621:
658:
3465:
1469:
604:
1054:
used in military VLF stations, their phases coincide every 20 ms. In MSK the frequency of the transmitter is switched only when the two sine waves have the same phase, at the point both sine waves cross zero in the same direction. This creates a smooth continuous transition between the waves, avoiding transients which can cause stress and arcing on the antenna. MSK can be used at data rates up to 300 bit/s, or about 35
637:
706:
409:
702:(often less than one ohm) they are inefficient, radiating only 10% to 50% of the transmitter power at most, with the rest of the power dissipated in the antenna/ground system resistances. Very high power transmitters (~1 megawatt) are required for long-distance communication, so the efficiency of the antenna is an important factor.
865:. The keying datastream is applied to the control winding. So when the frequency of the transmitter is shifted between the '1' and '0' frequencies, the saturable reactor changes the inductance in the antenna resonant circuit to shift the antenna resonant frequency to follow the transmitter's frequency.
1023:
FSK is the second oldest and second simplest form of digital radio data modulation, after CW. For FSK, the carrier shifted between two frequencies, one representing the binary digit '1' and the other representing binary '0'. For example, a frequency of 9070 Hz might be used to indicate a '1' and
1013:
the carrier cannot be switched abruptly on and off but requires a long time constant, many cycles, to build up the oscillating energy in the antenna when the carrier turns on, and many cycles to dissipate the stored energy when the carrier turns off. This limits the data rate that can be transmitted
981:
in the topload and ground system, and magnetic energy in the vertical wires and loading coil. VLF antennas typically operate "voltage-limited", with the voltage on the antenna close to the limit that the insulation will stand, so they will not tolerate any abrupt change in the voltage or current from
709:
A "triatic" or "flattop" antenna, another common VLF transmitting antenna. It consists of vertical radiator wires each connected at top to parallel horizontal capacitive topload wires stretching up to a kilometer, supported on tall towers. The transverse support cables suspending the horizontal wires
1053:
version of FSK designed specifically for small bandwidths, this was adopted by naval VLF stations in the 1970s to increase the data rate and is now the standard mode used in military VLF transmitters. If the two frequencies representing '1' and '0' are 50 Hz apart, the standard frequency shift
693:
antennas) cannot be built because of their physical height. Vertical antennas must be used because VLF waves propagate in vertical polarization, but a quarter-wave vertical antenna at 30 kHz (10 km wavelength) would be 2.5 kilometres (8,200 feet) high. So practical transmitting antennas
1503:
Because CRT monitors are strong sources of noise in the VLF range, it is recommended to record the spectrograms with any PC CRT monitors turned off. These spectrograms show many signals, which may include VLF transmitters and the horizontal electron beam deflection of TV sets. The strength of the
1005:
transmission with unmodulated carrier. The carrier is turned on and off, with carrier on representing the Morse code "dots" and "dashes" and carrier off representing spaces. The simplest and earliest form of radio data transmission, this was used from the beginning of the 20th century to the
1340:
techniques to remove the effects of atmospheric noise (largely caused by lightning strikes around the world) and adjacent channel signals, extending the useful reception range. Strategic nuclear bombers of the United States Air Force receive VLF signals as part of hardened nuclear resilient
550:
layers, by a refraction process, and spend most of their journey in the ionosphere, so they are much more affected by ionization gradients and turbulence. Therefore, VLF transmissions are very stable and reliable, and are used for long-distance communication. Propagation distances of
613:
in Cutler, Maine, USA. The central mast is the radiating element, while the star-shaped horizontal wire array is the capacitive top load. About 2 km (1.2 mi) in diameter, it communicates with submerged submarines at 24 kHz (12,500 meter wavelength) at a power of
1379:
Operations tend to congregate around the frequencies 8.27 kHz, 6.47 kHz, 5.17 kHz, and 2.97 kHz. Transmissions typically last from one hour up to several days and both receiver and transmitter must have their frequency locked to a stable reference such as a
920:). A typical AM radio signal with a bandwidth of 10 kHz would occupy one third of the VLF band. More significantly, it would be difficult to transmit any distance because it would require an antenna with 100 times the bandwidth of current VLF antennas, which due to the
506:
following the curvature of the Earth and so are not limited by the horizon. Ground waves are absorbed by the resistance of the Earth and are less important beyond several hundred to a thousand kilometres/miles, and the main mode of long-distance propagation is an
817:
results in very high voltages (up to 250 kV) on the antenna and very good insulation is required. Large VLF antennas usually operate in 'voltage limited' mode: the maximum power of the transmitter is limited by the voltage the antenna can accept without
1328:
or square kilometers), with transmitted power anywhere from 20 kW to 2,000 kW. Submarines receive signals from land based and aircraft transmitters using some form of towed antenna that floats just under the surface of the water – for example a
1068:
1396:
Radiated power from amateur stations is very small, ranging from 1 μW to 100 μW for fixed base station antennas, and up to 10 mW from kite or balloon antennas. Despite the low power, stable propagation with low attenuation in the
1320:
has stopped using ELF transmissions, with the statement that improvements in VLF communication has made them unnecessary, so it may have developed technology to allow submarines to receive VLF transmissions while at operating depth.
1235:
survey that relies on transmitted currents inducing secondary responses in conductive geologic units. A VLF anomaly represents a change in the attitude of the electromagnetic vector overlying conductive materials in the subsurface.
976:
of large VLF antennas is typically over 200; this means the antenna stores far more energy (200 times as much) than is supplied or radiated in any single cycle of the transmitter current. The energy is stored alternately as
788:, must handle very high currents, and must withstand the extremely high voltage on the antenna. These are usually huge air core coils 2-4 meters high wound on a nonconductive frame, with RF resistance reduced by using thick
1356:
for security reasons. Although it is relatively easy to receive the transmissions and convert them into a string of characters, enemies cannot decode the encrypted messages; military communications usually use unbreakable
542:" experienced at higher frequencies. This is because VLF waves are reflected from the bottom of the ionosphere, while higher frequency shortwave signals are returned to Earth from higher layers in the ionosphere, the
642:
Another type of large VLF antenna: the "valley-span" antenna, consisting of one or more long horizontal topload cables spanning a valley, fed in the center by vertical radiator cables. This example is at the US Navy
527:
at 60–90 km (37–56 miles) altitude, which reflects VLF radio waves. The conductive ionosphere and the conductive Earth form a horizontal "duct" a few VLF wavelengths high, which acts as a
1324:
High power land-based and aircraft transmitters in countries that operate submarines send signals that can be received thousands of miles away. Transmitter sites typically cover great areas (many
1256:
Powerful VLF transmitters are used by the military to communicate with their forces worldwide. The advantage of VLF frequencies is their long range, high reliability, and the prediction that in a
1488:
based on personal computers (PCs). An aerial in the form of a coil of insulated wire is connected to the input of the soundcard of the PC (via a jack plug) and placed a few meters away from it.
982:
the transmitter without arcing or other insulation problems. As described below, MSK is able to modulate the transmitted wave at higher data rates without causing voltage spikes on the antenna.
834:
The bandwidth of large capacitively loaded VLF antennas is so narrow (50–100 Hz) that even the small frequency shifts of FSK and MSK modulation may exceed it, throwing the antenna out of
889:. So small inefficient receiving antennas can be used, and the low voltage signal from the antenna can simply be amplified by the receiver without introducing significant noise. Ferrite
842:, increasing the bandwidth; however this also reduces the power output. A recent alternative used in some military VLF transmitters is a circuit which dynamically shifts the antenna's
1376:
and in some nations may be used license-free. Radio amateurs in some countries have been granted permission (or have assumed permission) to operate at frequencies below 8.3 kHz.
