HFBC Area coverage

The HFBC AREA COVERAGE program was developed by the U.S. Department of Commerce NTIA/ITS in Boulder, Colorado and is available by remote dial-in on the TA Services computer system. Questions concerning its operation should be addressed to Chris Behm (303)-497-3375.

This program provides area coverage contours of HF skywave propagation parameters (Field Strength, Reliability, S/N Ratio, MUF) plotted with world political boundaries. HF or High Frequency is propagation in the range of 1 to 30 MHz. Any of the following five HF propagation prediction models may be used:

• HFBC84 - developed for HFBC WARC 84
• CCIR91 - CCIR modification to HFBC84
• IONCAP - model developed at ITS
• VOACAP - VOA modification to IONCAP
• REC533 - current CCIR recommendation

Results may be sent by FAX or mail (Black/White LaserJet or Color PaintJet).

HFBC tries to be friendly and verify that each variable is reasonable. Generally, whenever a question is not understood, responding with '?' will produce a more VERBOSE question. To return to the main menu and start over, the user need only respond to any question with the 2 characters '::'. If you have run this program before and wish to use one of your old data sets, the main menu option "O" (for OLD DATA) will allow you to specify the data set name (hfxxxx). Responses may be either UPPER or lower case. Your name and address should be given case sensitive.

Since several models are allowed, a brief description of the input variables required for each model follows:

• HFBC84 & CCIR91 require the same variables.
• IONCAP & VOACAP require the same variables.
• HFBC84 variables are required for all models.

HFBC84 & CCIR91 required inputs:

• Name/Address - Your name and mailing address. Maximum of 8 lines long. No name, no plots.
• Results - sent to (Fax, Laserjet, Paintjet, Min/max) Min/Max will display to screen minimum and maximum values computed within the coverage area. This is a quick way to determine if your input data is correct.
• Process - Model name to process data with: (HFBC84, CCIR91, IONCAP, VOACAP, or REC533)
• Months - Up to 12 may be specified. Values [1-12]
• Hours - UT time for calculations. Up to 12 may be specified. [1=0100, 12=noon, 24=midnight]
• Sunspots - SunSpot Numbers for calculations. Up to 10 may be specified. [Range 0-200].
• Transmitter - Latitude/Longitude/Name of transmitter location. May be specified in Degrees-Minutes-Seconds or decimal degrees. (e.g. 35N30 45.5 Name = 35.50 North 45.50 East)
• Grid Parameters - These are the most confusing parameters to enter because you must think in projection coordinates. Options are either USER DEFINED or CIRAF ZONES. CIRAF ZONES: You specify CIRAF zones of interest and the plot area is 4% larger. If you don't know what CIRAF zones are, use USER DEFINED.
  • USER DEFINED:Plotting is done with an Azimuthal Equidistant projection. This has the property that straight lines from the center are great circles. Distances and azimuths can be measured from the center of projection. The center of projection should be defined as either the transmitter location or the center of the reception area. You then define a view rectange relative to this center in kilometers. Use a globe to locate your center, and then estimate the view rectangle in kilometers left/right and up/down from this center. Also, the ratio of XLENGTH/YLENGTH should be near 1.2. This is because the plots are done in landscape mode and the paper is longer than it is high. A ratio of 1.0 will produce a square plot, and there will be wasted space.
• Power - Transmitter power in kWatts. [Range 1.0 to 1000.]
• Antenna - Transmitter antenna is selected from a list of pre-defined antenna types. These are all curtain arrays:
  • 0=ISOTROPE 7=HR 2/4/1 14=HR 2/1/.3 21=TR 1/2/.5
  • 1=HR 4/4/1 8=HR 2/4/.8 15=HR 1/2/.5 22=TR 1/2/.3
  • 2=HR 4/4/.8 9=HR 2/4/.5 16=HR 1/2/.3 23=TR 1/1/.5
  • 3=HR 4/4/.5 10=HR 2/3/.5 17=HR 1/1/.5 24=TR 1/1/.3
  • 4=HR 4/3/.5 11=HR 2/2/.5 18=HR 1/1/.3 25=Omni 4dB
  • 5=HR 4/2/.5 12=HR 2/2/.3 19=TR 2/1/.5
  • 6=HR 4/2/.3 13=HR 2/1/.5 20=TR 2/1/.3
• However, the ability exists to define any antenna type from the following list:
  1. =Multiband Aperiodic Reflector Array
  2. =Dual-Band Center-Fed Half-Wave Dipole Array
  3. =Dual-Band End -Fed Half-Wave Dipole Array
  4. =Tropical Arrays
  5. =Horizontal Log-Periodic Arrays
  6. =Vertical Log-Periodic Arrays
  7. =Horizontal Rhombics
  8. =Quadrant Antennas
  9. =Crossed-Dipole Antennas
  10. =Vertical Monopoles

