The following list is a synthesis of data about stations and services operating below 22 kHz. This frequency limit is that of a SoundBlaster card operating at 44.1 kHz sampling rate, so monitoring this part of the spectrum is inexpensive and requires only a direct connection of the antenna to the S/B input – no receiver at all!

A reduced list may be found in The most consistent contribution is from Rick Warnett, who collected personal listenings and data from other sources, including LWCA. Thanks to Rick for the permission to publish his data here. Long notes and s/n reports are from him. Signals marked with –mb- are checked By Marco Bruno, IK1ODO, from Torino, Italy.
Signals marked with DG4BAS are checked By Manfred Kerckhoff, DG4BAS, from Bremen, Germany.
Paul Hawkins  is G4KHU.
Klaus Betke is DL4BBL.
The list is very tentative. Any addition or correction is welcome. Data come from different sources and cross-checking is sometimes confusing.

The frequency colours in a list represent the band, as shown below.
VLF  Very Low Frequency  3 kHz  30 kHz
VF  Voice Frequency  300 Hz  3 kHz
ELF  Extremely low Frequency  30 Hz  300 Hz
ULF  Ultra Low Frequency  3 Hz  30 Hz

21.4 kHz
NPM Lualualei in Hawaii - USN station. Traffic heard was MSK - Lowdown 2/99- 566kW ERP
12/7/98 1334, 4T untuned loop -95dbm noise floor @ 23K <-110dbm S/N >15db
28/8/98 2116, V40 L202 350Hz -400 -87dbm.

21.1 kHz
3SB, Datong, Peoples Republic of China.
28/12/95 0540, HF1000 LW7 CW 200Hz -400 -65dbm, sounds like fax!
21/4/96 2208, CW heard up to -80, about 10 wpm.

20.9 kHz
unid – 11/9/99, msk 50 Bd (-mb-)

20.6 kHz
3SB, see also 19.5 KHz. Longwave ID this as 3SA only 2/99.
UTR3/UQC3, no recent info, see 25.0 KHz
RAB99, RHJ77 and RHJ66, Russian stations at Khabarovsk, Arkangelsk and Bishkek. From Longwave 2/99.
23/7/99 2131, V40 L202 CW 500Hz needed to separate signals RTTY -86dbm.

20.5 kHz
3SA/3SB Datong Naval base, Peoples Republic of China.

20.3 kHz
ICV, Tavolara, ITALY, 20kW ERP (or 100kW?).
Oct./99 1015 received by DG4BAS in msk

19.8 kHz
NSW, Harold E. Holt, Australia, 1MW ERP
Unidentified! Longwave 5/98 listed as 100Hz 200 baud RTTY.
Longwave Feb 99 says this is North West Cape?
NWC identified by Longwave SWL in Japan - 8/98
23/9/95 2329, HF1000 LW7 CW 100Hz -800Hz offset S4, fax?
28/8/98 2113, V40 L202 500Hz -60dbm. Noise floor -91dbm. S:N 31db
27/2/99 1553, V40 VLF CW 500Hz -500 -68dbm.
23/7/99 2134, V40 L202 CW 500Hz -66dbm, noise -90dbm S:N 24db

19.6 kHz
GBZ, Criggons, UK, 30kW ERP. MSK, 50 Bd
Oct./99 2030 received by DG4BAS in msk

19.4 kHz
UGE, Arkhanghelsk, Russia, 105kW OP

19.0 kHz
GQD, Anthorn, UK, 25kW ERP

18.5 kHz
Rhauderfehn, Germany, 500kW ERP

18.2 kHz
VTX3 is an Indian Navy traffic station. Operates from Vijananarayanam. Has been heard in USA and UK.
23/7/95 1832, HF1000 CW 200Hz LW7 S2. CW again heard, copied by PL, confirmed callsign VTX3 and traffic a series of numbers and alpha characters. Pauses with II characters. A series of idents, v's traffic and II's after a break. Signal up to S2 at times, some fading.
27/6/99 1925z, VTX3 traffic heard from 1930, standard Morse. V40 CW 100Hz BW -550 Hz -90dbm peak.
11/7/99 2059z, VTX3 V40 CW 600Hz peaks to -86dbm
23/7/99 2137z, VTX3 V40 l202 CW 500Hz Morse traffic -87dbm
11/7/99 1530z, VVV DE VTX3 and tfc, then RTTY -mb-
Oct./99  1021 received by DG4BAS in msk