762:
in the soil, the ground conductors are buried shallowly, only a few inches in the ground, and the ground surface near the antenna is sometimes protected by copper ground screens.
3410:
571:
to a depth of at least 10–40 meters (30–130 feet), depending on the frequency employed and the salinity of the water, so they are used to communicate with submarines.
2492:
531:
confining the waves so they don't escape into space. The waves travel in a zig-zag path around the Earth, reflected alternately by the Earth and the ionosphere, in
2863:
1142:, one of the few remaining transmitters from that era that has been preserved as a historical monument, can be visited by the public at certain times, such as on
395:
838:, causing the antenna to reflect some power back down the feedline. The traditional solution is to use a "bandwidth resistor" in the antenna which reduces the
1420:
and a large wire antenna. Receivers employ an electric field probe or magnetic loop antenna, a sensitive audio preamplifier, isolating transformers, and a PC
1040:, which creates a sudden phase-shift transient which can cause arcing on the antenna. To avoid arcing, FSK can only be used at slow rates of 50–75 bit/s.
2114:
3070:
1779:
1260:
VLF communications will be less disrupted by nuclear explosions than higher frequencies. Since it can penetrate seawater VLF is used by the military to
735:
to increase the current in the vertical wires, increasing the radiated power and efficiency of the antenna. High-power stations use variations on the
727:, linked at the top with a network of cables, often shaped like an umbrella or clotheslines. Either the towers themselves or vertical wires serve as
3159:
2302:
1508:. These cause the ionization level to increase in the ionosphere producing a rapid change to the amplitude and phase of the received VLF signal.
1161:
systems which allowed ships and aircraft to determine their geographical position by comparing the phase of radio waves received from fixed VLF
482:) and for secure military communication. Since VLF waves can penetrate at least 40 meters (131 ft) into saltwater, they are used for
3403:
2217:
2726:
2200:
2168:
1373:
1245:
1107:
within the band starting from 20 kHz, but the result was unsatisfactory because the available bandwidth was insufficient to contain the
431:
620:
2476:
813:) to tune the antenna. The large VLF antennas used for high-power transmitters usually have bandwidths of only 50–100 hertz. The high
1154:
Due to its long propagation distances and stable phase characteristics, during the 20th century the VLF band was used for long range
3374:
766:
systems have also been used, consisting of radial networks of copper cables supported several feet above the ground under the antenna.
2856:
2280:
1180:
2270:
3396:
2366:
861:
with a second control winding through which a DC current flows, which controls the inductance by magnetizing the core, changing its
388:
2618:
2778:
2421:
795:
The high capacitance and inductance and low resistance of the antenna-loading coil combination makes it act electrically like a
754:
Due to the low radiation resistance, to minimize power dissipated in the ground these antennas require extremely low resistance
1406:
1099:, to communicate with other countries, their colonies, and naval fleets. Early attempts were made to use radiotelephone using
3060:
2468:
2315:
1505:
1024:
the frequency 9020 Hz, 50 Hz lower, to indicate a '0'. The two frequencies are generated by a continuously-running
2783:
2791:
NOTE: As of 05/03/2014, the "Listen live" links are down, but the site has some previously recorded examples to listen to.
3075:
2849:
2083:
2002:
1294:
1261:
902:
806:
644:
581:
VLF waves used to communicate with submarines have created an artificial bubble around the Earth that can protect it from
459:
3152:
1914:
1906:
1433:
1429:
1276:
763:
381:
3511:
3350:
1416:
The transmitter generally consists of an audio amplifier of a few hundred watts, an impedance matching transformer, a
1050:
1014:
to 15–20 words/minute. CW is now only used in small hand-keyed transmitters, and for testing large transmitters.
675:
2737:
685:
A major practical drawback to the VLF band is that because of the length of the waves, full size resonant antennas (
3916:
3506:
1787:
1398:
1381:
1195:) to send data, shifting between 20 kHz and 26 kHz. The WWVL service was discontinued in July 1972.
1104:
508:
2817:
1401:
enable very narrow bandwidths to be used to reach distances up to several thousand kilometers. The modes used are
1207:
for long range lightning location and for research into atmospheric phenomena such as the aurora. Measurements of
3101:
3065:
2623:
1876:
1655:
1425:
1337:
1330:
1169:
667:
948:
character codes. A small frequency shift of 30–50 hertz is used due to the small bandwidth of the antenna.
3806:
3419:
3335:
3050:
2675:
1673:
1665:
1580:
1564:
1548:
1517:
1135:
325:
148:
2125:
792:
several centimeters in diameter, consisting of thousands of insulated strands of fine wire braided together.
3911:
3856:
3185:
3145:
2088:
1943:
1815:
1647:
1265:
781:. At VLF the design of this coil is challenging; it must have low resistance at the operating RF frequency,
94:
1191:
began transmitting a 500 W signal on 20 kHz in August 1963. It used frequency-shift keying (
1980:
1691:
1489:
1305:
1192:
1075:
1032:
codes for the characters of the message. A problem at VLF is that when the frequency is switched the two
1017:
929:
610:
575:
483:
2361:. NATO Advanced Study Institute. Spåtind, Norway: Springer Science and Business Media. pp. 372–373.
2546:"The Central Italy Electromagnetic Network and the 2009 L'Aquila earthquake: Observed electric activity"
2044:
2027:
1960:
1932:
1924:
1768:
1760:
1283:
1155:
1025:
886:
862:
758:(Earthing) systems, consisting of radial networks of buried copper wires under the antenna. To minimize
627:
586:
723:. These are very large wire antennas, up to several kilometers long. They consist of a series of steel
1476:
and a sound card. The Morse code says "..33376.."; the vertical stripes are distant lightning strikes.
3816:
3811:
3320:
3305:
3037:
3019:
2557:
2344:. Naval Electronics Systems Command. Washington, DC: U.S. Navy. August 1972. Manual NAVELEX 0101-113.
2253:
1100:
1043:
978:
952:
921:
914:
910:
819:
774:
755:
699:
269:
143:
138:
905:
of the band, and the extremely narrow bandwidth of the antennas used, it is impractical to transmit
3851:
3846:
3821:
3801:
3552:
3290:
3215:
3200:
3011:
2991:
2971:
2961:
2933:
2923:
2918:
1088:
630:, UK, showing 6 insulator strings attaching the toploads to the 6 vertical radiator wires
532:
467:
417:
264:
153:
131:
104:
99:
951:
In high power VLF transmitters, to increase the allowable data rate, a special form of FSK called
3689:
3662:
3572:
3557:
3091:
2956:
2928:
2903:
2898:
2893:
2486:
1827:
1410:
1173:
873:
The requirements for receiving antennas are less stringent, because of the high level of natural
843:
1244:
VLF can also penetrate soil and rock for some distance, so these frequencies are also used for
1087:
Historically, this band was used for long distance transoceanic radio communication during the
3697:
3693:
3674:
3670:
3666:
3111:
3096:
3027:
2888:
2722:
2575:
2472:
2362:
2356:
2311:
2276:
2196:
2164:
2158:
2094:
1493:
1492:(FFT) software in combination with a sound card allows reception of all frequencies below the
1437:
1385:
1162:
874:
847:
810:
695:
657:
2646:
2336:
2190:
1028:. The transmitter is periodically switched between these frequencies to represent 8 bit
538:
VLF waves have very low path attenuation, 2–3 dB per 1,000 km, with little of the "
3831:
3602:
3577:
3445:
3260:
2565:
2515:
1682:
1635:
1613:
1472:
Timing diagram of a frequency-shift keyed 18.1 kHz VLF signal, picked up using a small
1208:
1158:
1143:
823:
740:
736:
728:
720:
690:
686:
663:
556:
471:
164:
121:
3464:
3880:
3793:
3635:
3567:
2821:
2010:
1891:
1847:
1804:
1727:
1587:
1468:
1298:
1232:
1222:
1092:
1002:
993:
759:
671:
603:
435:
83:
2561:
698:, a small fraction of the length at which they would be self-resonant. Due to their low
3826:
3610:
3275:
3168:
2948:
1717:
1485:
1457:
1119:
917:
502:
around large obstacles and so are not blocked by mountain ranges, and can propagate as
413:
259:
249:
126:
76:
31:
2836:
636:
3905:
3836:
3773:
3754:
3658:
3592:
3587:
3582:
3245:
2062:
1988:
1700:
1481:
1402:
1309:
1218:
1212:
1037:
969:
937:
855:
802:
302:
284:
239:
234:
229:
224:
219:
214:
209:
204:
199:
194:
189:
184:
179:
174:
116:
2799:
846:
between the two output frequencies with the modulation. This is accomplished with a
705:
3712:
3378:
1473:
1417:
1358:
1204:
1122:
to communicate at similar distances by reflecting their radio waves off a layer of
962:
906:
890:
882:
851:
770:
463:
1058:
characters (8 bits each) per second, approximately 450 words per minute.
