Tech Arsenal 1

home *** CD-ROM | disk | FTP | other *** search

/ Tech Arsenal 1 / Tech Arsenal (Arsenal Computer).ISO / tek-20 / jvfax50.zip / ENGLISH.DOC < prev next >

Wrap

Text File | 1992-06-17 | 99KB | 2,150 lines

▒▒▒▒▒ ▒ ▒ ▒▒▒▒▒ ▒▒▒ ▒ ▒ ▒▒▒▒▒ ▒▒▒ ▒ ▒ ▒ ▒ ▒ ▒ ▒ ▒ ▒ ▒ ▒ ▒ ▒ ▒ ▒▒▒▒ ▒▒▒▒▒ ▒ ▒▒▒▒ ▒ ▒ ▒ ▒ ▒ ▒ ▒ ▒ ▒ ▒ ▒ ▒ ▒ ▒ ▒▒▒ ▒ ▒ ▒ ▒ ▒ ▒ ▒▒▒▒ ▒ ▒▒▒ a FAX program for IBM PCs and compatibles by ▒▒▒▒ ▒ ▒ ▒▒▒ ▒▒▒▒▒ ▒ ▒ ▒ ▒ ▒ ▒ ▒ ▒ ▒ ▒ ▒ ▒ ▒ ▒▒ ▒▒▒ ▒ ▒ ▒ ▒ ▒ ▒ ▒ ▒ ▒ ▒ ▒ ▒ ▒ ▒▒▒▒ ▒ ▒ ▒▒▒ ▒▒▒ ▒ ^ ======== /│\ // \│/ │ // \\ │ ┌───────┴───────┐ ========>> ┌───────┴───────┐ │ ___ │ // │ ___ │ │ /. .\ │ │ /. .\ │ │ │ √ │ │ │ │ √ │ │ │ │ └─┘ │ │ │ │ └─┘ │ │ │ \_ _/ │ │ \_ _/ │ │ F │ │ F │ │ \A/ │ │ \A/ │ │ X │ │ X │ │Tx! / \ │ │Rx! / \ │ └───────────────┘ └───────────────┘ 920617 Eberhard Backeshoff, Obschwarzbach 40a, D-4020 Mettmann Germany T A B L E O F C O N T E N T S =============================== Introduction 3 ============ Interface hardware requirements 5 Program configuration 6 Running the program 13 =================== Program start 13 Fax reception 15 The mode editor 21 Date driven FAX reception and date editor 24 Show and send pictures 29 Movie options 32 SSTV 33 Something about FAX transmissions: 34 ================================== How the ATC works 36 Control characters for interfaces that can be controlled by software 36 Interface circuits and availability of interfaces 37 Some SVGA modes 41 Frequencies, reception etc. 43 Copyright notes etc. 45 ==================== JVFAX 5.0, a FAX program for IBM PCs and compatibles page 3 Introduction ============ JVFAX.EXE is a multi purpose program for the reception of both weather chart and photo style fax. For radio amateurs, there is an additional transmit-option and a simple implementation of a SSTV receiving facility. Fax reception can be performed fully automated, supporting time schedules. If your computer is equipped with a VGA/SVGA graphics card you can have created a weather movie automatically when receiving geostationary satellites. Depending on the interface an intensity resolution up to 256 grey shades can be gained. Spatial resolution depends on the index of co-operation selected and can be up to 1900 dots per line. In conjunction with an adequate interface a so called Automatic Tuning Control (ATC) can be enabled when receiving FM-FAX, which greatly facilitates the tuning process. This ATC also compensates a receive frequency drift within wide ranges. The program can be configured for a wide range of ports and interfaces. Sample schematics for several types of interfaces are available from the author. A list of sources for interfaces in Germany can be found at the end of this documentation. JVFAX runs on any IBM PC or 100% true compatible and under DOS versions higher or equal to 3.0. It supports all current graphic cards e.g. CGA, EGA, Hercules, VGA up to SVGA in 256 colours. Drivers for some 8/9 or 24 pin printers are includes, and a driver for the HP-Laserjet. Pictures can be viewed, stored or printed during reception. Stored pictured can be viewed, zoomed, printed or retransmitted. Zoom magnification and width/height ratio can be freely chosen. Zoomed portions of a picture can be stored as independent pictures. For the storage of the pictures the commonly used GIF file format is used. By this, you have access to many shareware or even freeware tools for picture post processing. Also, there are a lot of conversion programs to transfer this format to others, e.g. TIFF, PCX, ... An export routine to TIFF is directly implemented. If the program is run in SVGA 256 colour mode then weather pictures can be viewed in false colours. The following IOCs and drum speeds (LPMs) are available for FAX reception: IOC: between 255 and 576 LPMs : 48, 60, 90, 120, 180*, 240* LPMs marked with a * can be run on slow computers with reduced resolution only. APT operation is fully supported, including automatic recognition of IOC in weather chart transmissions. The APT mode can be replaced by choice with an so called "Squelch mode" e.g. for the reception of low-orbiting satellites. JVFAX 5.0, a FAX program for IBM PCs and compatibles page 4 Automatic phasing of pictures is possible with normal as well as inverted phasing sequences. For the coverage of the different types of FAX transmissions (weather charts, weather pictures, press ...) up to 10 modes can be defined within the program. These modes will store defaults for IOC, LPM, APT tones, number of grey shades etc. When displaying pictures on the screen always the full screen format will be used in order to achieve the maximum possible resolution. Internally, however, the program will generally use a much higher resolution that is by default: resolution (in dots per line) := IOC * Pi. By this, you can take zooms out of a stored picture that will show details not normally recognisable on the screen. Alternatively you can set the resolution for each mode individually. The programs time consumption to perform the necessary calculations for FAX reception grows proportionally with "resolution*LPM". The dot clock, that is the speed that subsequent dots in a line have to be stored with, calculates to (dots per line) * Pi * LPM / 60 [Hz]. On slow PCs (4,77 or 7 MHz) it might be necessary to put a limit to the maximum dot clock (also known as "interrupt frequency) ho have the program run properly. For this purpose a maximum interrupt frequency can be set in the configuration routine. By such a limit pictures received with higher drum speeds and high IOCs will be processed with reduced resolution. On screens/graphic cards that allow the display of true intensity levels (VGA/SVGA) this method will be used. By this, nearly photo quality is achieved. On other graphic cards and on the printer a technique called "ordered-dithering" is used. On VGA cards in 16 colour mode 16 true intensity levels are shown and an interpolation of intermediate intensity levels is done by dithering, too. On SVGA cards in 256 colour mode up to 64 real intensity levels will be shown, or up to 256 different colours. For each mode you can define with how many intensity levels a picture shall be stored or displayed. Maximum is 256 levels, minimum 2. Reducing the number of intensity levels to an amount adequate for the contents of the pictures will reduce disk storage requirements considerably. JVFAX 5.0, a FAX program for IBM PCs and compatibles page 5 Interface hardware requirements =============================== To operate this program you need some kind of interface. The purpose of such an interface is to convert the analogue audio signal that is provided by your receiver in a digital form that is readable from your computer. JVFAX uses for data input either a serial (e.g. COM1:) or a parallel port. Port addresses can be freely chosen from within the program. When running the program on a serial port however, not the serial input line of this port is used but instead the four handshake lines DCD, RI, DSR and CTS are utilised as a kind of 4 bit parallel port. That did help to reduce hardware expense on the interface side. If the interface shall deliver more than 16 grey levels on such a "serial port", a multiplexing technique is used: If RTS is set, (+ potential) the program awaits the 4 most significant bits of the signal to be put on the handshake lines. If RTS is reset, then the remaining bits of the signal are read in left aligned. I developed two interface circuits to operate together with this program. One is a simple design fir 16 grey levels FM-FAX, the other one is more complex for AM- or FM-FAX with 64 grey levels (transferring 7 bits for ATC operation). Schematics for both interface types are available by sending an SAE + IRC to my address. It would be nice if you include in your mail some compensation for the costs of the photo copies. In the meantime a lot of interfaces or interface kits are available. An overview of the kits and interfaces available in Germany follows at the end of this documentation. This overview might be incomplete. As an alternative you can have the computer done all the word and have it decode the audio signal. for that you must amplify the audio to a RS232 compatible level using a simple comparator circuit. This will only work if the comparator is connected to a serial port that is configured to use IRQ4 or IRQ3 and if the PC is fast enough. When using this method, some memory-management programs such as EMM386 might interfere with this "simplest" solution and might have to be disabled for the program to run with acceptable results. But even then the results obtained will be worse than these obtained with a "more sophisticated" type of interface. A circuit diagram for a simple comparator amplifier is shown later in this document. For transmitting purposes you can choose between a parallel or serial output or a signal output using the PC's built in speaker. The speaker signal can directly drive the transmitter after