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Author Topic: Is decent transmit SSB audio lost on most hams?  (Read 1934 times)
K7PEH
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« Reply #15 on: March 04, 2010, 06:27:17 AM »

Doing this ESSB stuff has never made any sense to me.  I mean, it's not like you're listening to yourself, is it?  I never hear my voice when I transmit other then the sound normally heard by my own ears.  I never operate with the monitor on.

And, what do I care what the other guy sounds like.  Most of the time, I don't know them well enough to know the timbre and tone of their voice anyway so it makes no difference to me.  Besides, in noisy or weak signal conditions, it is much easier to copy when the bandwidth is narrower.

So, it just does not make any sense.  If I want to hear high-fidelity sound over the radio I turn on my FM receiver to the local classic music radio station.
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K9FON
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« Reply #16 on: March 04, 2010, 06:53:15 AM »

Back 40 years ago when SSB was all the rage no one ever used this Hi Fi stuff. So why is it so popular now? I run mostly old tube gear so i dont use the silly processed stuff. A plain jane D 104 and my golden voice is all i use.
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SP5QIP
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« Reply #17 on: March 04, 2010, 07:25:20 AM »

You know how to use VFO? Use it. If it not enough you can use power switch and switch off your radio. Nobady cares, that you stop listening.
Is there any way to keep away moaning retards away?
Mike
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W8JI
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« Reply #18 on: March 04, 2010, 07:38:43 AM »

Back 40 years ago when SSB was all the rage no one ever used this Hi Fi stuff. So why is it so popular now? I run mostly old tube gear so i dont use the silly processed stuff. A plain jane D 104 and my golden voice is all i use.

Part of the reason is people have latched on to a "white paper" used to sell high fidelity expensive voice announcement or voice alarm systems, as a rationalization for using hi-Fi for communications.

Of course we know the high frequency hissing and spitting "sssses" are important for telling us one sibilant sound from another different sound when the letter or sound is totally out of context. The problem is, this does not apply to systems with low signal-to-noise ratios or to normal speech exchanges. It applies mostly to sterile tests of infinite bandwidth and extremely high signal-to-noise ratios that are unlike communication systems, especially HF communications.

What matters most for systems we use is packing the limited transmitter power into the narrowest slice of spectrum that does not seriously hurt readability. If we reduce bandwidth by half on the receiver and transmitter we improve signal to noise ratio 3 dB. We get the same transmitter power packed into a channel of half the bandwidth, and that means broadband noise or QRM is reduced 3 dB (or in some real cases much more)!

Try this yourself when listening to weak CW or weak SSB. As you narrow selectivity from 5 kHz down toward 1.5 to 2  kHz on the receiver, while adjusting the "IF shift" for best readability of the particular voice, SSB signals become easier to copy.  CW signals have increasing S/N ratios down to a few hundred Hz or less bandwidth.

I don't have a problem with ESSB or enhanced bass or highs on clear uncrowded bands. It does not do a thing for our systems on typical HF bands except aggravate people on adjacent channels. It certainly does not improve distance or reliability of communications for anyone, like it would with near infinite S/N ratio laboratory tests.
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AB0WR
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« Reply #19 on: March 04, 2010, 09:13:54 AM »

Huh? Limiting transmitted bandwidth doesn't pack "more" power into the transmitted signal. Instantaneous power is instantaneous voltage times instantaneous current. That won't change by changing the bandwidth of the transmitter. All that does is limit the low or high frequencies that are sent.

Cutting off the low frequencies allows the frequencies just above in the spectrum to be transmitted at a higher instantaneous value because you've removed the "loud" lower frequencies. It allows you to make better use of the dynamic range of your amplifiers in the transmitter.

But it won't change the power being transmitted.

Restricting received bandwidth *does* help with the noise that is received. But it doesn't necessarily help with intelligibility.

People who don't believe this should ask themselves why the MFJ Speech Enhancer works so well by allowing higher audio frequencies to be amplified on the receive end.

Years ago the ARRL did a study of accuracy on radiograms passed by voice in the Nat'l Traffic System. They were flabbergasted by the *low* level of accuracy. There is no doubt in my mind that a big reason for this is the high frequency restricted audio used in most transmitters.

Ask any audiologist about the term "selective hearing loss" that is used so often as an excuse for why men don't hear what their wives are saying.

They are not ignoring their wives, high frequency hearing loss associated with age ruins the ability to understand what the wives are actually saying.

If that high frequency hearing loss affects the ability of men to understand *accurately* what their wives are saying then *exactly* the same phenomenon will apply to restricted high frequency bandwidths being transmitted on the ham bands.

