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SbFFT User's Manual Version 1.2 Kevin McWilliams, KW5Q 23 November 1996 Copyright The program code, manual file, and associated graphics figures are Copyright (C) 1996 by Kevin J. McWilliams, KW5Q. All rights are reserved. License This program and associated files are copyrighted freeware. They may be freely distributed so long as they are distributed in their entirety, are not modified in any way whatsoever, and no charge is made for the copyrighted material. A maximum charge of $3 (three dollars U.S.) may be assessed for the duplication of these materials. No Warranties No warranties of any type are made for this program, its manual, and the associated graphics files regarding their functionality, usability, or suitability for any purpose. This software is provided on an "as is" basis. Users of this software bear the entire risk for its use. The author will not be liable for any special, incidental, consequential, indirect or similar damages due to loss of data or any other reason under any circumstances. In no event shall the author's liability for any damages ever exceed the price paid for the license to use the software, regardless of the form of the claim. Introduction SbFFT is a spectral display and filtering program for use in Amateur Radio and audiophile applications. It's features include: * Sound Blaster 16 (or 100% compatible) input and output * Band widths of 2K, 4K, 8K or 16K Hz * Spectral resolutions of 1 Hz to 16 Hz per pixel * Display of power density spectrum with 4 color maps in either linear or logarithmic scale * Define and use up to six filters simultaneously -- band pass, band stop, low pass, and high pass. Filters have 25 Hz skirts at 3 to 50 dB points * Filters are defined by mouse movement * Filters may be as narrow as 1 Hz * Net filter passband is displayed at all times * CDROM and line SB 16 inputs * .wav file inputs and outputs * Filters can be selectively enabled and disabled by a single keystroke or a single mouse click. This allows for quick reconfiguration in case of changing conditions, etc. PLEASE READ THIS FILE AT LEAST THROUGH THE ALPHABETICAL LIST OF COMMANDS BEFORE RUNNING THIS PROGRAM. For those who don't listen to advice: 'Q' (QUIT) stops the program and (up arrow, dn arrow) increase/decrease volume. I have spent many pleasant hours watching spectra from both Amateur Radio and audio CDROM's. Being able to 'see' a signal as well as hear it permits correlation the two senses -- visually spot a CW signal with clicks, chirps or microphonics, watch signals drift, spot an SSB signal with splatter. See RTTY mark and space tones fade selectively. Get a visual picture of music or a voice. SbFFT is also an aid for DX work by allowing a narrow band pass filter to be defined around a weak DX station quickly and without guesswork. Filters are defined graphically based upon displayed spectra, so they can be defined even after a station has paused in transmission and will be ready when transmission resumes. Your comments are welcome. I would like to thank the many people who provided feedback about SbFFT 1.1. email the author Kevin KW5Q at kevinm@mail.eden.com. Enjoy, and 73's -- KW5Q Differences from Version 1.1 1) The SbFFT executable has been built with a smarter graphics library. It should now operate with a much wider range of VESA SVGA cards. 2) The AGC algorithm has been enhanced. 3) Defaults have been assumed for the BLASTER environment variable. If the variable is set in your system, whatever information it contains will be merged in with the default values. See Installation, below. 4) An interrupt conflict between the MPU401 and the A/D converter on the Sound Blaster has been eliminated. Because of this comflict, SbFFT would start and terminate normally but would not display spectra on some sytems. 5) SbFFT now generates pcx files instead of tiff files. The pcx files are a fraction of the size of tiff files. Also, the graphics library that generated the tiff files failed to initialize the tiff header completely, causing some graphics viewer programs to crash. 6) Improved mouse response at fine resolutions. 7) Full screen mouse movement to make filter definition easier. 8) Filters may be enabled/disabled or deleted by mouse clicking in the filter active band. 9) Numerous typographical errors have been corrected in the manual. System requirements 1) MSDOS 3.0 or later -- LIMITED Windows 3.1/3.11 and Windows 95 operation (see 'Limited Windows Operation' below). SbFFT will NOT operate under Windows NT. SbFFT has not been tested with releases of 16-bit Windows prior to 3.1 2) mouse required; driver must use int 33h 3) >= 380K free memory, at least 250K contiguous 4) SB16 or 100% compatible 5) takes input from CDROM and line (simultaneously) 6) SVGA with 640 x 480 display minimum, 1024 x 768 preferable 7) VESA BIOS supporting 640x480 and 1024 x 768 screen resolutions 8) 486/66 or above recommended for spectral display. 