having passed some low-pass filter stages. In all transmitting modes the maximum intensity resolution is limited to 64 levels. JVFAX 5.0, a FAX program for IBM PCs and compatibles page 6 Program configuration ===================== You must have DOS 3.0 or higher to run this program. If you run the program for the first time a configuration routine will be called in which you have do define your graphic card, interface type etc. These settings are stored in a file JVFAX.CNF and won't have to be redefined on every program start. A program reconfiguration can be done anytime from the programs main menu. How to do the configuration: Run the program by entering JVFAX <-+. Depending on if you have run the program before or not you will find yourself in the main menu or the configuration menu. If in main menu, enter "C" to switch to the configuration menu. Now the configuration screen appears that looks somewhat like this: (JV)-FAX 5.0 configuration screen ╒══════════════════════════════════════════════════════════════════════════════╕ │ │ │ Demodulator: 7 bits serial port address:03F8h Bit 0 is SSTV-sync: yes │ │ │ │ Modulator: 6 bits on speaker address:0000h Baudrate: 57600 │ │ ____________________________________________________________________________ │ │ │ │ Graphics: SVGA (256 colors) │ Enable scrolling: yes │ │ SSTV-graph.: SVGA (256 colors) │ │ │ Printer: IBM/Epson 8/9-pins │ Formfeed at end of pict.: no │ │ ____________________________________________________________________________ │ │ │ │ Allow tone alert at end of picture: no │ Max. interrupt frequency: 7500 │ │ Enable autolock when ATC is on: yes │ Clock-timer frequency: 1193181 │ │ ____________________________________________________________________________ │ │ Default picture directory: │ │ C:\FAX │ │ │ │ Store pictures in GIF89a: yes │ Miscellaneous settings: │ │ Callsign: │ │ │ │ │ Set intensity resolution of demodulator using <+>, <-> or <space> │ ╘══════════════════════════════════════════════════════════════════════════════╛ Hit <Ctrl>+<Enter> to terminate configuration session JVFAX 5.0, a FAX program for IBM PCs and compatibles page 7 You can step through the fields using cursor or TAB keys. Change field values using +, - or space key, or on some fields by simply entering a new value. You can terminate the configuration by pressing <Ctrl>+<Enter> at the same time. In the third last screen line a short context sensitive help text is shown. Follow the meanings of the fields: Demodulator: You can define how many different intensity levels your interface is capable to deliver and to which port it is connected. You can choose between serial, parallel and comparator (on serial) port. Address: Enter the address of the port that your interface is connected to. When using a serial port you will have to enter the base address of your serial card, e.g. 03F8h for COM1:. Bit 0 is SSTV-Sync: Only applicable for SSTV-reception. You can receive SSTV either if your interface delivers the SSTV sync signal as LSB (active low) or if your it can be switched to cover 800 Hz deviation. Modulator: Choose between speaker, parallel or serial port. The following address field has the same meaning as above. Baud rate: Only relevant if you have chosen serial port in the modulator field. Data format is always 8 data bits, 1 stop bit and 1 start bit. The 6 bits of intensity information are right aligned within the byte. The baud rate field will also be used when a receiving interface that is capable of being controlled via the computer is connected to a serial port. The characters transferred for interface control purposes are defined elsewhere in this document. JVFAX 5.0, a FAX program for IBM PCs and compatibles page 8 Graphics: Select a graphic mode applicable to your graphic card / monitor. If you choose a SVGA mode you will have to define some additional parameters within a sub menu that you can activate by pressing the <Escape> key. This menu looks like that: ╒═ customise SVGA parameters ══╕ │ │ │ Chipset: │ │ Tseng ET 4000 │ │ │ │ AH:00h AL:30h BH:00h BL:00h │ │ │ │ Dots per line: 800 │ │ Number of lines: 600 │ │ Screen aspect ratio: 10000 │ ╘══════════════════════════════╛ The field Chipset is needed only when you have chosen a 256 colour mode. If you don't find the chipset of your card in the choices available you will have to choose a 16 colour mode, instead. If you can provide me with bank switching information of a chipset not contained in the choices, please let me know. I will then try to implement a driver for that special chipset. Register values normally can be found in your graphic card manual. In 99 % of all cases only the AL register has to be set to the correct value and the other registers have to be set to 0. The fields dots per line and number of lines are self explaining. Screen aspect ratio means the ratio between horizontal and vertical dot density on your screen. This ratio is multiplied with 10000 and entered in the according field. Since a monitor screen has a height/width ratio of 3:4, one obtains for a 800x600 display: 600 / (800 * 3/4) = 1. in this case you would have to enter 10000. Using a 800*560 display would result in: 560 / (800 * 3/4) = 0,9333, so you would have to enter 9333. JVFAX 5.0, a FAX program for IBM PCs and compatibles page 9 When using 16 colour SVGA modes the maximum resolution is limited to 800x600 pixels. This limitation is not valid for 256 colour SVGA modes. Terminate the SVGA parameter sub menu by hitting <Ctrl>+<Enter>. Enable scrolling: If set to yes you will have a scrolling type screen. If set to no, a picture on the screen will simply be overwritten by a new one. SSTV-Graph: For this field, everything discussed under "Graphics" is applicable. Since SSTV generally uses much less resolution than FAX, and on the other hand SSTV-reception is more time critical than FAX it would be a good choice to set here a video mode with less resolution than the mode selected for FAX. However, if you want to watch colour SSTV in colour this must be a 256 colour SVGA mode. Printer: Select a driver appropriate for your printer. If in doubt, choose IBM 8/9 pin. If your printer should not be compatible with any of the predefined ones you can invoke a printer customising menu to do some "fine tuning". I will not describe this procedure because it highly depends on your printer. Please contact me, if you should have problems to make your printer run with this program. Formfeed at end of pict.: Set to no if you don't want each picture to be printed on a new page. If you're using a laser printer, a Formfeed will always be output to the printer at the end of a picture. A fine tuning of the patterns sent to the printer to represent the different intensity levels within a picture can be done from within the main menu by invoking P)rinter test. Allow tone alert at end of picture: If set to yes a short melody will inform you that a picture reception has been completed whenever a APT stop tone is detected. Max. interrupt frequency: This defines in conjunction with the drum speed (LPM) and the index of co-operation (IOC) an upper limit for the obtainable resolution (dots per line). A weather chart transmitted with IOC 576 has a resolution of up to 1810 dots per line. Assuming a drum speed of 120 lines per minute this results in an interrupt frequency of 3620 Hz. JVFAX 5.0, a FAX program for IBM PCs and compatibles page 10 If you should recognise lost lines or similar strange effects when receiving fax pictures then your computer might be too slow to handle such high interrupt rates. You should then try to reduce the value indicated in this field to give your computer more time to "breathe". If you're running a machine with more than 12 MHz clock speed this normally won't be necessary. Enable auto lock when ATC is on: If set to yes the ATC will be "frozen" at the end of as phasing sequence until the end of the picture transmission. This is advantageous when receiving heavily jammed signals, since by excessive noise, the ATC might be interfered and produce unintended changes in picture intensity. Clock timer frequency: To guarantee for a proper FAX transmission both the transmitter and receiver have to use a highly constant scan speed. Not only this speed has to be highly constant but additionally it has to be exactly the same on the transmitting and receiving side to avoid slanting effects in the received picture. As a time base for this program serves the PC internal timer oscillator, that controls the PC's date/time clock. By reprogramming the timer controller, all necessary timings can be derived. Since this clock speed slightly varies from PC to PC you will recognise when first receiving FAX that the pictures will show some amount of skew. You can correct this with the "oblique skew" correction that will be explained later. If you know the exact frequency of your computers timer clock you can enter it here directly (a precision of some 10 Hz is absolutely