Two time-sharing, user-interactive propagation models are available via Program RAPIT, Radio Propagation over Irregular Terrain. One model, Area Prediction, is useful for mobile and broadcast propagation studies; the other model, Point-to-Point, lends itself to communication link or interference situations. At the user's option, either model will compute basic transmission loss, field intensity, power density, available received power, or received signal-to-noise power ratio. Both models also account for the received signal's variability over irregular terrain, a topic discussed in more detail in Section 5.3.
To use RAPIT, one merely logs onto TAS and selects RAPIT from the r the APPLICATIONS portion of the bulletin board. After a pause, RAPIT will start running. The user responds to requests for parameter values and obtains tables of computed values. The program recycles and one may make as many runs as desired.
Sections 5.2 through 5.4 give background information on the propagation programs. Section 5.5 give guidance on how to operate the programs and Section 5.7 gives sample RAPIT runs.
The computed values attempt to give a statistical description of received radio fields. They may be used for either system design or interference analysis. The statistics used are the situation variability, the location variability, the time availability, and the hourly median value. In what follows, we give brief descriptions of these.
On a fixed propagation path, the received signal varies with time in a random fashion. The magnitude of this variation changes with circumstances from the slight scintillations observed on a short line- of-sight paths to the rather large variations seen on a troposcatter paths of medium length.
The time availability separates naturally (both from a physical point of view and from that of the designer) into two parts characterized by the time scale involved. They are called the short-term variability and long-term variability. The short-term variability (which may also be called "rapid fading") describes how the signal varies within periods of an hour or less. It is normally accounted for in the original design of the system by using fade margins, diversity, good modulation and demodulation techniques, or a combination of these. Since such hardware solutions exist, RAPIT (and any similar program) does not consider short-term variability to be a part of the "propagation problem."
What remains after we remove the short-term variations is known as the hourly median value. It measures the brute power available to the system, if the system can properly use it. Within- the-hour values are, of course, greater than the median value for half the time, less for the other half. Values available to the user of RAPIT are the (hourly median) basic transmission loss Lb, the field intensity E, the power density S, the available power Pr, or the available power to receiver noise power ratio Pr/N. The latter four outputs require information about radiated power and antenna gains while the last output requires additional information about the receiver noise power.
From observations we note that the hourly medians also show random variations in time, and it is these "long-term" variations that RAPIT describes and with which the designer must cope. Long-term variations are due to:
In consideration of the long-term variation, we introduce the time availability qT. This is the fraction of time during which hourly median fields are larger than that given (and that propagation losses are smaller). The terminology given here is slanted toward the designer's point of view. For him or her, the number qT represents the fraction of time during which an adequate signal is available. On the other hand, if one wishes to avoid interference, then 1-qT is the fraction of time during which hourly median fields are smaller than the levels given. For desired fields, one wants qT large; for undesired fields one wants it small.
A second source of randomness is called location variability. A small change in the transmitting or receiving antenna location will often produce changes in path loss which are much larger than any calculation could predict on a deterministic basis. The random profusion of trees, buildings, and other obstructions makes futile any such attempt. The value predicted after considering time variability is for an average location. That is, an average of the many different locations in the immediate vicinity of the receiver location. To describe not just the average but the full range of possible signal levels over this small area, we introduce the concept of location variability, qL. Through a knowledge of the distribution of signal levels in the immediate vicinity of the receiver site, we provide the user with a description of the fraction of the local area that receives various signal levels.
Finally we come to the last statistical variation in the model that we call situation variability or qS. The model is based on many sets of propagation measurements made in the field at many locations. Since the model is based upon this measured data, we can bias the predicted propagation value obtained from the model with the situation variability term. For example, if we choose situation variability to equal 50 percent, then the model's predicted transmission loss will be equal to or greater than 50 percent of the measured losses on which the model is based. Likewise, choosing situation variability to equal 90 percent biases the model to predict a loss which is equal to or greater than 90 percent of the measured losses. Thus, situation variability allows the RAPIT user to have a certain assurance that the predicted loss has some predefined relation with measured losses.
Trying to pack these three varieties of statistical statements into one long sentence, we would say, "With situation variability qs, there will be a fraction of nearby locations at least as large as qL at each of which there will be a fraction of time at least as large as qT during which the hourly median available power (for example) is at least Wa."
The three numbers Wa, qT, and qL are often used together to define a grade of service. In that case Wa is the threshold level which gives satisfactory results in laboratory experiments; qT is the barely tolerable limit (to avoid, outages) of the fraction of time during which the threshold level Wa is to be exceeded and qL is the barely tolerable limit (to avoid say, having to reposition the antennas) of the fraction of nearby locations where the level Wa is exceeded for qT of the time. For example, the FCC has defined Grade A service for television broadcasting in the low VHF band to mean a minimum field strength of 61 dB V/m for at least 90 percent of the time at 70 percent of the locations. For a fixed communication link it is common to require 99 percent (or even more) time availability but to ignore entirely the location variability. One requires, say, a minimum of - 130 dBW for 99 percent of the time, it being assumed that sites will be carefully selected and well-cleared so that there is effectively no location variability. Users of RAPIT can stimulate this situation by setting qL equal to 50 percent. This will cause the program to make zero correction for location variability and hence to act as though there were none.
When a grade of service is defined, then the remaining statistic qS can be identified as the service probability; i.e., the probability that the proposed system will perform adequately. Often, however, this term implies also that equipment variability and ambient noise variability have been taken into account. The three statistics qT, qL, qS cause the program to add in correction terms which may be viewed as "factors of safety" - in the case of qT the correction may be called a "fade margin" (although this term usually includes an additional margin to overcome short-term fading). Generally speaking, the user should avoid applying too many of these factors of safety one on top of the other. And, as a matter of fact, the situation variability qS should be set to 50 percent for most uses since this causes the program to select the median of all the "measured data" upon which the model is based.
