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  Topic: Interace/ISSTV (7 replies)
#1     Tue Nov 28, 2006 6:24 pm
KG4LMU
Flat rock,Michigan
 
Join Date: Nov 2006
Posts: 19
Subject: Interace/ISSTV

I noticed some people using the interace or ISSTV in tandem with the software. Cant seem to get either one going? Possable Elmer net?
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#2     Wed Nov 29, 2006 12:09 am
N2QOJ
Queen Creek AZ
 
Join Date: Oct 2006
Posts: 52
Subject: Tech Net - Saturdays @ 16:00 Zulu (11:00 EST) @ 14.100 Mhz

Hi - Try the Tech Net on Saturday @ 16:00 Zulu and 14.100 Mhz.

They may have your solution!
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#3     Wed Nov 29, 2006 10:49 pm
K7EK
Spanaway, WA
 
Join Date: Nov 2006
Posts: 15
Subject: SSTV with CQ100 - My observations

So far it seems that everything but SSTV works well with CQ100 out of the
box. From the several days I have been using CQ100 I have yet to see any
quality SSTV pictures from anyone. A majority of this appears to be caused
by CQ100's interal workings. I am by no means criticizing or complaining,
just sharing my personal opinions and observations. For what CQ100 is
and what it does well, I am very pleased and impressed and will continue
to use it indefinetely.

Firstly, the basic makeup of CQ100 and how it does things internally seem
to be the major cause of low-quality SSTV pictures. No matter what SSTV
program I have used, the pics always come out smeared. It appears that
the audio CODEC in use has characteristics unlike a SSB transmitter for
which all of the SSTV programs are tailored. Thus one should not expect to
have great results. It has occurred to me that no matter how much
tweaking one does with audio levels, tones, program types, etc, you
may never get perfect pics. I believe that something in the CQ100
program must be looked at as the possible culprit in this case. I hope
that I am incorrect about this and that someone does come up with a
list of "golden settings" that we may apply to our SSTV programs.

Secondly, the remaining problems appear to be caused by the users of
the various SSTV software. In some cases it may be that they are
unaware of certain little things that they are doing in error, or are
just not familiar with what works and what may cause problems in
general. One major no no I have repeatedly observed is that people are
trying to feed SSTV transmit audio into their mics from an external
speaker and expect that this will go out and be decoded. It just does not
work that way. You require a hard wire circuit into the mic or line input
of your sound card. And MOST IMPORTANTLY: You must disconnect the
microphone element somehow to prevent extraneous noises from
being introduced into the transmitted signal. You can tell if those external
noises are being superimposed on the picture by how they look. They
will appear as dark horizontal lines or blips across the screen, caused
by loud noises. The deck is already stacked against you without
introducing external sounds into the SSTV signal. :D
My suggestion for now is this:

Get a microphone with a disconnect switch on it. Most quality
headset/mic combinations such as the Logitech Internet Headphones
have such a switch. Alternatively you can install a switch yourself.

Better yet, abandon the preceding altogether in favor of the following.
Since most of us are trying to run a SSTV program on the same
computer as CQ100, some internal means of piping the audio to and from
CQ100 must be incorporated. There are several software solutions out
there that appear to work, up to a point. They are 'Virtual Audio Cable'
and 'Wave Clone'. What those programs do if configured correctly is
set up software 'patch cables' between your SSTV program and CQ100.
In essence these software solutions are virtual sound interfaces that can
be configured in a number of ways to provide easy solutions to problems
such as ours. And by the way, I AM NOT AFFILIATED WITH THE
AUTHOR(S) OF EITHER OF THOSE PROGRAMS IN ANY WAY AND HAVE
NO INTEREST IN FURTHERING THOSE PRODUCTS FOR PROFIT, EITHER
THEIRS OR MINE. I am simply a user that happens to have discovered
those two fine products. IN MY CASE, I USE THE 'WAVE CLONE' PROGRAM,
WHICH SEEMS TO ALLOW ME TO VIRTUALLY PASS AUDIO BETWEEN THE
CQ100 PROGRAM AND SSTV PROGRAM OF CHOICE. So far I have used
Chromapix, MMSSTV, and MSCAN with good results using Wave Clone.
All of that having been said, there are still some technical problems
to be solved concerning the quality of our transmitted and received
SSTV signals. I am not sure if the author of CQ100 is able or willing to
take this into consideration and provide us with a fix. For those that
have paid their $32 I would suggest forwarding your concerns about
the SSTV problem to the author. It would be a major turn-off for
many of us if that was not fixed.

Here are the URL's for the virtual audio applications I mentioned:

VAC is http://software.muzychenko.net/eng/vac.html

WAVECLONE is: http://software.muzychenko.net/eng/waveclone.html

Also, please note that these two programs are NOT FREE. There are
demo versions of each available. Registering is accomplished by paying a
very nominal fee. In my personal opinion, that fee is worth every
penny. Like me, you will most likely find other situations in which
these two fine program will come to your rescue.

There you have it - My observations and opinions(s). I may be wrong
on some of this. If you have any information about how to improve SSTV
picture quality on CQ100 I heartily welcome it. SSTV is one of my very
favorite modes, next to CW and the digital modes. It would be great if
we could get it working correctly on CQ100. One thing I would be asking
myself if I was the creator of CQ100 is how do the successful internet
apps produce perfect SSTV? Some of them use the MMSSTV engine.
Perhaps a mode switch could be added to the CQ100 panel to allow us
to switch between voice and SSTV. Switching to SSTV would move us
over to the MMSSTV engine, thus producing perfect SSTV pictures both
ways. Just a thought. I am not a programmer or software engineer. :)
I do know what has worked in other situations however, and this came to
mind.