386 systems are usable provided they are equipped with a 387 FPU 9) Pentium 120 or above recommended for filtering at lower resolutions The JPEG graphics figures for this manual can be viewed with any DOS or Windows viewer (cshow, 2show, qpeg, Lview, etc.). These are available from anonymous ftp sites such as oak.oakland.edu at the following addresses: 2show, cshow, disp: ftp://oak.oakland.edu/pub/simtelnet/msdos/graphics in files 2show204.zip, cshow904.zip, disp189a.zip, disp189b.zip Lview: ftp://oak.oakland.edu/pub/simtelnet/win3/graphics in file lviewp1b.zip. Any of these viewers as well as numerous others are adequate to view the graphics figures of this manual. Please consult the oak.oakland.edu site or any other Simtel mirror site for the latest versions. The author makes no recommendations regarding circuits for connecting a receiver or transceiver to the SB line input. Many receivers and transceivers have a line output, and can be connected directly, or possibly through a coupling capacitor, to the SB card. Consult your receiver or transceiver documentation and the Sound Blaster documentation for specifics. In any case, follow the manufacturer's recommendations, and use good electrical wiring practices. Consult books such as the ARRL handbook for considerations of impedance matching. IMPORTANT If SbFFT does not terminate normally by returning to the DOS prompt, you must reboot your computer by pressing the reset button. SbFFT hooks the Sound Blaster interrupt vector. If the program does not terminate normally, this interrupt vector will point into invalidated storage, and may cause unpredictable results if other programs access the Sound Blaster. MSDOS, Windows, Windows 95, and Windows NT are trademarks of the Microsoft Corporation. Installation 1) create a directory C:\SBFFT 2) copy the .zip file to the directory C:\SBFFT 3) Unzip the .zip file. You should find files: SBFFT.EXE SBFFT.PIF MANUAL.TXT README.TXT FIGURE1.JPG FIGURE2.JPG FIGURE3.JPG FIGURE4.JPG FIGURE5.JPG FIG6-9.JPG FIG10-13.JPG FIGURE14.JPG FIGURE15.JPG RS-12.WAV WNU31.WAV 4) Make sure the Sound Blaster card is installed and functional 5) Insure that the BLASTER environment variable is set. If necessary, put into the autoexec.bat file on the boot drive a command of the form SET BLASTER=Aaaa Iii Dd Hh Pxxx where aaa = base address of the SB 16 card (usually 220) ii = number of free interrupt, i.e., one not used by another device d = 8-bit DMA channel (usually 1) h = 16-bit dma channel (usually 5) xxx = MIDI I/O port base address (usually 330) For more information, see the Sound Blaster documentation If the BLASTER variable is not set, defaults are assumed: BLASTER=A220 I10 D1 H5 P330 6) uninstall or disable screensavers 7) SBFFT.EXE is ready to run 8) as a minimum, read the sections 'Screen Display' and 'Alphabetical list of commands' below before you run the program 9) for a quick test, if you have a CDROM attached to your Sound Blaster, start an audio CDROM playing with a DOS CDROM player and run the program. Or, you can play the rs-12.wav file included with this package. Type 'B' 3 times to put SbFFT into 2K Bandwidth. Then type 'P' and when a file name is requested, type 'rs-12'<Enter>, without the quotes. IF YOU EXPERIENCE PROBLEMS, SEE TROUBLESHOOTING, BELOW. When you have verified operation of the SbFFT program, you may delete the .zip file if desired. IMPORTANT If SbFFT does not terminate normally by returning to the DOS prompt, you must reboot your computer by pressing the reset button. SbFFT hooks the Sound Blaster interrupt vector. If the program does not terminate normally, this interrupt vector will point into invalidated storage, and may cause unpredictable results if other programs access the Sound Blaster. Screen display Features of the display. See Figure 1. Figure captions are at the end of this file. Please note that graphics files loose sharpness when compressed. The SbFFT screen displays are considerably better! Inside grey box: BW bandwidth, Hz Res resolution, Hz per pixel in the power spectral density (PSD) display Gam photographic gamma, intensity displayed = PSD ^ gamma Cont contrast, PSD values below contrast x 10% of the maximum PSD are not displayed. Used to eliminate spectral clutter LIN color mapping based on PSD or log PSD LOG 16 C the current color map. Only one of these values will be displayed 224C 16 G 2 G Low lowest freq detected Max strongest freq detected High highest freq detected Freq freq of mouse cursor, Hz The mouse cursor is the tall vertical line extending from the frequency axes upward and moves left and right with the mouse movement. Filter shows filter mode on/off (green/red) View shows