If the situation is one of avoiding interference, we must turn the above inequalities around. Thus, we equally well may say that for the fraction of situations 1-qS there will be a fraction of locations greater than 1-qL at each of which there is a fraction of time greater than 1-qT during which the available power is less than Wa. For the desired signal, one wants for most situations (large qS) that there is a large fraction of locations (large qL) with a large time availability (large qT) to produce a good signal (large Wa, small loss Lb). But for an undesired signal, one wants for most situations (small qS) that there is a large fraction of locations (small qL) with a large fraction of time (small qT) during which there is a weak signal (small Wa, large loss Lb).
Additional discussion of variability is found in the report by Hufford, et al. (1982).
Program RAPIT contains two different models (or algorithms) which are to be used under different circumstances. The first of these is the "Area Prediction" model designed by Longley and Rice (1968), and is meant to be used when only moderate information about the propagation paths is known. It is particularly useful in mobile and broadcast situations, in the design of generalized systems, and in discussing general problems of interference between types of systems. It is less accurate at short ranges, particularly when high antennas are involved, for it will predict lower signal levels (higher losses) than it should. But for medium and long ranges it should give good results. A recent ITS report (Hufford, et al. 1982) gives additional guidance on the use of the Area Prediction model.
The Area Prediction will ask for a terrain roughness factor (delta-H), surface refractivity (Ns), and average terrain heights depending upon the options chosen. Figure A-1 of Appendix A shows how the terrain roughness varies across the United States. The program user can supply his or her own values for these parameters or else let the computer supply the values. The computer has stored values of delta-H, Ns, and average terrain heights on a grid which covers the U.S. The resolution of the grid is 30 minutes by 30 minutes of arc, or roughly 30 miles on a side. If the user supplies the latitude and longitude of a reference or transmitter location, the computer will calculate, from the stored data, values of terrain roughness, surface refractivity, and average terrain heights.
The second propagation model is designed to be used on a fixed path where certain gross features of the intervening terrain profile are known. The model is known as the point-to-point mode of the irregular terrain model and is based upon the ESSA '70 model (Longley, et al., 1971). The model is particularly good for communication links and for special interference problems. It is not at all valid on the standard microwave line-of-sight links and should never be used for that situation. (The treatment of such links is normally quite different from the RAPIT approach. Median signal levels are usually at or near free space values, and variability around the median follows a different set of laws). As mentioned above, one should usually set the location variability quantity qL equal to 50 percent. But, for example, if one wants to consider what effect a particular ridge will have on a land mobile system, then the signal variability can be simulated by adjustments to qL. Parameter values have the same limiting ranges as they do in the area prediction model. Again, to assist the user, Table 5-2 lists the requests, their meanings, and acceptable responses for the point-to-point prediction method.
One option requires the user to select how the profile is to be defined. The easiest method requires the user to define the location of the path end points (in latitude and longitude) and the program will compute the profile from the topographic data base. See Appendix A for description of the data base. The second method requires the user to enter the profile by supplying the terrain elevations along the path. The third method requires the user to define a simplified "profile."
The profile information needed consists of the ground elevations above mean sea level at the two antenna sites, the elevations and distances to horizon obstacles as seen from each antenna, and the elevations of "effective surfaces" which may be interpreted as average elevations of the middle foreground in front of each antenna.
The horizons indicated need not be actual horizons but only most likely ones. The program considers the input to describe a conventionalized terrain profile and actually conducts its own profile analysis. It superimposes the earth's curvature and then calculates horizons and horizon angles. The actual horizon may, indeed, be found to be on the "effective surface" if the earth's bulge masks out the obstacle presented by the user. Because of this simplified way of viewing the terrain profile input, there are restrictions that the "effective surfaces" must satisfy. Their elevations must always be less than or equal to the corresponding antenna site elevation and the corresponding horizon elevation. Some paths are difficult to treat in this way. Particularly so are those where the terrain follows a general upward or downward slope toward the horizon. The average elevation of the middle foreground may then be higher than allowed. One solution here is to set the effective surface elevation equal to the lower of the site and horizon elevations. Another is to adjust both site elevation and antenna height so as to keep the antenna elevation fixed. Both of these methods may lead to inaccurate results. To be preferred, although sometimes difficult to perform, is to tilt the entire profile so that the foreground slope is leveled out. In doing this, it should be remembered that it is the relative geometry between antennas and horizon that is important.
There are situations where the user may want to experiment with various antenna heights over the same path. If the "most likely" horizons do not change position, then the way in which the program handles the terrain has the advantage that one may proceed with his or her experiments without altering the input "profile."
If the path is an obvious line-of-sight path the user may set the transmitter horizon "distance" equal to 0. This sets a special switch within the program and horizon obstacles will be ignored, nor will the user be asked to supply them.
The program is largely self-explanatory and automatic in operation. Generally, parameter values are typed in by the user in response to a series of request statements. For example, frequency is typed in after the computer has typed:
20) FREQ ( 162.0 MHZ) =
The number 20 is the line number associated with the parameter FREQUENCY and may be used later on, in the edit mode, to change the frequency value for another run of the program without altering or reviewing other input data. The value in parentheses (in this case 162.0 MHz) is the value previously given by the user or the default value initially supplied by the program. If the user wished to retain this value, he or she merely types a carriage return. Otherwise, he or she should type in the new value as prompted by the program (units, if needed, are usually entered in a separate question from the actual data values or can appended to the data value using standard abbreviations for the units; e.g.; 600 watts or 0.6 kW will be interpreted as the same valued by the program) followed by a carriage return. Note that it is always the carriage return which completes the response and sends the program on to the next request.
Out-of-range values or otherwise inappropriate input are immediately recognized by the program, and the request is repeated in the verbose form.
As soon as RAPIT begins to run, the following "Menu" is printed:
CHOOSE FROM THE MENU:
H = HELP
D = PROGRAM DESCRIPTION
C = CONCISE DIALOG
V = VERBOSE DIALOG
E = EDIT DATA
S = SUMMARY OF DATA
P = PROCESS LAST DATA SET ENTERED
Q = QUIT
The computer then prompts a choice by printing:
MENU (VERBOSE) = ?
Typing "H" in response to the prompt produces the following "Help":
MENU OPTIONS:
H = HELP -PRINTS THIS LIST.
