This contains all NEWS files prior to 1994.

17 Dec 1992    News for NTIA/ITS HF Propagation Models

Whenever changes are made to any of the propagation models and a new
version is sent, the changes will be detailed in a NEWS file dated the
same as the version date.  Since this is the first NEWS file, I will
discuss a little of the evolution of some of the changes that may already
exist in some previous versions.

Antennas:
   Perhaps the one item that has produced the most significant change has
   been the incorporation of antennas into the propagation models.  It was
   desired to add the CCIR HF antenna package into VOACAP, REC533, and HFBC84.
   Previously, models such as REC533 and HFBC84 had predefined gain tables
   for antennas.  Thus, when an antenna was chosen, it was valid for all
   frequencies.  VOACAP (i.e. IONCAP) had a different, and more realistic
   approach.  For each antenna entered, a range of valid frequencies was
   also given.  Thus, several antennas can be specified for a given circuit.
   One valid for 2-9 MHz, another 9-15 MHz, and 15-30 MHz.  Each antenna
   can be of any type, design frequency, main beam direction, etc.

   To incorporate this ability with the CCIR antenna software became very
   difficult.  The most inner calculation loop in the propagation models
   is frequency.  As you change frequencies, you may change antennas.  The
   CCIR antenna software does initialization the first time you define a
   new antenna and saves this information to speed up calculations.  Since
   this information would be lost as frequencies change, it became very 
   difficult to implement.  I therefore took a major modification to remove
   all gain calculations from the propagation models.  Since these are
   point-to-point models, once the off azimuth direction is calculated, the
   only gain values that need to be calculated are for elevation angle.
   These gain values are calculated for frequencies 2-30 in 1 MHz and 
   elevation angles 0-90 degrees by 1 degree.  Further, since one antenna
   may be valid for 2-9 MHz and another 9-15 MHz, there will be a discontinuity
   at 9 MHz in this case.  A calculation at 8.5 MHz will have no problem.
   As 9.1 MHz will have no problem.  The gains for both 9 MHz are saved.
   A calculation at 9 MHz will use the antenna 2-9 MHz.  There are some major
   advantages to removing the antenna gains from the propagation models.
   To add new antennas, the models need not be changed, only the single
   antenna calculation program.  Measured antenna gains can easily be added.
   Output from other antenna programs such as NEC can be added.  By taking
   this approach, I also stumbled upon a limitation of the CCIR antenna 
   software.  To speed up the processing, the CCIR antenna software 
   pre-calculates trig functions.  It also truncates the elevation angle
   to the lower integer degree (very different from rounding).  The end
   result of this is that for an elevation angle of 15.9 degrees, the gain
   will be calculated at 15 degrees.  This can produce quite a difference.
   By using my external calculation method, I calculate gains at every
   degree (no problem with rounding or truncation) and then the gain is
   interpolated in the propagation model.  Thus a more accurate result is
   obtained.

   While incorporating this new scheme into REC533, I noticed a problem
   in the E-modes calculations.  Since REC533 (and precursor REP894) only
   ever used gain tables independent of frequency, the use of antenna gain
   for the E-modes had been removed from the frequency loop to speed up
   processing.  I have corrected this problem and I will notify CCIR of
   what must be done.

   The method of defining the antennas is very similar between the 3 models.
   The only difference is that VOACAP transfers you to a different screen
   to define the parameters.  This perhaps is a bit more difficult, but
   VOA required an ability to have 10 antennas defined and there was not
   enough room on the main input screen.  In REC533 and HFBC84, I allow a
   maximum of 5 antennas to be defined, and this is done on the main input
   screen.  Also, VOACAP can mix IONCAP and CCIR antennas.  This is not
   allowed with REC533 or HFBC84, because they have no knowledge of IONCAP!

CIRCUITS.DAT
   This is the data file containing valid Transmitter-Receiver coordinates
   and antenna information.  It should be customized by each user.  To
   accommodate the multiple antennas as discussed above, each circuit may
   now define multiple antennas.  Look at the new format of this file and
   it should be quite obvious.  One problem though, is that this file defines
   transmitter power for each antenna.  However, power (by IONCAP convention)
   has always been separate from the antenna definition.  It is my perception
   that at a transmitter site with 2 antennas valid for different frequency
   ranges, even different main beam directions, that they may actually have
   different power.  The users may wish to let me know if they would like
   power tied to each antenna, or separate as it is.  If it is linked to
   each antenna (hence frequency), then some additional changes in the
   propagation models will need to be made.

