Van : PA3EJU Aan : SSTV @NLDNET Datum/tijd : 22-Mrt 14:12 - Verzonden op: 22-Mrt 12:33 Type/status : BX - Bericht nr : 219863 Onderwerp : INFO MMSSTV versie 20 ------------------------------------------------------------------------------ De nieuwe versies van dit perfect werkende SSTV programma voor Windows en soundcard volgen elkaar in snel tempo op. Ditmaal heeft de auteur JE3HHT werkelijk zijn best gedaan om de frequentie afstemming in het waterval scherm te verbeteren, hetgeen hem goed gelukt is. Zie bijgaande beschrijving voor details betreffende installatie en nuttige tips t.a.v. het operationele gedeelte. Disclaimer: Het downloaden van de 7Plus filetjes uit uw BBS is uw eigen keuze. Er is dus geen enkele verplichting om dit programma te downloaden en/of te gebruiken. Succes, best 73, Andr‚ PA3EJU@PI8WNO Basic operations of MMSSTV Version 0.18 - March 18, 2001 by JE3HHT Makoto Mori Translated into English by JA7UDE Nobuyuki Oba =================================== Revision history Version 0.19 -> Version 0.20 =================================== * Fixed FFT gain bug. * Fixed some bugs and applied some improvements. ======== Preface ======== This program is for transmitting and receiving SSTV using a PC soundcard. I was making a utility to adjust the soundcard clock for PSK31 programs. However, I have changed my mind, and the utility has eventually become an SSTV program. I have made no SSTV QSO so far; I am not sure whether this program works well not. ======================== Uninstall MMSSTV ======================== MMSSTV does not touch the Windows registry. So, delete the entire directory where MMSSTV is installed. ======== System requirement ======== OS: Windows 95, 98, 98SE, ME, NT, 2000 Soundcard: 16-bit 11025Hz or 22050Hz Video adaptor: 256 or more colors (16- or 24-bit video adaptor is recommended) RAM: 32MB or more I managed to run MMSSTV on my old PC with a Pentium 100MHz, but I recommend a faster CPU. The operation speed of MMSSTV is highly dependent on the performance of the video adaptor. In other words, even if two PCs have the same CPU, they should give different performance in accordance with the equipped video adaptor. In particular, the 256-color video adaptor is likely to consume more CPU Power for the pallet calculation. For this reason, a 16- or 24-bit color Adaptor is strongly recommended. If a 256-color video adaptor is used, the displayed colors are affected by the performance of the pallet calculation. To save the CPU power, try the following steps. - Increase the buffer size of the soundcard (select Option, select the Misc tab, and increase the value in the sound buffer size) - Disable the RxBPF (select Option, select the RX tab, and check RxBPF OFF) - Disable the FFT display (select View and turn off the FFT display) - Decrease the order number of the PLL OutLPF (select Option, select the RX tab, and decrease the number in the order of OutLPF) - Choose RX buffer FILE or turn it off (select Option, select the RX tab, and check NONE or FILE in the RX buffer pane) - Turn the TX BPF off (select Option, select TX tab, and uncheck Tx BPF) The RX buffer temporarily stores the receiving or just received image to get it back to the RX window after adjusting the slant and phase. The buffer stores 270-second sound data, and therefore it would cause page swapping if the RAM is selected or if the physical memory size of your PC is not sufficient to keep the data on the memory. If you have intermittent halts during the receive operation, please select FILE or turn it off. ======== PC and radio hookup ======== You can use the same interface of MMTTY for MMSSTV. Refer to the MMTTY help. ======== PTT ======== You can use the same interface of MMTTY for MMSSTV. Refer to the MMTTY help. ======== SSTV modes ======== MMSSTV supports the following SSTV modes. Mode Duration (sec) Lines Method Robot 36 36 240 Color differentiation Robot 72 72 240 Color differentiation AVT 90 90 240 RGB (no synchronization pulse involved) Scottie 1 110 256 RGB Scottie 2 71 256 RGB Scottie DX 269 256 RGB Martin 1 114 256 RGB Martin 2 58 256 RGB SC2-180 182 256 RGB As far as I know, all the domestic SSTV QSOs in JA are made in the Scottie 1 mode. In US, Scottie 1 and 2 are commonly used. In EU, Martin 1 and 2 are commonly used. ======== SSTV operating frequencies ======== In JA, the most active frequency is 7.033 MHz LSB. The common frequencies in the world are: 14.230, 21.340, and 28.680 MHz USB. Needless to say, they are not for SSTV exclusive. ======== Receive SSTV ======== (1) Tone frequency SSTV's tone frequencies are defined as follows: Synchronization pulse 1200 Hz Low level of the image 1500 Hz High level of the image 2300 Hz There are four marker lines in the spectrum window of MMSSTV. From left to right: Green line 1200Hz Synchronization pulse Yellow line 1500Hz Low level of the image Yellow dotted line 1900Hz Center level of the image Yellow line 2300Hz High level of the image To tune the frequency, make the signal energy be laid between the 1500Hz and 2300Hz marker lines. Alternatively, you can tune the receiver so that the synchronization pulses are on the 1200Hz marker