18.1 kHz
UFQE, Matotchkinchar, Russia, 100kW OP rtty 50 hz shift
Oct./99 1309 received by DG4BAS in cw

17.2 kHz
17.2 KHZ SAQ is located at Grimeton in Sweden. The Alexanderson Alternator was built by GE of the USA and designedby Dr Alexanderson of Sweden. The Grimeton transmitter was used to connect Sweden with the USA and was officially opened by the King of Sweden on July 2nd 1925 - G4KHU-.
It is run every year – see  Old call was SAQ and it was originally on 16.7KHz to provide a telegraph link to the USA and some 16 other locations throughout the Americas and the world.
7/98 Reports of text sent in Longwave magazine. Not heard in many US states, but much of Europe copied the signal although noise was a problem. Now a national heritage. Operator reported that a period of rain on the day of the transmission made "tune-up" difficult, as it had been previously set up with dry conditions.

17.0 kHz
VTX2: Navy Vishayanarayanam, late October 2000, CW marker (by Trond Jacobsen)

16.8 kHz
FTA, St.Assise, France, 23kW ERP

16.4 kHz
JXN, Noviken, Norway, 45kW ERP

16.3 kHz
VTX1: Navy Vishayanarayanam, 01/11/2000 08:20 UTC, CW maker (by DL4BBL)

16.0 kHz
GBR, Rugby, UK, 45Kw ERP. R.Navy, MSK. Real center frequency is 15.980 kHz (-mb-)

15.1 kHz
Bombay, India
HWU, Rosnay, France, 400kW ERP

15.0 kHz
UIK, Vladivostok, Russia, 100kW OP

14.881 kHz
Alpha, USSR radionavigation system. Three stations spread across the old USSR. Not always detectable. Listed in May '98 Longwave as 14.881KHz
26/7/96 2132, HF1000 LW8 SAM 4K series of tones every 10s, probably LSB passband inclusion of OMEGA tones on 13.6, 13.1, 13 and 12.9KHz. When CW 500Hz -400 .5s tone every 3.5s heard again.
18/6/97 2100, Use Spectra-Plus to analyse tone spacing and duration. There are three tone pulses at 3.6 second intervals with a .6 second inter-pulse spacing. Setup of HF1000 was as above and signal about -97dbm.
Oct./99 2030 regular reception by DG4BAS

14.6 kHz
UVA, Batumi, Russia, 100kW OP

12.649 kHz
Alpha. Krasnodar, USSR 500KW. Komosomol'sk na Amure USSR 500KW. Novosibirk, USSR 500KW.
2/99 listed in Lowdown as navaid. Novosibirisk. 27/2/99 1547, V40 VLF CW nothing heard.
Oct./99 2030 regular reception by DG4BAS

11.905 kHz
Alpha, Krasnodar, USSR 500KW. Komosomol'sk na Amure, USSR 500KW. Novosibirsk, USSR 500KW.
2/99 listed in Lowdown as a Navaid. Komosomolkamur.
27/2/99 1546, VLF V40 nothing heard.
Oct./99 2030 regular reception by DG4BAS

9.999 KHz
Frequencies below this limit are NOT ALLOCATED by the International Telecommunications Union. Radiation that affects signals with modulation products below 10KHz is subject to ITU approval though.

8.999 kHz
No ITU comments or footnotes apply below this frequency. No administration limits on activity.