BATCH execution
   This option is selected from the OPTIONS menu after you accept the input
   data.  What it allows is for you to select a sub-set of circuits from
   the CIRCUITS.DAT data file.  This sub-set will then be run using the
   other parameters defined on the input screen (e.g. month, ssn, system
   parameters) in a non-interactive GRAPH mode.  What this means is it
   will calculate all frequencies (2-30 MHz) and all hours (1-24) for one
   month and SunSpot number and produce the graphs for Field Strength,
   Reliability, and S/N ratio and the table of Field Strength.  This will
   allow you to produce a book of results on an overnight basis.  Since
   this may produce much output and requires an HP LaserJet on LPT1, the
   actual printing has been commented out of the .BAT file.  Thus, to
   activate this, you need to edit the appropriate .BAT file (VOACAP.BAT,
   REC533.BAT, HFBC84.BAT) and remove the "rem" from the proper place.
   Since BATCH is a new concept and I am not yet quite sure how the users
   wish to use it, I think this is the easiest approach so far.

VIEW LAST CIRC
   I have written a new program called SCROLL that now controlls the viewing
   of the circuit calculations.  This program allows forward/backward and
   even left/right (for output greater than 80 columns) scrolling of the
   output files.  The arrow keys, HOME, END, PageUP, PAgeDOWN, TAB, and
   ENTER keys control your movement. The <esc> key exits the program.
   If desired, I could include a capability to search for character strings
   to greater flexibility.
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14 Jan 1993    News for NTIA/ITS HF Propagation Models

 4 Jan 1993  changed VOACAP so that when MULTIPATH POWER TOLERANCE or
             MULTIPATH TIME DELAY are set = 0., multipath probability
             (MPROB) is not computed.  Previously, setting these values to
             zero caused them to be set to their defaults (10 dB & .85 msec).
             This was a holdover from the card image format days when a
             blank value was used to set default values.

 8 Jan 1993  changed all RETRIEVE DATA options so that a 1 line summary of
             the data file is displayed. It includes the file name,
             Transmitter name, Receiver name, Month, SSN, and Time.

11 Jan 1993  You can now quickly display the CCIR vertical & horizontal
             antenna patterns to the screen during the antenna selection
             process. Press the <F2> key to display to screen.

14 Jan 1993  Changes made to REC533 calculations as per correspondence
             with Mike Dick, correcting NOISE and FADING calculations.
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22 Apr 1993    News for NTIA/ITS HF Propagation Models


22 Apr 1993  Many changes have been made since the first delivery of this
             software to accommodate user requests and to make some aspects
             more flexible.

             Users may now maintain libraries of TRANSMIT, RECEIVE, and
             CIRCUITS files.  While selecting transmitter or receiver
             coordinates, pressing the <F2> key will allow you to change
             the name of the file you are selecting from.  The names
             TRANSMIT, RECEIVE, and CIRCUITS are suffixed with a 3 character
             name of your choosing.  Please maintain the .DAT name for the
             default files supplied.  You may also build your data files
             by inputting the coordinates and names and pressing the
             <F6> to store the transmitter, <F7> to store the receiver, or
             <F8> to store the circuit information.  These files will
             automatically be maintained in alphabetical order.  Exact
             duplicates will be removed.  Upper/lower case is ignored.
             You may remove unwanted records with the <DELETE> key.

	     Also new is a vast selection of city coordinates from a
	     geographic data base. Pressing the <F4> key while in either
             the transmitter or receiver fields, allows access to these
             files. All but one of the files are ASCII and may be added
             to or new files in the same format may be created. They are
             located in the ..\GEO directory. Only the file USA_ONLY.GEO
             is not ASCII and can not be changed. It contains 32028 city
             names in the United States.

             The HFANT program has been changed to include a TYPE 11 which
             is a user supplied gain table versus elevation angle.  Currently
             these values are omni-directional and frequency independent.
             As the need arises, these features can also be added.
             For types 5,6,7,10, the directivity gain calculations in the past
             were not extensive enough, resulting in incorrect results. This
             has been fixed. Also a TYPE 12 which is a more general set of
             curtain arrays from NTIA Report 87-215. This allows for non-
             standard element spacing (e.g. not .5 wavelength).