line. However, the synchronization pulse is very short, so it would take time for you to get used to adjusting the frequency in this way. Since SSTV QSOs are made on the fixed common frequencies, you probably do not have difficulty in tuning the radio after you have done once. (2) Automatic start When the Auto button in the RX mode pane is depressed, MMSSTV automatically starts the receive operation in response to the start trigger signal. The start trigger signal is called VIS signal, which consists of the 1200MHz marker signal and the SSTV mode code (1100Hz and 1300Hz FSK). MMSSTV detects the signal by using a resonant FSK demodulator, and automatically starts the receive operation if it finds the mode supported. To automatically start receiving, MMSSTV provides another method, which measures the interval time of the synchronization pulses. If you do not want to use this method, go to Option, select RX tab and choose 'VIS only' in the auto start option. * Squelch Four levels (Lowest, Lower, Higher, and Highest) for the trigger threshold can be selected. Lowest makes MMSSTV trigger with the weakest signal. Highest makes MMSSTV trigger with the strongest signal. In other words, only the strong signal can kick off the receive operation. (3) Manual start In case MMTTY does not automatically start receiving or you want to start receiving not from the beginning, push one of the mode buttons below the Auto button. In JA, HL, and US, try Scottie 1. In EU, try Martin 1. (4) Automatic stop, restart and resync When the auto stop in the RX window of the Setup MMSSTV is checked, MMSSTV automatically stops receiving in case it has lost the synchronization signal (this does not work in AVT90). When the auto start in the RX window of the Setup MMSSTV is checked, MMSSTV restarts the receiving from the beginning in case it detects the VIS signal even during the receive operation. It should be noted, however, that MMSSTV would not be able to detect the VIS signal because of the RxBPF effect. When the auto resync box in the RX window of MMSSTV Setup is checked, MMSSTV automatically attempts to re-synchronize the RX image. This is useful if the MMSSTV has lost the synchronization during RX. However, a couple of lines are displayed with the old synchronization timing and therefore they might appear as a thin belt. (5) Slant adjustment (manual operation) MMSSTV measures the SSTV signal timing with the soundcard clock. If the soundcard clock is not correctly calibrated, you could have a slanted image. If you have a slanted image, click the Sync tab of the main window and do the following procedure. 1) Push Slant button 2) Click the upper right edge of the synchronization signal (white line) 3) Click the lower right edge of the synchronization signal (same white line) The synchronization signal is displayed in a relatively fat line, so you must click the same side. Immediately after you click once on the line, a guide cursor is displayed. Adjust the cursor in parallel with the synchronization signal line, and click again. According to this procedure, MMSSTV recalculates the sampling clock of the soundcard and adjusts the receiving or just received image. If you do not obtain the acceptable result, repeat the procedure. When you have obtained the successful adjustment and want to use it as the default frequency, push the Mem button; otherwise MMSSTV applies the adjustment to the current image only. * If you have a very slanted image with the default sampling frequency, try changing the source of the soundcard to Stereo (Left or Right) in the Misc page of the Setup window. Some soundcards have different sampling frequencies in Monaural and Stereo settings. * If you turn the RX buffer off, you cannot redraw the picture after adjusting the slant. (6) Slant adjustment (automatic) Although you have the sampling frequency accurately calibrated, he or she might not have it done so. To facilitate the slant adjustment, MMSSTV has an automatic slant adjustment function. To activate this function: Check "Auto slant" in the RX window of Setup MMSSTV option, or Right click the RX image window and check Auto slant adjustment. It should be noted, however, that this function will not always give a satisfactory result when you have multi-path or QRM, which causes jitters in the synchronization. Unless you push the Mem button in the Sync window, the sampling frequency, which was automatically adjusted, is applied only to the current image. Therefore, even if you leave the automatic slant adjustment turned on, your calibrated sampling frequency is not changed. * The automatic slant adjustment can be used only if the receive buffer is turned on. (7) Fine tune of the synchronization point MMSSTV automatically gets the receive operation synchronized with the transmitted image except in case of AVT90. However, it at times fails to do so in very bad conditions. You should immediately become aware of such a condition because the image is ill colored. If you are aware of the case, try the procedure below: 1) Push Sync tab of the main window. 2) Push Phase button. 