17:
2804:
2520:
1091:
era between about 1905 and 1925. Nations built networks of high-power LF and VLF
3885:
3562:
3544:
3440:
2872:
2788:
1969:
1497:
1287:
1257:
1184:
924:
would be enormous in size. Therefore, only text data can be transmitted, at low
878:
582:
503:
499:
479:
475:
466:(voice) transmission is highly impractical in this band, and therefore only low
2570:
1067:
3866:
3534:
3529:
3483:
3460:
2400:
2054:
1421:
1229:
1127:
1123:
1118:(skip) radio propagation method allowed lower power transmitters operating at
1096:
999:
986:
933:
724:
520:
455:
443:
2579:
2115:"Nomenclature of the frequency and wavelength bands used in telemmunications"
3875:
3722:
3498:
3476:
3455:
3430:
3116:
2826:
1353:
1131:
1071:
1033:
835:
789:
560:
528:
487:
3388:
2814:
626:
Central mast of a similar "trideco" antenna of the NATO VLF transmitter at
2545:
458:(an obsolete metric unit equal to 10 kilometers). Due to its limited
3890:
3707:
3685:
3680:
3650:
3450:
2981:
2880:
2771:
2664:
2338:
Naval Shore
Electronics Criteria - VLF, LF, and MF communications systems
1735:
1108:
1007:
957:
925:
858:
796:
782:
778:
748:
744:
614:
1.8 megawatts, one of the most powerful radio stations in the world.
589:; this occurred through interaction with high-energy radiation particles.
568:
547:
543:
512:
353:
2600:
1388:
in order to support such long duration coherent detection and decoding.
408:
3759:
3745:
3137:
3055:
3015:
2841:
2442:
1317:
1115:
809:
and to change the transmitting frequency requires a variable inductor (
648:
552:
524:
368:
358:
348:
307:
294:
2794:
551:
5,000–20,000 km have been realized. However, atmospheric noise ("
3783:
3778:
3768:
3740:
3735:
3730:
3701:
3630:
3045:
2976:
2966:
2831:
2382:
1361:
1139:
539:
363:
343:
320:
315:
289:
279:
274:
2683:
1225:
receivers to measure conductivity in the near surface of the Earth.
674:, Japan, which transmitted at 10-14 kHz; 389 meters high,
446:
from 100 to 10 km, respectively. The band is also known as the
1301:
state, which transmits on 24.8 kHz with a power of 1.2 MW
1006:
1960s in commercial and military VLF stations. Because of the high
3625:
3521:
3435:
2908:
2508:
Development of UKM-SID teaching module for space science education
2066:
1467:
1352:. Because these are military transmissions they are almost always
1349:
1325:
1066:
1055:
1029:
945:
704:
2160:
The high-latitude ionosphere and its effects on radio propagation
1130:, and long-distance radio communication stations switched to the
3620:
3615:
3121:
3106:
3001:
2996:
2938:
2510:. 6th International Forum on Engineering Education (IFEE 2012).
1639:
1617:
1345:
1188:
1172:
system used frequencies from 10 to 14 kHz, as did Russia's
941:
747:(triatic) antennas. For low-power transmitters, inverted-L and
719:
High power VLF transmitting stations use capacitively-toploaded
3392:
3141:
2845:
2218:"NASA's Van Allen Probes Spot Man-Made Barrier Shrouding Earth"
1372:
The frequency range below 8.3 kHz is not allocated by the
885:
introduced by the receiver circuit and determines the receiver
3640:
3126:
2986:
2913:
2443:"Some recent milestones with amateur radio experiments at VLF"
2121:
1290:, which transmits on 23.4 kHz with a power of 800 kW
516:
439:
52:
651:, which transmits on 24.8 kHz at a power of 1.2 MW.
3463:
511:
mechanism. The Earth is surrounded by a conductive layer of
2809:
2764:
574:
VLF waves at certain frequencies have been found to cause
996:(CW), Interrupted Continuous Wave (ICW), or On-Off Keying
961:
of the antenna. The huge capacitively-loaded antenna and
2738:"Very low wave reception with ferrite antennas 5-50 kHz"
1634:
Frequency for horizontal deflection of electron beam in
1612:
Frequency for horizontal deflection of electron beam in
1203:
Naturally occurring signals in the VLF band are used by
1344:
Two alternative character sets may be used: 5 bit
498:
Because of their long wavelengths, VLF radio waves can
470:
coded signals are used. The VLF band is used for a few
2754:
1428:
is required to retrieve the weak signals from beneath
1211:
are employed to infer the physical properties of the
555:") is high in the band, including such phenomena as "
2759:
773:
is required at the antenna feed point to cancel the
3865:
3792:
3721:
3649:
3601:
3543:
3520:
3497:
3084:
3036:
3010:
2947:
2879:
2832:
Internet based VLF listening guide with server list
1793:Used for submarine communication, 1 megawatt.
59:
44:
2331:
2329:
2327:
972:, which stores oscillating electrical energy. The
27:The range 3–30 kHz of the electromagnetic spectrum
2721:(in German). Meckenheim, DE: Siebel Verlag GmbH.
1440:. Useful received signal strengths are as low as
2772:Definition of frequency bands (VLF, ELF... etc.)
2422:"Sub 9 kHz spectrum in the Amateur Service"
2157:Hunsucker, R.D.; Hargreaves, John Keith (2002).
1460:typically between 1 and 100 bits per hour.
1312:which transmits on 24 kHz with 1.8 MW.
1268:frequencies are used for deeply submerged subs.
955:(MSK) is used. This is required due to the high
609:"Trideco" antenna tower array at the US Navy's
30:"VLF" redirects here. For the car company, see
2717:Klawitter, G.; Oexner, M.; Herold, K. (2000).
2539:
2537:
2535:
2533:
2531:
2296:
2294:
2292:
1095:stations that transmitted text information by
3404:
3153:
2857:
989:that have been used in VLF transmitters are:
519:in the upper atmosphere at the bottom of the
389:
8:
877:in the band. At VLF frequencies atmospheric
731:radiators, and the horizontal cables form a
37:
2601:"Shortwave HF VHF UHF utilities monitoring"
2491:: CS1 maint: numeric names: authors list (
2192:Electromagnetic theory and wave propagation
2163:. Cambridge University Press. p. 419.