whether filtered output is viewed in the spectral display or entire input signal is viewed INLINE indicates that the audio output is being produced digitally by SbFFT, e.g., during filtering operation, or simply by passing signals from the A/D to the D/A on the SB card. INLINE operation is required for hearing the results of filtering operations and hearing .wav files being played BYPASS indicates that the audio output is derived in analog form from the input on the SB card; the D/A capability is not being used AGC shows current agc mode SLOW/FAST/OFF Gain current A/D gain, controlled by AGC algorithm or manually with -+ keys when AGC is off PLY .wav file currently being played and time since playing started REC .wav file currently being recorded and time since recording started Filters (1) through (6) shows filters currently defined (maximum of 6) in the format indicated in the 'Filter commands' section Below the grey box and above the actual spectral display is a frequency scale with binary calibrations. The area between the frequency scale and the bottom of the grey box is used to display the filter passband. This consists of the NET passband of all filters defined. Below the frequency scale is the power spectral density (PSD) display. In the 16 or 224 color modes, the displayed color is proportional to the PSD, with best proportionality in the 224 color mode. (See 'C' command in the alphabetical list below, and see the section 'Screen commands'.) At higher resolutions (e.g., 1 Hz resolution in 2K BW), the PSD display cannot be accomodated on a single display line even in the 1024 x 768 VESA mode (see 'M' command in alphabetical list, and section 'Screen commands'). The left and right arrows shift the segment of the power spectrum that is displayed. The frequency axes will indicate this shift, as will the filter passband display. Alphabetical list of commands Commands All commands are single letter and may be entered upper or lower case. A AGC toggle slow/fast/off B BW toggle 2048/4096/8192/16384 C toggle color map: 16 or 224 colors, 16 or 2 levels grey scale D delete filter containing mouse cursor E enable/disable filter containing mouse cursor F filter on/off G Gamma - photographic gamma, intensity = power spectral density ^ gamma I inline/bypass L record wave file - enter 1-8 character file name only M VESA mode 101/105 (640x480 or 1024x768) N contrast 0 through 9 P play wave file - enter 1-8 character file name only Q QUIT R resolution/pixel 1/2/4/8/16 Hz (depends on BW) S scale log/lin T send spectrum display to top of screen V View filter output on/off - only works in filtering mode - view ON means spectral display is of filtered output, view OFF means spectral display is of unfiltered input signal Y write .pcx (version 3.0) file - enter 1-8 char file name only Z clear screen +- manual gain (AGC OFF only) (up arrow, dn arrow) increase/decrease volume (rt arrow, lft arrow) if resolution is set so entire BW cannot be displayed on one screen, the right/left arrow keys scroll the spectrum right/left one screen (space) toggle enabled/disabled filters 1-6 delete filter 1-6 (if defined) Mouse movement, clicks and drags are explained in the next section. Filter definition and filtering Filter description All filters have 3 to 50 dB skirts of 25 Hz and have no more than 0.5 dB ripple in the active band, independently of passband or stopband frequencies and bandwidth. A maximum of six filters may be defined and used simultaneously. Minimum pass band or stop band width is 1 Hz. Filter abbreviations: P bandpass (bandpass filter, BPF) S bandstop (notch filter or band stop filter, BSF) L low pass (low pass filter, LPF) H high pass (high pass filter, HPF) Filter display in the grey box: Filters are displayed by type, center frequency, and 3 dB BW. Examples: L 2500 a 2500 Hz LPF H 3500 a 3500 Hz HPF P 900 16 a 16 Hz BPF centered at 900 Hz S 1000 22 a 22 Hz BSF centered at 1000 Hz Filters displayed in BLUE are DISABLED. Filters displayed in other colors are ENABLED. A ">" character to left of a particular filter means the mouse cursor lies in that filter's active band. The net filter passband is plotted in the area above frequency axes and below the grey box. Individual filters displayed in this area are GREEN for ENABLED and BLUE for DISABLED. Filter outputs are combined by feeding the input signal to all LPF, HPF, and BPF's in parallel and summing their outputs. The summed output of the pass type filters is then fed to any defined stop type filters in series. Thus, several BPF's can be defined and used simultaneously with one or more BSF's. FILTERS MAY BE DEFINED INSIDE OF OTHER FILTERS. A bandstop filter may be defined inside a band pass filter, a narrow band pass filter can be defined inside a wide band pass filter (either or both may be enabled simultaneously, but