621:
658:
3468:
1472:
604:
637:
706:
1057:
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
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.
868:. 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.
1026:
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
1016:
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
984:
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
713:" 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 are called "triatics".
1056:
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
1506:
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
1008:
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
1071:
1343:
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
1382:
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
923:). 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
820:
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
1331:
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
1399:
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
1323:
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.
1238:
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.
979:
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
791:, 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
1359:
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
1327:
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
1259:
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
1491:
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.
985:
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.
837:
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
892:. 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
845:, 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
1379:
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.
3377:
765:
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.
1333:
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.
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
1145:, 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
841:, 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
1423:
and a large wire antenna. Receivers employ an electric field probe or magnetic loop antenna, a sensitive audio preamplifier, isolating transformers, and a PC
1043:, 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.
2117:
1263:
VLF communications will be less disrupted by nuclear explosions than higher frequencies. Since it can penetrate seawater VLF is used by the military to
3413:
738:
to increase the current in the vertical wires, increasing the radiated power and efficiency of the antenna. High-power stations use variations on the
730:, 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
2305:
2495:
1511:. These cause the ionization level to increase in the ionosphere producing a rapid change to the amplitude and phase of the received VLF signal.
1164:
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
2866:
2220:
1110:
within the band starting from 20 kHz, but the result was unsatisfactory because the available bandwidth was insufficient to contain the
395:
816:) to tune the antenna. The large VLF antennas used for high-power transmitters usually have bandwidths of only 50–100 hertz. The high
1157:
Due to its long propagation distances and stable phase characteristics, during the 20th century the VLF band was used for long range
3073:
1782:
769:
systems have also been used, consisting of radial networks of copper cables supported several feet above the ground under the antenna.
2273:
864:
with a second control winding through which a DC current flows, which controls the inductance by magnetizing the core, changing its
3162:
2621:
2781:
2424:
798:
The high capacitance and inductance and low resistance of the antenna-loading coil combination makes it act electrically like a
757:
Due to the low radiation resistance, to minimize power dissipated in the ground these antennas require extremely low resistance
3406:
1102:, to communicate with other countries, their colonies, and naval fleets. Early attempts were made to use radiotelephone using
2729:
2203:
2171:
1376:
1248:
1027:
the frequency 9020 Hz, 50 Hz lower, to indicate a '0'. The two frequencies are generated by a continuously-running
431:
2786:
2794:
NOTE: As of 05/03/2014, the "Listen live" links are down, but the site has some previously recorded examples to listen to.
2479:
581:
VLF waves used to communicate with submarines have created an artificial bubble around the Earth that can protect it from
2859:
2283:
1183:
1419:
The transmitter generally consists of an audio amplifier of a few hundred watts, an impedance matching transformer, a
3399:
2369:
1017:
to 15–20 words/minute. CW is now only used in small hand-keyed transmitters, and for testing large transmitters.
675:
388:
2740:
685:
A major practical drawback to the VLF band is that because of the length of the waves, full size resonant antennas (
1198:) to send data, shifting between 20 kHz and 26 kHz. The WWVL service was discontinued in July 1972.
2820:
1404:
enable very narrow bandwidths to be used to reach distances up to several thousand kilometers. The modes used are
1210:
for long range lightning location and for research into atmospheric phenomena such as the aurora. Measurements of
1409:
813:
620:
951:
character codes. A small frequency shift of 30–50 hertz is used due to the small bandwidth of the antenna.
3063:
2678:
2471:
2318:
1508:
2128:
795:
several centimeters in diameter, consisting of thousands of insulated strands of fine wire braided together.
3078:
2852:
2086:
2005:
1297:
1264:
905:
809:
644:
459:
784:. At VLF the design of this coil is challenging; it must have low resistance at the operating RF frequency,
3155:
1917:
1909:
1436:
1432:
1279:
1194:
began transmitting a 500 W signal on 20 kHz in August 1963. It used frequency-shift keying (
766:
381:
1035:
codes for the characters of the message. A problem at VLF is that when the frequency is switched the two
3514:
3353:
2364:. NATO Advanced Study Institute. Spåtind, Norway: Springer Science and Business Media. pp. 372–373.
1053:
2549:"The Central Italy Electromagnetic Network and the 2009 L'Aquila earthquake: Observed electric activity"
761:(Earthing) systems, consisting of radial networks of buried copper wires under the antenna. To minimize
3919:
3509:
1790:
1401:
1384:
1107:
726:. These are very large wire antennas, up to several kilometers long. They consist of a series of steel
508:
1479:
and a sound card. The Morse code says "..33376.."; the vertical stripes are distant lightning strikes.
3104:
3068:
2626:
2347:. Naval Electronics Systems Command. Washington, DC: U.S. Navy. August 1972. Manual NAVELEX 0101-113.
