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General Vintage Technology Discussions For general discussions about vintage radio and other vintage electronics etc. |
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9th Feb 2011, 3:24 pm | #21 | |
Rest in Peace
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Re: MW Transmitter with built in fading - suggestions
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Al. |
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11th Feb 2011, 11:59 pm | #22 |
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Re: MW Transmitter with built in fading - suggestions
Subjectively, a lot of the "fading" effect was not only the volume of the received signal, but also phase distortion caused by diverse propagation paths of the transmission resulting in signal arriving at the receiver at different times.To simulate this without resorting to digital processing, you could use a bucket-brigade device with a randomly varying clock rate, and mix the output with the original signal. (And vary the amplitude of the output of course). If you really want to !, Tony
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12th Feb 2011, 12:17 am | #23 | |
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Re: MW Transmitter with built in fading - suggestions
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Cheers n Beers, David.... Edit. I wonder what a spring Line reverb would sound like? |
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12th Feb 2011, 12:29 pm | #24 |
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Re: MW Transmitter with built in fading - suggestions
David - you no doubt realised that I was referring to delaying the audio signal in my post, not the R.F.!. If your enthusiasm runs to it, you could use two seperate random generators, one for the BBD clock, and one to vary the carrier amplitude. Make the mixing (raw/delayed signal) adjustable though. A CB echo mike sounds like a good basis for experimentation. The BBD clock will only require varying a very small amount to cause the effect required.
I suspect a spring line reverb will sound like ......a spring line reverb. But perhaps worth a try on the grounds of simplicity. Tony. Last edited by boxdoctor; 12th Feb 2011 at 12:36 pm. |
12th Feb 2011, 11:02 pm | #25 |
Heptode
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Re: MW Transmitter with built in fading - suggestions
If you fancy experimenting with phasing, Audacity (http://audacity.sourceforge.net/) has a 'Phaser' effect which you could use to see if it gives the sound you want.
I've just had a try with the default settings and it did sound something like the effect I remember. Jim |
12th Feb 2011, 11:36 pm | #26 | |
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Re: MW Transmitter with built in fading - suggestions
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Now that's a good idea but I will try the phaser in Virtual DJ as I used that extensively for my Mobile Disco before retiring (oldest DJ in town). I was going to be using a netbook running Virtual DJ in auto DJ mode to provide the music. I will also try your Idea as well Cheers n Beers, David..... |
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13th Feb 2011, 3:05 am | #27 | |
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Re: MW Transmitter with built in fading - suggestions
Update: I've been on the VirtualDJ downloads page and searched the plugins and found a HQ flanger with the following features:
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Thanks to jimmc101 for putting me on to this idea. Cheers n Beers, David..... |
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13th Feb 2011, 3:53 am | #28 |
Hexode
Join Date: Feb 2011
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Re: MW Transmitter with built in fading - suggestions
What about a Radio Northsea simulator with added jamming signal
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13th Feb 2011, 4:32 am | #29 |
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Re: MW Transmitter with built in fading - suggestions
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13th Feb 2011, 9:34 pm | #30 |
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Re: MW Transmitter with built in fading - suggestions
That sounds good David - all you need now is some random volume variation, and you've got it ! Tony
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18th Feb 2011, 3:40 pm | #31 | |
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Re: MW Transmitter with built in fading - suggestions
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For fading, spit the RF to feed two output stages. Feed one via a variable phase shift network, then combine the outputs. This will simulate the ground wave/sky wave fading that I remember so well in Essex. Variable gain in one channel will be useful - I would suggest the non phase shifted one, because it must be possible to run at exactly the same level in anti-phase to achieve the complete cancellation experienced with very heavy fading. [1] Much as I was a 'pirate' supporter and avid listener in the mid 60s, I was always appalled by such stupidity, which can only have worked against them as every complaint received by HMG from a legal broadcaster only reinforced their intention to ban them. The original Radio Caroline, later Radio Caroline North, operated co-channel with Radio Prague - some 1,500 miles away - on 1520kHz and closed down at night 'to avoid interference'. Ten out of ten for that! I don't know if we will ever know what frequency Radio Atlanta intended to use but, having lost the race to be first, they obviously just plugged in the first crystal they came across that was close to Caroline's frequency. Fine when they first started with short summer nights but, come the winter ... Then there was Radio Scotland who blasted their powerful transmission across the Irish Sea on the same frequency as Radio Eireann's 1kW Dublin repeater ... |
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