used a HF subcarrier mixed with the 4kHz telephone analogue voice standard, could be seen as the analogue precursors of DSL that provides the bulk of domestic broadband internet connections today. Some systems (I think the Swiss was one) used an additional pair of wires for the final connection, coming off common connections to the program source at building or neighbourhood connection points.

In America cable reticulation systems generally evolved from community-antenna systems aimed at correcting the deficiencies of overcrowded and underpoliced broadcast spectrum. Now cable systems are close to killing off the broadcasting business model.

Maven


 
 Return to top of page · Post #: 9 · Written at 2:07:00 PM on 10 September 2014.
GTC's avatar
 GTC
 Location: Sydney, NSW
 Member since 28 January 2011
 Member #: 823
 Postcount: 6010

Speaking of cable broadcasting, in the early 1900s, before radio, Americans could receive music over the telephone wires generated by the 14,000 watt 200 ton Telharmonium:

https://www.youtube.com/watch?v=PPlbXl81Rs0.

Some years later, Laurens Hammond would refine the electromechanical tone generation idea into the famous Hammond Organ.


 
 Return to top of page · Post #: 10 · Written at 1:09:13 PM on 23 February 2015.
Daro's avatar
 Location: Tanawha, QLD
 Member since 22 December 2012
 Member #: 1263
 Postcount: 45

IIRC there is a station in Coffs Harbour NSW that ran a cable audio distribution of its programs to schools & business in the town that station was 2CHY & that was back in the 70's. Now days it broadcast on FM & audio streaming on the internet.


 
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