D = DESCRIPTION -PRINTS A PROGRAM DESCRIPTION
C = CONCISE DIALOG -CAUSES ALL QUESTIONS TO BE
PRINTED IN THEIR SHORT AND
CONCISE FORM.
V = VERBOSE DIALOG -CAUSES ALL QUESTIONS TO BE
PRINTED IN THEIR LONG AND
VERBOSE FORM. THIS IS THE
SUGGESTED MODE UNTIL YOU BECOME
FAMILIAR WITH THE PROGRAM.
E = EDIT -ALLOWS THE INPUT DATA TO BE
EDITED. THIS MODE PERMITS
ERRORS TO BE CORRECTED OR DATA
TO BE MODIFIED FOR ADDITIONAL
RUNS.
S = SUMMARY -PRINTS A SUMMARY OF THE LAST
DATA SET ENTERED.
P = PROCESS -CAUSES YOUR DATA TO BE
SUBMITTED TO THE BATCH COMPUTER
FOR OFF-LINE PROCESSING OR
INITIATES ON-LINE CALCULATIONS
USING YOUR INPUT DATA.
Q = QUIT -EXITS THE PROGRAM AND RETURNS
YOU TO THE PROGRAM COMMAND
LIST.
PROGRAM CONTROLS
:: -ENTERING TWO COLONS IN
RESPONSE TO ANY QUESTION WILL
RETURN YOU TO THE MENU.
?? -ENTERING TWO QUESTION MARKS IN
RESPONSE TO ANY QUESTION CAUSES
THE VERBOSE FORM OF THE
QUESTION TO BE PRINTED.
BREAK KEY -CAUSES THE CALCULATIONS IN THE
PROCESS MODE TO TERMINATE. THE
PROGRAM RESPONDS WITH
S=XX COMMAND ?
THEN YOU TYPE
BR (CARRIAGE RETURN)
THE OUTPUT WILL STOP AFTER A
FEW LINES AND RETURN TO THE
MENU.
INPUT CONTROL
ANGLES -LATITUDE INPUT IS ASSUMED TO
BE DEGREES NORTH IF POSITIVE,
AND DEGREES SOUTH IF NEGATIVE.
LONGITUDE INPUT IS ASSUMED TO
BE DEGREES WEST IF POSITIVE,
AND DEGREES EAST IF NEGATIVE.
ANGELS CAN BE ENTERED AS
DECIMAL DEGREES (EG. 40.7500)
OR DEGREES, MINUTES, AND
SECONDS (EG. 40,45,000).
LENGTH -DISTANCES AND HEIGHTS CAN BE
ENTERED AS KILOMETERS AND
METERS, STATUTE MILE AND FEET,
OR NAUTICAL MILES AND FEET. IF
YOU SELECT, FOR EXAMPLE,
STATUTE MILES AND FEET AS YOUR
STANDARD INPUT, YOU CAN STILL
ENTER METRIC UNITS BY ANSWERING
A QUESTION WITH THE CORRECT
UNITS APPENDED TO YOUR ANSWER.
FOR EXAMPLE,
10) DIST (10.0 S MI) = ?
40 KM
WILL CONVERT YOUR 40 KM TO THE
EQUIVALENT VALUE IN STATUTE
MILES.
Typing "D" in response to the Menu prompt produces a summary
of the values for the area and point-to-point prediction parameters.
"VERBOSE," the initial default value for the Menu, prints a
detailed request for each question, while "CONCISE," the default value
for subsequent runs of the program, prints only the question number,
data name, and current default value. For example, "VERBOSE" prints:
PREDICTION OUTPUT
B = BASIC TRANSMISSION LOSS
F = FIELD INTENSITY
P = POWER DENSITY
A = AVAILABLE POWER
S = SIGNAL-TO-NOISE RATIO
1) OUTPUT (FIELD INTENSITY)?
while "CONCISE" prints:
1) OUTPUT (FIELD INTENSITY)?
"CONCISE" is the logical mode for a user already familiar with the
program's types of data values.
Once data input is completed, the computer prints:
DO YOU WANT A SUMMARY OF INPUT DATA (Y OR N)?
If the answer is yes, a summary of data is printed; if no, the summary
is skipped. In either case, the computer then prints:
DO YOU WANT TO PROCESS THIS DATA (Y OR N)?
If the answer is yes, the processed data is printed out in a tabular
display and the computer returns to the Menu, with "CONCISE" as the
default value. If the answer is no, the computer prints the Menu
prompt with "EDIT" as the default value.
The "EDIT" mode, which can only be used after some data has
been entered, is used to change individual data values, specified by
question number. If the user types "E" for the Menu choice or a
carriage return when "EDIT" is the Menu default value, the computer
prints:
QUESTION NUMBER?
The user types in the number of the desired question, and the computer
prints its CONCISE form, e.g., if the user had typed in the number 1,
the program would respond with:
1) OUTPUT (FIELD INTENSITY)?
Like every default value, the data within the parentheses is the value
of the most recent data input or confirmation of default. As with the
CONCISE mode, an incorrect answer results in the question being
repeated in the VERBOSE mode. The computer continues to print
"QUESTION NUMBER?" until every question is answered or until the user
responds with a carriage return. At that point the computer returns to
DO YOU WANT TO PROCESS THIS DATA (Y OR N)?
Typing "S" for the Menu question results in a summary of the
current input data. Answering with a "Y" to the computer's question,
"DO YOU WANT A SUMMARY OF THE INPUT DATA?" also gives a summary. This
can be used to check data after an EDIT. Typing "P"
results in data processing and output like that produced by a "Y"
answer to the question, "DO YOU WANT TO PROCESS THIS DATA?" Typing "Q"
for "QUIT" terminates RAPIT operation, returning the user to the
program command list. Special use of "::", "??", or the break key to
terminate data processing, request VERBOSE form a question, or return
to the Menu, is detailed in the "HELP" output above.
Timing. It takes from 4 to 10 minutes to read in a sequence
of parameters. Using the CONCISE dialog, the user can crowd the lower
limit. Each table of computed values requires on the order of 1 second
CPU time.
