                             FFTDSP Documentation

                           Version 42y - Dec 26, 1998


Dec 26, 1998 Update from FFTDSP42u to FFTDSP42y
   
   - Fixed Runtime Error for Fast Computers due to Pascal Compiler 
   - Fixed Date Change when Time Zone is not GMT
   - Fixed Initial Mouse Display problem
   - Fiexed Config forced to Time Zone = 0


PROGRAM DESCRIPTION

     FFTDSP is a Digital Signal Processing (DSP) program which can detect
very weak signals from a Radio Receiver using real-time Fast Fourier Transforms
(FFT).  Amplitude levels for each FFT frequency are converted to color and
displayed as a continuous spectrograph.  The resulting screen simultaneously
shows the output of 640, 2 Hz wide filters between approximately 300 and 1500
hertz.  Each horizontal line represents the output of all 640 filters during a
0.5 second period.  Over time, as each line is added to the screen, the eye
can begin to see weak signals emerge from the darker background.  These weak
signals may not be audible during a short listening period.

     Primary Features of the FFTDSP program are:

       - Real-time 4096 Point FFT for 2Hz Filtering
       - Signal Amplitude Conversion to color for continuous spectrograph
       - Numerical Frequency display of Max Amplitude Signal (2 Hz resolution)
       - Input Audio Signal Strength Meter for setting level from receiver
       - Color Level adjustment for color conversion range
       - Spectrograph screen Save and Display in standard GIF format
       - Mouse point and click for Frequency Measurement and Offset

       - Record and Playback WAV files for post spectral analysis
       - Automatic Color Gradiant for optimum visiblity
       - Integration mode for signal detection below the noise
       - Mouse point and click  for selective recording
       - On screen Moon position and TOD tracking
       - True S/N (in 100 Hz Ref) bar graph 
       - Selective area and mode for S/N display
       - Display Smoothing Filters
       - Zoom In/Out for wider frequency coverage
       - Improved Graphics Interface and Setup Screens
       - Find Call feature from partial information

       - On Screen Object tracking using RA and DEC
       - Data Logging for long term monitoring stored as file
       - Runs with GMT or Local Time with offset


SYSTEM REQUIREMENTS

     - 386, 40 Mhz with Coprocessor (Minimum System)
       486DX-33 recommended for full performance and future upgrades
     - Sound Card: ProSpectrum-16, ThunderCard, SoundBlaster,
                           SoundBlaster-Pro, SoundBlaster AWE32
     - Audio line from radio to sound card record (or line) input


DISTRIBUTION & PRICE

     - A fully functional, but time limited FFTDSP program is distributed
       via internet and  public BBSs.  Without the registration file,
       operation will stop after 1 minute.

     - Program and Registration by Mail Price:
                   $35 US, $37 Foreign (includes shipping & handling)

     - Registration File by Email:
                   $32 US and Foreign

     - Program and Registration Upgrade by Mail from FFTDSP38:
	      $11 US, $13 Foreign (includes shipping & handling)

     - Registration File Upgrade by Email from FFTDSP38:
	      $10 US and Foreign

       The registration file will allow the public FFTDSP demo program to
       operate continuously.

     - Available from:             Mike Cook, AF9Y
                                   501 E. Cedar Canyon Rd.
                                   Huntertown, IN  46748
                                   Tel: (219-637-3399)

       Sites  used by author for program updates and mail:

            Internet - http://www.webcom.com/af9y
            Internet - ftp.webcom.com/pub/af9y
            Email:  mwcook@cris.com
                        


******************************* NOTE **************************************

   If the program halts unexpectedly, it is strongly recommended that the computer be
forced thru RESET.  This program uses DMA and depends upon the program normal exit to
turn off DMA.  Improper program termination without computer RESET could cause file
overwrites.

***************************************************************************



Note:   I've always believed that good software requires little or no documentation.  In 
        keeping with that theory, here's a little:


MAIN SCREEN

   o Level Meter:  Rectangular box located in the upper left area of the
                   screen to show audio input level to the Sound card.