3) Click the left edge of the synchronization line (fat white line). MMSSTV arranges the image so that the clicked point becomes the leftmost position of the image window. If you do not get it right position, repeat the procedure. AVT90 does not have the synchronization signal in the image data. For this reason, you will see only a monochrome image in the Sync window. You can click one of the gaps (there are three gaps). * If you turn the RX buffer off, you cannot redraw the picture after you adjust the phase. ======== Receive history ======== MMSSTV can store up to 32 received images in default. To increase or decrease this number, click Option, select Setup, click Misc tab, and change the value in the History max box. If the number of stored images would exceed the specified value, the oldest image is erased in an FIFO manner. It should be noted that one image requires about 200KB disk space, and thus 256 images require about 50MB. Pay attention to the disk space of your PC. To reduce the disk space, you could use the JPEG format. Click the picture with the right button of your mouse and select Use JPEG format in the pop-up menu. The RX history is only used for a temporary buffer. The old pictures will automatically be deleted. If you want to keep them, right click and check the auto copy to another folder. With this automatic copy function turned on, MMSSTV records the index into the QSL field of the log so that it can retrieve the picture later. To manually copy the history picture to another folder, drag and drop the picture in the history window to the QSL box in the log window. To use this function, you must define the name of the target folder in advance. MMSSTV automatically records the index in the QSL field of the log, either if the auto copy is turned on or if the history image is dropped in the QSL box. Using the MMSSTV log facility, you anytime can refer to the image by pressing the Image button. ======== Transmit SSTV ======== To transmit an SSTV image, click TX tab of the main window. The image you have there is transmitted (What You See is What You Transmit). Adjust the mic gain appropriately. ***** DO NOT USE SPEECH PROCESSOR ***** (1) TX image preparation The are several ways to prepare the TX image. 1. Drag&drop an image from the stocked pictures gallery at the bottom in the main window to the TX window. 2. Drag&drop an image from the thumbnail window of the folder (View -> Always show thumbnails of files foler) to the TX window. 3. Drag&drop an image from Windows file manager (Explorer) to the TX window. 4. Drag&drop an image from another image manipulation tool that supports Drag&drop to the TX window. 5. Copy&paste an image from another image manipulation tool to the TX window through the Windows clipboard. You can make the TX image superimposed with a template. The template operation is explained in the later section of this document. Click the TX image with the right button of the mouse to get a pop-up menu that facilitates image manipulations, such as file load and save. Drag&drop from Internet Explore is also supported. (2) Mode selection Select the SSTV mode. * If you uncheck "SSTV mode fixed" in the TX page of MMSSTV Setup option, MMSSTV automatically uses the SSTV mode that was used by the most recently received RX image. (3) Transmission Push the TX button at the left bottom of the window to start transmission. The horizontal marker line moves from top to bottom as the image is transmitted. MMSSTV automatically returns to RX after it completes the transmission. If you want to abort the transmission, push the TX button again. MMSSTV has a 12-second sound buffer, which should be big enough in the normal environment. If your PC is not powerful, you had better not do other operations during the transmission. If MMSSTV has lost the timing during TX, it shows a caution message after the TX completion. In this particular case, you might be able to solve this problem by increasing the number of buffers in the Misc page of the Setup window. (4) Adjustment of the slant of the TX image Some soundcards (especially PCI form factors') have slightly different frequencies for recording and playing. In this particular case, even if you have correctly adjusted the clock in RX, you would have a slant image in TX. MMSSTV has a means to adjust the soundcard clock for TX and RX independently. Refer to the Soundcard section at the end of this document for details. (5) Tune button and CWID For repeaters in US, MMSSTV has a tone generator. Push the Tune button to transmit a 1750Hz tone. You can send a CWID after the TX completion. Check the CWID box in the TX of the Setup window. This is for a European friend of mine. ======== Template ======== Using a template, you can make a simple picture, which is superimposed to the TX image. For example, you can use a macro command that puts his/her callsign on the TX image. MMSSTV provides primitive image-manipulation functions, but has no support for the group operations now. Make picture items using the tool buttons at the bottom of the window. - Arrow button Turn on/off the selection mode - Line button Draw line - Square button Draw rectangle - Shaded square button Draw rectangle with color pasted - T button Draw text - Picture button Insert picture or history image - Color bar button Draw color bar - Scissors button Cut the item - Paste button Paste the item - Color palette button Change the color - L button Change the property of the selected item - f button Change the font To use a macro text, for example, push T button and then click the point in the window where the text is placed. The text input dialog box is displayed. Push Macro button and select %c to place his/her callsign there. To move the item, push Arrow button and use drag&drop it. Here I do not cover all the operations, but they are similar to the DRAW software. Give it a try by yourself. * You can use drag&drop to copy an image (BMP or JPG) from a file manager (e.g., Explorer) to the template box. * The sample templates included in the installer would have small characters. This is because I use large fonts in my PC. ====== Superimpose the template over the TX image ====== When you use a template, MMSSTV superimposes all the colors except a transparent one in the template over the TX image. The default transparent color is defined at the bottom right position of the template window. You can change the position by right clicking at the arbitrary spot of the window. However, you must click the spot which no template item resides in. Special care should be taken if you place a template item at the bottom left of the window. You can use any color as the transparent (background) color, but you must choose the color that you do not use in the template. However, a color bar and an image are the exceptions. In other words, you even can choose a color that is used in a color bar or an image as a transparent one. If you want to create or edit the TX picture during the QSO, I would recommend you use other editing software programs, which have excellent capability in manipulating images. The template of MMSSTV is supposed to offer the macro functions, such as his/her callsign, RSV report, and contest numbers. Therefore, you would not find good reason to use templates if you do not use the logging function. ======== Stock area ======== MMSSTV has a stock area that stores up to 300 images. Each stocked image has the image data and the template information. To manipulate the clipboard, save and load files, click the stock image with the right button of the mouse. You will have a popup menu. To save the disk space, you can use the JPEG format for the stocked images. Right click the image and select Use JPEG format in the pop-up menu. It is a good idea to make a template picture in association with the TX image in advance. The stocked area can store the images and the templates independently. However, if you use drag&drop to copy the stock image to the TX window, MMSSTV copies the associated template, too. This is effective only if the Show superimposed templates box is checked. If the box is not checked, MMSSTV copies the image and the template independently. The following table shows how MMSSTV performs the drag&drop operation. [Show superimposed templates ON] From To Action ------------------------------------------------------------------------------- Stocked image TX window Copy the image and template Stocked template Template window Copy the template only TX window Stocked image Copy the image and template Template window Stocked template Copy the template only [Show superimposed templates OFF] From To Action ------------------------------------------------------------------------------- Stocked image TX window Copy the image only Stocked template Template window Copy the template only TX window Stocked image Copy the image only Template window Stocked template Copy the template only You can drag&drop an image from Explorer or My Computer to the stock. It takes substantial time to make the text change in effect in the template. For this reason, the window redraw is slowed down during superimposing of the template in the stocked image area. If you do not like it, try checking off Show superimposed templates or checking on Draft. In addition, the JPEG format will require a little bit longer time to re-read the file. ======== Radio command ======== Refer to the MMTTY manual. ======== Demodulator ======== This section describes the digital signal processing used in MMSSTV. Refer to Digital.Txt of MMTTY for basic DSP operations. MMSSTV has two types of demodulators, PLL and zero-cross detector. (1) Demodulator configuration MMSSTV's demodulator has the following configuration. Sound --> BPF (FIR) --+> BPF1100 (IIR) --> VIS symbol '1' | +> BPF1300 (IIR) --> VIS symbol '0' | +> BPF1200 (IIR) --> Sync | ---> Zero cross det. --> Picture data (1500 to 2300) or | ---> PLL(1500 to 2300) --> Picture data The zero cross detector's configuration is ---> Differentiator ---> Counter ---> Out LPF ---> Pic. data The next figure shows the PLL configuration ---> Phase det. ---> Loop LPF ----> Out LPF ----> Pic. data | | <---- VCO <------------- In comparison with the zero cross detector, the PLL has higher frequency resolution. However, it seems to fail locking for the signals that has a rotating phase shift through the radio propagation. For