Terminating. After choosing Menu option "Q" (to quit), the
user is returned to the program command list. At this point, you may
run another services utility program or you may type "QUIT," and the
program will log you off the computer.
If the computer fails to respond during a session, you should
receive a "S = Command?" from the computer when you press a key if it
is working on your data. If you do not receive a response, the
telephone line or computer has probably failed.
5.6 References
Hufford, G.A., A.G. Longley, and W.A. Kissick (1982), A guide to the
use of the ITS irregular terrain model in the area prediction mode,
NTIA Report 82-100. This is the most recent model description.
Longley, A.G., and P.L. Rice (1968), Prediction of tropospheric radio
transmission loss over irregular terrain; a computer method -- 1968,
ESSA Technical Report ERL 79-ITS 67 (NTIS AD 676874). This is the
initial reference for the Area Prediction Method (Longley-Rice Model).
Longley, A.G., R.K. Reasoner, and V.L. Fuller (1971), Measured and
predicted long-term distributions of tropospheric transmission loss,
OT/TRER 16. This report presents comparisons of predictions made using
the point-to-point model documented in TN-101 and measured data.
Rice, P.L., et al. (1965), Transmission loss predictions for
tropospheric communications circuits, NBS Technical Note 101, Vol. 1
and 2 (NTIS, AD677820 AND AD687821). This is the basic reference to
the point-to-point model.
5.7 Sample RAPIT Runs
This section provides input and output samples of RAPIT.
Each sample is identified in the upper right-hand corner, and all user
input is underlined to distinguish them from program output. Note: In
many cases shown in the samples, the user was satisfied with the
parameter selection given in parentheses; acceptance of this parameter
was signified merely by typing a carriage return ( ) in the answer to
the parameter request.
Descriptions of the sample follow:
Sample #1
Propagation prediction method = Area. Transmitter and
receiver are separated by incrementally increasing
distances along a fixed bearing from the transmitter.
Input mode = Verbose, maximum dialog, and Edit. Output
= Basic transmission loss.
Sample #2
Propagation prediction method = Area. Transmitter and
receiver are separated by incrementally increasing
bearings at a fixed distance from the transmitter.
Input mode = Concise, minimum printout. Output = Field
intensity.
Sample #3
Propagation prediction method = Area. Transmitter and
receiver are separated by the incrementally increasing
distances along a fixed bearing from the transmitter.
Input mode = Verbose and Edit.
Sample #4
Propagation prediction method = Point-to-point.
Transmitter and receiver locations are supplied by the
user. Transmitter and receiver site elevations and path
profile are computed from the terrain data base. Input
mode = Verbose. Output = Basic Transmission Loss.
Sample #1
RAPIT - VERSION 6.4
Mon 17 Nov 1986 11:33:03
Choose from the menu:
H=Help
D=Program Description
C=Concise Dialog
V=Verbose Dialog
E=Edit Data
S=Summary of Data
P=Process Last Data Set Entered
Q=Quit
Menu(Verbose)=?
Prediction method
A=Area (Broadcast or mobile applications)
P=Point-to-point (Communication link applications)
Method (Area)? A
ENTER INPUT DATA FOR AREA PREDICTION
Prediction output
B=Basic transmission loss
F=Field intensity
P=Power density
A=Available power
S=Signal-to-noise power ratio
1) Output (Field intensity)? B
Units for distances and heights
K=Kilometers and meters
S=Statute miles and feet
N=Nautical miles and feet
2) Length units(Statute miles and feet)? S
Service or application to which predictions will be applied
Selection Output
M=Mobile Prediction for % reliability
B=Broadcast Prediction for % locations and time
F=Fixed Prediction for % time (50% locations)
U=User-defined Prediction for % locations and time
(This selection affects how the statistics are computed)
4) Service (Broadcast)?
Location variability ( .1 to 99.9 %)
5) Location variability (95.0 %)? 90
Prediction confidence ( .1 to 99.9 %)
6) Prediction confidence (50.0 %)?
Site selection option
ID=Calculations at incremental distances, fixed bearing
IB=Calculations at incremental bearings, fixed distance
LL=Calculations at discrete locations (lat-lon pairs)
DB=Calculations at discrete locations (dist-bearing pairs)
7) Site option (Inc bear)? ID
Option for supplying path parameters such as terrain
irregularity, average elevations, etc.
D = Data base supplied
U = User supplied
Parameters option (Data base )?
Initial Distance ( .0 to 3106.9 S MI)
8) Min Dist ( 31.1 S MI)? 5
Final Distance ( 5.0 to 31068.6 S MI)
9) Max Dist ( 62.1 S MI)? 95
Distance Increment ( .0 to 31068.6 S MI)
10) Dist Inc ( 6.2 S MI)? 10
Type site lat (followed by carriage return) and site lon (return)
for each of the sites. Enter the reference site location first.
Limits are- 17 <= lat <= 51 deg N
65 <= lon <= 165 deg W
Inputs of the form X,Y,Z imply degrees, minutes and seconds
Inputs of the form X.Y imply decimal degrees
11) Site 1 (ref) lat( 40.5083 deg or 40,30,30 dms)? 36,0,36
11) Site 1 (ref) lon( 105.5083 deg or 105,30,30 dms)? 83,55,57
Bearing from reference site.
Enter in degrees clockwise from north,
i.e. north = 0, east = 90, south = 180, west = 270.
Answer can be in decimal degrees(X.Y) or
in deg. min. and sec. (X,Y,Z), and must be
between 0.0 and 359.0 degrees
12) Bearing ( 0.0 deg)? 85
SYSTEM CHARACTERISTICS
System frequency ( 20.0 to 20000.0 MHz)
20) Freq( 162.0 MHz)? 97.1
Antenna polarization
H=Horizontal
V=Vertical
21) Polarization (Vertical)? H
Xmtr antenna height above ground( 1.6 to 9842.5 ft)
22) Xmtr height ( 636.5 ft)? 860
Rcvr antenna height above ground( 1.6 to 9842.5 ft)
23) Rcvr height ( 29.9 ft)? 6
Antenna siting option
Q=Qualitative siting (Random, fair, or good) selected by user
A=Average terrain heights provided by user or computer's data
base
24) Siting option (Ave ter hts )?
