On Fri, Aug 12, 2011 at 10:12 PM, Joe Subich, W4TV <[email protected]> wrote:
>
> > I just looked at my passband, with spectran, in DATA A and USB modes
> > with the bandwidth cranked up to 4.0kHz (in both cases) with a 2.7kHz
> > filter. Indeed, the passband seems to be cut off at about 200Hz on the
> > low end in DATA A mode, but not in SSB mode. What's that about?
>
> That should not be a problem since applying modulation (audio tones)
> that low will result in "tilt" on transmission in any case. In my
> experimentation with JT65 on HF working below 300 Hz or so resulted
> in power output varying with the specific tone even in DATA A with
> no TX EQ presumably due to the skirts of the roofing filter on TX.
Yeah, I wouldn't suggest transmitting that low in the AF range, but
one might be able to decode a received signal down there (then perhaps
QSY down 1kHz and call him, if interested).
In any case, I find the discrepancy between the passbands of DATA A vs
USB modes curious - can anyone (Lyle?) explain it?
~iain / N6ML
> On 8/12/2011 4:52 PM, iain macdonnell - N6ML wrote:
>> "DATA A" *is* USB with no equalisation, etc - that's the point. It
>> allows you to easily switch between SSB and data modes without having
>> to adjust audio processing for each.
>>
>> I just looked at my passband, with spectran, in DATA A and USB modes
>> with the bandwidth cranked up to 4.0kHz (in both cases) with a 2.7kHz
>> filter. Indeed, the passband seems to be cut off at about 200Hz on the
>> low end in DATA A mode, but not in SSB mode. What's that about?
>>
>> http://www.dseven.org/ar/passband.png
>>
>> ~iain / N6ML
>>
>>
>>
>>
>> On Fri, Aug 12, 2011 at 8:40 PM,<[email protected]> wrote:
>>> I continue to be puzzled by this thread. Given that WSJT (all modes) is
>>> WRITTEN for use on USB by Joe Taylor, WHY would we be interested in
>>> utilizing any K3 mode but USB?
>>>
>>> I have operated 441 and JT65 utilizing my K3 off the Moon, tropo and MS
>>> with no desire to fuss with any other K3 "mode". The K3 works great on USB
>>> ... end of story.
>>>
>>> Here, USB, no equalization, 2.7Khz filter (5 pole), no compression. M
>>> Audio Delta 44 Soundcard, XP dual core machine and no "audio" interface and
>>> a homebrew Opto-isolator for PTT
>>>
>>> In the log::
>>>
>>> 34 - QSOs JT44
>>> 702 - QSOs JT65
>>> 35 - QSOs JT6M
>>> 1057 - QSOs 441
>>>
>>> Many hours of HF WSPR as well.
>>>
>>> Not all with the K3 ... but many!!
>>>
>>> What am I missing???
>>>
>>> Respectively, Bill K0AWU EN37ed ....
>>>
>>>
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