Dayton 2004 - IVCA meeting presentation

Dayton 2004 - IVCA meeting presentation - SSTV-PAL Multi Mode 28APR04

Presentation by Dave Jones - KB4YZ

INTRODUCTION:

SSTV-PAL Multi Mode for XP version 28APR04 is the version I have tested. There is a new version out that I have not had time to test. It is version 10MAY04. I will only cover the basics of operation for pratical use and understansing. Time does not permit me to go into many of the nice features and abilities of this software.

The author is a ham, VK4AES, Erik Sundstrup from Australia. He developed his software on his system using Visual Basic under Windows XP PRO. SSTV-PAL Multi Mode, PAL for short, requires RDFT programs provided by Barry Sanderson, KB9VAK, to do the encoding and decoding. Erik states in his notes of JUN 2003 "Do not expect the program to be bug free." Pal was intended for use only on Windows XP. Attempts for use on Windows 98 or ME should be considered as experimental.

INSTALLATION:

PAL requires IrfanView and the JP2 plugins. Install IrfanView and plugins first. Note the installation location as you will need to set the path to this location later. The PAL download is a single 4 MB zip file. You may go through my web site listed here or visit the web sites of KC1CS or KB1HJ. Before unzipping and running the setup, you should use the standard Windows "Remove Programs" under Control Panel to uninstall any previous version. PAL runs in a resolution of 800 X 600 or higher.

(SHOW DESKTOP ICON)

The installation of PAL will place an Icon on the Desktop.

START & CLOSE: (Icon on Desktop)

Double click this icon to bring up PAL. PAL has two modes. Analog SSTV and Digital. The Analog SSTV mode uses the MM-SSTV engine and allows use of most analog SSTV modes. This review will cover the Digital mode only.

To switch the program over to Digital quickly on startup, hit the F4 function key on the keyboard. Next click the PENCIL and the DONE button. This will lock the program into the Digital mode. Analog SSTV pictures will still be copied in the "background" but the previous steps will prevent PAL from switching the front panel back to the analog SSTV mode. Selecting "VIS only" and "Auto Stop" in Setup will reduce the chance of receiving analog pictures in the background.

(SHOW MAIN SCREEN)

In most cases, you will want to select "Last RX Pics" for thumbnails when starting the program. This is for viewing images that have been received. The most recently received images are first.

To close the program use "Close" not the "X" button. This may be difficult to remember so you may want to stick a post-it note on the upper right corner of your monitor covering the "X" button. Clicking on "Close" is necessary to remove temporary files.

SETUP:

A standard SSTV interface can be configured to activate the transmit on your transceiver. If your transceiver allows "Rig Control", from your computer, it may be used to toggle your transeiver from receive to transmit.

RTS while scan is not available in the digital mode. The remaining items in SSTV Configuration may be set the same as you would for the MM-SSTV program.

In the Setup for PAL, you must check "Auto Save". Otherwise, the original file is not saved into the "Auto Saved Digital" folder.

You should want to alow confirmation of replacement files, as you may have a corrupted image want to overwrite a good image.

RX:

PAL uses standard SSTV VIS codes to open and close the capture buffer. The Start tone is the SC2-60 VIS code. The Stop tone is the PD-50 VIS code. These modes may still be received if PAL is locked into the analog mode. However, PAL does not allow these modes to be transmitted. VIS codes allow only a 50 Hertz tuning error. This means that the sending station and the receiving stations must have their operating frequencies within 50 Hertz. This tolerance level may require stations to adjust their frequency to be tuned within the range necessary for start and stop.

(SHOW IMAGE OF TUNING TONES)

The "Tuning Tones" button will transmit a pair of tones that can be used to check the frequency and adjust the VFO, if necessary. The waterfall image above shows a VFO tuned 50 Hz off frequency. The VFO should be adjusted so that the tuning tones will line up with the red marks between the spectrum display and the waterfall. The waterfall image below shows a properly tuned VFO.

The Windows Recording Control slider can be used to adjust the input level for the proper contrast in the waterfall.

(SHOW IMAGE OF "Capture error")

A quick test may be performed by right clicking the waterfall. This will transmit the start VIS code, a short burst of the tuning tones, and the stop VIS code. If the receiving station is using PAL, and is properly tuned, the message "Capture error" will appear. This is normal and means the stations are ready to exchange digital pictures.

(SHOW IMAGE OF MAIN SCREEN)

The "Last RX Pics" should be selected while receiving to allow quick access to the last pictures received using the thumbnails on the front pannel. Double clicking a thumbnail will bring the image into a window displaying the image in actual size and stating the resolution size in pixels. Thumbnails may be dragged and dropped into the TX window.

The nature of RDFT is that the entire transmission must be captured, beginning to end, or the decoder will not be able decode anything. Signal fade and noise within the captured transmission can be corrected. With PAL, if the receiving station misses the start, then if the stop is detected, the last received transmission will be decoded again. This will result in an extra copy of the image in the "Last RX Pics".

Clicking "Thumbs" will access images in any folder using IrfanView. This may be done while receiving without disturbing the reception of a transmission.

TX:

The Shareware program IrfanView is used to resize and convert images into the JPEG 2000 or standard JPEG file type. Images of any size and type that IrfanView allows, may be loaded. All loaded or pasted images larger than 640 X 480 are resized to 640 X 480. High levels of image compression are necessary to limit file size prior to transmission, otherwise the transmission time would be very long. The JP2 compression does a good job of maintaining image quality and detail while greatly reducing the file size. Once an image is in the TX window, the JP2 slider may be adjusted to find the best compromise between image quality and transmission time. This will change the size of the image file as well as the transmit time.

Click "Make wav" to encode the file for transmission. When the wave file has finished encoding, the TX button is available.

If you are working on an image in IrfanView, be aware that the image and any changes will be lost when PAL tries to display the next picture received. Save your image that you are working on before PAL needs IrfanView.

If you wish to use this image again, you can click on "Action", and "Save to Favorites". This will save the image and the wave file into the "Digital Favorites" folder for quick access for a transmission sent later.

"Digital Favorites" may be selected on the bottom of the main screen. The thumbnails in this folder may be dragged to the TX window. The wave file for these images are already made so the image is immediately ready for transmit.

Images that are pasted may not be stored into "Digital Favorites". This is also the case for some image types such as GIF.

The Windows "Volume Control" Wave slider is used to adjust the output level of the transmitted signal. It must be enabled. All inputs and other devices displayed in "Volume Control" should be muted. Any "Advanced" features of your soundcard should also be disabled.

Replay & Repair:

To replay the image of the last received transmission, drag the thumbnail from the "Last RX Pics" to the TX window. This does not send the exact file as received because the image is compressed again using JPEG 2000.

Anyone that successfully receives a picture may repair others that get one or more bad blocks. A "Repair Request" dialog box will appear on your screen when your system is ready and able to repair someone else. This box must be clicked before receiving other pictures.

You may "Send Requested Blocks" without loosing the wave file for the image previously set to send.

73 and enjoy your digital SSTV.

The above was the 2004 Dayton IVCA meeting presentation by Dave Jones, KB4YZ on May 14, 2004.