RDF_project

                    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

1	Description of the Project

2	How to get started

3	Sample Bandscans

4	Azimuthal map

5	Lower Frequency Spectrum

6	Loggings

7	Bearing Calculator

8	Links


9        Temporary files

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A: Information on stations and frequencies is often inadequate, unreliable, outdated, simply wrong or all these things at once.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

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 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 July 30, 2003 082830 utc - loop orientation as above - 23.4 kHz back - 18.1 kHz active

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 Bdu 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