        - Green/Red bar shows signal level for both positive and negative
          peaks on a logarithmic scale.

        - Recommended level is mostly Green with occasional Red peaks.

        - Numeric display below the box shows peak signal level (0-255)

         A bias adjustment can be made in the Setup area or with 
         the "B" key to keep an equal level of positive and negative
         peaks.  Some sound cards have a DC offset problem which
         this adjustment can correct.
  

   o Max Freq: Upper Right area which displays the highest average amplitude
               Frequency during each 0.5 second sample period.

        - Operates like a frequency counter with 2 Hz resolution


   o Mouse Operation: Used to point to area on the screen and show the
                      frequency and relative offset.

        - Point and Click left mouse button to show frequency

        - Point and Click right mouse button to show offset from last
          frequency (last click from left button)

        - Point and outline an area of the screen to save the associated
          area as a WAV file.  (Works only when in Record Mode)


   o CPU Time: Upper Right area that displays the measured CPU % time required
               to process the 0.5 second sample period.

        - Less than 100% is desired.  This indicates that the computer is
          keeping up with the real time data coming into the Sound Card.
          Any 486 computer with coprocessor will typically be below 100%.

        - Greater than 100% will result in some loss of detection for
          weak signals.  Every other 0.5 second sample will be used in
          this case.  Time will also be compressed so that it will take
          aprox 4 mins to fill the screen instead of the normal 2 minutes.



   o Color Level: Shows current Color Level scaling factor (0 to >5000)
               or Automatic Mode

        - Typical setting should be approximately 150 (default) if the Input
          Audio level is set for mostly green with occasional red peaks.

        - Use the + or - keys to change this value up or down.  The change
          in level may appear slow because of the 0.5 second updates periods.
          Holding down the + or - key too long will cause beeping due to
          keyboard buffer overflow.  The +/- buttons can also be selected
          with the mouse.

        - Recommended setting is a dark blue background for optimum weak
          signal detection.  See examples of demo spectrograph GIF pictures.

        - Brighter colors (ie light Green, Red, Yellow) require a larger
          signal level change for transition to the next color.  The total
          range for the 16 possible colors is greater than 30 db.

        - The AUTO mode provides an automatic color level set by the
          program based on the distribution of noise.  It should a little
          better in showing a weak signal buried in noise.

   o [F1] Setup & Help

       - This button will bring up a Setup screen.  Help menus have
         not yet been implemented.

       - Also not implemented is the processing for the Local time
         offset entry to GMT.

         
   o [F2] Save Pic (or Wav/Pic

       - This button will save the full screen as a GIF file,.  If in RECORD
         mode, the audio will also be saved as a WAV file.

       - After the image is stored and the operation continues, a
         horizontal white line is drawn across the screen as a marker
         showing where the screen save occurred.


   o [F3] Load File 

       - Retrieves a GIF or WAV file for display or post processing


   o [F4] Playback

       -  Not currently implemented


   o [F5] Playback & Filter

       - Not currently implemented


   o [F6]  Smooth
 
       - Toggles thru several filters for smoothing
         the FFT display.  The COSINE filter is good
         for strong signal S/N measurements.

       - These filters are somewhat experimental and
         will generally not improve weak signal detection.
         They can improve the accuracy of  S/N measurement
         for strong signals.  All filters are applied in the
         time domain before FFT processing.
     

    o [F7] Integration

       - Sets the integration period in multiples of 1/2 seconds.	
       - Hitting the left mouse button will increase the count. 
       - Hitting the right mouse button will decrease the count.
       - Going to SETUP allows a direct entry of large numbers.


   o [F8] Zoom

       - Toggles between narrow bandwidth and wide bandwidth
       - Zoom Out covers a typical radio's full bandwidth:
         200 Hz to 2700 Hz .  Zoom In covers half the range
         with better resolution.


   o [F] Find

      - Brings up a window for searching the EME.WS database.
        EME.WS can be produced from the EME directory database
        program which is publicly distributed.  The "EXPORT" feature
        of the PCF program produces this text listing of the calls.