necessary). If in doubt leave this field as is and perform the oblique skew correction later. Default picture directory: Enter a default directory for your received pictures to be stored within. If the directory doesn't exist, it will be created. Store pictures in GIF89a: At the moment, there are two kinds of GIF formats: 87a and 89a. While GIF89a enables the imbedding of application dependant information within the picture file, GIF87a does not. Unfortunately, some programs are not capable of handling the GIF89a format. FAX uses the application dependent information fields provided by GIF89a to store information about picture orientation etc. If you intend to use programs for the post processing of pictures received with JVFAX that cannot handle GIF89a frequently, you should set this field to no. In any other case this field should be set to yes. JVFAX 5.0, a FAX program for IBM PCs and compatibles page 11 Callsign: If you're a radio amateur and if you want to transmit pictures with this program, you must enter your callsign here. If this field is blanked, picture transmission will be inhibited. Miscellaneous settings: With the cursor positioned on this field, hit the <Escape> key to open a sub menu where you can set some default timing values etc. The miscellaneous sub menu looks that way: ╒════════MISC. SETTINGS════════╕ │ │ │ Start delay APT squelch: 5 │ │ Stop delay APT squelch: 30 │ │ │ │ TX start tone length: 4 │ │ TX stop tone length: 4 │ │ TX phasing sig. length: 6 │ │ │ │ Quick save: yes │ │ │ │ Initial RX mode: 5 Ham 288b │ │ Initial TX mode: 5 Ham 288b │ │ │ │ Max. # of pict./movie: 30 │ ╘══════════════════════════════╛ Start delay APT squelch: Time in seconds. If you have selected "squelch mode" when in FAX reception then a picture transmission is assumed to have started when for longer than the period entered here the program detects changes in signal amplitude. Stop delay APT squelch: Just like in the field above, the program assumes a transmission to have stopped when for longer than the time entered here there have been no further changes in the received signal. TX start tone length: Length of APT start tone for picture transmission, in seconds. TX stop tone length: Length of APT stop tone for picture transmission, in seconds. TX phasing sig. length: Length of phasing signal for picture transmission, in seconds. JVFAX 5.0, a FAX program for IBM PCs and compatibles page 12 Quick save: If set to yes, every received picture will be stored to a temporary file in case both "Store to disk" and "Printer" are in off condition. At the end of the picture transmission you have the choice to save the previously stored picture permanently by hitting the "U" (U for q"u"ick) key. This useful option can be disabled, e.g. if you have a PC with strongly limited disk space. Initial RX mode: Default mode for FAX reception. Initial TX mode: Default mode for FAX transmission. Max. # of pict./movie: If you are using the program for the automatic generation of weather movies you can limit the maximum number of pictures that will be stored in a movie file by this entry. If the number of pictures in a movie file exceeds the number given here the file will be truncated to this number minus one before a new picture is added to it. The truncation will affect the oldest pictures in the movie, so that the movie will always show the actual weather development. Terminate the miscellaneous sub menu by hitting <Ctrl>+<Enter>. JVFAX 5.0, a FAX program for IBM PCs and compatibles page 13 Running the program =================== Note: All interfaces used by this program assume that a higher audio frequency corresponds to a "whiter" picture content. For that, your receiver normally has to be tuned to upper sideband when receiving FM-FAX transmissions. If you're receiving in the wrong sideband, the following effects will occur: - automatic phasing won't work - picture is received as a negative If these effects should occur at your first receiving trials, please check for the proper sideband selection. Some basics on the different FAX transmission modes will be explained in the chapter "Frequencies, reception etc." Program start ============= Start the program by entering JVFAX <─┘. The following main menu will appear: ╒══════════════════════════════════════════════════════════════════════════════╕ │ ▀▀██ │ │ ██ ██▀▀▀▀▀ ▄█▀█▄ ██ ██ ██▀▀▀▀ ▄█▀▀▀█▄ │ │ ██ ██ ██ ██ ▄▄▄▄▄▄ ██▄▄▄▄ ██ ██ ▀█▄█▀ ▀▀▀▀█▄ ██ ██ │ │ ▀▀▀▀▀ ██ ██ ██ ██▀▀▀██ ▄█▀ ▀█▄ ▄▄ ██ ▄▄ ██ ██ │ │ ▀█▄ ▄█▀ ▀▀ ▀▀ ▀▀ ▀▀ ▀▀ ▀▀▀▀ ▀▀ ▀▀▀▀▀ │ │ ▀▀▀ │ │ The FAX program for IBM PCs and compatibles Rev: 920523 (c) DK8JV, 1992 │ ╘══════════════════════════════════════════════════════════════════════════════╛ Demodulator: 128 intensity levels on serial port Modulator: 64 intensity levels on speaker Graphics: SVGA (256 colors), true intensity display Printer: IBM/Epson 8/9-pins Save-filename: C:\FAX\JVFAX ╒══════════════════════════════ M A I N M E N U ══════════════════════════════╕ │F) FAX N) Change name for save files │ │S) SSTV M) Mode editor │ │H) Show and send pictures T) Screen test │ │O) Movie options P) Printer test │ │D) Date driven FAX reception Q) Quit │ │E) Edit date files C) Change configuration │ ╘══════════════════════════════════════════════════════════════════════════════╛ In the upper two thirds of the screen the program status is shown which can be changed with the configuration procedure described above. In the lower third the menu items are shown. Each menu item can be selected by hitting the character shown left to the ")", by positioning the cursor bar on the item and hitting <Enter> or by double - clicking on the item with the mouse. JVFAX 5.0, a FAX program for IBM PCs and compatibles page 14 First, an explanation of the less meaningful items: N) Change name for save file: The name entered here is used as a filename for picture storage. The length of this name must not exceed 5 characters, since a current number with three digits and the extension ".GIF" is added automatically. C) Change configuration: To change program configuration just as described above. T) Screen test: A simple screen test to check monitor geometry and correct selection of the graphics driver. P) Printer test: To check selection of correct printer driver and to change the assignment of print patterns to the different intensity levels. A graph appears that shows the current assignment of 16 out of 64 possible print patterns to the 16 intensity levels. This assignment can be changed using the cursor keys. To find out the optimum assignment you can activate your printer by hitting "P". A continuous grey step will be printed that shows the result of your assignment. Hitting "P" again will stop the printout. If using a laser printer you will have to stop printout in order to make the paper come out of the printer. Terminate this procedure by hitting "Q" and answer the question "Save changes" with "Y", if desired. Q) Quit: This is the one and only key that will terminate this program. JVFAX 5.0, a FAX program for IBM PCs and compatibles page 15 Fax reception ============= F) FAX reception is invoked from the main menu by hitting "F". An empty screen appears with a small window within: Tuning indicator ---------------------------v ┌─────────────┬──────────────┬───────────────────────────────────┐ │M): Wefax576 │ L)pm:120/576 │ │ │A)pt: waiting│ D)ev: 150 │ │ │P(h)ase:N)on │ R)otate │ │ │ ├─────────────┼──────────────┤ │ ││ │ │G)rey A(T)C │ L/R T/B│ 1810│ │ │ ││ │ │ 64 off │ <-) ^)│ *) │ │ │││ ││ │ ├────────────────────────────┤ │ ││││ │ │││ │ │P)rinter: off │ │ ││││ ││ │ │││ │ │S)ave to file: off │ │││││││││││││ │││ ││││ │ ├────────────────────────────┤ ┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬ │ │Q)uit JV-FAX 5.0 │ B autol(o)ck W │ └────────────────────────────┴───────────────────────────────────┘ *): Current picture resolution. All parameters shown in this window can be changed by hitting the character just before the ")". Changing of some parameters will be disabled when S)ave to disk or P)rinter is on. (P)rinter and S)ave may only be changed when A)PT is in the "waiting" or "SQ.off" state. The meaning of the parameters: M): To select a reception mode. Up to ten modes can be defined using the mode editor described below. JVFAX 5.0, a FAX program for IBM PCs and compatibles page 16 L)pm: Transmission speed, expressed in lines per minute. Most stations use 120 LPM transmission speed. Some stations on short-wave, mostly from east European countries use 90 LPM, too. Geostationary satellites such as Meteosat transmit with a speed of 240 LPM. During a FAX transmission the drum speeds on the transmitting and receiving side have to be equal. The number right to the LPM display shows the currently selected IOC. P)rinter,, S)ave to file: To switch on/off printer output or the save to disk option. Can only be changed if APT is in the "waiting" or "Sq.off" state. To have a picture get printed out