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1989-07-12
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IMPORTANT NOTE:
---------------
THIS PROGRAM IS ONLY DESIGNATED FOR AMATEUR AND EDUCATIONAL
PURPOSES. A COMMERCIAL USAGE IS ALLOWED ONLY WHEN THE AUTHOR'S
WRITTEN PERMISSION IS GIVEN.
THE PROGRAM MAY BE COPIED AND DISTRIBUTED TO OTHER USERS ONLY
IN ITS ORIGINAL STATE. AN EXCEPTION IS MADE FOR THE SO-CALLED
'TIPS'-FOLDER WHICH MAY BE USED FOR SUGGESTIONS OR COMMENTS.
NO GARANTEE IS GIVEN FOR THE CORRECTNESS AND ACCURACY OF ALL
DATA WHICH ARE ASSOCIATED WITH THE USAGE OF THE PROGRAM. THE
USAGE IS WITH THE USER'S PERSONAL RISK. THE AUTHOR WOULD
APPRECIATE INFORMATION ABOUT PROGRAM ERRORS AT ALL TIMES.
-/-
WICHTIGER HINWEIS:
------------------
DIES PROGRAMM IST NUR FUER AMATEUR- UND LEHRZWECKE VORGESEHEN.
EINE GEWERBLICHE NUTZUNG IST NUR MIT SCHRIFTLICHER GENEHMIGUNG
DES AUTORS ERLAUBT.
DAS PROGRAMM DARF FREI KOPIERT UND WEITERGEREICHT WERDEN,
SOFERN ES IN ALLEN SEINEN BESTANDTEILEN IM ORIGINALZUSTAND
BELASSEN WIRD. DIES BETRIFFT NICHT DEN 'TIPS'-ORDNER, IN DEM
DER ANWENDER HINWEISE FUER NACHFOLGENDE BENUTZER ABLEGEN KANN.
ES WIRD KEINE GEWAEHR FUER DIE RICHTIGKEIT DER DATEN UEBER-
NOMMEN, DIE AUS DEM GEBRAUCH DES PROGRAMMS RESULTIEREN. DIE
BENUTZUNG ERFOLGT AUF EIGENE GEFAHR. DER AUTOR IST FUER DIE
MITTEILUNG EVENTUELLER FEHLER JEDER ZEIT DANKBAR.
Volker Grassmann, DF5AI
Hannoversche Str. 103
D-3400 Goettingen-Weende
Fed. Rep. of Germany
-----------------------------------------------------------------
C H I R P
CHARACTERISTICS OF IONOSPHERIC RADIO PROPAGATION
------------------------------------------------
1. INTRODUCTION
CHIRP is a program designated for hf radio operators, for e.g.
radio amateurs, broadcast listeners or any other users of short
wave radio propagation. The program's name is reminiscent of
the real chirp-ionosonde. In fact CHIRP acts as a monitoring
system for hf propagation in the range 1-30 MHz which
calculates the best frequencies, times and paths to distant
radio stations. This information may be important when radio
schedules have to be established or when best conditions for
"dxing" must be known in advance.
The following disk files are part of the program package:
CHIRP.PRG the program
CHIRP.DOC this document
TIPS\TIPS.DOC further user information
CHIRP.DAT\CHIRP.MAP worldmap
CHIRP.DAT\MINIFTZ.DAT MINIFTZ's grip point data
2. THE HEART OF THE PROGRAM: MINIFTZ
Th. Damboldt and P. Suessmann at the "Forschungsinstitut der
Deutschen Bundespost beim Fernmeldetechnischen Zentralamt",
Darmstadt (Germany), developed an advanced grid point method
whiches makes the "CCIR data of ionospheric characteristics"
suitable for micro computer applications [1-3]. This work was
done because of the low accuracy obtained by former micro
computer evaluations, see [1] or [2] for more details. The
results obtained by the new FTZ-method have been tested against
measured data published by the CCIR. In field strength the
average difference was found be about 0 dB and the RMS error
was about 11 dB, [3]. In MUF(3000) the average difference was
less than 0.1 MHz with a standard deviation of 2.3 MHz, [2].
