RDF PROJECT
 
This site is an open lab for  RDF work  covering the frequency range of
0   to  150 kHz
  We welcome your  bearings  for signals received in this band.
We don't log frequencies without correlated bearings.
We are always glad of links to further information.
Please submit logs and any information to
Manfred F Kerckhoff  ews2@uni-bremen.de


Contents



  Description of the Project
  • Q: Why RDF?
  • A: Information on stations and frequencies is often inadequate, unreliable, outdated, simply wrong or all these things at once. We want to compile a list of  really active  stations. 
  • Q: What is "RDF"?
  • A: RDF means radio direction finding. That is the direction you "see" when you look towards a transmitter. This direction is called the bearing and is expressed by the angle in respect of True North. So, a bearing of, say, 90 degrees indicates that this station to the East of you. You sometimes find DF as a short form for RDF or you read about "radiolocation". 
  • Q: What is the physics behind this?
  • A: Radio waves contain both electric and electromagnetic fields. A vertical antenna (which is the case with most antennas) radiates a vertical electric field which simultaneously produces a horizontal magnetic field. Such a transmission is described as "vertically polarized". RDF utilizes the horizontal magnetic field. At very low frequencies we get the ground wave of such a transmitter. It is radiated omnidirectionally, "in circles" from the antenna. At higher frequencies additional sky waves are produced by reflection at ionospheric layers.
  • Q: What can I do to get a bearing?
  • A: You simply need a vertical mounted loop antenna turnable over a compass card. You get a maximum reading when the plane of the windings aims toward the transmitter and a minimum reading when it is 90 degrees away from this. The latter is called a NULL position. In this position,  looking through the aperture of the loop you would see the antenna of the transmitter, which is presumably a rare event ... This NULL position is strongly recommended because the ear is more responsive to a reducing signal. Using a ferrite rod antenna the rod is the pointer directly indicating the relative bearing. There is however a second NULL position 180° away from the first. Having a reading of, for example, 90° which means EAST, the transmitter could well be at 270° (90 + 180) which means WEST. You can't resolve this ambiguity without additional information. The required information can be obtained by technical means, e.g. the Bellini Tosi system, or Watson-Watt. But the job can also be done without technical effort by taking at least one more bearing made at another known location. By triangulation you will get a fix and hence the origin of the transmission. For doing this without drawing lines on a map you simply use Klaus's bearing calculator (see bottom of this page). Type in the observer's coordinates and bearings and get the coordinates of the transmitter.
  • And: An azimuthal world map where you can put your place in the centre (or that of others) is very helpful. If you need one just choose from the following links: azimuth3 (see Azimuthal map below) or gcmwin23 . Another very useful tool is the world atlas which comes with Encarta©. It allows you to create custom made maps (see map below).

map


Azimuthal map using AZIMUTH 3
map europe
                                                                                                                       
 
 
 
                                                                                How to get started

The first thing you need is a receiver. For frequencies from 5 Hz to 24 kHz your soundcard will be ok. 
Build a loop (e.g. 40 turns on a 30 cm diameter former), hook it up at a place well away from iron structures and electronic gear and connect it to the mic input of the card for a test. Run GRAM  using the settings shown in fig 1. Be sure that the mic input is active (test it with the tip of your finger). 


fig 1

If there is a VLF station nearby you may get a picture like fig 2. We see GBR on 15975 Hz (closed down) and DHO38 on 23400 Hz respectively. If you don't get any peaks you can use a TV set as a test generator. In Europe you will see a huge peak at 15625 Hz when you get near the set ( 2 to 3 m distance will be ok). 

fig 2

You can increase the sensitivity of this setup by a simple preamp. You can choose from one of the following designs:
smalloop  or easyloop . Sensitivity is so high that you may now need to use the line input of the soundcard.
For my qth this results in the graph shown in fig 3

fig 3

By turning the loop you should be able to null out the different stations one by one. 
Accuracy is most important as small reading differences often result in a deviation of the calculated transmitter location of up to hundreds of kilometres. The reference point of 0°/360° should equal True North within a limit of max. 1°. Calibrate your system by comparing measured values with computed values for known locations. This procedure is valid for transmitters nearby.
 