directly you must set P)rinter to on before the transmission starts. If you have set "Quick save" to yes when configuring the program, saving of pictures permanently to disk can be postponed until the end of a picture. Otherwise, you will have set S)ave to disk to "on" before transmission starts. You cannot activate P)rinter and S)ave to disk at the same time. P(h)ase: To manually start or abort the phasing routine. to achieve a running "in phase" of the transmitting and receiving machines, which means that the left margin of the picture transmitted will be at the leftmost position on the screen of the receiving side, at every start of a FAX transmission a so called phasing or synchronisation signal is transmitted for some seconds. This signal identifies the margin of the transmitted picture. Normally this signal consists of lines with 95% black and 5% white. The white vertical bar generated serves as a marker for the picture margin. Some stations transmit an inverted signal with 95% white and 5% black. The program will use this phasing signal to secure the correct positioning of the picture on the screen and to identify the beginning of the actual picture. JVFAX 5.0, a FAX program for IBM PCs and compatibles page 17 N),I): Toggles between recognition of normal or inverted phasing signals. (See above) If N is shown, the program assumes a normal phasing signal. By pressing the "N" key you will toggle to inverted phasing signal recognition and vice versa. A)pt: Means Automatic Picture Transmission. Most commercial FAX stations use APT to enable a fully automated unattended reception of the transmitted pictures. Before the transmission of the phasing signal, a so called start tone is transmitted for some seconds, that will be recognised by the receiving unit. Then, the receiving unit switches from standby to operational mode and waits for a phasing signal to appear. At the end of the transmission, another "stop tone" is sent that switches the receiving unit back to standby mode. Different IOCs of the transmitting station can be identified by different APT start tones in weather FAX transmission. In connection with a time table, APT operation makes it possible to selectively receive some desired pictures out of many. APT picture transmission uses the following protocol: First, APT is in the "waiting" state, and nothing will be written to the screen. As soon as a start tone is detected, APT switches to the "running" state, and the phasing routine is activated. (Eventually the correct IOC will be set, derived from the start tone frequency) During the transmission of the phasing signal, the phasing routine determines the correct position of the picture. When the phasing signal ends, the phasing routine will stop and the picture draw routine is enabled that will draw the picture to the screen, store it or print it. During the drawing process the APT routine will check for an APT stop signal. When this is detected, drawing of the picture will stop, eventually the save file will be closed and APT returns to the "waiting" state. The received picture will remain on the screen until it's overwritten by a new one. JVFAX 5.0, a FAX program for IBM PCs and compatibles page 18 By hitting the "A" key, you can toggle the program APT state manually. This is useful for the reception of stations not transmitting APT tones. When switching APT manually the phasing routine will not be affected. So, if you want to receive a station that transmits a phasing signal, but no APT signal, you should first switch P(h)ase to on and then set APT to "running". Alternatively you can disable the whole APT routine by hitting the "X" key to replace it with a "squelch" routine. (see below) A(T)C: To switch the automatic tuning control on or off. The functional principles of the ATC are described in a separate chapter. Q)uit: To terminate FAX reception and to return to the main menu. R)otate: If you have missed the phasing signal of a picture transmission you can use this option to have the remainder of the picture written correctly to the screen. Switch APT to running and Phase to off, and watch the picture being displayed. After having written some lines, if the margin of the picture isn't on the left or right side of the screen, hit the "R" key. Now move the cursor being displayed to the edge of the picture and hit <Enter>. The rest of the picture will be written correctly positioned. Using this routine will not affect the storage of the picture to disk. A stored picture can be rotated as a whole afterwards. G)rey: Determines with how many grey levels a picture shall be displayed or stored. ->),<-): To change scan direction You can choose between normal (left to right) or inverse scan direction. Receiving a picture with the wrong scan direction will result in a mirrored image. JVFAX 5.0, a FAX program for IBM PCs and compatibles page 19 v),^): Like above, but mirroring of the image will be bottom to top instead of left to right. Can be combined with the above function to rotate a picture by 180 degrees. D)ev: To select the proper deviation for the station being received. You can choose between 150, 300, 400 and AM. Since, with the exception of the "comparator interface", setting of deviation can only be done within the interface, this command is simply passed through to the interface by means of control characters described below. Most short-wave stations use a deviation of 400 Hz, while polar or geostationary satellites will use AM. When in ATC mode, the interface mist be set to twice the deviation of the transmitting station. Deviation means half the difference between the frequency representing white and the frequency representing black. The following commands are not shown in the window: Space key: To switch the window on or off. X): To toggle between APT and squelch mode. When in squelch mode, SQ.on or SQ.off is shown in the window instead of waiting and running. Other than in APT mode the squelch mode monitors for changes in the input signal instead of start or stop tones. If there are changes in input signal for more than a given time, this is interpreted just as an APT start tone in APT mode, If for more than another given time there are no more changes in the input signal, this will be interpreted as a stop condition. This mode can be used for the reception of polar satellites, if your receiver is equipped with an audio squelch circuit. All activity on the receiving frequency will be recorded without the need to calculate rising or setting times of the satellites. Note: phasing will be skipped when in squelch mode. F): Turn APT frequency counter on/off: When you hit "F", the currently detected APT tone frequency, preceded by a "F:" is displayed instead of the resolution. Can be used to find out which start/stop tone a station employs. JVFAX 5.0, a FAX program for IBM PCs and compatibles page 20 C): Turn on/off calibration display: works exactly like "F", but instead of the APT frequency the current intensity level delivered by the interface is displayed. You can use this for interface alignment etc. O): Freeze ATC on/off: When receiving pictures using the automatic tuning control it can be advantageous to have the ATC run only during the phasing procedure of the transmission. You can achieve this by setting "Enable auto lock when ATC is on" in the configuration menu. This key does exactly the same what the auto lock feature does at the end of the phasing signal. If auto lock is "frozen" then a "autol(o)ck" message appears right below the tuning indicator display. E): Activates the mode editor. Only applicable when APT is in the waiting state. Has the same meaning as the "M" key in the main menu. The mode editor will be described in the next chapter. /: Oblique skew correction: If the received pictures look slanted you can correct this with the following procedure: Receive a picture in a not phased condition, that means that the picture margin should be completely visible somewhere on the screen. With the picture on the screen and APT in the waiting state, press the "/" key. A vertical line appears that can be skewed using the cursor left and right keys. Using <Ctrl> + cursor keys the line cab be shifted without changing its skew. Now simply align this line with the picture margin and hit the enter key. All the following pictures will be received correctly. This procedure can be repeated as often as you like, but normally doing it once will be enough. JVFAX 5.0, a FAX program for IBM PCs and compatibles page 21 M) Mode editor: =============== Invoking the mode editor produces the following screen: (JV)-FAX 5.0 mode editor screen ╒══════════════════════════════════════════════════════════════════════════════╕ │ │ │ Mode: 3 Meteosat Alternate mode: - -------- │ │ │ │ IOC: 255 LPM: 240 Resolution: 800 │ │ │ │ Deviation: AM ATC: off Intensity levels: 64 │ │ ____________________________________________________________________________ │ │ │ │ APT-Mode: tone