Xmtr site height above mean sea level(-1640. to 16404. ft)
27) Xmtr site elev( 0.0 ft)? 1070
ENVIRONMENT CHARACTERISTICS
Ground conductivity ( 0.000 to 10.000 Siemens(mhos)/meter
0.001 for poor ground
0.005 for average ground
0.020 for good ground
5.000 for sea water
0.010 for fresh water
52) Conductivity( .005 S/m)?
Dielectric constant ( 1. to 81.)
4.0 for poor ground
15.0 for average ground
25.0 for good ground
81.0 for sea and fresh water
53) Dielectric constant (15.)?
Climate zone
1=Equatorial
2=Continental subtropical
3=Maritime subtropical
4=Desert
5=Continental temperate
6=Maritime temperate overland
7=Maritime temperate oversea
54) Climate(5)?
Input for area prediction is complete
Do you want a summary of the input data (Y or N)? Y
AREA PREDICTION INPUT SUMMARY
1) Output option: Basic transmission
loss
2) Length units: Statute miles and
feet
4) Service/Application: Broadcast
5) Location availability: 90.00 %
6) Prediction confidence: 50.00 %
7) Site selection option: Incremental distance
Parameter option: Data base supplied
8) Minimum distance: 8.0 km 5.0 mi
9) Maximum distance: 152.9 km 95.0 mi
10) Distance increment: 16.1 km 10.0 mi
11) Ref site: Latitude Longitude
Deg N Deg W
36.0100 36, 0,36 83.9325 83,55,57
12) Bearing from reference: 85.0 deg
20) Frequency: 97.1 MHz
21) Antenna polarization: Horizontal
22) Xmtr ant ht above ground: 262.1 m 860.0 ft
23) Rcvr ant ht above ground: 1.8 m 6.0 ft
24) Antenna siting option: Ave terrain hts
27) Xmtr base ground elevation: 326.1 m 1070.0 ft
52) Conductivity: .005 S/m
53) Dielectric constant: 15.0
54) Climate zone: 5
Do you want to process this data (Y or N)? Y
AREA PREDICTION Mon 17 Nov 1986 11:37:01
PARAMETERS FOR BASIC TRANSMISSION LOSS
Xmtr Rcvr
Ant ht above gnd: 262.1 m 1.8 m
860.0 ft 6.0 ft
Service: Broadcast Freq: 97.1 MHz Polarz: Horizontal
Climate: Cont temp Ground constants: .005 S/m, 15.
Prediction confidence: 50. %
Incremental distance calculations:
Ref site: Latitude Longitude
----------------- -------------------
(deg N) (deg W)
36.0100 36, 0,36 83.9325 83,55,57
Bearing Great circle Ave terrain
Site from ref site distance Delta-h heights
(deg E of N) (s mi) (ft) (ft)
1 85.0 5.0 1007 1391
2 85.0 15.0 1043 1427
3 85.0 25.0 1072 1476
4 85.0 35.0 1108 1548
5 85.0 45.0 1141 1564
6 85.0 55.0 1167 1564
7 85.0 65.0 1177 1564
8 85.0 75.0 1190 1564
9 85.0 85.0 1217 1564
10 85.0 95.0 1282 1564
Predicted maximum basic transmission loss (dB)
Free for a minimum of 90% of the locations and
space and time availability of:
Site loss 10% 50% 90% 95% 99%
(dB)
1 90 116 116 116 116 116
2 100 135 135 136 136 136
3 104 148 150 151 151 151
4 107 159 162 164 165 166
5 109 170 174 177 178 179
6 111 175 181 184 186 188
7 113 179 186 191 193 195
8 114 183 192 198 199 203
9 115 187 197 204 206 210
10 116 192 203 211 213 218
Menu(Edit)=?
Question number? 23
23) Rcvr height ( 6.0 ft)? 30
Question number?
Do you want to process this data (Y or N)? Y
AREA PREDICTION Mon 17 Nov 1986 11:37:56
PARAMETERS FOR BASIC TRANSMISSION LOSS
Xmtr Rcvr
Ant ht above gnd: 262.1 m 9.1 m
860.0 ft 30.0 ft
Service: Broadcast Freq: 97.1 MHz Polarz: Horizontal
Climate: Cont temp Ground constants: .005 S/m, 15.
Prediction confidence: 50. %
Incremental distance calculations:
Ref site: Latitude Longitude
(deg N) (deg W)
36.0100 36, 0,36 83.9325 83,55,57
Bearing Great circle Ave terrain
Site from ref site distance Delta-h heights
(deg E of N) (s mi) (ft) (ft)
1 85.0 5.0 1007 1391
2 85.0 15.0 1043 1427
3 85.0 25.0 1072 1476
4 85.0 35.0 1108 1548
5 85.0 45.0 1141 1564
6 85.0 55.0 1167 1564
7 85.0 65.0 1177 1564
8 85.0 75.0 1190 1564
9 85.0 85.0 1217 1564
10 85.0 95.0 1282 1564
Predicted maximum basic transmission loss (dB)
Free for a minimum of 90% of the locations and
space and time availability of:
Site loss 10% 50% 90% 95% 99%
(dB)
1 90 108 108 108 108 108
2 100 125 125 126 126 126
3 104 136 138 139 139 139
4 107 146 148 150 151 151
5 109 154 158 161 162 163
6 111 160 166 169 170 172
7 113 164 171 176 177 179
8 114 168 176 182 183 186
9 115 171 181 188 190 193
10 116 175 186 194 196 200
Menu(Edit)=? Q
END RAPIT
Sample #2
RAPIT - VERSION 6.4
Mon 17 Nov 1986 11:47:51
Choose from the menu:
H=Help
D=Program Description
C=Concise Dialog
V=Verbose Dialog
E=Edit Data
S=Summary of Data
P=Process Last Data Set Entered
Q=Quit
Menu(Verbose)=? C
Method (Area)?
ENTER INPUT DATA FOR AREA PREDICTION
1) Output (Field intensity)?