The following screen shots were taken at the same time (280602-065700utc). Note the differences for different settings of GRAM and different directions of the antenna respectively.


11 to 24 kHz in scroll mode, bearing 0/180°


  11 to 24 kHz in line mode, bearing 90/270°


                                                                              11 to 24 kHz in line mode, bearing 0/180°
 

 


 


                                                    Sample Band Scans
Band scan July 29, 2003  233500 utc    -      loop receiving signals from eastern and western directions    -    nighttime
band scan daytime
Band scan July 30, 2003  074100 utc    -    loop orientation as above    -    daytime    -    weak TV line frequency    -    23.4 kHz maintenance break    -    22.1 kHz active    -
Band scan 3
Band scan July 30, 2003  082830 utc    -    loop orientation as above    -    23.4 kHz back    -    18.1 kHz active


latest screenshot

                    ACTUAL  BAND SCANAAAA


AAADSSFFFFF 

 
Lower frequency spectrum 
Symbols
Frequency range
Name
Wavelength
Time for 1 cycle
Remarks
AF
20 ... 20 000 Hz
Audio Frequency
15 000 ... 15 km
50 ms ... 50 µs
 
 
 
 
 
 
 
 SLF
 < 3 Hz
 Super Low Frequ.
 > 100 Mm
 > 330 ms
 Band number 0
ULF
 > 3 to 30 Hz
 Ultra Low Frequ.
 < 100 to 10 Mm
 < 330 to 33 ms
 Band number 1
ELF
> 30 to 300 Hz 
 Extremely Low F.
 < 10 to 1 Mm
 < 33 to 3.3 ms
 Band number 2
VF
> 300 to 3 000 Hz
Voice Frequency
< 1 000 to 100 km
< 3 300 to 330 µs
 Band number 3
VLF
> 3 to 30 kHz
Very Low Frequ.
< 100 to 10 km
< 330 to 33 µs
 Band number 4
LF
> 30 to 300 kHz
Low Frequency
< 10 to 1 km
< 33 to 3.3 µs
 Band number 5
MF
> 300 to 3 000 kHz
Medium Frequency
< 1 000 to 100 m
< 3 300 to 330 ns
 Band number 6
  blue  =  according to ITU






 
                                                                             Logs

                                                    Location:    Bremen, Germany (53N04'10''/8E50'20'') (JO43KB) 

                                                    Station  :    Single turn loop of 80 cm diameter + amplifier + various receivers
 
 
Frequency
kHz
Call
Country
Location, Modulation
Coordinates
latitude/longitude 
Date
year
Bearing/ ° 
11.905
NAVAID,
RSDN-20
RUS
3 LOCATIONS, PULSES
see Renato's site

2006

23/49/96
12.091
NAVAID,
RSDN-20
RUS
REVDA, PULSES (4th location)
68N02/34E41
see Renato's site
2006
23.5
12.649
NAVAID,
RSDN-20
RUS
3 LOCATIONS, PULSES
see Renato's site
2006
23/49/96
13.000
VL3DEF
AUS
WOODSIDE
FINAL TRANSMISSION ...

38S29/146E56
2004


13.333

NAVAID,
RSDN-20

RUS

REVDA, PULSES (4th location)
68N02/34E41

see Renato's site

2005

23.5
14.881
NAVAID,
RSDN-20
RUS
3 LOCATIONS, PULSES
see Renato's site

2006

23/49/96
15.625

NAVAID
,
RSDN-20

RUS

REVDA, PULSES (4th location)
68N02/34E41

see Renato's site

2005

23.5
16.000
GBR
GB
RUGBY

FINAL TRANSMISSION
MARCH 31 2003 2400 utc

REPLACED BY SKELTON
AND ANTHORN
52N22/1W11,u
2003



16.400
JXN
NOR
HELGELAND, 
NOVIK,
MSK, 200 Bd
u valley span antenna;
since June 2007 predominantly national use
66N25/13E01, u
66N58/13E54, 
ANTENNA SITE
2006
5
5
17.000

