Operating FAX To operate FAX, you must press either the WFAX or the NFAX buttons. The HAM screen will be closed, and a 640x400, 16 grey level screen will be opened. If the Amiga you are using has more than 1 megabyte of memory, the AVT system will attempt to allocate a BIG memory for use with the FAX images. This memory consumes about 615k bytes. Yes, 615 THOUSAND bytes. This is because FAX images are extremely high resolution, at least compared to the images we are used to working with in desktop systems like the Amiga. If you have 1 megabyte of memory (like the base a2000 does, or a nominally expanded a500) A second screen will be opened. This screen is also 640x400, but is 4 luma levels. Black, two grey levels, and white. This secondary screen is displayed while FAX reception goes on, so that the system will have enough CPU "horsepower" to get the job done. When a 640x400 screen is displayed, a 1 meg a2000 or a500 runs about 50% slower, and so if we left the normal screen showing during receive, the routines that handle the FAX reception would not be able to get everything done in the time available. Once the image is in the system, you can manipulate the screens as you see fit, of course - this restriction only applies during receive. In general, select the 1/3 button (the default, anyway) before receiving a FAX image. This means that the system will receive 1200 lines of video - and every 3rd one will be drawn on the screen while receiving. This is the only way to receive a full fax image on a 1 megabyte machine. If you select the 1/2 button, every second line will be shown, and only 800 lines will be recieved. If you select the 1/1 button, every line will be shown, and only 400 lines wil be received. The filter button (explained in the file 'Scope.doc') does affect FAX reception. In order to receive a FAX image, you simply press the RX button, and the system will then go into a search mode where it is looking for a start signal from the station transmitting fax. When this signal is heard by the system, "phasing" pulses from the transmitting FAX station are utilized to effect a clean alignment of the incoming FAX image at the left edge of the display. When the system is waiting for the start signal, a red dot (if your preferences colors are still set for a red arrow) will appear in the "busy" pointer. Once a start signal is detected, the red center dot will change to two dots, and this is an indication that you are in phasing-lockup mode, as just described. If you have missed the start signal, simply press the left mouse button once, quickly, and the system will be forced to enter the phasing-lockup mode. This mode looks for the white bar at the left edge that is sent at the beginning of each FAX image, and uses it to align the image with the left edge of the display, and of course the FAX memory, if available. If you have also so missed the phasing pulses, or the system misses them due to noise or interference, press the left mouse button once more. The actual image will begin coming in immediately. It will very likely NOT be aligned correctly, however - in order to accomplish this, press the left mouse button once again, quickly. Note that the information now coming in has "slid" to the left. FAX images always start with a "phasing" period, which is a short time (10-20 seconds) when the video being sent consists of a short white area and then all black. If you are catching a fax image from this phasing period near the beginning, and believe it is too noisy for the system to phase properly (you'll get a "feel" for this after a while) tap the left mouse button until this white phasing pulse is aligned to the left edge of the screen. It's more difficult to align a FAX image if you caught it in the middle somewhere, but with practice, you'll be able to do it. If you hold the left mouse button for about 4-8 scan line times, the receive will abort completely. Likewise, if the system is waiting for a new FAX image, and you hold the left button for a few seconds instead of simply tapping it, the system will completely abort the receive mode and return to the control panel. Once the FAX image has been received, IF you have the fax memory allocated, you can pan around it by using the cursor keys on the keyboard. 1 Megabyte machines will not be able to pan, as there is not enough memory to store the fax image (this takes 614,400 bytes, as mentioned previously). FAX control window In addition, for users with 1.5 meg of memory or more, there is a window with PAN and other controls available if you click "on" the scope display. The controls in this window work as follows: The four diagonal arrows move you to the four corners of the image, respectively. The center of this group of controls moves you to the center of the image. The text gadgets can be used to pan to any location in the image by simply typing in the X and/or Y co-ordinates that you wish to be located at the upper left of the display. The LED simulations indicate the current position. The left-right arrow button flips the image horizontally; The up-down arrow flips it vertically, and the curved arrow rotates the image 90 degrees. The four non-diagonal arrows move you around the image - if you press the center gadget, they go further with each press. The ALL gadget redraws the FAX memories into one 640x400 screen again. It takes a little while, so be patient. This is the gadget to use if you want to save a standard sized IFF image of the entire area you received. The blue gadget with the "N" inside it changes the image into a negative of itself. This would be useful if you catch an image using the wrong sideband - that makes an image dark in light areas and vice-versa. The Negative function will reverse this for you. It is also handy when used on weather maps - sometimes they look nicer as white lines on black. This function is reversable - that is, do it once, you have a negative. Do it twice, you have the original back again. The blue gadget with the "T" inside it is the THRESHOLD limit control. This is intended for use with pure black and white images such as weather maps, which are often only black and white - that is, they contain no intermediate grey levels. At least, they aren't SENT with any. Unfortunately, things being what they are, a fax map will often have intermediate grey levels in it where they don't belong. The threshhold gadget takes all the pixels that are above middle grey, and makes them white. All those that are below middle grey, it makes black. Congratulations - you just changed a high definition image to a low definition image! Seriously, there are times when it's