there are advantages to enabling only one and toggling back and forth with the space bar). FILTERS MAY OVERLAP ONE ANOTHER. A series of filters can be overlapped at the edges to give continuous coverage of a passband. See Figure 4. Filters can be selectively enabled/disabled by mouse clicks, and the enable/disable state ov all filters can be toggled by the space bar. NOTE: some filter combinations do not make sense, e.g., a band stop filter in the stop band of a band pass filter! SbFFT does not check for such combinations. Entering/leaving filtering mode 1) define one or more filters (see below) 2) use the 'F' command to TOGGLE filter mode ON/OFF Filter creation/deletion Version 1.2 of SbFFT features a full screen mouse with greatly enhanced capabilities and performance. Filters may be created, deleted, or enabled/disabled via the mouse, or by a combination of mouse movement and keyboard commands. The filter display in the grey box has a ">" character before the filter containing the mouse cursor. No ">" will be present if the mouse cursor isn't in any filter. For band stop filters, the mouse cursor is considered to be in the filter only if the cursor is in the actual stop band. To create or delete filters: 1) look at the spectral display of the signal you wish to filter; 2) with the mouse in the SPECTRAL DISPLAY AREA (the area below the frequency axes, point the mouse at either the low frequency or high frequency side of the signal. Create filters by dragging with left or right (not both) mouse buttons: drag with left button creates pass type filters (BPF, LPF, HPF) drag with right button creates a bandstop filter (BSF) You can also use the 'Freq' display in the grey box to read the mouse cursor frequency to determine the filter pass or stop frequencies; 3) filters may be deleted by any of 3 methods: (a) tapping 1-6 on keyboard corresponding to number of filter to be deleted; (b) single RIGHT click the mouse with the mouse cursor in the filter passband that is drawn ABOVE the frequency scale. Remember to check for the ">" character in the filter display in the grey box to verify that the mouse is in the active band of the filter you wish to delete; (c) with the mouse cursor in the spectral display BELOW the frequency scale and positioned in a filter's active band as indicated by the ">" character in the filter display, type 'd' to delete the filter; 4) additional filters may be created while in the filtering mode as in (2), and filters may be deleted while filtering as in (3). If all defined filters are deleted while filtering, SbFFT drops out of filtering mode. To create high pass filters, left drag the mouse from the lowest pass frequency to the right hand edge of the spectrum display, or vice versa. To create low pass filters, left drag the mouse from the highest pass frequency to the left hand edge of the spectrum display, or vice versa. Filter enable/disable. Three methods may be used to enable/disable filters: 1) single LEFT click the mouse with the mouse cursor in the filter passband that is drawn ABOVE the frequency scale. Remember to check for the ">" character in the filter display in the grey box to verify that the mouse is in the active band of the filter you wish to enable or disable; 2) with the mouse cursor in the spectral display BELOW the frequency scale and positioned in a filter's active band as indicated by the ">" character in the filter display, type 'e' to toggle the filter's enable/disable state; 3) Use the space bar to toggle the enable/disable states of all filters at once. In the passband display: Filters displayed in BLUE are DISABLED. Filters displayed in GREEN are ENABLED. Filters may be enabled or disabled while in filtering mode. If all defined filters are disabled while filtering, SbFFT temporarily suspends filtering mode. In this case, enabling one or more filters or pressing the space bar to enable all filters causes SbFFT to resume filtering. Other filter commands V Toggles View on/off -- active in filter mode only. If view is on, spectral display is of filtered output. View off shows unfiltered spectrum. I Toggles BYPASS/INLINE mode. In BYPASS, audio is routed directly from the SB 16 input to the output, even though SbFFT is still displaying spectra. In filter mode, the program still filters the input signal and the filtered spectra are displayed, but the filtered data are discarded without being sent to the D/A converter. INLINE mode is required for the user to hear the filtered audio. INLINE mode can be used without SbFFT being in Filter mode. SbFFT switches automatically to INLINE mode and VIEW mode when filter mode is enabled by the 'F' command. View mode can be toggled with the 'V' command. Hints and notes To enter filtering mode, define one or more filters first, then start filtering with the 