Phasing signal: inverted Scan direction: └ │ │ │ │ APT start tone frequency (Hz) 300 +/- 30 Min. duration (lines): 2 │ │ APT stop tone frequency (Hz) 450 +/- 10 Min. duration (lines): 3 │ │ ____________________________________________________________________________ │ │ │ │ Display width usage: (%) 100 Printer width usage: (%) 100 │ │ │ │ Which color palette shall be used: STANDARD │ │ │ │ Execute DOS command: │ │ │ │ Use <+>, <-> or <space> to select the mode you want to edit │ ╘══════════════════════════════════════════════════════════════════════════════╛ Hit <Ctrl>+<Enter> to terminate mode editor session To edit a specific mode, first select it by positioning the cursor on the mode number field, then hit the space key until the desired mode name appears in the field right to the mode number. To create a new mode, hit the space key until the name field becomes empty. Now you can enter a name for the new mode in the name field. The other fields have the following meanings: Alternate mode: Select the mode number of an alternate mode here of which the APT start frequency shall be checked in parallel to the start frequency of the edited mode. Serves for the automatic recognition of IOC in weather FAX reception. IOC: Means Index Of Co-operation. The IOC must be selected according to the IOC of the transmitting station, else the pictures will not be displayed with the correct height/width ratio. JVFAX 5.0, a FAX program for IBM PCs and compatibles page 22 LPM: You can choose between different transmission (drum) speeds. Intensity levels: Determines with how many intensity levels a picture is to be stored or displayed. APT mode: You can choose between APT tone or squelch mode. Has been described earlier. Phasing signal: Normally set this to normal. For some stations, like Meteosat, this must be set to inverted. Scan direction: Determines how the picture will be displayed on the screen. Normal scan direction is from left to right and from top to bottom. By changing this field you can have a picture display flipped horizontally or vertically or have it rotated by 180 degrees. APT start tone Frequency, min duration, APT stop tone Frequency, min duration: To enter the tone frequencies of APT start and stop signals. Tone frequencies are entered in the first field, the second field is used to enter a bandwidth. Min duration determines, for how many picture lines the tone signal must be present to be recognised. Enlarging the bandwidth or shortening the min duration value will both make the APT routine more sensitive, but will increase the possibility of the routine being triggered to noise or some patterns that are part of a picture. If bandwidth is set to 0, this mode can be started (or stopped) only by hand. ("A" key) Display width usage: If you receive pictures that are higher than 3/4 of their width these pictures will not fit completely on the screen. To avoid this, you can reduce the display width to such an amount that the picture fits completely onto the screen. If you choose 75% for example, the quadratic Meteosat pictures will fit on the screen. Printer width usage: Same as above, for printer output. Since the printer has no limitation on display height, this will be mainly used to reduce picture size. Which colour palette shall be used: You can enter the name of a colour palette here that has been previously defined in the "Show and send pictures" routine. This will only work if your program is configured for a SVGA 256 colour mode. If you enter a palette name here, this palette will be used when receiving pictures. This puts no limitation on the ability to re-colorize the received pictures afterwards. JVFAX 5.0, a FAX program for IBM PCs and compatibles page 23 Execute DOS command: Optionally enter the name of a DOS command to be executed just before the program switches to this mode. The program to be executed should be fast and should not need too much memory. You can terminate the mode editor by pressing <Ctrl>+<Enter>. Please regard that you can only edit one mode at the time, that means that after having edited a mode, before editing another one, you must quit the mode editor and re-invoke it, or nothing will be stored. JVFAX 5.0, a FAX program for IBM PCs and compatibles page 24 D) Date driven FAX reception and E) Edit date files: ==================================================== Date driven FAX reception in connection with the APT makes it possible to selectively receive pictures. For this you must first define a "date file", where all the dates for the pictures to be received will be defined. Dates can be entered as occurring once or daily. Every date file may contain up to 96 dates. To edit a date file, invoke the item "E) Edit date files" from the main menu. A screen like this appears: (JV)-FAX 5.0: date file editor ╒══════════════════════════════════════════════════════════════════════════════╕ │ Select one of the date files below to be modified. │ │ │ │ Press <ENTER> to accept or <F2> to create a new one. │ │ │ │ │ │ │ │ │ │ ╒ C:\JVFAX\*.TIM╕ │ │ │ d2.tim │ │ │ │ hugo.tim │ │ │ │ test.tim │ │ │ ╘═══════════════╛ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ ╘══════════════════════════════════════════════════════════════════════════════╛ Hit <CTRL>+<ENTER> to terminate date editor session If there are already some date files defined then you can choose one of them to be edited. To create a new date file, simply hit <F2>. JVFAX 5.0, a FAX program for IBM PCs and compatibles page 25 Now, the edit screen opens: (JV)-FAX 5.0: date file editor ╒══════════════════════════════════════════════════════════════════════════════╕ │ File being processed: D2 │ │ │ │╒ yy/mm/dd hh:mm ---mode--- dur --APT--- ovp file ═ │ ││ everyday 00:30 3 Meteosat 5 active 2 D2 ▓ │ ││ everyday 00:58 3 Meteosat 5 active 2 D2 │ │ ││ everyday 01:30 3 Meteosat 5 active 2 D2 │ │ ││ everyday 01:58 3 Meteosat 5 active 2 D2 │ │ ││ everyday 02:30 3 Meteosat 5 active 2 D2 │Select entry with ^,v │ ││ everyday 02:58 3 Meteosat 5 active 2 D2 │ │ ││ everyday 03:30 3 Meteosat 5 active 2 D2 │ <─┘ : edit │ ││ everyday 03:58 3 Meteosat 5 active 2 D2 │ <F2>: add/copy │ ││ everyday 04:30 3 Meteosat 5 active 2 D2 │ <F3>: delete entry │ ││ everyday 04:58 3 Meteosat 5 active 2 D2 │ │ ││ everyday 05:30 3 Meteosat 5 active 2 D2 │ │ ││ everyday 05:58 3 Meteosat 5 active 2 D2 │ │ ││ everyday 06:30 3 Meteosat 5 active 2 D2 │ │ ││ everyday 06:58 3 Meteosat 5 active 2 D2 │ │ ││ everyday 07:30 3 Meteosat 5 active 2 D2 │ │ │╘══════════════════════════════════════════════════════ │ │ │ ╘══════════════════════════════════════════════════════════════════════════════╛ Hit <CTRL>+<ENTER> to terminate date editor session Using the cursor keys you can pick one of the dates in order to change it (<Enter>), to copy it (<F2>) or to delete it (<F3>). If there are no dates in the file, use <F2> to add a new date. When adding or changing a date the following entry mask is used: ╒═══════Date editor════════╕ │ Date: / / │ │ Time: 00:30 │ │ │ │ Mode: 3 Meteosat │ │ │ │ APT routine: active │ │ Max. duration: 5 │ │ Time overlap: 2 │ │ Filename: D2 │ │ │ │ Execute DOS command: │ │ │ │ Exit to DOS: no │ ╘══════════════════════════╛ The meaning of the fields is as follows: Date: If this date shall occur only once, you must enter a valid date using the picture "yy/mm/dd". For dates that are to occur daily, all sub fields must be blanked. JVFAX 5.0, a FAX program for IBM PCs and compatibles page 26 Time: Enter the start time of the picture to be received here. This time entry must correspond to your computers time, i.e. if your computer clock is set to UTC, for example, all times must be entered in UTC. Mode: Use +, - or <space> to select the proper mode for this date. APT routine: If you set this field to inactive, acquisition of pictures will start immediately after having reached the time given above, disregarding all APT tones and phasing signals. Acquisition will last for the period given in the Max. duration field. Max. duration: Determines the maximum duration of a picture acquisition. After this time has passed, counting from the reception of an APT start signal (when APT routine is "active") or from the time entered above (when APT routine is "inactive"), acquisition will be terminated anyway, even if no stop signal has been received. Time overlap: If APT routine is "active", an APT start tone has to be detected within this period, or the reception for this date will be cancelled. This field makes possible overlapping dates: If the acquisition of a previous picture will terminate after the time of the following picture has already been reached, the routine will wait until the time entered in the Time: field plus the time given in the time overlap field for the new picture to start before this date will be cancelled. Filename: Enter an filename that will be used for picture storage or to determine to which movie the received picture shall be added. Maximum length of the