useful. When you try this out, we suggest that you SAVE the fax map before you threshold it - the operation is not reversable, and truly does remove a great deal of information. It's worth the time it takes to save the image to ensure that some of the information you lose isn't something you actually wanted. There is a gadget that has a yellow arrow pointing to the left, at a vertical purple line. This is the fax realignment gadget. It is used after you have received a fax image that is NOT correctly aligned to the left edge. If you get an image like this, for whatever reason, you can cause it to be re-aligned within 8 pixels by using the following proceedure. If the image is full-screen, as it was just received, you are ready to try this. If not, you must press the "ALL" gadget and wait for the screen to be completely re-drawn as a full screen image before you start. Normally, you notice a misalignment right away after an image is received, so you would not normally have to wait for this. In any case, once the image is full screen you can proceed. Simply press the re-alignment gadget, and the control panel will become hidden, and the FAX screen will come to the front. Move the pointer so that it is directly over the horizontal position in the image you want to become the left edge - you can usually tell where this is, easily. Click the left button once. The pointer changes to the BUSY indicator, and you must wait a few seconds. After a short while, the screen will be re-drawn in the magnify mode, and the left edge will be aligned as specified. FAX controls available directly at the keyboard: Cursor Keys: Pan around image F6: Flip Image Horizontally F7: Flip Image Vertically F8: Rotate Image 90 degrees, with flip (takes about 90 seconds, be patient) Saving FAX images You can save IFF, which saves a 640x400 bw screen, or you can (again, only if the fax memory was allocated) save the actual FAX image, by selecting the appropriate option from the menu. If you go back to sstv mode without saving the FAX image (by pressing any SSTV mode button) then the fax image will be lost. FAX stations you may be interested in: Freq: Demod: Mode: Type: 7933 LSB NFAX News 8078 USB WFAX Weather maps, geosynchronous earthsat images 8168 LSB NFAX News 10680 LSB NFAX News 10863 USB WFAX Weather - same as 8078 12742 USB NFAX Japanese marine information; maps, Katakana text 13582 LSB NFAX News 13755 LSB NFAX News 17069 LSB NFAX News 17674 LSB NFAX News 18435 LSB NFAX News 20738 LSB NFAX News Russian text, newsfax! (Manual start only) 21722 LSB NFAX News FAX on Amateur Radio: You can run FAX, any speed, on the ham bands, mostly. Check the band plan, of course, but in general, it's legal. Keep in mind though, that there is on FAX, like every other mode, a requirement that you ID by CW or Voice. Naturally, the AVT can do either one for you. Use the third menu to control these options. The WFAX mode can be fully utilized, as the 1024 by 1200 image takes exactly 10 minutes to transmit. just be certain to ID before and after the transmission, so as to stay legal. We strongly suggest you at least use the "CW After TX" selection to ensure your compliance with this very important rule. Also keep in mind that any continuous duty mode like FAX or RTTY can place a very heavy strain on a transmitter if it was not specifically designed for this type of operation. Consult your transceiver's manual for details on how long, and at what amount of input/output power, you can use your transceiver at 100% duty cycle. Some radios, like the Kenwood TS440s, can run for up to an hour at full rated power with no problems. Others can not - and will blow fuses or finals, so CHECK IT OUT FIRST! Special command line operations There are four keywords that can be used from either the CLI or the Workbench. They are primarily designed to be utilized from the CLI, however. These keywords are: wfax, nfax, phase, and start. if you enter either of the keywords wfax or nfax, when the program starts it will go directly to that mode as soon as it has initialized properly. This is useful for those of you who mostly plan to operate fax. The start key word is only recognized when used with one of the other two keywords (wfax or nfax). The "start" keyword causes the program to immediately enter the start-pulse search mode. This is extremely useful if you want to have the Amiga automatically capture a particular map for you and you're not going to be around at the time. It's kind of like a VCR's timer control. The phase keyword tells the AVT that you do NOT want the system to look for start pulses, but rather to go directly into the phasing search state when the system begins reception of a fax signal. You can set this up manually in the program as well, by entering the SET window and pressing the phase button. If you are looping reception of a news fax station, this is important, because they don't SEND a start signal, and so the program will not restart when a new image comes in unless you have the phase button selected, or you supplied the approprate option in the tooltypes (For WorkBench users) or the CLI's command line. Here's how it works: You make a very small execute file called fx (or whatever you like), using ED or another editor, that reads as follows: Wait UNTIL 20:28 AVT_Master wfax start you run this by typing: execute fx What this does is causes your amiga to wait until 8:30 pm, your local time, and then start the AVT_Master program, which then goes right into receive mode in weather fax (120 lpm). The presumption here is that a map or satellite image is to be broadcast at this time and you want to catch it. This little batch file will take care of that for you! If this was a news station, which, in general, do NOT send a "start" signal, then you would also use the "" keyword. This tells the AVT system to bypass the search for a start signal and go directly into the phasing mode. The batch file might then look like this: Wait UNTIL 20:28 AVT_Master nfax start  There is one additional feature built in here; When the fax modes are started from the CLI or the WB in this fashion, they are on automatic for ONE image only. Once that image has been receieved, the AVT_Master software will exit the fax receive mode and wait for your next MANUAL command. After the first image, the effect of both the start and phase keywords is cancelled, and the system operates as usual in FAX mode. This is in sharp contrast to what the system does if you initiate fax receive manually - it won't come out of receive until you actually press the left mouse button, so successive images just scan over the previously existing images.