'F' command. Additional filters may be defined 'on the fly'. Filters can be deleted while filtering by typing the number of the filter to be deleted, or by positioning the mouse cursor in the filter to be deleted and using the 'D' command. It is useful to define two filters, one on each side of a CW QSO, disable one, then toggle between the two with the space bar as the QSO passes back and forth. Define a narrow filter around a DX station, and a wider one containing the narrow one. Disable the wide filter, and use the space bar to toggle between wide & narrow. This way, the DX alone can be heard, or the pileup of calling stations can be heard (Figure 2). Define two filters, one LP, the other HP to split the RCVR passband in half. Disable one, and use the space bar to toggle between the halves of the passband (Figure 3). Define a narrow BPF containing a CW or SSB signal, then define a wider BPF about the narrow BPF, disable one, then use the space bar to toggle narrow/wide as conditions permit (Figure 4). Band stop (notch) filters may be defined inside LPF's, HPF's, or BPF's (Figure 5). Note that multiple BSF's can be defined inside the pass type filters to notch more than one carrier, and that multiple BSF's can be defined even if no other filters are defined. The BSF's then act as multiple notch filters. Band pass filters can be defined for each RTTY mark and space tone (Figure 6). One filter can be enabled at a time depending on interference and fading. Custom data filters can be defined as BPF's. Figure 7 shows a WEFAX filter. I have personally used BPF's as narrow as 8 Hz in ham communications. Filters as narrow as 1 Hz may be defined. The limitation of usability is determined by ringing. Notice the ripple in the filter passbands when filtering and viewing white noise in the LOG scale! If this ripple is disturbing, turn off View, or switch to the LIN scale. If the filtered output contains pops and clicks, turn the AGC OFF with one or more repetitions of the 'A' command and use the +/- keys to set the A/D gain manually until the clicks stop. A fast CPU is required to run filters at the lower resolutions (i.e., 8 or 16 Hz per pixel). Also, the CPU power required to run more than one filter simultaneously increases with the number of filters ENABLED at one time. The CPU requirements also increase with increasing filter bandwidth. It is more time consuming to run a 2300 Hz BPF than a 2 Hz BPF! If SbFFT detects that the CPU is pegged, it will either drop out of filter mode or terminate with an error message. I have succeeded in running 3 fairly broad BPF's at 16K Hz Bw and 16 Hz/pixel resolution on a P133 with a CPU utilization averaging 95%. Screen commands M toggles VESA mode: 640x480 or 1024x768 C changes color map G cycles gamma 1-8 -- the intensity of a displayed pixel is approximately Intensity = pixel value ^ gamma. This is the photographic gamma N cycless contrast 0-9 -- contrast of zero means all non-zero Fourier components of the power spectral density are displayed. Setting the contrast to N means the lowest 10N % of power spectral density bins are not displayed. R changes spectral resolution; cycles among resolutions available at the selected bandwidth S toggles scale LOG/LIN T move the PSD display line to the top of the screen Z clear the PSD display area (rt arrow, lft arrow) if resolution is set so entire BW cannot be displayed on one screen, the right/left arrow keys scroll the spectrum right/left one screen Hints The contrast command 'N' is used to remove spectral clutter to make signals more distinct. Signals that are not plainly visible at one resolution may be visible at a lower resolution (more Hz/pixel) since this amounts to the coaddition of power spectral density bins. Color Maps There are four color maps available for viewing power spectra. These are selected cyclically with the 'C' command. The maps are: 16 C 16 colors, basic VGA palette 224C 224 colors, custom palette, rainbow from Blue through Red with the addition of White, fairly smooth color gradation 16 G 16 level grey scale 2 G 2 level grey scale where pixels are either black or maximum intensity white Each of the four maps can be used in either linear or logarithmic scale. SbFFT selects a default Contrast and Gamma as each map is selected with the 'C' command. The user may change these settings with the 'N' and 'G' commands. The author has found the various maps useful in different circumstances as outlined below. All color maps were used with the default Gamma and Contrast. The properties of the maps are greatly affected by Gamma and Contrast in LINEAR scale and by Contrast in LOG scale. As the preferred screen display is a matter of personal taste, some experimentation will be required. Map Colors Scale Comments 16 C 16 LOG General purpose viewing, bright screen 16 C 16 LIN General purpose viewing, darker screen, cooler colors 224C 224 LOG Fine color resolution of spectrum with relatively faithful color mapping. Map runs rainbow colors plus White: Blue->Green->Yellow->Orange->Red->White with largest PSD values in White, smallest in Blue. Suitable for viewing strong signals. Screen is bright. 