VTX2

IND

VIJAYANARAYANAM, MSK

8N26'55''/77E44'43''

2005

102
17.200
SAQ
SWE
VARBERG/GRIMETON, CW
pictures see here
57N07/12E24
2006
-
18.100
RDL uu
RUS
KRASNODAR, MSK, CW
ARKHANGELSK MSK, CW
?,  MSK, CW
KRASNODAR, MSK, CW
ARKHANGELSK, MSK, CW

?
45N02/38E39
64N22/41E35
?
45N02/38E39
64N22/41E35

?
2006

118
55
55
100
42
75
18.200
VTX3
IND
VIJAYANARAYANAM, MSK
8N26'55''/77E44'43''
2006

18.300
HWU, uu
FRA
LE BLANC (Rosnay), MSK, uu
46N37/1E05
2005

218

      18.500
DHO35 
GER
BURLAGE,RAMSLOH, MSK
53N05/7E37
2006

272


18.600

?

AUS

WOODSIDE, MSK, ex-OMEGA SITE, ex-13 kHz
 

38S28’45’’/146E56



2006


~90
18.900
UMB/RDL?
RUS
ROSTOV?, MSK
57N14/39E48
2005
88
19.200

VTX

IND

VIJAYANARAYANAM, MSK

8N26'55''/77E44'43''

2005

108
19.600
GBZ

?
GB
FINAL TRANSMISSION FROM
CRIGGION
MARCH 31 2003 2400 utc

REPLACED BY
ANTHORN(55N00/3W30)
52N43/3W04



2003

2008



292

19.800
NWC
AUS
H.E. HOLT/NORTH WEST CAPE/
EXMOUTH

21S47/114E09

2006

90

20.270
ICV
ITA
TAVOLARA, MSK
40N55/9E45
2006

175

20.500
RJH63/66/77
RUS
ARKHANGELSK,  etc
CARRIER, MSK
transmissions 5 - 7 min long
Information on time ?
64N22/41E35
see Renato's site
2006
77, 105
20.900
HWU(?), uu
FRA
SAINTE ASSISE, MSK, uu
48N33/2E34
2006
222
21.100
RDL, uu
RUS
various, CW, MSK, uu
various
2005
see 18.1
21.750
HWU
FRA
LE BLANC (Rosnay), MSK
46N37/1E05
2006
220

22.100

?

GB

SKELTON


54N43/2W53
55N00/3W30

2008

288
22.200
NDT
JAP
EBINO
32N05/131E51
2006

-

23.400
DHO38
GER
BURLAGE,RAMSLOH, MSK
picture see here
53N05/7E40
2006
276
24.000
NAA
USA
CUTLER, ME, MSK
44N38/67W17
2006

293
25.000
RJH77
RUS
ARKHANGELSK, CW, PULSES
64N22/41E35

2006
75 
25.200
NML4
USA
LA MOURE, MSK
46N22/98W20
2005
315
26.700
TBB
TUR
BAFA, MSK
37N28/27E30
2005

130
27.350
RDL, uu
RUS
?, MSK
?

2003

30
        36.000
DHO37
GER
BURLAGE, RTTY
53N05/7E37
2006
272
37.500
TFK/NRK?
ICE
GRINDAVIK, RTTY
63N57/22W28
2006

317
38.000
SRC/SHRu
SWE
RUDA, MSK, CW,
50BD,160HZ
57N12/16E18
2003
36
40.400
SAS/SRC?u
exSAS2
SWE

KARLSBORG
, RTTY

58N29/14E29
2006
25
40.750
NAU
P.RIC
AGUADA, RTTY
18N23/67W11
2006
270
44.200

SRC/SAS?