2) Length units(Statute miles and feet)?
3) Power units ( W)? DBK
4) Service (Broadcast)?
5) Location variability (95.0 %)? 50
6) Prediction confidence (50.0 %)?
7) Site option (Inc bear)?
13) Min bear( 0.0 deg)?
14) Max bear( 360.0 deg)? 300
15) Bear inc( 60.0 deg)?
16) Site 1 (ref) lat( 40.5083 deg or 40,30,30 dms)? 33,58,24
16) Site 1 (ref) lon( 105.5083 deg or 105,30,30 dms)? 117,56,31
17) Distance ( 31.1 S MI)? 23
SYSTEM CHARACTERISTICS
20) Freq( 162.0 MHz)? 512
21) Polarization (Vertical)? H
22) Xmtr height ( 636.5 ft)? 500
23) Rcvr height ( 29.9 ft)? 30
24) Siting option (Ave ter hts )? Q
25) Xmtr siting(Rndm)? G
26) Rcvr siting(Rndm)?
30) Xmtr power ( -10.0 dBk)? 10
31) Xmtr gain ( 3.0 dBi)? 0
32) Xmtr line loss( 0.0 dB)?
ENVIRONMENT CHARACTERISTICS
52) Conductivity( .005 S/m)?
53) Dielectric constant (15.)?
54) Climate(5)?
Input for area prediction is complete
Do you want a summary of the input data (Y or N)? Y
AREA PREDICTION INPUT SUMMARY
1) Output option: Field intensity
2) Length units: Statute miles and
feet
3) Output power units: dBk
4) Service/Application: Broadcast
5) Location availability: 50.00 %
6) Prediction confidence: 50.00 %
7) Site selection option: Incremental bearing
13) Initial bearing: 0.0 deg
14) Final bearing: 300.0 deg
15) Bearing increment: 60.0 deg
16) Ref site: Latitude Longitude
Deg N Deg W
33.9733 33,58,24 117.9419 117,56,31
17) Distance from ref site: 37.0 km 23.0 mi
20) Frequency: 512.0 MHz
21) Antenna polarization: Horizontal
22) Xmtr ant ht above ground: 152.4 m 500.0 ft
23) Rcvr ant ht above ground: 9.1 m 30.0 ft
24) Antenna siting option: Qualitative siting
25) Xmtr ant siting: Good
26) Rcvr ant siting: Random
30) Xmtr output power: 10.0 dBk
31) Xmtr antenna gain: 0.0 dBi
32) Xmtr line losses: 0.0 dB
52) Conductivity: .005 S/m
53) Dielectric constant: 15.0
54) Climate zone: 5
Do you want to process this data (Y or N)? Y
AREA PREDICTION Mon 17 Nov 1986 11:50:23
PARAMETERS FOR FIELD INTENSITY
Xmtr Rcvr
Power: 40.0 dBw
Line losses: 0.0 dB
Ant gain: 0.0 dBi
Ant ht above gnd: 152.4 m 9.1 m
500.0 ft 30.0 ft
Ant siting: Good Random
Service: Broadcast Freq: 512.0 MHz Polarz: Horizontal
Climate: Cont temp Ground constants: .005 S/m, 15.
Prediction confidence: 50. %
Incremental bearing calculations:
Ref site: Latitude Longitude
(deg N) (deg W)
33.9733 33,58,24 117.9419 117,56,31
Bearing Great circle Ave terrain
Site from ref site distance Delta-h heights
(deg E of N) (s mi) (ft) (ft)
1 0.0 23.0 2942 2326
2 60.0 23.0 2975 2299
3 120.0 23.0 2011 1417
4 180.0 23.0 1115 725
5 240.0 23.0 1135 830
6 300.0 23.0 1998 1548
Predicted minimum field intensity (dBu)
Free for a minimum of 50% of the locations and
space and time availability of:
Site loss 10% 50% 90% 95% 99%
(dB)
1 118 29 26 25 24 23
2 118 29 26 24 24 23
3 118 41 38 37 36 35
4 118 58 55 53 53 52
5 118 57 55 53 52 51
6 118 41 39 37 37 36
Menu(Edit)=? Q
END RAPIT
RAPIT - VERSION 7.0
3:27 PM WED., 25 MAY , 1988
Choose from the menu:
H = Help
D = Program Description
C = Concise Dialog
V = Verbose Dialog
E = Edit Data
S = Summary of Data
P = Process Last Data Set Entered
Q = Quit
Menu (Verbose)? C
Method (Area)?
ENTER INPUT DATA FOR AREA PREDICTION
1) Output parameter (Field Intensity)?
Prediction output parameter
B = Basic transmission loss
F = Field intensity
P = Power density
A = Available power
S = Signal-to-noise power ratio
1) Output parameter (Field Intensity)? S
2) Length units(English)?
3) Power units ( W)? DBK
4) Service (Broadcast)?
5) Location variability (95.0 %)? 50
6) Situation variability (50.0 %)?
7) Site option (Inc bear)? ID
Parameters option (Data base )?
8) Minimum distance ( 31.069 mi)? 12
9) Maximum distance ( 62.137 mi)? 40
10) Distance increment ( 6.214 mi)? 4
11) Site 1 (ref) lat( 40.5083 deg or 40,30,30 dms)? 36,0,36
11) Site 1 (ref) lon( 105.5083 deg or 105,30,30 dms)? 83,55,57
12) Bearing ( 0.0 deg)? 60
SYSTEM CHARACTERISTICS
20) Frequency ( 162.0 MHz)? 93.1
21) Polarization (Vertical)? H
22) Xmtr height ( 636.5 ft)? 1086
23) Rcvr height ( 29.9 ft)? 6
24) Siting option (Ave ter hts )?
27) Xmtr site elev(1068.5 ft)? 69
30) Xmtr power ( -10.0 dBk)? 20
31) Xmtr gain ( 3.0 dBi)?
32) Xmtr line loss( 0.0 dB)?
33) Rcvr gain ( 3.0 dBi)? 0
34) Rcvr line loss( 0.0 dB)?
