Audio Processing
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I designed the processing parameters of the Omnia ONE AM broadcast
processor, and have spent almost a half century adjusting broadcast audio. My suggestion is to apply a "sensible" amount of compression and limiting to increase the perceived loudness level to the maximum amount the equipment is capable of and STOP THERE! Adding more just muddies up the sound. We should aim for a balance between ultimate "loudness", as well as sensible EQ to enhance intelligibility, and depth of processing. Specifically, for speech processing on the ham bands, you MUST start with a good microphone. I have found that using about 7 - 10 db compression with a 3:1 compression curve, followed by 3 - 6 db of hard limiting, maximizes the perceived loudness, without reducing intelligibility. In broadcast, 1 or 2 db of clipping will add a little bit more "punch", but cranking the clipping up more than that passes the point of usefulness quickly. Additionally, the transmitter should faithfully reproduce the audio sent to it. Any additional distortion or EQ applied AFTER processing usually results in a significant deterioration of the desired audio. We hear a LOT of that on the air these days. To my ear, a well controlled but not overblown audio signal is both the easiest to listen to for long QSO's, but also has the punch to get through in crowded and/or weas signal conditions. 73 Ted W8IXY ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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For those who haven't tried it but don't like it, here's a timely little
anecdote: T31A, just on the air since late last night, is needed by nearly everybody, and hence is causing spectacular pileups. The west coast guys have a clear and easy shot, and on 15 phone he's been barely audible here, while he works them bing-bing-bing. This morning I finally heard him about S2, the loudest he'd been. Punched the button to send my call processed as previously described, and snagged him second try with my peanut whistle, right through the mob. I needed T31, too. Tony KT0NY ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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In reply to this post by AMFMTV
> Any additional distortion or EQ applied AFTER processing usually > results in a significant deterioration of the desired audio. That may be (is) true in broadcast audio but not necessarily so in communications audio. The typical compressor and/or clipper increases the amount of power producing low frequency components at the expense of the intelligibility producing higher frequency components. For communications work it is generally worthwhile to equalize after clipping/compression to increase the relative level of high frequency components ... just like FM and (analog) TV transmitters used to apply pre-emphasis to the processed audio before it went to the modulator. For an SSB transmitter, the key is a proper balance in the clipping. Low frequency components should be clipped/compressed no more than 10 dB while high frequency components can often benefit from much higher levels of clipping/compression. In that regard, it is a shame that modern amateur transmitters don't use a split band DSP processor to allow balancing the 10 to 20 dB difference in levels between the low and high formats of the human voice. 73, ... Joe, W4TV On 4/22/2011 1:22 PM, [hidden email] wrote: > I designed the processing parameters of the Omnia ONE AM broadcast > processor, and have spent almost a half century adjusting broadcast > audio. My suggestion is to apply a "sensible" amount of compression > and limiting to increase the perceived loudness level to the maximum > amount the equipment is capable of and STOP THERE! Adding more just > muddies up the sound. We should aim for a balance between ultimate > "loudness", as well as sensible EQ to enhance intelligibility, and > depth of processing. > > Specifically, for speech processing on the ham bands, you MUST start > with a good microphone. I have found that using about 7 - 10 db > compression with a 3:1 compression curve, followed by 3 - 6 db of hard > limiting, maximizes the perceived loudness, without reducing > intelligibility. In broadcast, 1 or 2 db of clipping will add a little > bit more "punch", but cranking the clipping up more than that passes > the point of usefulness quickly. > > Additionally, the transmitter should faithfully reproduce the audio > sent to it. Any additional distortion or EQ applied AFTER processing > usually results in a significant deterioration of the desired audio. > We hear a LOT of that on the air these days. > > To my ear, a well controlled but not overblown audio signal is both the > easiest to listen to for long QSO's, but also has the punch to get > through in crowded and/or weas signal conditions. > > 73 > Ted W8IXY > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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In reply to this post by Tony Estep
KT0NY,
Got'em here also...just keyed the CM-500 and dropped my call sign...seemed easy. They have varied from S2 to S5 which surprises me as we are used to hearing signals in this area of the pacific and to the north of us and a good deal louder. The audio from T31A sounds good here also...I believe they are all Icom's too! 73's Gary On 23 April 2011 03:37, Tony Estep <[hidden email]> wrote: > For those who haven't tried it but don't like it, here's a timely little > anecdote: T31A, just on the air since late last night, is needed by nearly > everybody, and hence is causing spectacular pileups. The west coast guys > have a clear and easy shot, and on 15 phone he's been barely audible here, > while he works them bing-bing-bing. This morning I finally heard him about > S2, the loudest he'd been. Punched the button to send my call processed as > previously described, and snagged him second try with my peanut whistle, > right through the mob. I needed T31, too. > > Tony KT0NY > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > -- VK4FD - Motorhome Mobile Elecraft Equipment K3 #679, KPA-500 #018 Living the dream!!! ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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In reply to this post by AMFMTV
100% in agreement with your comment:
Moreover: >In that regard, it is a shame that modern amateur transmitters don't use a split band DSP processor to allow balancing the 10 to 20 dB difference in levels between the low and high formats of the human voice. A resounding YES! From your mouth to Lyle's ear! However, give us an adjustable crossover point a la the cheap but effective (and sadly discontinued) Behringer Utramizer Pro for all us Tenors amongst all you Baritones and Basses out there :) -lu-W4LT- K3 # 3192 ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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