this reason, the zero cross detector will give an image with less noise. MMSSTV virtually raises the sampling frequency for the zero cross detector in order to obtain the higher counter resolution even with a lower sampling frequency. However, this trick by nature uses approximation and therefore it would lower the brighness resolution compared with the PLL (this can be compensated by using higher sampling frequency). You can also compansate this error by checking the Polynimial box in the RX window of MMSSTV setup. (2) Zero cross detector parameters [Out LPF] This filter smoothes the frequency ingredients obtained by the counter. If you want a sharp image, increase the cut-off frequency. If you want a low-noise image, decrease the cut-off frequency. It is dependent on your preference. (3) PLL parameters The parameters of the PLL affect the picture quality. Since the behavior of this PLL is just the same as that of the hardware PLL, try adjusting the parameters as you have better results. [VCO Gain] VCO gain has a strong impact on the response of the PLL. The default value (gain = 3) is a little bit over responsive, but I dare to have chosen this value for the sharp appearance of pictures. If you decrease the VCO gain, you have less overshoot, but at the same time you will have less margin for the lock range. [Loop LPF] In addition to the VCO gain, the Loop LPF is another parameter that dominates the dumping factor for the PLL loop. You should use the filter of order one. If you increase the cut-off frequency, the filter is apt to oscillate in the 1500Hz range. However, it is not so significant in the picture quality because the energy of this range is relatively small. It is a good idea to see how it works by using the built-in oscilloscope. [Out LPF] The Out LPF filter does not affect the response of the PLL because it sits outside of the loop. It, however, should be noted that it strongly affects the picture quality. If you want a sharp picture, set the cut-off frequency higher. If you want to a low-noise picture, set it lower. Adjust it according to your preference. [Use limiter option] The limiter reduces the noise even for a weak signal, but it increases the phase distortion and lowers the picture quality. If the sampling frequency is set higher, the phase distortion will be decreased and therefore will not be observed. (4) Differentiator When the Differentiator box is checked, MMSSTV compensates the LPF effect by boosting the high-frequency ingredient of the received image. However, it makes the receive image be more likely affected by the noise. Try adjusting the effect with the slider for your preference. As the slider goes right, the differentiator takes sharper effect. *The differentiator is not related to the differentiator of the zero-cross detector. (5) Level converter The level converter translates the frequency value derived by the decoder into the color amplitude values. MMSSTV provides two types of converters, which can be selected in the RX window of MMSSTV Setup. - Linear converter (uncheck the polynomial box) It assumes that the frequency and the color level are linearly related. It is simple, but the frequency characteristics of the decoder must be linear. - Polynomial converter (check the polynomial box) It uses a 17-th order polynomial formula for the level conversion. It works better if the frequency characteristics of the decoder are not linear. Since the converter uses a pre-calculated table to boost the processing speed, it should not require much more CPU load. It is a good idea to use the polynomial converter for the 11025MHz zero-cross detector because it has a little linearity problem in 2200 to 2300Hz. As the sampling frequency goes higher, the decoder will have better linearity. However, even in 11025Hz, the conversion error is 2/256 - 3/256, and therefore the error might not be visible. MMSSTV starts the automatic calibration by pressing the calibration button in the RX window of MMSSTV Setup. It takes about 20 seconds. After the calibration, MMSSTV shows the frequency characteristics figure. If the line of the figure goes straight down to the right, you can uncheck the polynomial converter (you can use the linear converter). =============== Profile =============== The default PLL parameters are settled according to my experiments, which, however, are very limited. I have had no sufficient time for the parameter optimization. If you are a master of SSTV, you already have found good parameters. With the Profile function, you can easily save and load up to 8 sets of the PLL parameters. Each set can be named as you like. It is a good idea to save your favorite PLL parameter set as MyDefault before you try many different parameters. If you got lost in the parameter setting, you will be able to step back to the start point. MMSSTV has a special profile "MMSSTV Default," which cannot be modified by the user. This is the MMSSTV default parameter set. * It should be noted that the Profile memorizes the PLL parameters only. ======== Sample frequency ======== MMSSTV has an option that allows the following sampling frequencies: 8000 Hz Secondary