Posted by
Tom Arntzen-2 on
Jun 29, 2007; 7:49pm
URL: http://elecraft.85.s1.nabble.com/Swapping-Standard-2-7-kHz-5-pole-Filter-tp449658p449665.html
In my opinion 2,1 khz isn't to narrow , but it would be desireable to be
able to go 2,4 or 2,7 for ragchewing.
Have you ever tried to narrow down a ESSB signal on the reciever side?
You lose talkpower and the signal sounds lousy.
Do the same with a signal transmitting standard BW will still get the
talkpower through.
So under noisy conditions if you transmitt 2,1 and the other station recieve
2,1 or 1,9
the signal will get through very good.
Another hint with ESSB if you think the "humming" is annoying you could use
the dsp.
Set for full BW but cutoff att 300 or 400hz and the signal sounds very nice.
The humming occure when they try to transmitt under about 100hz.
So fellows , if you want to try ESSB please don't go under 150 hz.
It sounds like crap .... At least to me.
A really good ESSB signal is lovly to copy , but not the 30 hz stations.
73 de Tom LA1PHA
K2/100 3829
----- Original Message -----
From: "Doug Faunt N6TQS +1-510-655-8604" <
[hidden email]>
To: <
[hidden email]>
Sent: Friday, June 29, 2007 7:11 PM
Subject: Re: [Elecraft] Swapping Standard 2.7 kHz 5-pole Filter
>>>> Is 2.1kHz really overly narrow for SSB transmit? I know people are
>>>> talking about 1.8kHz filters for RX, and it seems useless to transmit
>>>> energy that's not going to be used. It's certainly wide enough for
>>>> data modes. In fact, it might be useful to be able to TX through the
>>>> 400Hz filter in some of those modes.
>>>>
>
> I seem to have lost track of (or even lost) some of the discussion here.
>
> Ed, W0YK commented on why a somewhat wider signal is good tactics
> for SSB contesting (that's much more relevant to his station then
> mine), but an interesting POV.
>
> Eric, WA6HHQ said that 2.1kHz bandwidth audio would sound "thin", and
> that was apprently undesireable. Is this just a marketing issue, or
> is it truly the case for communication? I know almost nothing about
> pyschoacoustics, but I do know that once upon a time, the Collins
> 2.1kHz mechanical filters were the standard in military comm gear.
> And I thought that the frequencies between 500Hz and 2500Hz were the
> significant ones for understanding speech.
> I note that the transmit audio can be tailored within that bandwidth
> by the 8-band TX EQ.
>
> The TX filter width is irrelevant if the signal going into the filter
> is very clean and bandwidth limited by the DSP, but I'm a belt and
> suspenders kind of person in some cases.
>
> I also note that these are 6db bandwidths, so that frequencies on the
> edge are going to be attenuated somewhat, which is why I wouldn't
> choose to use a 250Hz filter for a 170Hz FSK signal (I think some of
> those sidebands are significant, but haven't done any real research on
> this). But if I wanted to transmit a particularly clean signal, I
> might choose the 400Hz filter for that.
>
> 73, doug
>
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