1280 Hz
Test done at Kaford, Norway in 1979/80. ERP was 29W.

1200 Hz
MIDAC a system used by cavers to communicate with the surface. CW is used down to 1200' below ground.

1025 Hz
Bynary tones on electric mains power, to change accounting rates in home counters (e.g., used in Switzerland).
OOK modulation.

983 Hz
A ULF beacon available for testing purposes in the USA. John Wright runs this from Durant Oklahoma when requested.
Ident is "R"

874 Hz
A frequency mentioned in BREAK-IN in reference to an underground caving expedition. No details of equipment or manufacturer was given. The VLF pages.

470 Hz
Bynary tones on electric mains power, to change accounting rates in home counters, like 1025 Hz

76 Hz

SANGUINE or Project ELF. A US navy submarine communications network, originally experimental but active in '93 at latest reports. There are now two transmitter systems, both must operate to give world wide coverage. Both are long wire radiators (about 20 miles of wire 20-30 feet above ground level). Now an established system – see:

Normal 76 Hz transmitters are limited to Narrow band extremely high power transmitters, with obviously low antenna efficiency. There are three stations world-wide, one was located in Maine, but this has since moved to Michigan. A second was in Puerto Rico (de-commissioned < 1997) and the third in Panama (also de-commissioned <1998). One station is operating at all times, the others on standby or maintenance. Greg (VGC) worked in the Maine transmitter for some time, "you could walk through the loading coils with another person on your back" i.e. 10 foot diameter coils. The Maine transmitter has moved and is now located at Escanaba River State Forest in Michigan's upper peninsula. A 56 mile long antenna is mounted on top of 55' poles. A second site at Clam Lake, Wisconsin is 28 miles long. GTE is the contractor. The transmitters were built by Continental Electronics. No receivers at the sites. Messages can be sent to subs at 300-400' below sea level. Data transmission rate is very low, but this is no problem as the system is only intended to send a ‘come up’ message to the sub, which will then receive the VLF transmissions. Power quoted in Longwave is 6W, but this may be erp. Alternate test frequency is 45Hz.

75 Hz
Used during US tests in the 1970's. Replaced by 76Hz. See also 45Hz.

70 Hz
Submarine communications

60 Hz
Mains power (N. America and other countries)

50 Hz
Mains power (Europe)

50 Hz - 7.04 kHz
Range of frequencies to be transmitted by Space Shuttle mission STS-45 in mid March 1992. A particle accelerator beam will directly inject electromagnetic energy into the middle ionosphere. This will propagate downward, being processed & directed by the earth's magnetic field. It can be received by ground stations using ELF receivers. Details of a receiver to be constructed were in December 92 "73" magazine.

45 Hz
Navy test frequency for submarine communications from US sites. Early 1970's tests used either 45 or 75 Hz and were located at Clam Lake Wisconsin and Republic MI = Michigan/Minnesota. These have since been converted to 76Hz according to Naval advice. Antennas reported as "underground" are actually large loops, half above ground, which look like miles of power lines with either 1, 2 or 3 conductors on wooden poles. Tests were being opposed by the public at Clam lake. Referred to as "Project ELF" Exotic modulation methods being attempted by HAARP which tries to effect the circumpolar loop current in the ionosphere. Not yet (99) effective, but can be detected at ground level.

16.6667 Hz
Mains power frequency for railways (Norway). Also referred as ‘industrial frequency’.

13 Hz
Second Schumann resonance

10 Hz
Emissions from MIR, INSPIRE Project

7 Hz
The first Schumann resonance for the earth ionosphere cavity. Signal level peaks at several harmonics are also found, but higher harmonics are swamped by other random noise.

1 Hz
Frequencies in this range may be related to earthquake & seismic events. An increase in the sub-Hertz flux appears to precede major earthquakes & is (1991) being monitored in California as an early warning system for possible San Andreas fault activity. "Antennas" miles long are laid on the ground & signals are transferred back to a central point by optical fibre for analysis.

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