Clearly the new method is comparable in accuracy to predictions
calculated on mainframe computers.
These developments have been incorporated into the program
MINIFTZ. For a specific radio link and for a particular season
of the year MINIFTZ calculates the diurnal variations of
several parameters.
Table: Output parameters obtained with MINIFTZ
----------------------------------------------
- basic MUF (MUF: maximum usable frequency)
- field strength at MUF
- skip mode at MUF (E- and F-region "hops")
- antenna elevation for skip mode at MUF
- frequency of optimum traffic (FOT)
- field strength, skip mode and elevation angle at user
defined frequencies (max. 11)
The author of CHIRP would like to express his thanks to Dr.
Thomas Damboldt, Forschungsinstitut der DBP beim FTZ, who made
the MINIFTZ FORTRAN- and BASIC-source listings available.
The MINIFTZ-source has now been translated for the Atari ST and
is used by CHIRP. It is expected that the user is already
familiar with the terminology and usage of radio predictions.
Refer to [4] if further explanation is required.
3. THE WORLD MAP INDICATOR
The world map indicator (WMI) is a graphic display which
generally works independently from MINIFTZ. In accordence with
the mouse cursor setting on the screen map the WMI calculates
short/long distance and antenna bearing in relation to the
location of reference (e.g. your home city) and indicates the
actual QTH-locator. Ray paths may be calculated and plotted on
the screen by clicking the right mouse button or by entering a
location via keyboard. This gives the user an impression of how
the radio waves travel around the world. Instead of a radio
beam, which is in fact an idealization, the real antenna
characteristic which distributes radio power into an angular
section may be taken into account.
Both MINIFTZ and the WMI are coupled only in a certain case:
when clicking the RUN command in the menu. The very last radio
path which was plotted on the screen map defines the geo-
graphical input data for MINIFTZ's purposes. These are the
geographical locations of both the radio terminals and whether
short or long path is required.
4. INPUT OF GEOGRAPHICAL LOCATIONS VIA KEYBOARD
A certain geographical location (e.g. your home city) is taken
as reference for all calculations performed by CHIRP. This
location must be entered by keyboard and is indicated by a
special symbol on the map. A second location is defined by
simply pointing with the mouse cursor to the corresponding
place on the screen map or by another keyboard input.
Keyboard entries may be performed by using one of three
different data formats:
a. Geographical coordinates which are a pair of numerical
values separated by a slash ("/"). The first number is the
geographical latitude and the second is the longitude.
Geographical coordinates must be entered as decimal numbers
e.g. 52 degrees 30 minutes must be entered as '52.5'.
Negative latitudes are used to describe the southern hemi-
sphere, a minus-sign in front of longitude indicates a
meridian west of Greenwich. Instead of using negative values
the user may also indicate northern and southern hemisphere
by 'N' or 'S' and western or eastern longitudes by 'W' or
'E' identifiers respectively. Examples of valid geographical
coordinates: "52.41/10.2275", "5.03n/12.987e",
"68.3S/129.0W".
b. Worldwide locators which are always given as a six-
character-code. Examples of valid inputs: "JO52CJ",
"em57xx".
c. European locators: EUlocs consist of at least five
characters. This system which was developed in the sixties
is valid only for the European area. On some occasions
suffixes are necessary to avoid ambiguous locators because
the same locator may occur in different parts of Europe. The
extensions (N, NE, E, SE, S, SW, W, NW which means north,
northeast etc.) must be separated by a blank from the
original locator. When no extension is supplied the central
European locator alphabet (all the squares AA to ZZ from
Spain to Russia) is assumed. An extension specifies the
adjacent alphabet in northern, northeastern etc. direction.
Examples of valid European locators are: "FM42F", "hv12f"
which is located in Sweden, "HV12f S" which is located in
the Mediterranean. The user may refer to the program QTH_LOC
for further explanation.