2152:
2150:
2148:
2146:
3480:
3411:
3397:
3389:
3178:
3160:
3146:
3138:
2864:
2850:
2842:
2789:NASA live streaming ELF -> VLF Receiver
2712:(in Italian). Albino, Italy: SANDIT S.r.l.
1521:
396:
382:
72:
36:
2569:
2519:
2512:Procedia - Social and Behavioral Sciences
2052:
2036:
2019:
2000:
1978:
1958:
1940:
1922:
1904:
1889:
1874:
1860:
1845:
1832:
1812:
1796:
1777:
1758:
1744:
1725:
1708:
1689:
1663:
1645:
1623:
1601:
1585:
1569:
1553:
1537:
454:as the wavelengths range from one to ten
407:
2506:Mardina Abdullah; et al. (2013) .
2275:. John Wiley and Sons. pp. 55–58.
2184:
2182:
2180:
2106:
1448: volts/meter (electric field) and
1271:Examples of naval VLF transmitters are
1199:Geophysical and atmospheric measurement
334:
248:
163:
82:
75:
2484:
2355:Holtet, J.A., ed. (17–27 April 1974).
2247:
2245:
2243:
2241:
2239:
2237:
2235:
1364:since the amount of text is so small.
2795:World Wide Lightning Location Network
2544:Fidani, Cristiano (8 December 2011).
1994:Used for submarine communication, at
1741:Frequently inactive for long periods
1374:International Telecommunication Union
1246:through-the-earth mine communications
165:EU / NATO / US ECM
7:
2805:University of Louisville VLF Monitor
2124:. Rec. ITU-R V.431-7. Archived from
2815:Mark's Live Online VLF Receiver, UK
1480:VLF signals are often monitored by
1456: tesla (magnetic field), with
1336:Modern receivers use sophisticated
1150:Navigation beacons and time signals
2033:Used for submarine communication.
1424:to digitise the signal. Extensive
1114:In the 1920s the discovery of the
478:(broadcasting time signals to set
25:
2514:. Vol. 102. pp. 80–85.
2401:"Geonics Limited - VLF Receivers"
2301:Johnson, Richard C., ed. (1993).
1679:Only active at special occasions
1228:VLF signals can be measured as a
3372:
2216:Susannah Darling (17 May 2017).
1504:signal received can vary with a
893:are usually used for reception.
805:. VLF antennas have very narrow
656:
635:
619:
602:
2810:Larry's Very Low Frequency site
2619:"Naval base link to jet plunge"
826:, and arcing from the antenna.
438:(RF) in the range of 3–30
2627:. Sydney, AU. 14 November 2008
2469:Radio Society of Great Britain
2463:Renato Romero, IK1QFK (2008).
2358:ELF-VLF Radio Wave Propagation
2272:Introduction to RF Propagation
1516:For a more detailed list, see
1506:sudden ionospheric disturbance
1496:simultaneously in the form of
1:
3076:Quasi-Zenith Satellite System
2800:Stanford University VLF group
2310:(3rd ed.). McGraw-Hill.
2084:Communication with submarines
1955:Time signal transmitter Beta
1716:various locations, including
1295:Jim Creek Naval Radio Station
2556:(1) (published 2012): 3–25.
2521:10.1016/j.sbspro.2013.10.716
2304:Antenna Engineering Handbook
1828:Time signal transmitter Beta
1277:Skelton Transmitting Station
1138:at Grimeton near Varberg in
3512:Ultra-high-energy gamma ray
1331:Buoyant Cable Array Antenna
1262:communicate with submarines
1183:broadcasts. In the US, the
1181:standard time and frequency
850:in series with the antenna
494:Propagation characteristics
412:A VLF receiving antenna at
3933:
3507:Very-high-energy gamma ray
2571:10.3390/geosciences1010003
1952:various locations (Russia)
1868:various locations (Russia)
1824:various locations (Russia)
1752:various locations (Russia)
1577:various locations (Russia)
1561:various locations (Russia)
1545:various locations (Russia)
1484:using simple homemade VLF
1382:GPS disciplined oscillator
1306:Cutler Naval Radio Station
1240:Mine communication systems
1105:single-sideband modulation
777:of the antenna to make it
611:Naval Radio Station Cutler
509:Earth-ionosphere waveguide
416:, Antarctica, operated by
29:
3426:
3368:
3176:
3066:Global Positioning System
2719:Langwelle und Längstwelle
2624:The Sydney Morning Herald
2269:Seybold, John S. (2005).
2195:. CRC Press. p. 89.
1790:, Western Australia (AUS)
1512:List of VLF transmissions
1426:digital signal processing
1338:digital signal processing
1083:Early wireless telegraphy
928:. In military networks
743:" antennas, or multiwire
739:such as the "delta" and "
715:VLF transmitting antennas
676:it was dismantled in 1998
3420:Electromagnetic spectrum
2837:List of VLF-transmitters
2827:IW0BZD VLF TUBE receiver
2760:Radio waves below 22 kHz
2755:Longwave club of America
2252:Watt, Arthur D. (1967).
1975:submarine communication
1531:Location of transmitter
1518:List of VLF-transmitters
1264:near the surface, while
1136:Grimeton VLF transmitter
1076:Grimeton VLF transmitter
567:VLF waves can penetrate
2736:Friese (January 2006).
2089:OMEGA Navigation System
1399:earth-ionosphere cavity
1252:Military communications
1036:usually have different
668:Omega navigation system
3468:
2784:Gallery of VLF-signals
2779:PC-based VLF-reception
2653:. Military Facilities.
1774:Many operation modes.
1656:Gildeskål Municipality
1490:Fast Fourier transform
1477:
1438:VLF radio atmospherics
1179:VLF was also used for
1079:
1018:Frequency-shift keying
940:data using 5 bit
930:frequency-shift keying
869:VLF receiving antennas
830:Dynamic antenna tuning
711:
710:are called "triatics".
587:coronal mass ejections
576:electron precipitation
484:military communication
420:
3467:
2255:VLF Radio Engineering
2045:LaMoure, North Dakota
2028:Arlington, Washington
1855:Saint-Assise (France)
1710:RDL UPD UFQE UPP UPD8
1699:VLF station (NAA) at
1471:
1070:
1026:frequency synthesizer
901:Because of the small
887:signal-to-noise ratio
708:
691:quarter wave monopole
628:Anthorn radio station
474:services, government
411:
2873:Time signal stations
2765:VLF Discussion Group
2189:Ghosh, S.N. (2002).
1434:power line harmonics
1101:amplitude modulation
1044:Minimum-shift keying
979:electrostatic energy
953:minimum-shift keying
936:is used to transmit
922:Chu-Harrington limit
775:capacitive reactance
700:radiation resistance
3553:Extreme ultraviolet
2708:Romero, R. (2006).
2562:2011Geosc...1....3F
1279:in Skelton, Cumbria
1089:wireless telegraphy
985:The three types of
733:capacitive top-load
533:transverse magnetic
476:time radio stations
442:, corresponding to
418:Stanford University
41:
3558:Vacuum ultraviolet
3469:
2820:2009-02-28 at the
2769:Tomislav Stimac, "
2131:on 31 October 2013
1478:
1464:PC based reception
1080:
856:ferromagnetic core
844:resonant frequency
712:
696:electrically short
424:Very low frequency
421:
335:Other TV and radio
39:Very low frequency
18:Very Low Frequency
3917:Radio electronics
3899:
3898:
3603:Visible (optical)
3386:
3385:
3363:
3362:
3135:
3134:
3028:Radio Data System
2728:978-3-89632-043-8
2258:. Pergamon Press.
