New release of MULTIPSK 4.45.3 (QR Code in "B/W24" SSTV mode) #multipsk


Patrick Lindecker
 

New release of MULTIPSK (4.45.3)

 

Pour les francophones: la version en français de ce message se trouve sur mon site (http://f6cte.free.fr). Il suffit de cliquer sur le lien "Principales modifications (courriel avertissant de la sortie de la nouvelle version)".


Hello to all Ham and SWL,

 

The new releases of Clock (1.11.11) and MultiPSK (4.45.3) are on my Web site (http://f6cte.free.fr/index_anglais.htm).
The mirror site is Earl's, W8BR: https://www.paazig.net/f6cte/MULTIPSK_setup.exe

The MD5 signature of the downloaded MULTIPSK_setup.exe file to, possibly, check (with WinMD5 for example), that the downloading works without error, is equal to:

8a907eb9187f25843e41f2610851d728

Multipsk associated to Clock are freeware programs but with functions submitted to a licence (by user key).

 

Modifications of Clock 1.11.11: the HBG station has been removed and FRANCE-INTER is now called "FLE".

 

The main improvement of MULTIPSK 4.45.3 is the following:

 

Insertion of a QR Code in SSTV, sub-mode "B/W24"


In the B/W24 sub-mode (black and white format, permitting the transmission of a 320x240 pixels picture in 24 seconds), it is proposed to insert a QR Code label. This one, of normal or small size, can code up to 47 characters. At reception, this QR Code label will be decoded, stored and the Ham position (Locator) possibly displayed on a map. This label can also, of course, be decoded by a QR Code application installed on a PC, a tablet, or a mobile phone.

 

The SSTV mode and, consequently, the QR Code are freeware, so without time limitation.

About the QR Code implemented in Multipsk, see general specifications below, as well as instructions to operate QR Code in RX/TX.

 

Other improvements:

 

·                     Possibility to scroll the fax image using the mouse wheel,

·                     Multipsk can be used as a VLF (Very Low Frequencies, 0 to 24 kHz) receiver on the sound card, the AF signal having been previously filtered and amplified, then directed to the microphone sound card input. In this case, the HF frequency can be forced to 0 Hz by clicking on "->0".

·                     Possibiliy, in EPIRB, to fix one error (on a bit) or none. In this last case, the probability to decode a not valid frame becomes extremely weak.  Moreover, not valid positions are detected.

·                     Addition of the "No duplicate" option in POGSAG, so as not to display the successive repetitions of the same message.

·                     Update of the VDL2_Ground_Stations.txt (for the VDL2 mode). Thanks to Sergio. Note the extension to 5000 lines of this file.

 

Note about translation of Multipsk.exe and Clock .exe:  the 4.45.2 version of Multipsk has been translated to Spanish by Joachin (EB4Z), from French.

See: http://f6cte.free.fr/Translation_files.htm.

 

 

73

Patrick

 

Particular specifications of the QR Code used by Multipsk in the "B/W24" sub-mode

 

In the B/W24 sub-mode (black and white format, permitting the transmission of a 320x240 pixels picture in 24 seconds), it is proposed to insert a QR Code label. This one, of normal or small size, can code up to 47 characters. At reception, this QR Code label will be decoded, stored and the Ham position (Locator) possibly displayed on a map. This label can also, of course, be decoded by a QR Code application installed on a PC, a tablet, or a mobile phone.

 

Multipsk codes the QR Code according to the "ISO/IEC 18004 - First edition 2000-06-15" standard. The QR Code has been invented by Denso-Wave and made public in 1999.

The specificities of the QR Code used by Multipsk are:

·                     The version 2 (25 x 25 modules) is the sole used, but the 4 correction levels (H, Q, M and L) are used.

·                     The "Alphanumeric" mode is the sole used.

·                     To simplify the coding and the decoding, the sole mask used for data is the one which carries the conditon "(i+j) mod 2=0", i.e. the "Mask Pattern Reference=000" according to the table 23 of the ISO reference.
The other masks are not used.

·                     The width of the quiet zone is standard and equal to 4 modules.

 

Note: these specificities permit to maximize the QR Code decoding quality, by limiting the number of possibilities.

 

The QR code is located in the lower right corner of the SSTV picture (320x240 pixels in B/W24).

A module is equal to 6 x 6 pixels for the standard format and 3 x 3 pixels for the small format.

 

Use of the QR Code in the sub-mode B/W24

If snapshots don't appear, directly download the file: http://f6cte.free.fr/Use_of_the_QR_Code_in_the_SSTV_sub-mode_BW24.pdf

It is described a basic use. For the other options in RX and in TX (as the header or not...), see the different possibilities in the SSTV manual.

It is reminded that SSTV frequencies are, in kHz: 3730 (LSB), 7035 (LSB), 14230 (USB), 21340 (USB), 28680 (USB) and 144500 (FM).

Start Multipsk, click on "RX/TX screen", then on the "SSTV" mode and finally on the "B/W24" sub-mode.

To transmit a QR Code

Confirm that the "QR Code insertion" button is pushed. Enter in the editor, without carriage returns and separating words with spaces, as a minimum, your Ham call sign, first name and Locator, as for example "FX9XYZ PIERRE JN18FT".
Try to limit your text to 20 characters, so as to keep with the best correction level (H) and so to be confident about the good decoding of your QR Code.

Add the same text in the "SSTV TEXT" editor and position it in the upper part of the picture. You can store this picture, using the "diskette" icon, in a FX9XYZ.BMP file (for example). Once done, the next time you will only have to load this file.

Transmit this picture clicking on the "Transmit" button.

You can choose between a standard QR Code format and a small one. The second one is 4 times smaller than the standard format, but it is also 4 times less sensitive (in terms of Signal to Noise ratio).
See the difference below.

To receive a QR Code

Each time you want to receive a new SSTV picture, click on the "Synchro" button. For completely automatized SSTV reception, see the SSTV manual ("Auto Save" and "Auto synchro" options).
The synchronization and reception are automatic. Of course, you are going to receive all SSTV pictures, not only the ones with the QR Code.

Click on the "Pos" button to see on a map, the positions from where the SSTV pictures are transmitted. Note that the received QR Code is stored and is accessible by clicking on the "QSO" button

Note that Hams receiving the QR Code with other programs (Mixw for example), will decode this one using a QR Code application installed on a PC, a tablet, or a mobile phone.

Example

Suppose that another Ham receives your SSTV picture. In the snapshow below you will find, to the left, the transmitted picture and, to the right, the same picture received, with decoded text at the bottom and the Ham position on the map.