CHIRP makes use of a build-in interface which analyses the
user's input data. There is no need to tell the program which
type of data was entered. The user will be alerted when illegal
locations of reference are entered. In all other cases illegal
input is ignored.
5. MINIFTZ INPUT
The PARAMETER menu is used to pass input parameters for
MINIFTZ's purposes. The location of reference is labeled as the
transmitter's geographical position while the second radio
terminal is labeled as receiver. In fact this distinction is
introduced just for convenience and has no meaning for the
calculation itself. Transmitter and receiver locations may be
interchanged without affecting the results.
The transmitter POWER is entered in watts (W) and the trans-
mitter's ANTENNA gain is entered in decibels with respect to an
isotropic radiator (dBi).
Because of ground effects real short wave antennas, even when
horizontally mounted, radiate power along a line of sight which
is tilted with respect to the horizontal. The antenna's MINimum
ELEVATION angle is entered in degrees.
The electic field strength of the radio wave is measured in
uV/m (micro volts per meter). A threshold may be given as MIN.
FIELD STRENGTH which is used to suppress output data if too low
a level is found to be present. The electric field strength is
entered in decibels above 1 uV/m and should not be mixed up
with the signal-to-noise ratio which is controlled by the
receiver's specifications.
Due to seasonal variations in the ionosphere the user must
specify the month for which the calculation is to be performed.
The year which must also be entered has no meaning for the
calculation.
The solar-terrestrial relations are respected by the actual
sunspot number which is published by certain bulletin services.
Because radio predictions have a statistical meaning the user
must enter a desired percentage of time. MINIFTZ data may be
calculated to be valid for 10%, 50% or 90% of time.
MINIFTZ will calculate the diurnal variation of field strength
and skip mode on certain frequencies which are of special
interest to the user. A maximum of eleven frequencies may be
specified by the USER DEF. FREQ. function. When HAM FREQUENCIES
is selected MINIFTZ will analyse predefined frequency settings
according to the international amateur radio bands.
All settings may be stored on diskette. The SAVE PARMS command
in the OPTION menu is used to create the disk file CHIRP.INF
which holds all user data. The next time CHIRP is loaded from
diskette the previous settings will be again available.
6. MINIFTZ-OUTPUT
The calcualtion is initiated by clicking the RUN command in the
MINIFTZ menu. Under certain conditions the RUN command is not
available and MINIFTZ cannot be invoked. The previous output
may be recalled to the screen by the RECALL DATA function.
Furthermore, the output data may be redirected to a line
printer when PRINTER is active. A dialog box is used to ask the
user whether field strengths or modes and elevation angles
should be displayed. The data is calculated for each hour per
day (1h - 24h UTC).
The FIELD STRENGTH tables shows the estimated field strength
levels at the user frequencies. In addition to this the MUF
(maximum usable frequency), the skip mode at MUF and the FOT
(frequency of optimum traffic) is displayed.
The MODES AND ELEVATION ANGLES table displays which ionospheric
hop modes are expected at the user frequencies in accordence
with the time of day. MUF, field strength at MUF and FOT is
supplied furthermore. The modes and elevation angles are given
by a code which is best explained by an example:
2F04
//\\
two hops via F-layer elevation 4 degrees
7. REFERENCES
[1] Die Berechnung von foF2, M(3000) und von Vorhersagen der
Raumwellenfeldstaerke im Kurzwellenbereich mit Hilfe eines
"Home Computers"
Th. Damboldt, P. Suessmann
Kleinheubacher Berichte, Band 30, 1987
ISSN 0343-5725
[2] A simple method of estimating foF2 and M(3000) with the aid
of a home computer
Th. Damboldt, P. Suessmann
FTZ Darmstadt, 1988
[3] FTZ high-frequency sky-wave field strength prediction
method for use on home computers
Th. Damboldt, P. Suessmann
FTZ Darmstadt, 1988
[4] Wellenausbreitung I und II
J. Grosskopf
BI-Hochschultaschenbuecher Band 141/141a und 539/539a
Mannheim 1970