Thanks for reading. I look forward to hearing from you in the near future.



Best regards,

Gary, K7EK
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#4     Thu Nov 30, 2006 9:53 am
W0SDG
Apple Valley MN
 
Join Date: Oct 2006
Posts: 101
Subject:

Some good information here Gary and thanks for sharing your thoughts with us. I guess the proof is is the pudding though. I am starting to monitor 14.230 lately and would love to see some improvement using SSTV. Virtual communications relies on Audio Codec, (Doug told me so!), and bandwidth, etc. The other minor problem is startup time before the channel catches up to the audio signal. In digital we see that in the first several characters sent, usually garbled. I would reason from that SSTV software would have to be adapted for that condition, in otherwords, delay the heading for a few seconds and maybe this is even possible currently? There are a few more reasons for poor quality that I don't understand, plus, the internet connections are not always stable. Small little dropouts are quite frequent and SSTV relies on uninterupted syncing for quality as well.

I am hopeful that these problems will be addressed by the software developers, if possible. VOIP is still very new to these modes and with the growth of virtual radio such as CQ100, I am sure we will see improvements, etc., as time moves forward. Since I enjoy Multimode operation, I quite satisfied with CQ100 and not being able to operate SSTV will not be a deterent for me. In perspective, there are allot of Hams on HF that don't operate SSTV, CW, PSK, etc. But, I am willing to bet that all of these digital modes will be addressed, improved, and implemented in Virtual communications eventually. Until then, I am still a happy camper with this new toy..

Steve - W0SDG
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#5     Fri Dec 01, 2006 2:43 pm
KG4LMU
Flat rock,Michigan
 
Join Date: Nov 2006
Posts: 19
Subject:

I got the mmsstv working but its a little complicated from the desktop. I really wasnt impressed with it however I can see a possability of use with links and repeaters during emergency situations. I found interace to be extremly freindly for photo sharing.
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#6     Sat Dec 02, 2006 1:12 am
W7RJR
Spokane, WA
 
Join Date: Oct 2006
Posts: 114
Subject: SSTV

I have certainly seen a large increase in SSTV interest on CQ100.
Perhaps it is the challenge that makes it interesting? Had SSTV worked right off the bat, like PSK or CW it would be less interesting :-)
As hams we like to tinker and we would love to be the first to introduce the solution to a difficult problem.

Like Gary, I have also tried just about every different setting in MMSSTV to get an improvement in the image quality. Oddly enough, just when I think I have struck on something the next image comes along and destroys my theory. There have been several stations noted that produce what I would call 'acceptable' images, but nothing of normal expected quality. When properly fed into CQ100 what I hear is discernably the same as what I hear on HF. I have studied the waveforms in MMSSTV as produced on HF and then again on CQ100. The data is supposed to fall between 1500 and 2300 hertz with a center frequency of 1900 Hz. Additionally there is a timing marker at 1200 Hertz. While there is some minor deviance in the data bandpass I note that there is a remarkable attenuation of the timing pulses at 1200 hertz, as compared to those received on HF. While I don't presume this to be the problem, it may be a contribution to the problem(s).

As we know, the SSTV algorithms decode analog audio signals. On HF there are many forms of QRM/QRN that will disturb this; however, the overall quality is not ruiined as it is on CQ100. I can then conclude that whatever must be wrong on CQ100 must be either a limitation in the bandwidth of the audio signal received/transmitted or a distortion of the signals. I have no idea how the CODEC processes all of this so I submit this as suspect. The other processes that could contribute to poor quality is internet latency and packet loss although I believe they would only cause temporary loss of sync, not uncommon on HF.

I applaud all those who have been diligently pursuing a solution to this problem. I would like to suggest that the frequency 14.230 Mhz be reserved for actual image exchange. Perhaps discussions, tests and coordination could be accomplished on an adjacent frequency?

I would encourage anyone that obtains the solution to these problems to post them here for all to see. Since SSTV is becoming more relevant perhaps the developer could devote some resources to study this as well?

Thank you Doug for presenting us with this unique program.
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#7     Sun Dec 03, 2006 6:51 pm
JA7UDE
Sendai, JAPAN
 
Join Date: Nov 2006
Posts: 1
Subject:

Hello, gentlemen,

I am not an exert, but allow me to get you some thoughts.

The poor image quality of SSTV might be due to the codec used in QsoNet. I am not sure, but I think QsoNet uses the GSM codec, which is optimized for human voice. This is not a fault of QsoNet. You will find out that other VOIP systems, such as EchoLink and Skype, do not work well for SSTV, either. This is because "Voice" Over IP is designed for the "human voice" communication.

I did some experiences using two PCs interconnected by private wireless LAN. The PCs in both ends were running MMSSTV. To send the sound over LAN, I used SM5VXC's ip sound (http://www.svenstedt.se/ip-sound/). You could choose one from several codecs including GSM and G711. It is interesting to see how the codecs make an effect on the image quality.

73 de JA7UDE Oba
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#8     Sun Dec 03, 2006 7:09 pm
W7RJR
Spokane, WA
 
Join Date: Oct 2006
Posts: 114
Subject: SSTV

Here is an interesting bit of information for those testing/experimenting with SSTV on CQ100. The TEST SERVER used on Echolink can be used quite handily to transmit an image to and then receive back immediately.
No need to ask for comments on CQ100, you can see for yourself!

This is handy if you want to try to tweak settings in MMSSTV for an optimal image (should such a thing exist). Considering the audio quality of echolink I was quite surprised to see that the quality was almost acceptable.

73
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