Andrew
I'm not seeing what you are. I can get the filter width in both USB and
DIGU down as small as 40hz and still get something decoded. what AF freq
are you centering the filter on in USB. Im using 1500hz as the center
for both, it is harder to get a filter centered at 1500hz in USB mode
but can manage it. it's also kind of tough to get a 31hz signal centered
in a 40hz filter, but I'm not seeing any difference in the width of the
filters I can set in either mode.
To get the sharpest filter skirts you need to raise your Buffer size to
4096 for both SSB and Digital. you do have them set the same don't you.
Also under Setup/Audio/Primary have the Buffer size set to 2048 with a
48000 sample rate. Im using the WDM-KS driver for VAC1 with 2048 for the
buffer and 48000 for the sample rate.
Have you verified that your set at 48000 for both recording and
playback in Control Panel /Sound. I checked mine and found them set back
to 44100, probably by windows update. I'd advise rechecking that to be
sure they are all still 48000.
After just now changing the sample rates to 48000 for all the VAC cables
in Windows/Control Panel I can get the filter widths down to 33hz and
successfully decode signals.
I'm getting the same results using 192000 sample rate for the
Audio/Primary using the same buffer sizes I used for 48000. so maybe
that setting isn't as big of a factor as I was thinking.
It's good to know I can manage filters this narrow, I've never needed or
tried them this small before. Let me know if your still getting
different results after checking all the settings I mentioned. There are
articles in the Flexradio Knowledge Center and I think there was one on
the Wiki, about the problems caused by windows causing sample rate
conversions and how to fix it. It degrades the performance of any of the
Digital programs not just Fldigi.
If anyone reads this and spots any errors on my part, Please jump in and
let us both know.
I'm betting your radio can also do 33hz filters in USB/DIGU.
Jay - NO5J
On 6/21/2013 7:26 AM, Andrew O'Brien wrote:
Thanks Jay. I am aware of the advantages youbsuggested , BUT... my
main part of the question is why a waterfall in Fldigi is not as
narrow when Digu is selected versus USB? Try it, Set USB and Digu to
the same width/sift and a filter width of around 75 Hz. Toggle between
them and look at the waterfall in you digital mode software. Here,
despite the same width /shift , there is a 800 Hz difference .
Andy
On Fri, Jun 21, 2013 at 2:50 AM, Jay <[email protected]> wrote:
Andy
There are plenty of reasons for for using DIGU/DIGL instead of USB/LSB for
digital with Fldigi and VAC.
1. Your Filters in PowerSDR are programmable and can all be customized
anyway you want them ,
so thats not a reason to choose USB over DIGU. In DIGU mode just Right
click on the 75hz filter and you'll be able
to narrow that down to a minimum of 10hz or a maximum of about 10khz,
and rename the button from 75 to 10 or any other value you choose.
2. The DIG-X modes don't pass the audio from VAC through the mic mixer, EQ,
Compander, Leveler, ALC or DX compresser, the audio stays Digital and clean
from PowerSDR into Fldigi. so your going to see cleaner waterfalls and
better decoding. The Signal from Fldigi stays Digital and clean headed to
PowerSDR transmit also. Once you get the VAC levels set in DIG-X you don't
have to remember to reset them after running SSB. and since you wont have to
turn off all the EQ, Compander, or DX compresser functions, when you decide
to run SSB again all your Transmit audio settings will still be the way you
want them.
The Radio isn't in the hardware it's in the software and that's
reconfigurable so there's no reason to prefer one mode over the other. The
only difference between DIG-X and X-SB that im aware of is that DIG-X
doesn't mess up the signals.
I run PSK31 in DIGU with a 1Khz Filter and set the AGC to Fixed then adust
the AGC/T lower until all the noise disappears from the Fldigi waterfall if
I suspect there might be something decode-able that's to faint to be seen
then toggling The Preamp on makes it show up. but I get better decodes by
not over driving Fldigi. With the AGC turned off you dont have to worry as
much about a strong signal swamping out the waterfall. Keep in mind the TNF
notch filters you can lay one, or several on top of whatever your trying to
avoid and your back in business even if there's nearly no space in between.
But if you like running Digital in USB with the Flex then knock yourself
out, The radio is supposed to be fun to use. Use it how you like. Digital is
fun, its "funner" with a Flex.
You might have already Seen this info. Using Fldigi with PowerSDR
<https://fedorahosted.org/fldigi/wiki/Documentation/HOWTO/PowerSDR>
I hope you've Seen this one too. Flex Radio Wiki
<http://flexradiowiki.abrohamnealsoftware.com/mw/index.php?title=Main_Page>.
Don't get in a huge rush to "Know It All now" Take your time and learn it
right, You'll likely praise it more than cussing it! and that's a good
feeling to have. Here's hoping you have it often.
73
Jay - NO5J
On 6/20/2013 10:34 PM, Andrew O'Brien wrote:
Those folks at Flex are going to regret ever selling me a radio, so
many questions!
I am intrigued about the difference between "USB" and "Digu" in
PowerSDR and the Flex 3000. I see one major difference for us finicky
digital mode operators, one where USB is better than Digu, both with
VAC on. It seems that using Digu with a VERY narrow PowerSDR filter
setting (e.g 50 Hz), a waterfall in a digital mode application like
Fldigi still displays about 900 Hz of signals. If I switch to USB
mode with exact same Low and High settings , Fldigi's waterfall can be
narrowed down to around 80Hz. There are some advantages to the
narrower Fldigi display in terms of getting rid of adjacent strong
signals. What is the technical explanation for USB being able to
cause a much narrower minimum bandwidth display than Digu ?
Andy K3UK
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