35) Noise option (Powr)?
System noise power option
P=System noise power (dBm)
F=Rcvr noise figure (dB)
T=Ant and rcvr Noise temperatures (deg Kelvin) and rcvr IF BW
(MHz)
35) Noise option (Powr)?
36) System noise power ( -90.0 dBm)? -75
ENVIRONMENT CHARACTERISTICS
52) Conductivity( .005 S/m)?
53) Dielectric constant (15.)?
54) Climate(5)?
Input for area prediction is complete
Do you want a summary of the input data (Y or N)? Y
AREA PREDICTION INPUT SUMMARY
1) Output option: Signal-to-noise power
ratio
2) Length units: English
3) Output power units: dBk
4) Service/Application: Broadcast
5) Location availability: 50.00 %
6) Situation variability: 50.00 %
7) Site selection option: Incremental distance
Parameter option: Data base supplied
8) Minimum distance: 19.3 km 12.0 mi
9) Maximum distance: 64.4 km 40.0 mi
10) Distance increment: 6.4 km 4.0 mi
11) Ref site: Latitude Longitude
Deg N Deg W
36.0100 36, 0,36 83.9325 83,55,57
12) Bearing from reference: 60.0 deg
20) Frequency: 93.1 MHz
21) Antenna polarization: Horizontal
22) Xmtr ant ht above ground: 331.0 m 1086.0 ft
23) Rcvr ant ht above ground: 1.8 m 6.0 ft
24) Antenna siting option: Ave terrain hts
27) Xmtr base ground elevation: 325.8 m 1069.0 ft
30) Xmtr output power: 20.0 dBk
31) Xmtr antenna gain: 3.0 dBi
32) Xmtr line losses: 0.0 dB
33) Rcvr antenna gain: 0.0 dBi
34) Rcvr line losses: 0.0 dB
35) Rcvr noise option: Noise Power
36) System noise power: -97.5 dBm
52) Conductivity: .005 S/m
53) Dielectric constant: 15.0
54) Climate zone: 5
Do you want to process this data (Y or N)? N
Menu (Edit)?
Question number? 27
27) Xmtr site elev(1069.0 ft)?
Question number?
Do you want to process this data (Y or N)? N
AREA PREDICTION
PARAMETERS FOR SIGNAL-TO-NOISE POWER RATIO
Xmtr Rcvr
Power: 50.0 dBW
Noise power: -97.5 dBm
Line losses: 0.0 dB 0.0 dB
Ant gain: 3.0 dBi 0.0 dBi
Ant ht above gnd: 331.0 m 1.8 m
1086.0 ft 6.0 ft
Service: Broadcast Freq: 93.1 MHz Polarz: Horizontal
Climate: Cont temp Ground constants: .005 S/m, 15.
Situation variability: 50. %
Incremental distance calculations:
Ref site: Latitude Longitude
(deg N) (deg W)
36.0100 36, 0,36 83.9325 83,55,57
Bearing Great circle Ave terrain
Site from ref site distance Delta-h heights
(deg E of N) (s mi) (ft) (ft)
1 60.0 12.0 410 1062
2 60.0 16.0 423 1079
3 60.0 20.0 433 1092
4 60.0 24.0 442 1108
5 60.0 28.0 459 1128
6 60.0 32.0 472 1145
7 60.0 36.0 485 1164
8 60.0 40.0 498 1167
Predicted minimum signal-to-noise power
ratio (dB) at the rcvr
Free for a minimum of 50% of the locations and
space and time availability of:
Site Loss 10% 50% 90% 95% 99%
(dB)
1 98 72 72 71 71 71
2 100 66 66 65 65 65
3 102 62 61 60 60 60
4 104 57 56 55 55 54
5 105 53 51 50 50 49
6 106 49 47 46 45 44
7 107 45 43 41 40 40
8 108 42 38 36 36 35
Menu (Edit)?
Question number? 1
1) Output parameter (Signal-to-noise power ratio)? F
Question number?
Do you want to process this data (Y or N)? Y
AREA PREDICTION
PARAMETERS FOR FIELD INTENSITY
Xmtr Rcvr
Power: 50.0 dBW
Line losses: 0.0 dB
Ant gain: 3.0 dBi
Ant ht above gnd: 331.0 m 1.8 m
1086.0 ft 6.0 ft
Service: Broadcast Freq: 93.1 MHz Polarz: Horizontal
Climate: Cont temp Ground constants: .005 S/m, 15.
Situation variability: 50. %
Incremental distance calculations:
Ref site: Latitude Longitude
(deg N) (deg W)
36.0100 36, 0,36 83.9325 83,55,57
Bearing Great circle Ave terrain
Site from ref site distance Delta-h heights
(deg E of N) (s mi) (ft) (ft)
1 60.0 12.0 410 1062
2 60.0 16.0 423 1079
3 60.0 20.0 433 1092
4 60.0 24.0 442 1108
5 60.0 28.0 459 1128
6 60.0 32.0 472 1145
7 60.0 36.0 485 1164
8 60.0 40.0 498 1167
Predicted minimum field intensity (dBu)
Free for a minimum of 50% of the locations and
space and time availability of:
Site loss 10% 50% 90% 95% 99%
(dB)
1 98 91 91 90 90 90
2 100 86 85 85 84 84
3 102 81 80 79 79 79
4 104 76 75 74 74 74
5 105 72 70 69 69 68
6 106 68 66 65 64 64
7 107 65 62 60 60 59
8 108 61 58 56 55 54
Menu (Edit)? Q
END RAPITSample #3
Sample #4
RAPIT - VERSION 7.0
3:43 PM WED., 25 MAY , 1988
Choose from the menu:
H = Help
D = Program Description
C = Concise Dialog
V = Verbose Dialog
E = Edit Data
S = Summary of Data
P = Process Last Data Set Entered
Q = Quit
Menu (Verbose)?
