Digisonde Antenna Arrays
Two different types of antenna arrays can be implemented in
the Digisonde system. 7-antenna array is used for the DGS256 (DISS)
system while 4-antenna array is used with the DPS system. Figure 1
shows two types of standard-per-manual antenna configurations.
|
|
|
|
(a)
|
(b)
|
Figure
1. a)
Standard Digisonde 7-antenna array configuration. b) Standard Digisonde
4-antenna array configuration
Antenna Array Specification for DDA
DDA Antenna configuration is specified in the ddasetup.onl
file, at the line *185 with the following format:
*185 StationName
< LAT, LONG, CGPLAT, CGPLONG, COMPN,
MAXSEP, DEVN, ROTATA >
For example,
*185 HAARP
< 62.24, 214.91, 80.00, -80.00, 23.8, 103.92,
-30.0, 13 >
Parameters LAT, LONG, CGPLAT, CGPLONG, COMPN
referring to the station location are explained below.
LAT - Station Latitude
LONG - Station Longitude
CGPLAT - Corrected
Geomagnetic Pole Latitude
CGPLONG - Corrected Geomagnetic Pole Longitude
COMPNTD - Compass North Deviation (a.k.a. Magnetic
Declination Angle). Positive angles correspond to the compass north
deviation to the East of geographic north.
Figure 2. Definition of the COMPN parameter
Parameters MAXSEP, DEVN, ROTATA specify the antenna
configuration itself.
MAXSEP: This variable
specifies the maximum antenna separation of the largest triangle in the
seven antenna array configuration (Figure 1a). Namely, MAXSEP is the
distance in meters from antenna 5 to 6, 6 to 7, or 7 to 5.
MAXSEP always refers to the outer antennas
of the seven-antenna system, even if they are not present (as for the 4-antenna setup of the DPS). In the case of the DPS where only four
antennas are available, the MAXSEP is specified as the distance between
the virtual antennas 5, 6, and 7. For example, in the standard DPS
antenna layout, with 60 m long triangle side (distance between antennas
2 and 3) MAXSEP should be set to103.92 m. In this case, the DPS
antennas 2, 3, and 4 are referred to as the inner antennas of
the 7 antenna array.
DEVN:
Figure 3. Specification of the DEVN parameter.
ROTATA. This parameter (a) defines the antenna array
configuration, and (b) also specifies the output coordinate system for
skymap and velocity data calculated by the DDA software. Possible
values for the ROTATA parameter are defined in the following table.
|
ROTATA
|
Antenna setup
|
|
0
|
3
|
6
|
Clockwise rotating 7
antenna setup
|
|
1
|
4
|
7
|
Clockwise rotating 4 Inner
antenna setup
|
|
2
|
5
|
8
|
Clockwise rotating 4 Outer
antenna setup
|
|
9
|
12
|
15
|
Counter-clockwise rotating
7 antenna setup
|
|
10
|
13
|
16
|
Counter-clockwise rotating
4 Inner ant. setup
|
|
11
|
14
|
17
|
Counter-clockwise rotating
4 Outer ant. setup
|
|
-1
|
-2
|
-3
|
Non-standard antenna setup
|
|
Corrected
Geomagnetic
|
Geomagnetic
|
Geographic
|
|
|
Output coordinate system
|
Rotation Sense: This
specifies the actual position of the antennas in the triangular array. In a seven‑antenna setup, antennas 6, 2, and 5
are located west of antenna 1, while antennas 4 and 7 are located east
of antenna 1. This antenna field is said
to be a counter-clockwise rotating field since spiraling from antenna
2, 3, 4, 5, 6 to 7 the spiral is in a counter-clockwise direction. For the mirror image array where antennas 7
and 4 are located west of antenna 1 and antennas 6, 2, and 5 are
located east of antenna 1, the spiraling from antenna to antenna goes
in a clockwise direction.
Standard
Antenna Array Configurations
Historically,
three standard Digisonde antenna array configurations were considered
in the UMLCAR software for ionogram processing (ADEP, Viewer, SAO
Explorer):
·
Standard per manual
·
Mirrored (rotated 180°
about the X axis)
·
Rotated
(rotated 180° about the Z axis
Recently, in
support of our DIDBase (Digital Ionogram DataBase) development, we have
introduced a new scheme for specification of the Digisonde antenna
array configurations. The following
antenna array nomenclature is now used:
·
Seven
antennas standard
·
Seven
antennas mirrored
·
Four
antennas standard
·
Four
antennas mirrored
DDA
antenna specification examples for some of commonly used antenna
layouts can be found in the tables below.
Four Standard Antenna Array Configurations
|
Commonly
used in Digisonde 256 and DISS
DEVN = 0
MAXSEP =
100.0
ROTATA =
{ 9, 12, 15 }
|
|
|
Known installations:
- Millstone Hill
- Goose Bay DISS
DEVN = 0
MAXSEP =
100.0
ROTATA =
{ 0, 3, 6 }
|
|
In the "standard" configuration, antenna 1 to antenna 7 are
walked counter-clockwise.
In the "mirror" configuration, antenna 1 to antenna 7 are
walked clockwise.
|
Commonly used in DPS.
DEVN = -30
MAXSEP =
103.92
ROTATA
= { 10, 13, 16 }
|
|
|
Known installations:
DEVN = 30
MAXSEP =
103.92
ROTATA
= { 1, 4, 7 }
|
|
Other known
cases
Here's
more examples of existing Digisonde antenna arrays configurations in
the new encoding scheme:
|
Formerly "ROTATED DGS-256".
Known installations:
·
Karachi
·
Kokubunji
·
Beijing
DEVN =
180
MAXSEP = 100.0
ROTATA = { 9, 12, 15 }
|
|
|
DPS
working on the internal loop of the array configuration "MIRRORED 7
ANTENNA DEVN=0"
·
Millstone Hill
DEVN = 0
MAXSEP = 103.92
ROTATA
= { 1, 4, 7 }
|
|
|
DPS
working on the internal loop of the array configuration "STANDARD 7
ANTENNA DEVN=0"
·
Sondestrom
·
Ramey AFB
DEVN = 0
MAXSEP = 100.0
ROTATA = { 10,13, 16 }
|
|
|
Formerly
known as "DPS ROTATED"
·
Juliusruh?
DEVN =
150
MAXSEP = 103.92
ROTATA = { 10,13, 16 }
|
|
Non-standard Antenna Array
Configurations
If
the antenna array configuration is not one of the standard (listed
above), such a non-standard setup is described by direct specification
of each antenna coordinates in the lines 170-183 of the ddasetup.onl
file or lines 080-082 of the Station UDD file.
The
ROTATA parameter shall be set negative in this case:
ROTATA = -1
DDA output is in Corrected Geomagnetic
coordinates
ROTATA = -2
DDA output is in Compass coordinates
ROTATA = -3
DDA output is in Geographic coordinates
Individual antenna specifications should made in the system of
coordinates (Figure 4), where
·
X points to the Compass North at the
time of installation
·
Z is the local vertical pointing up,
and
·
Y forms the right-hand
system (i.e., points to the West).
Figure 4.
Coordinate system used in DDA for antenna orientation
Note: For non-standard antenna configurations, there is no need
to specify parameters MAXSEP, COMPN, DEVN in ddasetup.onl file.