If you require one of these antennas, please contact us. The main beam azimuth (from North) is also required.

• Frequencies - Up to 6 may be specified in the range [1 to 30 MHz]. Design frequencies for the transmitting antenna are also required. A design frequency of zero will set design frequency equal to operating frequency.
• Outputs - You may plot Field Strength (F), Reliability (R), Signal-to-Noise (S), or MUF (M). You may also choose contour values or let the program choose default values.

The number of plots you will produce is determined by how many parameters
you enter for MONTHS, HOURS, SUNSPOTS, FREQUENCIES, OUTPUTS.
   # of plots = #MONTHS * #HOURS * #SUNSPOTS * #FREQUENCIES * #OUTPUTS

You can easily see the number of plots can add up quickly. The charge on
TA Services is:
	       $3.00 per minute connect time
			+
	       FAX      =  $5.00 per plot
	       LaserJet = $10.00 per plot   (Black/White)
	       PaintJet = $20.00 per plot   (Color)
	       Min/Max  = no additional charge


IONCAP & VOACAP additional inputs required:

     Takeoff Angle- Minimum takeoff angle of the antenna main lobe.
		    Range is [.01 to 40 degrees].  Default is 3 degrees.
     ManMade NOISE- Man Made noise in dB below a Watt.
		    Affects only Reliability or Signal-to-Noise plots.
		    Preset values are:
				      -1 = 125 = industrial
				      -2 = 136 = residential
				      -3 = 148 = rural
				      -4 = 164 = remote
                    Other values may be specified with positive numbers.
     LUF          - Required Circuit Reliability.  This is an esitmate of the
		    % of days that the Required Signal-to-Noise will be met.
		    Range is [10 to 90].  Median is 50.
		    Affects only Reliability or Signal-to-Noise plots.
     Req S/N ratio- The required Signal-to-Noise ratio of the hourly median
		    signal power relative to the hourly median noise in a
		    1 Hertz bandwidth.  Combines with the LUF parameter.
		    Range is [-20 to 100].
		    Affects only Reliability or Signal-to-Noise plots.
  

REC533 additional inputs required:
     NOTE: While these may look the same as IONCAP & VOACAP, there are
	   slight differences so read closely!

     Takeoff Angle- Minimum takeoff angle of the antenna main lobe.
		    Range is [3 to 40 degrees].  Default is 3 degrees.
		    REC533 is not valid below 3 degrees.
     ManMade NOISE- Same as IONCAP/VOACAP.
     LUF          - Same as IONCAP/VOACAP.
     Req S/N ratio- The required Signal-to-Noise ratio of the hourly median
		    signal power relative to the hourly median noise in the
		    receiver BANDWIDTH.  Note difference with IONCAP/VOACAP.
		    Combines with LUF and BANDWIDTH.  Range is [-20 to 100].
		    Affects only Reliability or Signal-to-Noise plots.
     Bandwidth    - Receiver bandwidth in Hertz.  Range is [1-30000].

Once parameters have been entered, they may be EDITed with the Edit option from the main menu. To change a paramater, you need to enter the name of the paramater you wish to change. Typing ? will list the valid names. Only 1 or 2 characters (whatever uniquely defines it) are needed. When done changing parameters, enter a for the CARD NAME, and you will be given a summary of your input values.

Be especially alert when the MENU(PROCESS with ...) appears. A carriage return will begin calculations on your input data. Make sure this is what you want (review the parameter summary for errors).

The default data entry is in the VERBOSE mode. This gives you the most information available about each input parameter. Once you become familiar with the input data, you can use the CONCISE mode to speed up data entry.