224C 224 LIN Same color resolution as above. Weak signal search in background of noise. Dark screen. Mixed weak/strong signals with higher Gamma settings. 16 G 16 LOG General viewing, bright screen. 16 G 16 LIN General viewing, darker screen. 2 G 2 LOG Shows all PSD components detected when contrast is zero. Useful for locating very weak Fourier components. 2 G 2 LIN Same as 2G LOG scale. Bandwidth and resolution commands B cycle bandwidth amoung 2048, 4096, 8192 and 16384 Hz R cycle pixel resolution among 1, 2, 4, 8 and 16 Hz (not all resolutions are available at all bandwidths). AGC and volume control commands A toggles AGC SLOW / FAST / OFF When AGC is OFF, grey -+ keys change the gain manually from 0-31. (up arrow, dn arrow) increase/decrease volume Hints If filtered output contains pops and clicks, turn the AGC OFF with one or more 'A' commands, and use the +/- keys to set the A/D gain manually until the clicks stop. Wave input/output P play a wave file -- only 4k, 8k 16k or 32k samples/second, 16 bits. Enter file name without extension, ESC cancels entry. SbFFT will not play wave files recorded at other sampling rates. L record wave file -- 16 bits and 4k, 8k, 16k or 32k samples/second, depending on bandwidth. Enter file name without extension, ESC cancels entry. Hints and notes Watch disk space at high bandwidths! Simultaneous play and record are not supported. While playing a .wav file, set SbFFT for the same bandwidth at which the .wav file was recorded to hear and display frequencies correctly. Otherwise, the displayed spectrum and reproduced audio frequencies will be 2, 4, or 8, or 1/2, 1/4 or 1/8 times those of the original signal. Sometimes you may want to use a bandwidth other than that at which the signal was recorded to slow down or speed up the signal and decrease/increase it's audio frequencies. SbFFT drops into INLINE mode when playing a .wav file to permit the user to hear the audio. The user may put SbFFT into BYPASS mode by the 'I' command if only spectral display is desired. In this case, SbFFT will reproduce the spectrum as fast as it can read and display the data. As an example of .wav input capability, put SbFFT into 2048 Hz BW ('B' command), and use the 'P' command to play rs-12.wav: type 'P' and enter rs-12<CR> at the prompt. This is the 29408 KHz CW beacon of the RS-12 satellite. This file was recorded with SbFFT from an actual satellite transmissiion. Note the Doppler shift! Refer to Figure 11 for a spectral display captured from this same transmission. The file RS-12.WAV can also be played on a standard WAVE player. Graphic output Y write pcx file. Requests file name, do not enter extension. ESC cancels entry. The file written conforms to version 3.0 of the pcx specification. Command line parameters SbFFT accepts a number of command line parameters that will cause the program to start in various user-defined modes. The default startup mode is 4096 Hz BW 8 Hz/pixel resolution LOG scale 16 colors Gamma=1 Contrast=3 640x480 VESA mode. The startup configuration may be altered by the user by entering one or more command line parameters when the program is invoked. Options set on the command line will be merged with the defaults shown above. Usage: SBFFT [-m<xxx>] [-c<c>] [-b<b>] [-r<r>] [-s<s>] [-n<n>] [-g<g>] Where: xxx 101 or 105, indicating 640x480 or 1024x768 VESA modes, respectively c 0,1,2,3 - specifying color maps 16C, 224C, 16G, and 2G, respectively b 0,1,2,3 - specifying bandwidths 2048, 4096, 8192, and 16384, respectively r 0,1,2,3,4 - specifying resolutions of 1, 2, 4, 8, or 16 Hz, respectively. Note: not all bandwidths support all resolutions. If you enter a resolution not supported for a given bandwidth, the closest available resolution will be selected. s 0,1 - LIN or LOG scale n 0 through 9, inclusive, the Contrast g 1 through 8, inclusive, the Gamma Do not enter a space between the -option and the following digit(s). Limited Windows Operation SbFFT is an extremely high performance real-time program that does direct hardware control for efficiency, hence has difficulty operating in multiprogrammed environments. In particular, it is incompatible with and will not function under Windows NT and has only limited functionality under Windows 3.1/3.11 and Windows 95. SbFFT has not been tested with releases of 16-bit Windows earlier than 3.1. SbFFT has limited functionality under 16-bit Windows 3.1 or 3.11 as follows. A file SBFFT.PIF has been provided with this release, and should be in the same directory