I agree that the use of extended bandwidths have to be done in a cooperative way when the bands are crowded. When you *need* high intelligibility speech, however, trying to get by with restricted bandwidths can cause more problems than it helps.

tim ab0wr
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VA3DXV
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« Reply #20 on: March 04, 2010, 09:22:27 AM »

Is this the thread where I come to complain about how crappy a 4khz wide SSB signal sounds on my 2.7khz wide rx passband?

Ok, thought so.


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K8KAS
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« Reply #21 on: March 04, 2010, 09:37:15 AM »

Tim just a comment, What world are you from and what are you trying to say anyway. Your logic gets a bit fuzzy for me. Denny K8KAS
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AD6KA
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« Reply #22 on: March 04, 2010, 10:19:30 AM »

"Ask any audiologist about the term "selective hearing loss" that is used so often as an excuse for why men don't hear what their wives are saying."

Better to ask any audiologist about a Carhart Notch,
which is a conductive hearing loss around 2,000 Hertz in middle aged men.
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K9FON
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« Reply #23 on: March 04, 2010, 10:50:21 AM »

Yes i know how to use a VFO! Do you?Huh? And no im not a "retard". BTW using the word "Retard" is politically incorrect.
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KB4QAA
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« Reply #24 on: March 04, 2010, 10:50:37 AM »

Yes, narrowing the transmitted signal allows better reception.  It's all about signal to signal+noise ratio and bin width/band width matching.

Simply: what gives you more taste in a single bite:  A teaspoon of peanut butter spread across a foot long roll or across half a piece of sliced bread (disregarding sesame seeds)?

Wink

Bill
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K9FON
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« Reply #25 on: March 04, 2010, 10:54:49 AM »

If that high frequency hearing loss affects the ability of men to understand *accurately* what their wives are saying then *exactly* the same phenomenon will apply to restricted high frequency bandwidths being transmitted on the ham bands.

Well thats called selective hearing!!! :-)
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KAISERSOUSE
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« Reply #26 on: March 04, 2010, 12:23:57 PM »

Retard really is a fun word to say.  With that in mind:

"Is there any way to >keep away moaning retards away?<"

^^much irony in the fact that someone who can't construct a sentence correctly is alluding to the original poster being retarded.
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K1DA
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Posts: 473




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« Reply #27 on: March 04, 2010, 12:50:42 PM »

With all this interesting talk about TRANSMITTED audio, it seems an assumption that receivers are "transparent" and what goes in comes out.  Not actually the case.  Being an old R4C fan, I found that
replacing the stock audio output stage and changing the product detector to a double balanced type made the audio CLEANER,  with less distortion and therefore easier to understand.  That was a gain.  then I installed an 8 pole 6kc filter (now commonly called a "roofing filter) in place of the 8 kc wide 4 pole and while the reduced bandwidth made crowded band work easier, the receiver lost some of the pleasant sound it had.  Also, the "slow" agc time constant has a lot to do with how "clean" a receiver sounds on SSB.  There is a tradeoff in smoothness vs recovery after a noise burst or in going from "T" to "R"  which has been an endless topic on the Collins S line boards.  

Some years ago QST published some information on how to add hang AGC to the the ICOM 723 -729 series and how to clean up the audio hiss at the high end and roll off at the low end.  They were not expensive radios, and the filters were no more than average, but "after treatment" the receivers were (and are) very pleasing to listen to on SSB.  

Back in the good old days, manufacturers often limited low end response on SSB receivers to "cover up" lousy
power supply design (Drake!) (120 cycle hum) and filter and detector quality.  

I have an FT 102 which was the first radio I used which sounded good right out of the box, even on the "hifi audio signals.  Among other things it has an audio output chip good for about 8 watts.
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W9PMZ
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« Reply #28 on: March 04, 2010, 01:32:09 PM »

"They are not ignoring their wives, high frequency hearing loss associated with age ruins the ability to understand what the wives are actually saying. "

On the other hand my wife hasn't heard a thing I've said for years...

73,

Carl - W9PMZ
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WB2WIK
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« Reply #29 on: March 04, 2010, 02:48:00 PM »

"Ask any audiologist about the term "selective hearing loss" that is used so often as an excuse for why men don't hear what their wives are saying.

They are not ignoring their wives, high frequency hearing loss associated with age ruins the ability to understand what the wives are actually saying."

Nah, not for me.  I can hear what she's saying just fine.

I really am ignoring her.
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