VLF Receiver Installation
University of Crete
Iraklion, Greece
15 July – 18 July 2003
Contents
1.
2.
3.
4.
5.
6.
Trip Summary
Site Specifications
Calibration
Calibration Data
Site Photos
Equipment Photos
1. Trip Summary
15 July 2003
Troy Wood arrived in Iraklion and met with Prof. Christos Haldoupis of the
University of Crete. Unpacked equipment and checked for damage during
shipment. Installed GPS antenna.
16 July 2003
Constructed 1.7 meter antenna on roof of university. Fabricated NULL modem
cable for connecting GPS to PC. Connected full system and ran full system test.
Set up broadband to take synoptic recordings overnight.
17 July 2003
Changed secondary gain stages to 20 dB and 14 dB respectively. Performed full
calibration. Set up internet connection. IP: 147.52.180.208.
18 July 2003
Installed narrowband software. Frequencies set to 40.75 kHz (NAU, Puerto
Rico), 37.5 kHz (NRK, Keflavik, Iceland), 23.4 kHz (DHO, Rhauderfehn,
Germany), 22.1 kHz (Anthorn, UK), 20.9 kHz (Rosnay, France), 18.3 kHz (Le
Blanc, France).
2. Site Specifications
University of Crete, Iraklion, Greece
Latitude:
Longitude:
35o 18’ 25.0” = 35.31o
25o 04’ 54.9” = 25.08o
Declination:
Inclination:
03.06o
51.07o
Transmitter Settings
18.3 kHz
20.0 kHz
22.1 kHz
23.4 kHz
37.5 kHz
40.75 kHz
HWU
HWU
G??
DHO
NRK
NAU
North/South Antenna Orientation:
North/South Antenna Dimensions:
Le Blanc, France
Rosnay, France
Anthorn, UK ???
Rhauderfehn, Germany
Keflavik, Iceland
Puerto Rico
15o West of magnetic North
1.7 m X 1.7 m square
No East/West Antenna at site.
3. Calibration
Equivalent Field Strength Calculation
Eequivalent = (2*c*Lant)/(N*A*Rcal)*Vcal
c = 3e8
Lant = 1 mH
N = 11
A = 2.89 m2
Rcal = 10 kΩ
To get the equivalent field strength of a recorded signal:
a) Find amplitude of recorded signal
b) This is a narrowband system so the narrowband filter gain must be removed
c) Relate signal amplitude to +/- 5 volts (32768 = 5 volts, -1000 = -152 mV)
d) Use calibration data to determine input voltage
e) Substitute input voltage for Vcal
NOTE: There may be a DC offset in the data which needs to be removed
4. Calibration Data
Device #20030007
f
5000
7000
9000
11000
13000
15000
17000
20000
23000
25000
27000
30000
33000
37000
40000
43000
47000
50000
53000
57000
60000
63000
67000
70000
73000
77000
80000
83000
87000
90000
93000
97000
10000
in ptp
150
150
150
150
150
150
150
150
150
150
150
150
150
150
150
150
150
150
150
150
150
150
150
150
150
150
150
150
150
150
150
150
150
Device #20030008
out ptp
400
1100
2800
5200
6400
7000
7500
8100
8600
9000
9400
9800
10500
11300
12000
12700
13400
13800
13900
13500
12900
12000
11000
10400
10000
9800
10000
10200
10400
10900
3500
900
200
System Calibration
f
10000
20000
25000
30000
35000
40000
45000
50000
60000
70000
in ptp
600
600
600
600
600
600
600
600
600
600
out ptp
460
2650
3400
4200
4600
4400
6400
6200
740
150
f
100
300
500
700
1000
3000
5000
7000
10000
13000
15000
17000
20000
23000
25000
27000
30000
33000
35000
37000
40000
41000
42000
43000
45000
47000
50000
in ptp
1000
1000
1000
1000
1000
1000
1000
1000
1000
1000
1000
1000
1000
1000
1000
1000
1000
1000
1000
1000
1000
1000
1000
1000
1000
1000
1000
out ptp
2200
2200
2200
2200
2200
2300
2300
2300
2300
2100
2100
2100
2300
2300
2300
2200
2300
2500
2400
2300
3200
1600
860
530
220
100
50
5. Site Photos
The 1.7 meter antenna in all its glory
Antenna View from South
Antenna view from West
Antenna View from Northeast
System Equipment Set-Up
6. Equipment Photos
TVLF Receiver (Front)
TVLF Receiver (Rear)
TVLF Receiver (Inside Top)
TVLF Receiver Card (Main)
TVLF Receiver Card (Spare)
Anti-Alias Filter Box (Front)
Anti-Alias Filter Box (Rear)
Anti-Alias Filter Box (Inside)
Anti-Alias Filter Box Power Supply (Front)
Anti-Alias Filter Box Power Supply (Rear)
Anti-Alias Filter Box Power Supply (Inside)