filename is limited to 5 characters. Execute DOS command: Enter the mane of a program to be executed right before picture acquisition will start. You can use this for example, if you have a receiver that can be remotely set to a specific frequency by your computer. As in the case of the execute DOS command option in the mode editor, the program to be run should be fast and short. Exit to DOS: If you set this field to yes, operation of the JVFAX program will be terminated at the end of the picture acquisition for that date, and control will be give back to DOS. Terminate the date editor with <Ctrl>+<Enter>. JVFAX 5.0, a FAX program for IBM PCs and compatibles page 27 To do date driven FAX reception you must invoke item "D) Date driven FAX reception" from the main menu. First, you must select a date file to be processed: (JV)-FAX 5.0: date driven FAX reception ╒══════════════════════════════════════════════════════════════════════════════╕ │ Select one of the date files below. │ │ │ │ Press <ENTER> to accept. │ │ │ ╘══════════════════════════════════════════════════════════════════════════════╛ ╒ C:\JVFAX\*.TIM╕ │ d2.tim │ │ hugo.tim │ │ test.tim │ ╘═══════════════╛ After having chosen the desired date file, you must tell the program what to do with the received pictures: (JV)-FAX 5.0: date driven FAX reception ╒══════════════════════════════════════════════════════════════════════════════╕ │ │ │ (S)ave, make (M)ovie, (P)rint or (V)iew pictures? (S/P/V/M/<ESC>): │ │ │ │ │ ╘══════════════════════════════════════════════════════════════════════════════╛ If you choose S)ave, the received pictures will be stored as files one by one using the file names given in the date editor, with a numeric extension being added to them. M)ake movie will add the pictures received to the movie file given under "file name" in the date editor. If a movie file contains more pictures than given in the "Maximum # of pictures / movie" field of the miscellaneous menu, the movie will be trimmed to this number minus one, before a new picture will be added. Always the newest pictures will remain in the movie. P)rint works the same way as S)ave, the only difference is that the pictures will be printed instead of being of saved to disk. By choosing V)iew, the pictures will only be displayed on the screen and nothing else will happen. JVFAX 5.0, a FAX program for IBM PCs and compatibles page 28 After having taken your choice you will be back in the main menu (with the exception of V)iew), and you can proceed doing anything with the program like before. (e.g. view movies) As an information that date driven reception is active, an additionally bottom line will appear in the main menu that tells you the actual time, the time of the next date and about what will happen when the next date will be reached. 20 seconds before the next date comes, the program will suspend its current action, switch to receive mode and start picture acquisition. When the transmission has completed, it will return to the previously suspended action. You can invoke the program directly in Date driven reception mode by adding some command line parameters when running the program. For that, start the program this way: JVFAX /DM Filename Filename must be replaced by the name of the date file to be activated. /DM means "Date" to "Movie" and can be replaced by "/DP" (to printer), "/DS" (save to file) or "/DV" (just view). JVFAX 5.0, a FAX program for IBM PCs and compatibles page 29 Show and send pictures ====================== This menu item serves for the viewing and editing of stored pictures. For radio amateurs, there is an additional transmit option. You can do zooms with freely selectable width/height ratio; zoomed portions of a picture can be stored as unique pictures. When invoking this menu item, the following screen appears: ╒══════════════════════════════════════════════════════════════════════════════╕ │ ▀▀██ │ │ ██ ██▀▀▀▀▀ ▄█▀█▄ ██ ██ ██▀▀▀▀ ▄█▀▀▀█▄ │ │ ██ ██ ██ ██ ▄▄▄▄▄▄ ██▄▄▄▄ ██ ██ ▀█▄█▀ ▀▀▀▀█▄ ██ ██ │ │ ▀▀▀▀▀ ██ ██ ██ ██▀▀▀██ ▄█▀ ▀█▄ ▄▄ ██ ▄▄ ██ ██ │ │ ▀█▄ ▄█▀ ▀▀ ▀▀ ▀▀ ▀▀ ▀▀ ▀▀▀▀ ▀▀ ▀▀▀▀▀ │ │ ▀▀▀ │ │ The FAX program for IBM PCs and compatibles (c) DK8JV, 1992 │ ╘══════════════════════════════════════════════════════════════════════════════╛ ╒═══════════ D:\WASSER\*.GIF ═══════════ │ .. <dir> 2/07/92 11:51p ▓ │ afsk.gif 223k 5/18/92 6:40p │ │ d2___001.gif 326k 5/26/92 5:30p │ <F2>: Info │ jvfax044.gif 213k 5/17/92 8:04a │ │ jvfax045.gif 269k 5/17/92 8:08a │ <F3>: Change drive/path │ jvfax046.gif 253k 5/17/92 8:12a │ │ jvfax047.gif 264k 5/17/92 8:15a │ <F4>: Delete file │ jvfax048.gif 272k 5/17/92 8:19a │ │ jvfax049.gif 246k 5/17/92 8:22a │ ╘═══════════════════════════════════════ Select a file with <ENTER>, <ESC> to abort Use the cursor bar to select a picture file. <Enter> will show the picture while <F2> will give some additional information on this file. Use <F3> to change to another drive or to quickly change the directory. JVFAX 5.0, a FAX program for IBM PCs and compatibles page 30 <F4> is to erase files. After hitting the <Enter> key, picture display will start. You can interrupt the building up of the picture on the screen at any time by pressing <Enter> again. Every picture will be displayed in a way that it will fit completely onto the screen. When the picture has been displayed completely or after you have interrupted picture display by hitting <Enter>, a menu line will appear at the bottom of the screen that will inform you about the available options. You can switch on or off that menu line anytime by hitting the space bar. Use E)dit to change picture orientation. Furthermore, you can export the picture in TIF-Format (24 bit, uncompressed) or in GIF87a, if the picture is stored in GIF89a. By using the R)otate option you can shift the picture horizontally. This is useful if phasing did not work properly when the picture was received. Z)oom shows a little frame that can be moved over the screen with the cursor keys. Frame size can be changed with +, -, x or y. Hitting <Enter> will show the framed portion magnified to full screen size. Besides being viewed, this zoomed portion of a picture can be saved or transmitted. JVFAX 5.0 uses the well known GIF format for picture storage. This greatly reduces disk storage requirements. Many GIF viewers or other programs to process GIF pictures are available on the PD and shareware market. If JVFAX is running in 256 colour mode, you can use "Pa(I)ette" to colorize your pictures. Just play around a bit with this option to get a feeling of how it works. JVFAX 5.0, a FAX program for IBM PCs and compatibles page 31 For radio amateurs, there is a transmit option, that can be used to transmit complete pictures or zoomed portions of a picture. When you hit the "A" key, a small menu appears that shows the modes available for transmission. After having chosen the desired mode you can enter some text that will be overlaid to the picture. (Maximum text size is 24 columns * 8 lines) Text entry can be skipped by hitting <Escape>. Terminate text entry with <Ctrl>+<Enter>. After that, a small frame shows the size and position of the text on the picture. Use + or - to resize and cursor keys to reposition. S)tyle changes the appearance of the text. When all looks good, hit <Enter> and the transmission will start. While transmitting, a cursor line shows the proceeding of the transmission process. You can abort transmission by hitting any key. Each transmitted picture is preceded by a small header that contains a grey step, a small program logo and a Callsign within. JVFAX 5.0, a FAX program for IBM PCs and compatibles page 32 MOVIE Options ============= Invoking this item opens a sub menu that has two items: "S) Show movie" and "A) add pictures to a movie". S) Show movie will come up with a file selection menu from which you can choose which movie shall be replayed. To enable a fast display rate when showing movies, JVFAX tries to establish as many RAM buffers as possible in XMS and conventional memory. (EMS memory will not be used yet) If you are running an XMS memory manager such as HIMEM.SYS, you should tell it to provide a sufficient number of XMS handles. In the case of HIMEM.SYS this is done by adding the parameter "/numhandles=99" to the HIMEM.SYS device line in CONFIG.SYS. If you're using HIMEM.SYS, the entry in CONFIG.SYS should look as follows: DEVICE = c:\HIMEM.SYS /numhandles=99 If the /numhandles parameter is omitted, HIMEM.SYS will only provide 32 handles, of which DOS 5.0 will use two in case you're using the "DOS=UMB" option. After having chosen the desired movie, JVFAX will first look if all the pictures in the movie will fit in the buffers. If so, the movie will be loaded and display will start. If not, you will be asked if you want to see all of the pictures in the movie (dynamic reload) or if you prefer to see only the last pictures that will fit in the buffers (fully buffered mode). The dynamic reload mode will be much