HFU HF Underground

General Category => Huh? => Topic started by: Shortwave_listener on August 03, 2022, 1730 UTC

Title: How to save images in MMSSTV?
Post by: Shortwave_listener on August 03, 2022, 1730 UTC
I have finally got my sound card working and I can now successfully decode SSTV images with MMSSTV. My problem is that I can’t figure out how to save images as file to my computer. Does anyone know how to?
Title: Re: How to save images in MMSSTV?
Post by: Skipmuck on August 03, 2022, 1822 UTC
In MMSSTV, when the image has completed decoding, it is automatically copied to the History. Right click on History and in the drop down list there are options to save to file With or Without Timestamp. You can either save them to "desktop" or create a file on the desktop to save them to. I usually save them each to desktop for easy access when I save the files to "IMGUR". IMGUR is a free app for storing images and pictures for use in blogs and chatrooms. Good luck!
Title: Re: How to save images in MMSSTV?
Post by: Shortwave_listener on August 03, 2022, 1840 UTC
Thank you  :)
Title: Re: How to save images in MMSSTV?
Post by: Shortwave_listener on August 05, 2022, 0320 UTC
Now I am having a different problem. Some of the images I have decoded do not line up for the whole image (parts of the image are shifted over). It does not happen for all images. For example, all the SSTV's on this page https://www.sigidwiki.com/wiki/Slow-Scan_Television_(SSTV) decode properly with MMSSTV. I tried to see if it had anything to do with static so I added noise to one of the SSTV's from that page in audacity but that did not cause the problem I am having on some other images. The images I have been having problems with are ones received from pirates on 43 meters and hams on 14230 kHz. While some of them have the problem other SSTV's decode without issue.  I have added some images to show the problem. Is there anything I can do about this?

(https://i.ibb.co/YjdjMjF/6925-Free-USB-Aug-4-0321-UTC-Scottie-DX.jpg) (https://imgbb.com/)

(https://i.ibb.co/bL9fSw7/Image1.jpg) (https://imgbb.com/)
Title: Re: How to save images in MMSSTV?
Post by: flexoman61 on August 05, 2022, 1604 UTC
You can try this... On the top left of screen click - Option/set up MMSSTV/auto slant   (make sure auto slant has a check next to it)


Good luck
Title: Re: How to save images in MMSSTV?
Post by: Shortwave_listener on August 05, 2022, 1856 UTC
Thank you for the suggestion, but it did not fix the problem. I have now found out that MMSSTV should be calibrated to the sound card as described on this website: https://f6ikyradioamateur.pagesperso-orange.fr/images%20sstv/sstv%20anglais.html
The problem I am having is that it states I should have a slanted straight line and once it has been adjusted it should be a vertical straight line. The line I have is wobbly and I cannot adjust it to be straight. The image below shows what I get when I try to calibrate to WWV.

(https://i.ibb.co/X2hqxKr/8-AADB7-A9-AFE1-414-A-B259-30-F008-BB1947.jpg) (https://ibb.co/xCpNqBt)
Title: Re: How to save images in MMSSTV?
Post by: ~SIGINT~ on August 05, 2022, 1920 UTC
It appears as you are having either severe frequency drift or sampling rate issues. The main objective is to determine the amount of clock drift from the top of the line and the bottom of the line (putting aside any other issues). From what I can see from your screen shot, that line looks pretty good and straight.

It is difficult at this juncture to determine the cause of the issue as we do not know what your setup looks like, I.E. what is the receiver, how is the decoder receiving audio, what are the sound card settings etc ... There are a number of factors which will need to be taken into consideration.
Title: Re: How to save images in MMSSTV?
Post by: Shortwave_listener on August 06, 2022, 0522 UTC
What do you mean by severe frequency drift? In the receiver or sound card?

The receiver was the W3HFU KiwiSDR (I also tried the Northwest Ireland KiwiSDR and got the same results), my sound card is the Sound Blaster Audigy Rx, the audio source is set to “what u hear” (the program will hear whatever is playing through the computer), and what sound card settings do you need to know?
Title: Re: How to save images in MMSSTV?
Post by: ~SIGINT~ on August 06, 2022, 1202 UTC
Yes, the drift would be from the receiver but we can rule that possibility out as most Kiwi SDRs are generally locked to GPS reference and will be stable.

I have historically found Sound Blaster cards to also be stable. The sound card settings would be the sample rate, I.E. 44100 Hz, 48000 Hz etc ... Make sure that the "playback" and "recording" devices are all set to the same sample rate or else you will be re-sampling the audio. Also make sure there are no "enhancements" such as virtual sound, loudness equalization etc ... turned on.

The “what u hear” is a Sound Blaster software implemented feature. Windows XP was that last version of the OS to natively support this feature in the audio mixer, so I cannot comment on it's use. Is it possible that other "Windows sounds" such as e-mail notifications or even hum from the microphone input or line in are occurring? “what u hear” will be picking up everything and feeding it to MMSSTV.