Prediction method
A = Area (Uses general terrain features to predict signal losses)
P = Point-to-point (Uses path profile features)
Method (Area)? P
Enter input data for point-to-point prediction
Prediction output parameter
B = Basic transmission loss
F = Field intensity
P = Power density
A = Available power
S = Signal-to-noise power ratio
1) Output parameter (Field Intensity)? B
Units for distances and heights
M = Metric (Kilometers and meters)
E = English (Statute miles and feet)
N = Nautical (Nautical miles and feet)
2) Length units(English)? E
Service or application to which predictions will be applied
Selection Output
M=Mobile Prediction for % reliability
B=Broadcast Prediction for % locations and time
F=Fixed Prediction for % time (50% locations)
U=User-defined Prediction for % locations and time
(This selection affects how the statistics are computed)
4) Service (Broadcast)?
Situation variability ( .1 to 99.9 %)
5) Situation variability (50.0 %)? 90
Paths to be analyzed are defined from the transmitter site (ref
site)
to the receiver site(s). The transmitter site is defined by its
latitude and longitude. The receiver site(s) can be defined by:
L = Latitude longitude pairs
D = Distance - bearing pairs
IB = Incremental bearing at a fixed distance
ID = Incremental distance at a fixed bearing
II = Incremental distance, incremental bearing
6) Path option (Latitude - longitude pairs)? L
Profile selection option
D=Data base supplied values of terrain elevations
U=User-supplied values of terrain elevations along path
P=Path parameters (ie horizon distances and elevations)
13) Profile option (Data Base elevs)?
Type site lat (followed by carriage return) and site lon (return)
for each of the sites. Enter the reference site location first.
Limits are- 17 <= lat <= 63 deg N
65 <= lon <= 165 deg W
Inputs of the form X,Y,Z imply degrees, minutes and seconds
Inputs of the form X.Y imply decimal degrees
17) Xmtr site lat( 40.5083 deg or 40,30,30 dms)? 36,0,36
17) Xmtr site lon( 105.5083 deg or 105,30,30 dms)? 83,55,57
Type site lat (followed by carriage return) and site lon (return)
for each of the sites. Enter the reference site location first.
Limits are- 17 <= lat <= 63 deg N
65 <= lon <= 165 deg W
Inputs of the form X,Y,Z imply degrees, minutes and seconds
Inputs of the form X.Y imply decimal degrees
17) Rcvr site lat( 41.7400 deg or 41,44,24 dms)? 35.5930
17) Rcvr site lon( 104.2500 deg or 104,15, 0 dms)? 82.5570
Xmtr site height above mean sea level ( 0.0 to 30000. ft)
18) Xmtr site elev(1068.5 ft)?
Rcvr site height above mean sea level ( 0.0 to 16404. ft)
22) Rcvr site elev(2121.0 ft)?
SYSTEM CHARACTERISTICS
System frequency ( 20.0 to 20000.0 MHz)
26) Frequency ( 162.0 MHz)? 97.1
Antenna polarization
H=Horizontal
V=Vertical
27) Polarization (Vertical)? H
Xmtr antenna height above ground( 1.6 to 30000. ft)
28) Xmtr height ( 636.5 ft)? 860
Rcvr antenna height above ground( 1.6 to 30000. ft)
29) Rcvr height ( 29.9 ft)? 30
ENVIRONMENT CHARACTERISTICS
Ground conductivity ( 0.000 to 10.000 Siemens(mhos)/meter
0.001 for poor ground
0.005 for average ground
0.020 for good ground
5.000 for sea water
0.010 for fresh water
52) Conductivity( .005 S/m)?
Dielectric constant ( 1. to 81.)
4.0 for poor ground
15.0 for average ground
25.0 for good ground
81.0 for sea and fresh water
53) Dielectric constant (15.)?
Climate zone
1=Equatorial
2=Continental subtropical
3=Maritime subtropical
4=Desert
5=Continental temperate
6=Maritime temperate overland
7=Maritime temperate oversea
54) Climate(5)?
Input for point-to-point prediction is complete
Do you want a summary of the input data (Y or N)? Y
POINT-TO-POINT PREDICTION INPUT SUMMARY
1) Output option: Basic transmission
loss
2) Length units: English
4) Service/Application: Broadcast
5) Situation variability: 90.00 %
6) Path option: Latitute/Longitude
13) Profile selection option: Data base elevations
17) Site location:
Site Latitude Longitude
Deg N Deg W
Xmtr 36.0100 36, 0,36 83.9325 83,55,57
Rcvr 35.5930 35,35,35 82.5570 82,33,25
18) Xmtr site elevation: 325.7 m 1068.5 ft
22) Rcvr site elevation: 646.5 m 2121.0 ft
26) Frequency: 97.1 MHz
27) Antenna polarization: Horizontal
28) Xmtr ant ht above ground: 262.1 m 860.0 ft
29) Rcvr ant ht above ground: 9.1 m 30.0 ft
52) Conductivity: .005 S/m
53) Dielectric constant: 15.0
54) Climate zone: 5
Do you want to process this data (Y or N)? Y
POINT-TO-POINT PREDICTION
PARAMETERS FOR BASIC TRANSMISSION LOSS
XMTR RCVR
Ant ht above gnd: 262.1 m 9.1 m
860.0 ft 30.0 ft
Site elevation: 325.7 m 646.5 m above msl
1068.5 ft 2121.0 ft
Horizon distance: 93.7 km 30.2 km
58.2 mi 18.7 mi
Horizon elev angle: .1 deg 1.2 deg
Eff ant height: 440.1 m 33.3 m
1443.9 ft 109.2 ft
Path distance: 132.7 km
82.4 mi
Service: Broadcast Freq: 97.1 MHz Polarz: Horizontal
Climate: Cont temp Ground constants: .005 S/m, 15.
Terrain delta h: 497.2 m 1631.2 ft Situation variability: 90.
%
Free space loss = 115 dB
Double-horizon path
Tropospheric scatter is the dominant mode
Predicted maximum basic transmission loss
(dB)
Minimum time for a minimum location variability of:
Availability 10% 50% 90% 95% 99%
10% 161 173 186 190 198
50% 168 180 193 197 205
90% 173 185 198 202 210
95% 174 187 200 204 211
99% 177 189 203 207 214
Menu (Edit)? Q
END RAPIT