SWE


KARLSBORG
, RTTY


58N29/14E29


2006


25

45.900
NSY
ITA

NISCEMI, RTTY
37N06'16''/14E6'25''
2006

167
49.000
SXA
GRE
AGMARINA ATTIK, RTTY
38N11/24E04
2005

139
51.950
GYA? GYW1?
GIZ1?
MTO?
GB
THURSO, RTTY
56N36/3W30


2005

313
53.000
DHJ59
GER
WILHELMSHAVEN,RTTY
FINAL TRANSMISSION 2002, dismanteled 2004/05
53N33/8E05
2000


53.400
TBG
TUR
KANAKKALE, RTTY
40N06/26E26
2005

130
53.700
RTO
RUS
MOSKVA, RTTY
FINAL TRANSMISSION 2000
55N45/37E38
2000

56.350
GLP20
GB
ONGAR, RTTY
51N43/00E11
2000


57.400
GXH
GB
THURSO, RTTY
56N36/3W30
2005

318
57.700
LBA/H
NOR
TRONDHEIM, RTTY, u qrt spring 2007, antennas still standing
AKA: TARVA, GOSSEN,
RINNLEIRET
63N25/10E30, u
2008


60.000
MSF
GB
RUGBY, TIME
52N22/1W11
2005

267

        61.800
GIZ20?
GB
SKELTON?, RTTY
ANTHORN?
?
2005

285
        62.600
FUG
FRA
LA REGINE, RTTY
43N23’30’’ / 2E6’14’’
2005

219

65.800

FUE
FRA
BREST, RTTY
48N25/04W14
2005

250

66.700


RBU


RUS


MOSCOW, CARRIER


55N49/37E18

2005


70

        68.000
GBY20?
GB
RUGBY, RTTY
THURSO?
52N22/1W11
58N36/3W30
2001

312
68.900
DHJ58
GER
FLENSBURG, GLÜCKSBURG,RTTY
FINAL TRANSMISSION 2002, dismanteled end 2004
54N50/9E32
2000

        73.600
CFH
CAN

HALIFAX
,  RTTY

44N36/61W30
2006

289
        75.000
HBG
SWI

PRANGINS, TIMECODE
46N24/01E15
2006

193
        77.500
DCF77
GER

MAINFLINGEN, TIMECODE
50N01/09E00
2006

178
81.000
 
GYN2?
GB
SKELTON?, RTTY
54N43/2W53?
2005

285
        82.750

?
GB
CRIMOND?, CARRIER
?
2005

312
87.000
ALC?
USA?
FAIRBANKS, ALASKA?, RTTY
64N50/147W43
2000
348

100.000

-

GER

SYLT, LORAN, PULSES

54N49/8E18

2006

350
      122.300
OUA
DK
ARHUS, RTTY
56N10/10E13
2000
190
129.000
DCF49
GER
MAINFLINGEN, ASCII
50N01/09E00
2005
178
      135.820
SXV/SXA?
GRE
SPATA ATTIKIS
ATHINAI, RTTY
37N58/23E55
37N55/23E49
2000
132
137.xxx
137.100
CFH?
?
CAN?
?
HALIFAX? RTTY
?, CARRIER
44N58/63W59
?
2000
293
165/345
139.000
DCF39
GER
BURG, PULSES, ASCII
52N17/11E54
2006

111

147.300
DDH47
GER
PINNEBERG, RTTY, METEO
picture see here
53N41/09E41
2006

44

 
abc     =    no logs in 2005 or shut down

u
      =   according to ITU list; real data may differ
uu =   different stations using different frequencies/same call

 


 
 

Klaus Betke's bearing calculator
v0.98e
Observer A   Observer B   Baseline info
deg min N S deg min N S Course AB 
deg min W E deg min W E Course BA 
Bearing to X deg  Bearing to X deg  Length AB 
Location X
Exact Range Distance AX
Approx. Distance BX 

 
 
 



 
                      Links
  Klaus Betke :  www.longwave.de
        Visit Renato Romero's  OPEN LAB SITE : www.vlf.it
                         Join the LWCA :  www.lwca.org
                    RETURN TO THE MAIN INDEX OF RBW 22 
                             
                                                                                                                                                               





27-03-2008