             VOACAP has a completely new graphics output program.  You are now
             allowed to plot contours of any parameter on the output file.
             Thus, selecting different methods, (e.g. 16 thru 23) will allow
             you to plot different results.  The default parameters plotted
             in the batch more are DBU, REL, SNR, FDAYS.  To change these
             requires a simple change in the VOACAP.BAT files.

	     Also new for VOACAP, methods 11 & 28 will now produce graphics
	     plots on the screen and printer instead of the old line printer
	     graphics with +,*,. symbols. Try it and see if you like it.

             REC533 still only allows Field strength, Reliability, S/N, and
             a table of field strengths to be plotted.

             The cursor can now "wrap" from the top of the input screen to
             the bottom (using UP arrow), or from the bottom to the top
             (using DOWN arrow).
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18 May 1993    News for NTIA/ITS HF Propagation Models

18 May 1993  VOACAP fixes/enhancements :
             1. The following variables have been added to VOACAP:
                TGAIN - Transmitter gain of strongest mode
                RGAIN - Receiver gain of strongest mode
                SNR90 - Signal-to-Noise ratio attained 90% of time.
                DBM   - Power Density (dBu - 30)
                They may be printed with METHOD 20 (all parameters), or
                by using the METHOD 23 modifications below.
             2. Using METHOD 23 of VOACAP, you may now choose the order
                and number of variables sent to the output file. The other
                methods are unaffected. Read the HELP window for the METHOD
                parameter.
             3. Median/Lower Decile S/N parameter removed because of new
                parameter SNR90 from above is calculated. To plot this
                parameter, either select METHOD 23 and choose SNR90, or
                select METHOD 20 (all parameters).

18 May 1993  VOACAP & REC533 fixes/enhancements :
             1. BEGINNING/ENDING HOURS may now wrap around midnight.
                You may now specify hours 22 to 04. Previously, this would
                have produced hours 04 to 22.
             2. MONTHs & SUNSPOTs are now taken as pairs. This was a major
                departure and very important to frequency planners.
                To run testing such as benchmarks, you are allowed to make
                12 pairs.
             3. The NOISE parameter was changed to avoid math errors.
                You now specify either levels 1,2,3,4 or -dBW values in
                the range [100 to 200]. Levels are no longer negative and
                you cannot specify -dBW values below 100 as these were 
                deemed inappropriate.
             4. A few problems were corrected concerning the Geo city database
                files.  The major problem corrected had to do with the amount
                of memory required to access the .GEO files. This has been
                reorganized and should cause no more problems.
             5. The TRANSMIT.*, RECEIVE.*, CIRCUITS.* files no longer reside
                in the DATABASE directory. Since they have become user specific
                data files, they now will have their own sub-directory called
                USERDB. This should make it easier for users to maintain.

18 May 1993  REC533 fixes/enhancements :
             1. The contour plotting for REC533 has been converted to
                the same as VOACAP.
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24 May 1993    News for NTIA/ITS HF Propagation Models


24 May 1993  VOACAP & REC533 fixes/enhancements :
             1. Whenever you view a CIRCUITS.??? file (either in
                choosing circuit coordinates or in BATCH selection),
                you now can view all of the parameters associated with each
                circuit.  Previously, you could only see the lat/long/name
                of transmitter & receiver.  Now you can see all of the
                antenna parameters.
             
24 May 1993  HFANT fixes/enhancements :
             1. Type 10 (Vertical Monopoles) now save the vertical gain
                pattern for frequencies 2-30 MHz.  Since this is an
                omni-directional antenna, the horizontal gain pattern
                is not necessary.  This is saved because vertical monopoles
                have a large overhead during initialization (i.e. when the
                frequency changes).  Thus during propagation calculations,
                too much time was lost.  
             2. Dipole arrays (type 1,2,3,4,8,9) are not valid below the
                frequency ratio .7 or above 1.4.  Frequency Ratio (Fr) is
                Operating/Design Frequency.  In the propagation models,
                if you specify a design frequency (not 0.0), for any operating
                frequency outside these limits, the gain will be -30.  If you
                specify the design frequency=0.0, the design frequency will
                be set to the operating frequency.  This allows studies to be
                done when you do not know all of the antenna information.
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09 Jun 1993    News for NTIA/ITS HF Propagation Models

               1. Antenna types 5 & 6 (Horizontal & Vertical Log Periodic)
                  have been changed to allow up to 30 (from 20) elements.

               2. Under advisement from Keith Edwards and Mike Dick, the
                  useable frequency range for Vertical Monopole (Type 10)
                  is now limited to [.05 to .35 times the wavelength].
                  What this means is .05*300/Height of monopole in meters to
                  .35*300/Height. Frequency is in MHz.

