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Author Topic: AM Audio Quality on Shortwave  (Read 1827 times)

Offline jordan

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AM Audio Quality on Shortwave
« on: April 09, 2016, 1441 UTC »
If I were to broadcast some bluegrass music on shortwave radio in AM mode, using 50 watts of power, would the audio be comparable to a standard-broadcast AM station, even if listening from afar?

Would the audio sound better if I used 6930 kHz or 13,920 kHz to broadcast?  Or about the same?

Offline MDK2

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Re: AM Audio Quality on Shortwave
« Reply #1 on: April 09, 2016, 1520 UTC »
I'm an absolute noob and probably shouldn't be the one answering the question, but having heard some pirate broadcasts in recent weeks my guess is that it will sound good to listeners near you and not so much as the distance grows, although propagation obviously is a tricky variable.

Are you planning on trying to transmit during daylight hours? I'm unaware of pirates doing so at that higher frequency, but as I said I'm very new to this. Seems like most use that 43m band just after sunset locally.
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Offline Pigmeat

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Re: AM Audio Quality on Shortwave
« Reply #2 on: April 09, 2016, 1542 UTC »
Broadcast frequency won't make a bit of difference in how the audio sounds. Working with the audio frequencies of the music to compliment the audio frequencies your transmitter will handle is the first step.

If I didn't feel like crap today, I'd go into more details than you'd ever want read. Tailor your audio for the transmitter then adjust the bandwidth to match that of most receivers listening. That will get you sounding solid. When you've got that down, start experimenting with audio processing to get that fat radio sound.

It's a learning curve that never stops. I've been at this for two decades, there's not a week that goes by that I don't run across a bit of audio info or a trick that makes me go "wow!"

I'm sure some of the other guys will jump in. We'll all start talking audio processing and really confuse the piss out of you.

Offline Josh

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Re: AM Audio Quality on Shortwave
« Reply #3 on: April 09, 2016, 1954 UTC »
It would depend upon the quality of the audio and its bandwidth going into the transmitter and of course the transmitters output, the frequency of operation determines pretty much who will hear a given signal more so than its quality of audio. That being said, a poorly propagating frequency will make for weak and/or fading audio to the listener, with fading causing loss of carrier or sideband, hence distortion in an am product detector if such is employed by the receiver. Using a synch detector or manual ecssb at the receiver will likely maximise audio quality of received am signals and reduce the effects of fading, but you don't have any control over what the receiver employs for demodulation. Given the two freqs, use the lower at evenings/night/mornings and the higher during daylight hours. If you just want to cover a few hundred miles locally, use a low to the ground dipole on the lower freq 24/7 and be done with it. For more distant coverage, use the higher freq and a vertical antenna for lowest radiation angle. Just some thoughts on the subject.
« Last Edit: April 09, 2016, 1956 UTC by Josh »
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