slower than the fully buffered mode, but on machines with limited RAM memory this is the only choice to watch longer movies. While the movie is being displayed you can change display speed with the "+" and "-" keys. Hitting the "Pause" key will temporarily halt the movie; hit any key to restart it. The actual maximum display rate depends on your PC's speed and in the case of the "dynamic reload mode" on your hard disks speed. If you want to view your movie in false colours this can be done by creating a palette with just the same name as the movie. If present, such a palette will be used. A)dd pictures to movie file enables you to manually create movies. Normally, you will not need this option unless you're planning to create a kind of "slide show". All movie pictures are displayed using a resolution of 640 by 350 dots in 16 colour mode. Since dithering is used, a total of 64 intensity levels will be displayed. This mode is the only one that works on any VGA card. On the other hand you can see that the movie option will not run on graphic cards other than VGA/SVGA. JVFAX 5.0, a FAX program for IBM PCs and compatibles page 33 SSTV ==== This program segment is yet kept very simple. You can choose between 8, 16 and 32 second b/w pictures and 24, 48 or 96 second colour pictures. When in colour SSTV, you can change palette assignment manually in case that the automatic assignment didn't work. You cannot store or re transmit the received pictures. You can watch colour pictures in colour only if you have configured the program for a SVGA 256 colour mode (SSTV-graph.). JVFAX 5.0, a FAX program for IBM PCs and compatibles page 34 Something about FAX transmissions: ================================== Modulation type of transmission: FAX pictures on short-wave and long wave are normally transmitted in FM. That means that the transmitter is keyed between two frequencies of which the one corresponds to white, the other to black. When transmitting half tone pictures, the transmitter frequency is continuously shifted between the frequency for black and the frequency for white. Half the difference between the frequency for white and the frequency for black is called signal deviation. This deviation is, by standard, 400 Hz for short-wave and 150 Hz for long wave transmissions. Furthermore, the higher transmitter frequency should correspond to white. Press stations sometimes use a deviation of 300 Hz, too. Such a modulation can be achieved by direct frequency modulation of a transmitter or by frequency modulating an audio sub carrier (mostly 1900 Hz) and then modulating a SSB transmitter with this sub carrier. On the receiver side, you can use direct frequency demodulation, but this will work only if your receiver demodulator is capable of handling frequencies down to the DC level. More preferably one receives the FAX signals with a SSB receiver that, at it's audio output, delivers a FM-modulated audio sub carrier. (Just the opposite as on the transmitting side) This sub carrier is then fed to the interface that converts the different audio frequencies into digital intensity information that can be processed by the computer. For each distinct intensity level the interface must deliver a binary coded value that computes to (n= number of intensity levels that the interface can deliver) n Intensity := (audio frequency - freq. for black) * ---------------------------------- (freq. for white - freq. for black) JVFAX 5.0, a FAX program for IBM PCs and compatibles page 35 If you are using the comparator type interface, frequency measurement is done by software. The program "counts" the length of the periods of the audio frequency by means of the programmable interval timer that can be found in every PC. Each edge of the audio signal generates an interrupt that invokes a small routine that counts the number of timer ticks that have occurred since the last interrupt. Because interrupt response times can vary significantly, this computation of the audio frequency isn't very precise. That results in some "noise" in the received pictures, where the amount of noise depends on many factors such as processor speed, type of CPU, etc. Running a memory manager such as EMM386 on some machines will result in nearly completely jammed pictures. In such cases, the only solution is to disable the memory manager operation when running JVFAX. The better solution, of course is to use a more sophisticated interface, that frees the computer from the need to measure the audio frequency itself. Polar satellites as well as geostationary satellites are using another modulation method for signal transmission: A FM transmitter is modulated with an audible sub carrier (mostly 2400 Hz), of which the amplitude is modulated by the video signal. That's why this is called AM-FAX. One receives these transmission with a FM receiver. The audio output of the receiver must be rectified to regain the original video signal. This demodulated signal will be fed to an A/D converter that can be connected to the computer. JVFAX 5.0, a FAX program for IBM PCs and compatibles page 36 How the ATC works: ================== The automatic tuning control (ATC) implemented in this program for the reception of FM-FAX has been completely realised by software. The only hardware requirements are that the interface must be able to deliver a signal of which the intensity levels correspond to twice the frequency range of the signal actually received. So, if you want to receive a station transmitting with a deviation of 400 Hz, your interface must be set to 800 Hz deviation. Using the ATC results in the loss of one bit of intensity resolution, i.e. in order to resolve a signal with 64 (6 bits) intensity levels, your interface must be able to deliver at least 128 intensity levels (7 bits). When ATC is on, the program calculates by means of signal averaging the center (audio) frequency of the received signal and assumes, that the actual signal spectrum is within the range of (center frequency +/- deviation of transmitted signal) Frequency drifts up to +/- half the deviation of the transmitted signal will be completely compensated. As long as none of the two small vertical lines appearing below the frequency spectrum display will not reach the left- or rightmost positions, the ATC will be able to compensate frequency drifts. Control characters for interfaces that can be controlled by software ==================================================================== To enable a fully program controlled mode switching of your interface by the program, JVFAX sends, whenever a change in program mode will take place, a control character to the interface. This character indicates to which deviation or mode (AM/FM/SSTV) the interface has to be switched. Each character comes with the 7th bit set. By this, the interface can differentiate between control characters and picture data. List of control characters: 41h: FM, 150 Hz deviation 42h: FM, 300 Hz deviation 43h: FM, 400 Hz deviation 44h: FM, 600 Hz deviation 48h: FM, 800 Hz deviation 45h: AM 46h: SSTV JVFAX 5.0, a FAX program for IBM PCs and compatibles page 37 Interface circuits and availability of interfaces ================================================= Follows a list of addresses known to me in Germany where interfaces or kits are available. This list might be incomplete, and the ordering of the addresses does not' tell anything about the quality of the interfaces offered. All these interfaces should co-operate with JVFAX, but I cannot guarantee for that. PCBs and kits from DL5JM: Achim Kündahl, DL5JM in Wetter, has PCBs and kits for both the 16 grey scale and 64 grey scale interfaces that I developed. His address: Achim Kündahl DL5JM Grünewalder Str. 21 5802 Wetter 2 Tel.: 02335/60572 "Easyfax" kit from Ulrich Bangert, DF6JB: Ulrich developed a µP-based interface that is easy to assemble and that needs no alignment. It can handle up to 256 grey scales, AM and FM FAX as well as SSTV. The interface is offered as a complete kit including a reassembled case and can be easily updated by EPROM exchange. Ulrichs address: Ulrich Bangert DF6JB Weddigenstr. 28 5600 Wuppertal 22 Tel.: 0202/602537 JVFAX 5.0, a FAX program for IBM PCs and compatibles page 38 Both Achim and Ulrich are working on an extension of their interfaces for transmit operation. "MMI" by C-Data: This interface should co-operate with JVFAX, too. However, C-data offers a FAX program of their own for this interface. Address: C-Data Hohenwarter Str. 6 8068 Pfaffenhofen Tel.: 08441/6145 "DK8JV-FAX-Konverter" by NSK: A 64 grey scale interface foe AM and FM FAX Address: Ingenieurbüro für Satellitentechnik Dipl.-Ing. B. Ewert Mühlenweg 11 2306 Stakendorf Tel.: 04344/6758 "Processor-FAX-Konverter PFC1" 64 grey scale FM-interface, available from Fa. VHT-Impex Bredenstr. 