as the program file SBFFT.EXE. Start Windows and do not start any application programs that access the Sound Blaster. Start SbFFT by either: (1) from File Manager, open a window on the SbFFT directory, and double click on SBFFT.EXE, or (2) from the Run menu item of the Program Manager File menu, browse to the SbFFT directory, and start SbFFT by double clicking on SBFFT.EXE. The program usually starts, and will show varying degrees of functionality. Don't be surprised if Windows pops back on screen with a message that an application has 'violated system integrity' or that the Sound Blaster card is in use by another device. In that case, terminate Windows and reboot. To switch from the SbFFT window, QUIT the program first. DO NOT try application switching directly. This produces unpredictable results. SbFFT has limited functinality under Windows 95 as follows. Double click on the My Computer icon, double click on the hard drive on which SbFFT is installed, and open the directory containing SBFFT.EXE. RIGHT click on SBFFT.EXE, select Properties, go to the Program tab, go to Advanced, select MS DOS program. Select OK, select OK. Start SbFFT by double clicking on SBFFT.EXE. To switch from the SbFFT window, QUIT the program first. DO NOT try application switching directly. This produces unpredictable results. Windows, Windows 95, and Windows NT are trademarks of the Microsoft Corporation. Troubleshooting Can't set mode 101 or 105 A very common problem is a buggy VESA BIOS extension (VBE), an outdated VBE, or you may have a graphics card with a chipset that isn't supported by the graphics library used to build SbFFT. If SbFFT can't set mode 101 or 105 on your card, you can get the SciTech Software Display Doctor that contains the UniVBE drivers. This is available at http://www.scitechsoft.com or ftp://ftp.scitechsoft.com. Look for the Display Doctor link. The UniVBE drivers support over 200 chipsets and make graphics boards more usable. This is probably your best bet for making your card work with SbFFT. The author has made every effort to obtain a modern graphics library that supports many SVGA chipsets, but there will always be some chipsets that aren't supported by a given graphics library. SB 16 compatibility SbFFT uses nearly every feature of the Sound Blaster card, and many "compatibles" are simply not sufficiently compatible! Some "compatible" cards may be command compatible but not data compatable. They will accept all SB16 commands given by SbFFT but return only 8 bits of data when 16 bits are requested (and required). BLASTER environment variable If SbFFT starts and stops but does not display spectra, the BLASTER environment variable may be set inconsistently with actual Sound Blaster hardware settings. These settings are configured with the SB16SET and SBCONFIG programs supplied by Creative Labs. See the Sound Blaster documentation. DMA or IRQ conflicts If the sound card is 100% compatible and you've checked the BLASTER environment variable, it's possible you have DMA and/or IRQ conflicts. Use the DOS 'msd' command to list IRQ's and DMA channels in use. Consult with a DOS guru since this is an arcane subject. Plug 'N' Play If you have a Plug 'N' Play BIOS, remember that PNP can shuffle IRQ's and I/O port addresses. Consult the BIOS documentation that came with your computer. Out of memory SbFFT allocates extra buffers for writing .pcx graphics files. If you run out of memory, you may move DOS to upper memory, de-install tsr programs, or elect not to dump graphics files. Consult MSDOS documentation. Hiss If the hiss generated by the Sound Blaster is troublesome, you can elect to not use the Blaster's audio amplifier (by changing jumpers on the Sound Blaster card), and instead run the speaker outputs to the line inputs of a stereo amplifier or a pair of amplified speakers. See the Sound Blaster documentation. CPU power required As noted in the 'Filter commands' section, SbFFT requires a reasonable amount of CPU power to filter. If SbFFT drops out of filter mode after defining another filter, either switch to a higher resolution (fewer Hz/pixel), define narrower filters, define fewer filters (or no filters!), or run SbFFT in a faster CPU. We're up against the wall of thermodynamics here... Figure captions All figures included in this package were captured with SbFFT using the 'Y' command. They were converted offline to JPEG format to save space. With the exception of Figure 11 (RS-12 satellite), they are from live transmissions. Figure 11 was produced by first recording a live RS-12 beacon transmission with the 'L' command. The spectrum in Figure 11 was then produced by playing the .wav file with the 'P' command. Please note that graphics files loose sharpness when compressed. The SbFFT screen displays are considerably better! Figure 1. Basic SbFFT