        EME.WS is just a simple list of calls and can easily
        be produce from any database program.

      - Single, grouped or spaced grouping of characters can be entered.
        The ENTER key starts the search.

      - A space between characters or groups will show all calls
        containing the characters or groups anywhere in the call.

         For example:   "F9 A"   would find AF9Y and UF9DA
                                 
      - A personal file, "WORKED.TXT", will also be searched.  This
         is a simple text file in which the user can list stations already
         worked.  A search result will show a different color for calls
         found in both WORKED.TXT and EME.WS files.


   o [R] Record toggle

        - Selecting this button will toggle between Record (shown as Red)
          and non Record Mode (shown as Black)


   o [C] Clear Screen

        - This key will clear the screen and restart the spectrograph
          at the top.


   o [Alt-X] Exit

        - Terminates the program and returns to DOS

   o [LT] Long Term Data Logging
 
        - Creates a continuous running log file called lngtrm01.dat in which
          the bit mapped screen information is stored.  
 
        - Activated when toggled with the mouse or the "L" key.

        - The [LT] button is green when active, gray when inactive.
 
        - Information is not written to the file until the first 200 lines
          of display is reached.  When exiting from the program or turning
          off the LT mode, the last 200 lines may not be saved.  This will
          be corrected in a future version.

        - The log file, lngtrm01.dat will be overwritten when the logging
          is restarted.  Rename it if you want to save it.
 
        - The log file can be read using the "Replay.exe" program.

        
   o [SN] Signal to Noise Measurements
     
        - This button allows several modes of S/N measurement.
   
        - Selecting "Average" will produce a finger ICOM which
          allows a selection of the Signal Bar area to be
          average.

        - Hitting any key will return the program to normal
          operation.


   o S/N Bar Graph and Measurement Box

        - When enabled (from Setup Area), the S/N levels are
          shown against four vertical lines representing 10 db
          per line.  

        - The S/N is calculated for the Maximum signal
          in a bandwidth of 100 Hz.  One of the options
          under the S/N button will allow a window area
          for S/N measurement.  

   o Time

        - GMT is show in a box with identification of East
          and West periods of EME operation.

        - Setup allows entry of Local Offset for use with
          computers not setup for GMT.


   o Moon Az./El Position
 
        - When Enabled and the user Grid Square or Lat/Long
          has been set, this box show the current Moon Az and El.

        - Computer time must be set to GMT for correct Az/El.


   o Frequency Scale

        - Horizontal scale across the screen showing Frequency in Khz.


   o Time Markers

        - 1 Minute GMT Time marks are printed along the left side of the
          spectrograph.

        - Normally 3 Time marks will be shown since a full screen represents
          a little more than 2 minutes.  On slower computers, more time marks
          may be seen due to a compressed time scale. (See CPU Time)

        - Time Marker increments are varied in Integration:
 
          Integration of 1 to 9 has 1 Minute Markers
          Integration of 10 to 99 has 10 Minute Markers
          Integration of 100 to 999 has 1 Hour Markers


   o [ESC] Return to Main Screen

        - Upon return to the Main Screen, a horizontal white line will mark
          the point where spectrograph operation was suspended.


HOT Keys:

C/c   - Clear the screen
+     - Increase Color Level
-     - Decrease Color Level
A/a   - Toggle between auto and normal Color Level
L/l   - Toggles long term data loggin on/off
ESC   - redraws header and draws line on display
S     - advance clock 1 sec
s     - decrease clock 1 sec
M     - advance clock 1 min
m     - decrease clock 1 min
H     - advance clock 1 hour
h     - decrease clock 1 hour

b     - decrease sound card bias by 1 count
B     - increase sound card bias by 1 count
         
       Note:  Some sound cards have a DC offset problem which
              the bias adjustment can correct.  The bias should
              be set to keep an equal level of positive and negative
              peaks in the level display.

Alt-X - exit program
F     - Find Utility
 