2202:978-0-8493-2430-7
2170:978-0-521-33083-1
2095:Radio atmospheric
2075:
2074:
2059:14–25.2? kHz
1494:Nyquist frequency
1392:Amateur equipment
1386:rubidium standard
1163:navigation beacon
1134:frequencies. The
1078:, Varberg, Sweden
881:is far above the
875:atmospheric noise
848:saturable reactor
760:dielectric losses
721:monopole antennas
645:Jim Creek station
436:radio frequencies
406:
405:
159:
158:
71:
70:
16:(Redirected from
3924:
3490:
3488:
3481:
3474:
3413:
3406:
3399:
3390:
3379:Radio portal
3377:
3376:
3375:
3179:
3162:
3155:
3148:
3139:
2866:
2859:
2852:
2843:
2744:
2742:
2732:
2713:
2695:
2694:
2692:
2691:
2682:. Archived from
2672:
2661:
2655:
2654:
2643:
2637:
2636:
2634:
2632:
2615:
2609:
2608:
2597:
2591:
2590:
2588:
2586:
2573:
2541:
2526:
2525:
2523:
2503:
2497:
2496:
2490:
2482:
2478:9781-9050-8637-5
2460:
2454:
2453:
2451:
2449:
2439:
2433:
2432:
2430:
2428:
2418:
2412:
2411:
2409:
2407:
2397:
2391:
2390:
2379:
2373:
2372:
2352:
2346:
2345:
2343:
2333:
2322:
2321:
2309:
2298:
2287:
2286:
2266:
2260:
2259:
2249:
2230:
2229:
2227:
2225:
2213:
2207:
2206:
2186:
2175:
2174:
2154:
2141:
2140:
2138:
2136:
2130:
2119:
2111:
1997:
1996:2 megawatts
1840:Tavolara (Italy)
1686:
1683:Alexanderson Day
1581:Alpha-Navigation
1565:Alpha-Navigation
1549:Alpha-Navigation
1522:
1455:
1453:
1447:
1445:
1159:radio navigation
1144:Alexanderson Day
1051:continuous phase
1011:
975:
968:
960:
841:
816:
800:
786:
737:umbrella antenna
687:half wave dipole
664:Umbrella antenna
660:
639:
623:
606:
472:radio navigation
434:designation for
398:
391:
384:
91:
90:
73:
67:
61:Wavelength range
55:
42:
40:
21:
3932:
3931:
3927:
3926:
3925:
3923:
3922:
3921:
3902:
3901:
3900:
3895:
3861:
3788:
3763:
3749:
3717:
3645:
3597:
3539:
3516:
3493:
3486:
3479:
3472:
3470:
3422:
3417:
3387:
3382:
3373:
3371:
3364:
3359:
3356:
3355:300 GHz/1 mm
3354:
3344:
3341:
3339:
3329:
3326:
3324:
3314:
3311:
3310:300 MHz/1 m
3309:
3299:
3296:
3294:
3284:
3281:
3279:
3269:
3266:
3265:300 kHz/1 km
3264:
3254:
3251:
3249:
3239:
3236:
3234:
3224:
3221:
3220:300 Hz/1 Mm
3219:
3209:
3206:
3204:
3194:
3191:
3189:
3172:
3166:
3136:
3131:
3080:
3032:
3006:
2943:
2929:TDF time signal
2875:
2870:
2822:Wayback Machine
2751:
2740:
2735:
2729:
2716:
2707:
2704:
2702:Further reading
2699:
2698:
2689:
2687:
2674:
2673:
2663:
2662:
2658:
2645:
2644:
2640:
2630:
2628:
2617:
2616:
2612:
2605:Random Abstract
2599:
2598:
2594:
2584:
2582:
2543:
2542:
2529:
2505:
2504:
2500:
2483:
2479:
2462:
2461:
2457:
2447:
2445:
2441:
2440:
2436:
2426:
2424:
2420:
2419:
2415:
2405:
2403:
2399:
2398:
2394:
2387:plasmon.elte.hu
2381:
2380:
2376:
2369:
2354:
2353:
2349:
2341:
2335:
2334:
2325:
2318:
2307:
2300:
2299:
2290:
2283:
2268:
2267:
2263:
2251:
2250:
2233:
2223:
2221:
2215:
2214:
2210:
2203:
2188:
2187:
2178:
2171:
2156:
2155:
2144:
2134:
2132:
2128:
2117:
2113:
2112:
2108:
2103:
2080:
2011:Oso, Washington
1995:
1899:Rosnay (France)
1680:
1628:15.734 kHz
1606:15.625 kHz
1595:Rosnay (France)
1574:14.881 kHz
1558:12.649 kHz
1542:11.905 kHz
1514:
1486:radio receivers
1466:
1458:signaling rates
1451:
1449:
1443:
1441:
1409:, and coherent
1394:
1370:
1316:Since 2004 the
1299:Oso, Washington
1254:
1242:
1233:electromagnetic
1223:electromagnetic
1201:
1152:
1093:radiotelegraphy
1085:
1072:Flattop antenna
1065:
1009:
1003:radiotelegraphy
994:Continuous Wave
973:
966:
956:
899:
871:
839:
832:
814:
798:
784:
717:
683:
682:
681:
680:
679:
672:Tsushima Island
661:
653:
652:
640:
632:
631:
624:
616:
615:
607:
596:
496:
452:myriameter wave
448:myriameter band
402:
373:
330:
311:
298:
244:
65:
62:
50:
47:
46:Frequency range
38:
35:
28:
23:
22:
15:
12:
11:
5:
3930:
3928:
3920:
3919:
3914:
3912:Radio spectrum
3904:
3903:
3897:
3896:
3894:
3893:
3888:
3883:
3878:
3872:
3870:
3863:
3862:
3860:
3859:
3854:
3849:
3844:
3839:
3834:
3829:
3824:
3819:
3814:
3809:
3804:
3798:
3796:
3790:
3789:
3787:
3786:
3781:
3776:
3771:
3766:
3761:
3757:
3752:
3747:
3743:
3738:
3733:
3727:
3725:
3719:
3718:
3716:
3715:
3710:
3705:
3683:
3678:
3655:
3653:
3647:
3646:
3644:
3643:
3638:
3633:
3628:
3623:
3618:
3613:
3607:
3605:
3599:
3598:
3596:
3595:
3590:
3585:
3580:
3575:
3570:
3565:
3560:
3555:
3549:
3547:
3541:
3540:
3538:
3537:
3532:
3526:
3524:
3518:
3517:
3515:
3514:
3509:
3503:
3501:
3495:
3494:
3492:
3491:
3458:
3453:
3448:
3443:
3438:
3433:
3427:
3424:
3423:
3418:
3416:
3415:
3408:
3401:
3393:
3384:
3383:
3369:
3366:
3365:
3361:
3360:
3347:
3345:
3340:30 GHz/10 mm
3332:
3330:
3317:
3315:
3302:
3300:
3295:30 MHz/10 m
3287:
3285:
3272:
3270:
3257:
3255:
3250:30 kHz/10 km
3242:
3240:
3227:
3225:
3212:
3210:
3205:30 Hz/10 Mm
3197:
3195:
3182:
3177:
3174:
3173:
3169:Radio spectrum
3167:
3165:
3164:
3157:
3150:
3142:
3133:
3132:
3130:
3129:
3124:
3119:
3114:
3109:
3104:
3099:
3094:
3088:
3086:
3082:
3081:
3079:
3078:
3073:
3068:
3063:
3058:
3053:
3048:
3042:
3040:
3034:
3033:
3031:
3030:
3024:
3022:
3008:
3007:
3005:
3004:
2999:
2994:
2989:
2984:
2979:
2974:
2969:
2964:
2959:
2953:
2951:
2945:
2944:
2942:
2941:
2936:
2931:
2926:
2921:
2916:
2911:
2906:
2901:
2896:
2891:
2885:
2883:
2877:
2876:
2871:
2869:
2868:
2861:
2854:
2846:
2840:
2839:
2834:
2829:
2824:
2812:
2807:
2802:
2797:
2792:
2786:
2781:
2776:
2767:
2762:
2757:
2750:
2749:External links
2747:
2746:
2745:
2733:
2727:
2714:
2703:
2700:
2697:
2696:
2656:
2651:GlobalSecurity
2638:
2610:
2592:
2527:
2498:
2477:
2471:. p. 77.