standard frequency 11025 Hz Primary standard frequency 12000 Hz 14000 Hz 16000 Hz 18000 Hz 22050 Hz Primary standard frequency 24000 Hz 44100 Hz Primary standard frequency If you are a quality chaser, use as high frequency as possible. It should be noted that not all the soundcards support the frequencies listed above all. All the soundcards, however, should support 11025Hz, 22050Hz and 44100Hz. In addition, the high frequency dissipates more CPU power and more memory space. Tips: * If you use a high sampling frequency, it is recommended to increase the buffer size for sound processing. This can be done in the Misc page of the Setup window. For instance, 4096, which is twice bigger than the default value, is recommended for the 22050Hz sampling frequency. * MMSSTV always calculates the FFT with 2048 points. To obtain the proper frequency resolution, MMSSTV uses a half frequency for FFT in case the sampling frequency is 18000Hz or higher. In the same manner, MMSSTV uses a quarter frequency in case of 44100Hz. ======== Clock calibration ======== In SSTV, the discrimination of the clock appears as a slanted image. For MMSSTV, you are not required to have the absolute and exact clock frequency value (e.g. 11025Hz). But it is important to get MMSSTV informed on what the frequency of your soundcard has. In normal situations, you would only have to adjust the slant by using the Sync window. If you want to calibrate your soundcard very accurately, listen to the standard radio or fax wave. 1) Go Option, Setup, Misc page, and push Adj button. 2) Receive standard radio wave (e.g., WWV and JJY). 3) Tune into the tick sound. 4) Continue listening to the sound for a while. You have a vertical line. 5) Click the upper point of the line. 6) Click the lower point of the line. You could use FAX broadcasting instead of WWV or JJY, but be sure it has exact timing. Refer to the MMTTY help for details. If your soundcard seems to have different clock sampling frequencies for TX and RX, adjust the offset frequency with the following procedure. 1) Adjust the slant in RX. 2) Let the current sampling frequency be RxSamp. 3) Go Option, Setup, and TX page. Select External in the Loopback. 4) Go Misc page. Put 0.00 in Tx offset. 5) Connect the Line-out to the Line-in of your soundcard. 6) Transmit an image. 7) You should have an image through the external feedback. 8) After completing the image receive, go Sync page and adjust the slant. - You could use the automatic slant adjustment. - Do not push the Mem button 9) Let the obtained sampling frequency be LoopSamp. 10) Compute Txoffset by TxOffset = RxSamp - LoopSamp. 11) Go Option, Setup, and Misc page. Put TxOffset to the Tx offset box. 12) End You can use the LoopBack function of a mixer program instead of using the external feedback line. Although this procedure can be applied only for the soundcard that supports the full-duplex mode, the soundcard that does not support the full-duplex mode should not have different frequencies for TX and RX, and therefore you do not need this calibration. If you have a report that your TX image is greatly slanted, try changing the soundcard modes, monaural or stereo (Source in the Misc window of Setup MMSSTV). Some soundcards seem to use different sampling frequencies for the full-duplex and no-full-duplex operations. In such a case, the offset calibration using the external loop back does not help. You should always have the loop back External or consult the QSO report. ========== Setup MMSSTV Misc ========== [Buff] Buff is the buffer size of the low level sound processing. You should enlarge the buffer size if you increase the sampling frequency; otherwise you possibly lose the sound. Use 2048 or larger buffer size for the sampling frequency 11025Hz. Use 4096 or larger buffer size for the sampling frequency 22050Hz. [Priority] Priority defines the task priority for low level sound processing. If you lose the sound during RX or TX, raise the priority. If the response of the menu operations is slow, lower the priority. Normal is the lowest and Critical is the highest priority. [DeviceID] DeviceID specifies the ID number of the sound card. When you have only one sound card, put -1 or 0 to DeviceID. -1 uses the default sound card. The sound card IDs are sequentially assigned as 0, 1, 2, .... When you have two sound cards, for example, and want to use the second one for MMSSTV, put 1 to DeviceID. [Source] Source defines the channel of the sound card. Mono makes the sound card work in the monaural mode. Left or Right makes the sound card work in the stereo mode and uses one of the channels. In TX, MMSSTV outputs the sound to both channels irrespective of the Source setting. [Clock] Clock is the sampling frequency of MMSSTV. Refer to Sample frequency and Clock calibration sections. ====== Closing remarks ====== MMSSTV is a freeware program for amateur radio use. You can redistribute it as you like. Please join the following reflector for detailed information, http://groups.yahoo.com/group/MM-SSTV/ The JPEG converter in MMSSTV is based on the freeware source code, "IJG code," provided by Independent JPEG Group. 73 de JE3HHT Mako