That is a large amount of sheer in that audio calibration line so something is upsetting the sampling rate. I agree that the MMSSTV calibration is poorly explained. The first thing you should do is right click on the WWV tick line. This will move that dotted green line located on the right side of your screen on top of the WWV sample. Then you can left click at the bottom of the sample followed by another left click at the top of the sample. That will get you calibrated but will not cure the sheer issue.
Title: Re: How to save images in MMSSTV?
Post by: radiogaga on August 06, 2022, 1540 UTC


The receiver was the W3HFU KiwiSDR (I also tried the Northwest Ireland KiwiSDR and got the same results), my sound card is the Sound Blaster Audigy Rx, the audio source is set to “what u hear” (the program will hear whatever is playing through the computer),

Do the images look ok using the kiwis built-in sstv decoder?

rgg
Title: Re: How to save images in MMSSTV?
Post by: Shortwave_listener on August 06, 2022, 1700 UTC


The receiver was the W3HFU KiwiSDR (I also tried the Northwest Ireland KiwiSDR and got the same results), my sound card is the Sound Blaster Audigy Rx, the audio source is set to “what u hear” (the program will hear whatever is playing through the computer),

Do the images look ok using the kiwis built-in sstv decoder?

rgg

They might but the KiwiSDR SSTV decoder can only work on 3630, 3730, 3845, 7171, 14230, 14233, 21340, and 28680 kHz. Those are all ham frequencies and are of no use for decoding pirate SSTV images.
Title: Re: How to save images in MMSSTV?
Post by: ~SIGINT~ on August 06, 2022, 2122 UTC
Since you are using “what u hear”, grab yourself a copy of SSTV Tools and use the SSTV Signal Generator to create a local WAV file which you can then play back in a media player. All you need a 320x256, 24-bit BMP image as an input. You will not get a more "digital pure" and error free test file than this.

Afreet Software SSTV Tools
http://www.dxatlas.com/sstvtools/ (http://www.dxatlas.com/sstvtools/)
Title: Re: How to save images in MMSSTV?
Post by: Shortwave_listener on August 07, 2022, 0549 UTC
I cannot find that program on the downloads page. I did try decoding images from the Sigid Wiki which should be equally error free. The images on that site decoded properly. Below is the Scottie 1 SSTV from the Sigid Wiki ( https://www.sigidwiki.com/wiki/Slow-Scan_Television_(SSTV) ) as decoded with MMSSTV. I made sure to disconnect my microphone or any other inputs while using MMSSTV and didn't have any other audio in the system (e.g. email notifications). Where would I find the settings such as sample rate and enhancements? Also, is there anything I can do to correct the sampling rate problem?

(https://i.ibb.co/ThygCz0/202208070535.jpg) (https://imgbb.com/)
Title: Re: How to save images in MMSSTV?
Post by: NJQA on August 07, 2022, 0952 UTC

They might but the KiwiSDR SSTV decoder can only work on 3630, 3730, 3845, 7171, 14230, 14233, 21340, and 28680 kHz. Those are all ham frequencies and are of no use for decoding pirate SSTV images.

The KiwiSDR SSTV decoder works on any frequency the KiwiSDR is tuned to.  I use it to decode pirate radio SSTV all the time. 

Tune in the pirate normally.  Then start the SSTV decoder from the <extension> drop down menu.  Do NOT select anything from the SSTV decoder subwindow dropdown menu <freq>.  The SSTV decoder will be operating, listening on the frequency the KiwiSDR is tuned to.
Title: Re: How to save images in MMSSTV?
Post by: ~SIGINT~ on August 07, 2022, 1309 UTC
For the audio settings, how you access this has changed with the various versions of Windows.

Try a right click on the speaker icon in the task bar then selecting either "Playback devices" or "Recording devices".  There you should see a bunch of available devices. Select a device and click "Properties". From there you will have a bunch of tab, General, Levels, Enhancements, Advanced etc ... The Advanced tab is where you general find the sampling rate under "Default Format". It is most likely set to 44100 Hz. That is CD audio quality and is more than enough. Sound Blaster might also install a control panel found under the Windows Control panel.

That Sigid Wiki decode looks good. No slant and no apparent sampling rate issue.
Title: Re: How to save images in MMSSTV?
Post by: Shortwave_listener on August 07, 2022, 1743 UTC

They might but the KiwiSDR SSTV decoder can only work on 3630, 3730, 3845, 7171, 14230, 14233, 21340, and 28680 kHz. Those are all ham frequencies and are of no use for decoding pirate SSTV images.

The KiwiSDR SSTV decoder works on any frequency the KiwiSDR is tuned to.  I use it to decode pirate radio SSTV all the time. 

Tune in the pirate normally.  Then start the SSTV decoder from the <extension> drop down menu.  Do NOT select anything from the SSTV decoder subwindow dropdown menu <freq>.  The SSTV decoder will be operating, listening on the frequency the KiwiSDR is tuned to.

Thank you! I tried that and it works perfectly!
Title: Re: How to save images in MMSSTV?
Post by: Shortwave_listener on September 15, 2022, 0307 UTC
I have discovered that MMSSTV decodes properly if I am playing a recording (including from YouTube) but not when listening on a KiwiSDR  ??? I have been using the KiwiSDR SSTV decoder but it isn’t very good (often doesn’t detect images at all, must be on when the image starts).