2455:
2434:
2413:
2392:
2374:
2367:
2347:
2323:
2316:
2288:
2282:978-0471743682
2281:
2261:
2231:
2208:
2201:
2176:
2169:
2142:
2105:
2104:
2102:
2099:
2098:
2097:
2092:
2086:
2079:
2076:
2073:
2072:
2070:
2060:
2057:
2051:
2050:
2048:
2042:
2039:
2035:
2034:
2031:
2025:
2022:
2018:
2017:
2014:
2008:
2005:
1999:
1998:
1992:
1986:
1983:
1977:
1976:
1973:
1966:
1963:
1957:
1956:
1953:
1950:
1947:
1939:
1938:
1936:
1930:
1927:
1921:
1920:
1918:
1912:
1909:
1903:
1902:
1900:
1897:
1896:21.75 kHz
1894:
1888:
1887:
1885:
1882:
1879:
1873:
1872:
1871:rarely active
1869:
1866:
1863:
1859:
1858:
1856:
1853:
1850:
1844:
1843:
1841:
1838:
1837:20.76 kHz
1835:
1831:
1830:
1825:
1822:
1819:
1811:
1810:
1808:
1802:
1801:20.27 kHz
1799:
1795:
1794:
1791:
1785:
1782:
1776:
1775:
1772:
1766:
1763:
1757:
1756:
1755:Rarely active
1753:
1750:
1747:
1743:
1742:
1739:
1733:
1730:
1724:
1723:
1721:
1718:Matochkin Shar
1714:
1711:
1707:
1706:
1704:
1697:
1694:
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1540:
1536:
1535:
1532:
1529:
1526:
1513:
1510:
1498:spectrogrammes
1482:radio amateurs
1465:
1462:
1393:
1390:
1369:
1366:
1348:or 8 bit
1314:
1313:
1302:
1291:
1280:
1253:
1250:
1241:
1238:
1200:
1197:
1168:The worldwide
1165:transmitters.
1151:
1148:
1120:high frequency
1084:
1081:
1074:towers of the
1064:
1061:
1060:
1059:
1047:
1041:
1021:
1015:
997:
944:or 8 bit
918:radiotelephony
898:
895:
883:receiver noise
870:
867:
831:
828:
716:
713:
662:
655:
654:
641:
634:
633:
625:
618:
617:
608:
601:
600:
599:
598:
597:
595:
592:
591:
590:
579:
572:
495:
492:
414:Palmer Station
404:
403:
401:
400:
393:
386:
378:
375:
374:
372:
371:
366:
361:
356:
351:
346:
340:
337:
336:
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331:
329:
328:
323:
318:
313:
309:
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300:
296:
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287:
282:
277:
272:
267:
262:
256:
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252:
246:
245:
243:
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232:
227:
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202:
197:
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187:
182:
177:
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167:
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160:
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146:
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135:
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129:
124:
119:
113:
112:
107:
102:
97:
87:
86:
80:
79:
69:
68:
63:
60:
57:
56:
48:
45:
32:VLF Automotive
26:
24:
14:
13:
10:
9:
6:
4:
3:
2:
3929:
3918:
3915:
3913:
3910:
3909:
3907:
3892:
3889:
3887:
3884:
3882:
3879:
3877:
3874:
3873:
3871:
3868:
3864:
3858:
3855:
3853:
3850:
3848:
3845:
3843:
3840:
3838:
3835:
3833:
3830:
3828:
3825:
3823:
3820:
3818:
3815:
3813:
3810:
3808:
3805:
3803:
3800:
3799:
3797:
3795:
3791:
3785:
3782:
3780:
3777:
3775:
3772:
3770:
3767:
3765:
3758:
3756:
3753:
3751:
3744:
3742:
3739:
3737:
3734:
3732:
3729:
3728:
3726:
3724:
3720:
3714:
3711:
3709:
3706:
3703:
3699:
3695:
3691:
3687:
3684:
3682:
3679:
3676:
3672:
3668:
3664:
3660:
3657:
3656:
3654:
3652:
3648:
3642:
3639:
3637:
3634:
3632:
3629:
3627:
3624:
3622:
3619:
3617:
3614:
3612:
3609:
3608:
3606:
3604:
3600:
3594:
3591:
3589:
3586:
3584:
3581:
3579:
3576:
3574:
3571:
3569:
3566:
3564:
3561:
3559:
3556:
3554:
3551:
3550:
3548:
3546:
3542:
3536:
3533:
3531:
3528:
3527:
3525:
3523:
3519:
3513:
3510:
3508:
3505:
3504:
3502:
3500:
3496:
3489:
3485:
3478:
3466:
3462:
3459:
3457:
3454:
3452:
3449:
3447:
3444:
3442:
3439:
3437:
3434:
3432:
3429:
3428:
3425:
3421:
3414:
3409:
3407:
3402:
3400:
3395:
3394:
3391:
3381:
3380:
3367:
3358:
3357:3 THz/0.1 mm
3353:
3352:
3346:
3343:
3342:300 GHz/1 mm
3338:
3337:
3331:
3328:
3327:30 GHz/10 mm
3325:3 GHz/100 mm
3323:
3322:
3316:
3313:
3312:3 GHz/100 mm
3308:
3307:
3301:
3298:
3293:
3292:
3286:
3283:
3280:3 MHz/100 m
3278:
3277:
3271:
3268:
3263:
3262:
3256:
3253:
3252:300 kHz/1 km
3248:
3247:
3241:
3238:
3237:30 kHz/10 km
3235:3 kHz/100 km
3233:
3232:
3226:
3223:
3222:3 kHz/100 km
3218:
3217:
3211:
3208:
3203:
3202:
3196:
3193:
3190:3 Hz/100 Mm
3188:
3187:
3181:
3180:
3175:
3170:
3163:
3158:
3156:
3151:
3149:
3144:
3143:
3140:
3128:
3125:
3123:
3120:
3118:
3115:
3113:
3110:
3108:
3105:
3103:
3100:
3098:
3095:
3093:
3090:
3089:
3087:
3083:
3077:
3074:
3072:
3069:
3067:
3064:
3062:
3059:
3057:
3054:
3052:
3049:
3047:
3044:
3043:
3041:
3039:
3035:
3029:
3026:
3025:
3023:
3021:
3017:
3013:
3009:
3003:
3000:
2998:
2995:
2993:
2990:
2988:
2985:
2983:
2980:
2978:
2975:
2973:
2970:
2968:
2965:
2963:
2960:
2958:
2955:
2954:
2952:
2950:
2946:
2940:
2937:
2935:
2934:Time from NPL
2932:
2930:
2927:
2925:
2922:
2920:
2917:
2915:
2912:
2910:
2907:
2905:
2902:
2900:
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2892:
2890:
2887:
2886:
2884:
2882:
2878:
2874:
2867:
2862:
2860:
2855:
2853:
2848:
2847:
2844:
2838:
2835:
2833:
2830:
2828:
2825:
2823:
2819:
2816:
2813:
2811:
2808:
2806:
2803:
2801:
2798:
2796:
2793:
2790:
2787:
2785:
2782:
2780:
2777:
2774:
2773:
2768:
2766:
2763:
2761:
2758:
2756:
2753:
2752:
2748:
2739:
2734:
2730:
2724:
2720:
2715:
2711:
2706:
2705:
2701:
2686:on 2011-09-27
2685:
2681:
2680:ludb.clui.org
2677:
2670:
2666:
2660:
2657:
2652:
2648:
2642:
2639:
2626:
2625:
2620:
2614:
2611:
2606:
2602:
2596:
2593:
2581:
2577:
2572:
2567:
2563:
2559:
2555:
2551:
2547:
2540:
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2536:
2534:
2532:
2528:
2522:
2517:
2513:
2509:
2502:
2499:
2494:
2488:
2480:
2474:
2470:
2466:
2459:
2456:
2444:
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2423:
2417:
2414:
2402:
2396:
2393:
2388:
2384:
2378:
2375:
2370:
2368:9789401022651
2364:
2360:
2359:
2351:
2348:
2340:
2339:
2332:
2330:
2328:
2324:
2319:
2313:
2306:
2305:
2297:
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2289:
2284:
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2274:
2273:
2265:
2262:
2257:
2256:
2248:
2246:
2244:
2242:
2240:
2238:
2236:
2232:
2219:
2212:
2209:
2204:
2198:
2194:
2193:
2185:
2183:
2181:
2177:
2172:
2166:
2162:
2161:
2153:
2151:
2149:
2147:
2143:
2127:
2123:
2116:
2110:
2107:
2100:
2096:
2093:
2090:
2087:
2085:
2082:
2081:
2077:
2071:
2068:
2064:
2063:Karachi coast
2061:
2058:
2056:
2053:
2049:
2046:
2043:
2041:25.2 kHz
2040:
2037:
2032:
2029:
2026:
2024:24.8 kHz
2023:
2020:
2015:
2012:
2009:
2007:24.6 kHz
2006:
2004:
2001:
1993:
1990:
1989:Cutler, Maine
1987:
1984:
1982:
1979:
1974:
1971:
1967:
1965:23.4 kHz
1964:
1962:
1959:
1954:
1951:
1948:
1945:
1941:
1937:
1934:
1931:
1929:22.2 kHz
1928:
1926:
1923:
1919:
1916:
1913:
1911:22.1 kHz
1910:
1908:
1905:
1901:
1898:
1895:
1893:
1890:
1886:
1883:
1881:21.4 kHz
1880:
1878:
1875:
1870:
1867:
1865:21.1 kHz
1864:
1861:
1857:
1854:
1852:20.9 kHz
1851:
1849:
1846:
1842:
1839:
1836:
1833:
1829:
1826:
1823:
1821:20.5 kHz
1820:
1817:
1813:
1809:
1806:
1803:
1800:
1797:
1792:
1789:
1786:
1784:19.8 kHz
1783:
1781:
1778:
1773:
1770:
1767:
1765:19.6 kHz
1764:
1762:
1759:
1754:
1751:
1749:18.9 kHz
1748:
1745:
1740:
1737:
1734:
1732:18.3 kHz
1731:
1729:
1726:
1722:
1719:
1715:
1713:18.1 kHz
1712:
1709:
1705:
1702:
1698:
1696:17.8 kHz
1695:
1693:
1690:
1684:
1678:
1675:
1672:
1670:17.2 kHz
1669:
1667:
1664:
1660:
1657:
1654:
1652:16.4 kHz
1651:
1649:
1646:
1641:
1638:televisions (
1637:
1633:
1630:
1627:
1624:
1619:
1616:televisions (
1615:
1611:
1608:
1605:
1602:
1597:
1594:
1592:15.1 kHz
1591:
1589:
1586:
1582:
1579:
1576:
1573:
1570:
1566:
1563:
1560:
1557:
1554:
1550:
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1544:
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1533:
1530:
1527:
1524:
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1520:
1519:
1511:
1509:
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1499:
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1491:
1487:
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1475:
1470:
1463:
1461:
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1439:
1435:
1431:
1427:
1423:
1419:
1414:
1412:
1408:
1404:
1400:
1391:
1389:
1387:
1383:
1377:
1375:
1367:
1365:
1363:
1360:
1355:
1351:
1347:
1342:
1339:
1334:
1332:
1327:
1322:
1319:
1311:
1310:Cutler, Maine
1307:
1303:
1300:
1296:
1292:
1289:
1285:
1281:
1278:
1274:
1273:
1272:
1269:
1267:
1263:
1259:
1251:
1249:
1247:
1239:
1237:
1234:
1231:
1226:
1224:
1220:
1219:Geophysicists
1216:
1214:
1213:magnetosphere
1210:
1206:
1205:geophysicists
1198:
1196:
1194:
1190:
1186:
1182:
1177:
1175:
1171:
1166:
1164:
1160:
1157:
1149:
1147:
1145:
1141:
1137:
1133:
1129:
1126:atoms in the
1125:
1121:
1117:
1112:
1110:
1106:
1102:
1098:
1094:
1090:
1082:
1077:
1073:
1069:
1062:
1057:
1052:
1048:
1045:
1042:
1039:
1035:
1031:
1027:
1022:
1019:
1016:
1012:
1004:
1001:
998:
995:
992:
991:
990:
988:
983:
980:
971:
970:tuned circuit
964:
959:
954:
949:
947:
943:
939:
938:radioteletype
935:
931:
927:
923:
919:
916:
912:
908:
907:audio signals
904:
896:
894:
892:
891:loop antennas
888:
884:
880:
876:
868:
866:
864:
860:
857:
853:
849:
845:
837:
829:
827:
825:
821:
820:air breakdown
812:
808:
804:
803:tuned circuit
801:
793:
791:
787:
780:
776:
772:
767:
765:
761:
757:
752:
750:
746:
742:
738:
734:
730:
726:
722:
714:
707:
703:
701:
697:
692:
688:
677:
673:
669:
665:
659:
650:
646:
638:
629:
622:
612:
605:
593:
588:
584:
580:
577:
573:
570:
566:
565:
564:
562:
559:", caused by
558:
554:
549:
545:
541:
536:
534:
530:
526:
522:
518:
514:
510:
505:
501:
493:
491:
489:
485:
481:
477:
473:
469:
465:
461:
457:
453:
449:
445:
441:
437:
433:
429:
425:
419:
415:
410:
399:
394:
392:
387:
385:
380:
379:
377:
376:
370:
367:
365:
362:
360:
357:
355:
352:
350:
347:
345:
342:
341:
339:
338:
333:
327:
324:
322:
319:
317:
314:
312:
306:
304:
301:
299:
293:
291:
288:
286:
283:
281:
278:
276:
273:
271:
268:
266:
263:
261:
258:
257:
255:
254:
251:
247:
241:
238:
236:
233:
231:
228:
226:
223:
221:
218:
216:
213:
211:
208:
206:
203:
201:
198:
196:
193:
191:
188:
186:
183:
181:
178:
176:
173:
172:
170:
169:
166:
162:
155:
152:
150:
147:
145:
142:
140:
137:
136:
133:
130:
128:
125:
123:
120:
118:
115:
114:
111:
108:
106:
103:
101:
98:
96:
93:
92:
89:
88:
85:
81:
78:
74:
64:
58:
54:
49:
43:
33:
19:
3841:
3471:
3370:
3349:
3348:
3334:
3333:
3319:
3318:
3304:
3303:
3297:300 MHz/1 m
3289:
3288:
3282:30 MHz/10 m
3274:
3273:
3267:3 MHz/100 m
3259:
3258:
3244:
3243:
3230:
3229:
3228:
3214:
3213:
3207:300 Hz/1 Mm
3199:
3198:
3192:30 Hz/10 Mm
3184:
3183:
2770:
2718:
2710:Radio Natura
2709:
2688:. Retrieved
2684:the original
2679:
2668:
2659:
2650:
2641:
2629:. Retrieved
2622:
2613:
2604:
2595:
2583:. Retrieved
2553:
2549:
2511:
2507:
2501:
2465:Radio Nature
2464:
2458:
2446:. Retrieved
2437:
2425:. Retrieved
2416:
2404:. Retrieved
2395:
2386:
2377:
2357:
2350:
2337:
2303:
2271:
2264:
2254:
2222:. Retrieved
2211:
2191:
2159:
2133:. Retrieved
2126:the original
2109:
2016:192 kW
1942:RJH63 RJH66
1884:Hawaii (USA)
1814:RJH63 RJH66
1703:, Maine (US)
1598:400 kW
1515:
1502:
1479:
1474:loop antenna
1430:interference
1418:loading coil
1415:
1395:
1378:
1371:
1359:one-time pad
1343:
1341:operations.