45 4904 Enger Tel.: 05224/7279 JVFAX 5.0, a FAX program for IBM PCs and compatibles page 39 "Meteosat-Empfangs-Set" Complete rig for the reception of geostationary weather satellites such as Meteosat, including receiver, antenna and interface. available from Fa. Bogerfunk Funkanlagen GmbH Grundesch 15 7960 Aulendorf Tel.: 07525/451 "WX-Satelliten-Empfänger MR-9202" A 137-Mhz receiver for polar orbiting satellites with a built in interface. available from: Volker Wraase Elektronik Kronsberg 10 2300 Altenholz/Kiel Tel.: 0431/32528 You can get photocopies of the schematics for the two interface types that I developed my own by sending a SAE and two IRCs to my address. My address can be found at the end of this document. JVFAX 5.0, a FAX program for IBM PCs and compatibles page 40 Here follows the circuit of the "simplest" comparator type interface, that requires only a few parts, but doesn't give superior performance. You can use the "Hamcomm" interface (see below) as well. RS232 Pins (25-pin receptacle) 100 nF 741 ┌─────────────O RTS 4 ││ 3 │\ │7 O─────┤├───█─────────┤+\│ ││ │ │ \ 6 AF in │ │ >────────────O DSR 6 │ 2 │ / O───┐ │ ┌────┤-/│ │ │ │ │/ │4 ─┴─ ┌┴┐ │ └─────────────O DTR 20 │ │ ─┴─ 47k │ │ └┬┘ │ ┌─────────────O GND 7 ─┴─ ─┴─ The 741 operates as a limiting amplifier with full free-run amplification. It forms the audio frequency to a rectangular wave form with RS232 compatible level. Power is supplied from the computer via DTR (-) and RTS (+). A similar circuit, known as "Hamcomm modem" is available from Dieter Dippel, DF4RD Fenitzerstr. 33 8500 Nürnberg 20 Tel.: 0911/559296 (after 18:00h) JVFAX 5.0, a FAX program for IBM PCs and compatibles page 41 Some SVGA modes: ================ To facilitate the configuration of JVFAX to your specific graphic card, here the register values for some SVGA cards: XP means dots per line, YP lines per picture and ASP screen aspect ratio. A): 16 colour modes: AH AL BH BL XP YP ASP GENOA Super-EGA Hires 0 79h 0 0 800 600 10000 SAMPO-Mira VGA (Taiwan) 0 64h 0 0 800 600 10000 ATI-VGAWONDER 0 54h 0 0 800 600 10000 " " 0 53h 0 0 800 560 10714 ELT VGA PLUS 16 0 58h 0 0 800 600 10000 Paradise Professional VGA 0 58h 0 0 800 600 10000 VIDEO 7 FASTWRITE 6Fh 05h 0 62h 800 600 10000 (and other Video- 6Fh 05h 0 61h 720 540 10000 seven/VEGA cards) 6Fh 05h 0 60h 752 410 13756 EIZO MDB10 0 29h 0 0 800 600 10000 MVGA/TVGA 0 5Bh 0 0 800 600 10000 JVFAX 5.0, a FAX program for IBM PCs and compatibles page 42 B) 256 colour modes: Chipset AH AL BH BL XP YP ASP TSVGA ET4000 0 30h 0 0 800 600 10000 (and others ET4000 " 0 2Eh 0 0 640 480 10000 based cards) " 0 38h 0 0 1024 768 10000 VIDEO 7 FASTWRITE Video seven 6Fh 05h 0 67h 640 480 10000 (and other Video- " 6Fh 05h 0 69h 800 600 10000 seven/VEGA cards) Paradise Profess. Paradise 0 5Fh 0 0 640 480 10000 " " " 0 5Ch 0 0 800 600 10000 Cards with Trident Trident 0 5Dh 0 0 640 800 10000 chipset (TVGA, " 0 5Eh 0 0 800 600 10000 MVGA...) " 0 62h 0 0 1024 768 10000 Genoa cards Genoa 0 5Ch 0 0 640 480 10000 " 0 5Eh 0 0 800 600 10000 Cards with OAK OAK 067 0 53h 0 0 640 480 10000 chipset " 0 54h 0 0 800 600 10000 VESA VESA 4fh 02h 01h*) 01h*) 640*) 480*) 10000 " 4fh 02h 01h*) 03h*) 800*) 600*) 10000 *)for further VESA modes see manual of your graphics card. The VESA mode number is always entered in the register pair BHBL. JVFAX 5.0, a FAX program for IBM PCs and compatibles page 43 Frequencies, reception etc. =========================== Frequencies of some FAX stations: Freq.(kHz) Stn. LPM MOD HUB remarks ----------------------------------------------------------------- 117,4 DCF37 (DWD) 120 576 150 charts (Air) 134,2 DCF54 (DWD) 120 576 150 charts/Meteosat 3855,0 DDH3 (DWD) 120 576 400 charts (ship) 4782,0 GFE21 (Bracknell) 120 576 400 charts 7880,0 DDK3 (DWD) 120 576 400 charts (ship) 144,700 MHz radio amateur FAX transmissions Just for example. Please be aware that in many cases the reception of commercial services is not free and that you must be authorised by these services to receive their transmissions. However, the reception of most weather chart transmitters as well as the reception of the polar orbiting satellites (NOAA and METEOR) is free. FM-FAX transmissions should be received using a SSB-receiver in upper sideband position. Normally you will have to tune in a frequency that is 1.9 kHz below the frequency given in frequency lists. This does not apply, if your receiver has a special "FAX" reception mode. In that case, simply tune in the frequency listed. Since the accuracy of the frequency display on many receivers is not too high, you will eventually have to do some fine tuning before you will obtain satisfying results. A problem arises when receiving FAX transmissions with a receiver that can only be tuned in coarse frequency steps such as 100 Hz. Using the ATC facility of the JVFAX program could be a solution on this. JVFAX 5.0, a FAX program for IBM PCs and compatibles page 44 Tuning in a weather chart station is not difficult when you keep in mind that most parts of such a chart are white. Favourably you first tune in a frequency somewhat higher than the correct one, (this results in lower audio frequencies) and then decrease the receiving frequency slowly until the spectral maximum shown in the tuning indicator just reaches the right margin. AM-FAX transmissions must be received using a FM receiver. In AM-FAX, a FM transmitter is modulated with an AM modulated sub carrier. (mostly 2400Hz) The amplitude of this AM sub carrier contains the intensity information of the picture. Use your receiver's AF volume knob to optimise picture contrast. JVFAX 5.0, a FAX program for IBM PCs and compatibles page 45 Copyright notes etc. ==================== This program is neither shareware nor public domain. JVFAX is the Copyright property of Eberhard Backeshoff, DK8JV. (c) 1992 by Eberhard Backeshoff, Obschwarzbach 40a, D-4020 Mettmann, Germany. You have the right to use this program for non commercial purposes without further permission. You can copy it and share it as long as you don't charge any money for it other than the cost for the transfer media, not exceeding the equivalent of $4. Any commercial distribution without the w r i t t e n p e r m i s s i o n of the author is strictly prohibited. If you like this program you should register your copy to be kept informed of new releases of this software. Enclosing an amount of money at choice to support program development will be highly appreciated. Send your registration to the above address. The Graphics Interchange Format(c) is the Copyright property of CompuServe Incorporated. GIF(sm) is a Service Mark property of CompuServe Incorporated. When copying the program the following files must be included: JVFAX.EXE (programm) JVFAX.DOC (German documentation) ENGLISH.DOC (English documentation) D2.TIM (Sample file for date driven FAX reception) The programs must not be modified in any way, copyright notes must not be removed. Any commercial use of this program as well as a distribution of this program by shareware dealers is prohibited. Distribution via mailboxes and computer networks is free as long as the files mentioned above will remain complete. The name "JVFAX" should be maintained in case the files are packed to an archive. Companies and single persons who want to sell hardware that co-operates with this program are allowed to distribute the program together with their hardware, if they get my written permission. I reserve to charge fees, e.g. on a per disk base in such cases. When giving this software as an add-on to some hardware, it must be clearly pointed out by the seller that having got the software when purchasing the hardware doesn't mean that anything has been paid for the software. Program users be aware that the acquisition of this program together with some hardware doesn't mean that you have bought it. Even in such a case all copyright notices given above are fully valid. JVFAX 5.0, a FAX program for IBM PCs and compatibles page 46 As you can see from the above notes, you don't have to pay anything to get or use this program. However, if you should like this program and should use it frequently then you should consider to promote the authors eagerness for further program development by some kind of acknowledgement. Suggestions and criticism are always welcome, but I cannot promise any further development of this program, since I have to do it all in my leisure time. I will do my best to keep this program up to date, but my family has the higher priority. Anyone who has paid some amount of money as an acknowledgement will be informed about new releases of this program. Let me say thank you to the numerous persons that with their suggestions and criticism made the program be what it is today. Finally, have fun using this program and always good pictures. For further questions, you can contact me via phone, but please use this only in "cases of emergency"; my family will appreciate that. Mettmann, June 1992 Eberhard Backeshoff DK8JV Obschwarzbach 40a D-4020 Mettmann Germany Phone: (49) 2058/4684 (please only between 1800 and 1900 CET)