display screen, 640 x 480 mode. BW Bandwidth = 4096 Hz Res Resolution = 8 Hz/pixel LOG Scale is logarithmic 224C Color map contains 224 colors Gam Gamma = 1 Cont Contrast = 3 Low Lowest frequency present = 188 Hz Max Strongest frequency present = 1416 Hz High Highest frequency present = 2504 Hz Freq The mouse cursor is at 1568 Hz PLY Not playing .wav file REC Not recording .wav file Filter Not filtering View Not viewing BYPASS Audio is passing through the SB card with no filtering and is not being reproduced in software by SbFFT AGC SLOW Gain Current A/D gain = 16 Six filters are defined: (1) LPF Highest pass freq. 288 (2) BPF CF 1944 BW 720 (3) BPF CF 2500 BW 296 (4) HPF Lowest pass freq. 3264 (5) BPF CF 460 BW 72 (6) BSF CF 2108 BW 24 Notice that filter (6) is defined INSIDE filter (2). The mouse cursor is in filter (5), indicated by the ">". The net audio passband is displayed in green between the frequency axis and the bottom of the grey box. Notice the mouse cursor inside the narrow BPF. The cursor frequency is 472 Hz. The spectrum is from 40 meter CW operation on a typical evening. Figure 2. A narrow BPF is defined inside a wide LPF. The wide LPF is disabled by placing the mouse cursor inside the LPF, indicated by a ">" next to the filter display, and using the 'E' command. The narrow filter encloses a DX station and the wide filter brackets the pile up of calling stations. Pressing the space bar toggles the enable/disable status of each filter defined, so the wide LPF would be enabled and the narrow BPF would be disabled. Pressing the space bar again would return the filters to the state shown. This is a serious DX pileup heard on 40 meter CW. Figure 3. The output of a receiver passband can be conveniently split into two parts by defining two side filters and disabling one. This permits a quick assessment of the usage of each half of the passband. The other half of the passband can be heard by pressing the space bar. Figure 4. A wide LPF is defined for an SSB signal, and a narrow LPF is defined inside the wide LPF. The wide LPF is disabled. The user can toggle between the wide and narrow filters using the space bar as QRM and QRN conditions require. Figure 5. A wide LPF is used to eliminate QRM from an SSB signal, and a BSF is defined inside the LPF to notch out a carrier. Note that multiple BSF's can be defined inside the LPF to notch more than one carrier, and that multiple BSF's can be defined even if no other filters are defined. The BSF's then act as multiple notch filters. Figure 6. Two narrow BPF's can be defined around RTTY tones. This is a very simple operation since the individual tones can be seen in the spectral display. Note that the top of the display was in 16 colors prior to defining the filters. The filters were defined and filter mode is switched on. The resulting 'two-legged' display is the View mode of the filters' output. The bottom of the display is in 224 colors, also in View mode. Figure 7. Custom data filters can be defined visually. This is a filter for a WEFAX signal. Figure 8. This signal consists of 7 binary FSK channels and a single carrier on the right hand side of the display. Several BPF's were defined to separate out a few channels of interest. Notice the selective fading of all of the channels. Figure 9. WWV at 5 MHz. Notice the 100 Hz BCD time code, the 500 and 600 Hz carriers, and the 'ticks' near 1000 Hz. Note also the one minute tone marker at 1000 Hz and the voice announcement near the top of the figure. Figure 10. On the left is a drifting signal from Cuba heard on 40 meter CW. This figure was made with version 1.1 of SbFFT. Figure 11. The 29408 KHz CW beacon from the RS-12 satellite. Notice the Doppler shift! This spectral display was generated by playing a wave file '29408.wav' with the 'P' command that had been previously recorded with the 'L' command. Figure 12. A packet QSO next to an FSK signal. This figure was made with version 1.1 of SbFFT. Figure 13. ARRL Sweepstakes 1996. 40 meter CW at 0555 UTC 4 November. This figure was made with version 1.1 of SbFFT. Figure 14. High high resolution spectrum of WWV. Notice the wealth of spectral detail in the one second ticks centered at 1000 Hz. Figure 15. High resolution spectrum of WNU31 at 4294.69 KHz LSB. The bottom half of the figure is the signal filtered through an 8 Hz BPF. The BPF was defined to contain the center frequency and one of the sidebands. Some of the audio from this filter has been recorded as wnu31.wav. Put SbFFT into 2K BW, 8 Hz resolution, and play wnu31.wav using the 'P' command. You will see that the missing sideband is reproduced on the screen! This is because an amplitude modulated signal (CW is an extreme case of AM) can be faithfully reproduced from one of its sidebands. While ringing is clearly evident, the signal is still readable.