1335:
1323:
1315:
1270:
1255:
1243:
1227:
1217:
1202:
1178:
1167:
1153:
1113:
1086:
1063:Applications
984:
965:form a high
963:loading coil
950:
900:
872:
863:permeability
854:. This is a
852:loading coil
833:
794:
771:loading coil
768:
764:Counterpoise
753:
732:
718:
684:
583:solar flares
537:
504:ground waves
497:
480:radio clocks
451:
447:
427:
423:
422:
109:
3886:Medium wave
3563:Lyman-alpha
3545:Ultraviolet
3484:wavelengths
3477:frequencies
3441:Ultraviolet
2631:14 November
2550:Geosciences
2135:20 February
2091:, 1971–1997
1985:24 kHz
1970:Rhauderfehn
1949:23 kHz
1946:RJH77 RJH99
1818:RJH77 RJH99
1368:Amateur use
1288:Rhauderfehn
1258:nuclear war
1230:geophysical
1185:time signal
879:radio noise
725:radio masts
535:(TM) mode.
523:called the
456:myriameters
444:wavelengths
77:Radio bands
3906:Categories
3867:Wavelength
3723:Microwaves
3535:Hard X-ray
3530:Soft X-ray
3499:Gamma rays
3431:Gamma rays
2690:2009-07-13
2665:"20–25kHz"
2585:14 January
2317:007032381X
2101:References
2069:(Pakistan)
1528:Frequency
1422:sound card
1282:Germany's
1275:Britain's
1156:hyperbolic
1128:ionosphere
1097:Morse code
1034:sine waves
1000:Morse code
987:modulation
934:modulation
897:Modulation
811:variometer
751:are used.
749:T antennas
670:beacon on
521:ionosphere
488:submarines
51:3–30
3881:Shortwave
3876:Microwave
3456:Microwave
3117:Radio VNG
3038:Satellite
2949:Shortwave
2580:2076-3263
2487:cite book
2383:"AWDANet"
1972:(Germany)
1525:Callsign
1354:encrypted
1248:systems.
1209:whistlers
1132:shortwave
1109:sidebands
926:bit rates
903:bandwidth
836:resonance
807:bandwidth
790:litz wire
561:lightning
557:whistlers
529:waveguide
513:electrons
468:data rate
460:bandwidth
66:100-10 km
3891:Longwave
3651:Infrared
3451:Infrared
2982:ROA Time
2881:Longwave
2818:Archived
2676:"WA3248"
2647:"Cutler"
2078:See also
1805:Tavolara
1738:(France)
1736:Le Blanc
1720:(Russia)
1676:(Sweden)
1674:Grimeton
1658:(Norway)
1534:Remarks
1333:(BCAA).
1221:use VLF-
1187:station
1008:antenna
859:inductor
779:resonant
769:A large
729:monopole
594:Antennas
569:seawater
500:diffract
154:12 (THF)
149:11 (EHF)
144:10 (SHF)
3482:longer
3475:higher
3446:Visible
3085:Defunct
3061:Galileo
3056:GLONASS
2558:Bibcode
2406:13 June
2224:11 June
1935:(Japan)
1915:Skelton
1807:(Italy)
1788:Exmouth
1769:Anthorn
1362:ciphers
1318:US Navy
1124:ionized
1116:skywave
745:flattop
741:trideco
666:of the
649:Seattle
553:sferics
525:D layer
430:is the
139:9 (UHF)
132:8 (VHF)
110:4 (VLF)
105:3 (ULF)
100:2 (SLF)
95:1 (ELF)
3784:L band
3779:S band
3774:C band
3769:X band
3755:K band
3741:Q band
3736:V band
3731:W band
3636:Orange
3631:Yellow
3611:Violet
3522:X-rays
3436:X-rays
3046:BeiDou
2977:JN53DV
2967:HD2IOA
2725:
2669:vlf.it
2578:
2475:
2448:13 May
2427:13 May
2365:
2314:
2279:
2220:. NASA
2199:
2167:
1701:Cutler
1140:Sweden
1038:phases
932:(FSK)
824:corona
756:ground
540:fading
127:7 (HF)
122:6 (MF)
117:5 (LF)
3869:types
3794:Radio
3690:Bands
3663:Bands
3626:Green
3461:Radio
3171:(ITU)
3071:IRNSS
3051:DORIS
2909:DCF77
2741:(PDF)
2342:(PDF)
2308:(PDF)
2129:(PDF)
2118:(PDF)
2067:Sindh
2047:(USA)
2030:(USA)
2013:(USA)
1991:(USA)
1968:near
1961:DHO38
1944:RJH69
1933:Ebino
1816:RJH69
1432:from
1384:or a
1350:ASCII
1326:acres
1304:U.S.
1293:U.S.
1284:DHO38
1174:Alpha
1170:Omega
1056:ASCII
1046:(MSK)
1030:ASCII
1020:(FSK)
946:ASCII
797:high
783:high
647:near
486:with
464:audio
250:IEEE
3764:band
3750:band
3708:LWIR
3686:MWIR
3681:SWIR
3621:Cyan
3616:Blue
3122:WWVL
3107:OLB5
3002:YVTO
2997:WWVH
2939:WWVB
2904:Beta
2723:ISBN
2633:2008
2587:2021
2576:ISSN
2493:link
2473:ISBN
2450:2017
2429:2017
2408:2014
2363:ISBN
2312:ISBN
2277:ISBN
2226:2024
2197:ISBN
2165:ISBN
2137:2013
2055:PNSH
1917:(UK)
1771:(UK)
1640:480i
1618:576i
1436:and
1411:BPSK
1407:MFSK
1403:QRSS
1346:ITA2
1189:WWVL
1103:and
942:ITA2
694:are
585:and
546:and
517:ions
515:and
84:ITU
3857:ELF
3852:SLF
3847:ULF
3842:VLF
3822:VHF
3817:UHF
3812:SHF
3807:EHF
3802:THF
3713:FIR
3659:NIR
3641:Red
3593:UVA
3588:UVB
3583:UVC
3578:NUV
3573:MUV
3568:FUV
3351:THF
3336:EHF
3321:SHF
3306:UHF
3291:VHF
3231:VLF
3216:ULF
3201:SLF
3186:ELF
3127:Y3S
3112:OMA
3102:NAA
3097:HBG
3092:BSF
3020:UHF
3012:VHF
2992:WWV
2987:RWM
2972:HLA
2962:CHU
2957:BPM
2924:RTZ
2919:RBU
2914:JJY
2899:BSF
2894:BPL
2889:BPC
2566:doi
2516:doi
2122:ITU
2038:NML
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