               3. Antenna type 1 (Multiband Aperiodic) is limited to the
                  Frequency Ratio (Fr=Operating/Design) of .7 to 1.4.
                  Antenna types 2,3,4,8,9 are limited to .85 <= Fr <= 1.2.

               4. Corrections to the Atmospheric Noise variability with
                  frequency have been made. The routine GENFAM in both
                  VOACAP and REC533 was incorrect. The change will 
                  probably not be noticed because ManMade Noise is dominate
                  at the HF frequencies involved. Occasionally you may
                  notice a 1 or 2 dB change in SNR and N DBW.
    
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09 Jul 1993    News for NTIA/ITS HF Propagation Models

               1. ANTCALC has been modified to now create a FORMATTED file
                  rather than an unformatted one. This should allow you to
                  create your own antenna file with any compiler and not
                  have a read error in the HF model.
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14 Jul 1993    News for NTIA/ITS HF Propagation Models

               1. ICEPAC has been added as a model.
               2. With ICEPAC, you can make short term predictions by
                  specifying current foF2 values at known lat/long/time
                  locations.  The program will calculate an "effective"
                  SunSpot Number, and you can use this "instantaneous"
                  SSN to make the predictions for the next hour or so.
                  Anything beyond a few hours should be suspect.
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20 Jul 1993    News for NTIA/ITS HF Propagation Models

               1. ICEPAC BATCH mode has been fixed.
               2. a NEWS.BAT facility has been made to allow easy viewing
                  of all the NEWS files.
               3. HFBC.BAT has been updated to include access to the NEWS.BAT
                  batch file.  Just type in HFBC and you have access to all
                  of the propagation programs on your system, HFANT, and the
                  NEWS facility.
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08 Oct 1993    News for NTIA/ITS HF Propagation Models

               1. This version of VOACAP (called 93.1001) has now been
                  benchmarked against the VOA NRL version 93.04 distributed
                  at IES 93 in Washington, D.C.  Differences were originally
                  discovered because of 2 reasons.  First, the FORTRAN
                  compiler used uses 80-bit registers for intermediate results.
                  When that was changed to save in 32-bit registers, the
                  results matched.  Second, 93.04 uses what has been found
                  to be an incorrect noise routine (GENFAM).  When this noise
                  routine was inserted, results between 93.1001 and 93.04 were
                  identical (within allowed tolerances).  The version now
                  employed, is called 93.1001, and includes the corrected noise
                  routine GENFAM.  You may therefore expect differences in the
                  results for frequencies above 10MHz.  Frequencies below 10MHz
                  should be unaffected.

               2. An error was corrected in the geographical data base search
                  routines.  Previously, if you specified a NATION or STATE to
                  search for, and you gave a name that did not exist, the 
                  program would abort.
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05 Nov 1993    News for NTIA/ITS HF Propagation Models

               1. Area coverage calculations and plots has been added to
                  VOACAP, REC533, and ICEPAC.  Since the inputs are different,
                  these are controlled by 3 new .BAT files (VOAAREA.BAT,
                  RECAREA.BAT, & ICEAREA.BAT).  To access all models installed
                  on your system, execute ITSHFBC.BAT.  This will detect which
                  programs exist and display a menu for you to select from.

               2. New self-extracting files are now being supplied.
                  READ.ME     - describes point-to-point models
                  HFBC1.EXE   - general files for all models
                  VOAPK.EXE   - specifics for VOACAP point-to-point
                  RECPK.EXE   - specifics for REC533 point-to-point
                  ICEPK.EXE   - specifics for ICEPAC point-to-point
                  RDAREA.ME   - describes area coverage models
                  WORLD.EXE   - world political data base for plotting
                  VAREA.EXE   - additional files for VOACAP area coverage
                  RAREA.EXE   - additional files for REC533 area coverage
                  IAREA.EXE   - additional files for ICEPAC area coverage

               3. The current version of the appropriate propagation model
                  is now listed on all plots (point-to-point & area coverage).
                  This should avoid probelms if the results change.  You will
                  know which version was used.  The current naming convension
                  of the versions for the different models is:
                      VOACAP - Version 93.1001          (Year.month_day)
                      REC533 - ITS VER-1.43 09.Jul.93
                      ICEPAC - Version ITS.01           (Numerical number only)
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-------------------------------- End of 1993 -----------------------------------
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