2256:
1879:
1428:
1340:
1172:
667:
1658:
908:
of the band, and the extremely narrow bandwidth of the antennas used, it is impractical to transmit
3809:
3422:
3338:
3053:
1676:
1668:
1583:
1567:
1551:
1520:
1138:
743:
630:, UK, showing 6 insulator strings attaching the toploads to the 6 vertical radiator wires
325:
148:
954:
In high power VLF transmitters, to increase the allowable data rate, a special form of FSK called
3914:
3859:
3188:
3148:
2091:
1946:
1818:
1650:
1268:
876:
The requirements for receiving antennas are less stringent, because of the high level of natural
94:
1983:
1694:
1492:
1308:
1247:
VLF can also penetrate soil and rock for some distance, so these frequencies are also used for
1195:
1090:
Historically, this band was used for long distance transoceanic radio communication during the
1078:
1020:
932:
610:
575:
483:
2359:
2161:
1495:(FFT) software in combination with a sound card allows reception of all frequencies below the
2649:
2339:
2193:
2047:
2030:
1963:
1935:
1927:
1771:
1763:
1286:
1158:
1031:. The transmitter is periodically switched between these frequencies to represent 8 bit
1028:
889:
865:
627:
586:
538:
VLF waves have very low path attenuation, 2–3 dB per 1,000 km, with little of the "
1475:
Timing diagram of a frequency-shift keyed 18.1 kHz VLF signal, picked up using a small
3819:
3814:
3323:
3308:
3040:
3022:
2560:
1103:
1046:
981:
955:
924:
917:
913:
822:
777:
758:
699:
269:
143:
138:
8:
3854:
3849:
3824:
3804:
3555:
3293:
3218:
3203:
3014:
2994:
2974:
2964:
2936:
2926:
2921:
1091:
532:
467:
417:
264:
153:
131:
104:
99:
17:
2564:
698:, a small fraction of the length at which they would be self-resonant. Due to their low
3692:
3665:
3575:
3560:
3094:
2959:
2931:
2906:
2901:
2896:
2489:
1830:
1413:
1176:
846:
710:
502:
around large obstacles and so are not blocked by mountain ranges, and can propagate as
2839:
3700:
3696:
3677:
3673:
3669:
3114:
3099:
3030:
2891:
2725:
2578:
2475:
2365:
2314:
2279:
2199:
2167:
2097:
1496:
1440:
1388:
1165:
877:
850:
695:
2802:
849:
between the two output frequencies with the modulation. This is accomplished with a
249:
3834:
3605:
3580:
3448:
3263:
2568:
2518:
1685:
1638:
1616:
1211:
1161:
1146:
1125:
to communicate at similar distances by reflecting their radio waves off a layer of
826:
739:
731:
723:
690:
686:
663:
556:
471:
164:
121:
1405:
1061:
characters (8 bits each) per second, approximately 450 words per minute.
3883:
3796:
3638:
3570:
2824:
2807:
2523:
2013:
1894:
1850:
1807:
1730:
1590:
1301:
1235:
1225:
1095:
1094:
era between about 1905 and 1925. Nations built networks of high-power LF and VLF
1005:
996:
762:
671:
435:
83:
2791:
927:
would be enormous in size. Therefore, only text data can be transmitted, at low
466:(voice) transmission is highly impractical in this band, and therefore only low
3829:
3613:
3278:
3171:
2951:
2573:
1720:
1488:
1460:
1122:
920:
413:
259:
126:
76:
31:
2403:
1121:(skip) radio propagation method allowed lower power transmitters operating at
657:
3908:
3839:
3776:
3757:
3661:
3595:
3590:
3585:
3248:
2582:
2118:"Nomenclature of the frequency and wavelength bands used in telemmunications"
2065:
1991:
1703:
1484:
1312:
1221:
1215:
1040:
972:
940:
858:
805:
302:
284:
239:
234:
229:
224:
219:
214:
209:
204:
199:
194:
189:
184:
179:
174:
116:
3467:
2829:
3715:
3710:
3688:
3683:
3391:
3381:
2817:
1476:
1471:
1420:
1361:
1207:
965:
909:
893:
885:
854:
773:
626:
Central mast of a similar "trideco" antenna of the NATO VLF transmitter at
603:
463:
2548:
458:(an obsolete metric unit equal to 10 kilometers). Due to its limited
3888:
3565:
3547:
3443:
2875:
2774:
2667:
2341:
Naval Shore
Electronics Criteria - VLF, LF, and MF communications systems
1972:
1500:
1290:
1260:
1187:
881:
614:
1.8 megawatts, one of the most powerful radio stations in the world.
589:; this occurred through interaction with high-energy radiation particles.
582:
503:
499:
479:
475:
2603:
1391:
in order to support such long duration coherent detection and decoding.
636:
3869:
3537:
3532:
3486:
3463:
3140:
2844:
2445:
2057:
1424:
1232:
1130:
1126:
1099:
1002:
989:
936:
812:
and to change the transmitting frequency requires a variable inductor (
727:
705:
520:
455:
443:
2797:
551:
5,000–20,000 km have been realized. However, atmospheric noise ("
3878:
3725:
3501:
3479:
3458:
3433:
3119:
2834:
2385:
1356:
1134:
1074:
1036:
838:
792:
560:
528:
487:
2686:
1228:
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
3893:
3653:
3453:
2984:
2883:
1738:
1304:
state, which transmits on 24.8 kHz with a power of 1.2 MW
1111:
1070:
1010:
1009:
1960s in commercial and military VLF stations. Because of the high
960:
928:
861:
799:
785:
781:
751:
747:
568:
547:
543:
512:
353:
2511:
Development of UKM-SID teaching module for space science education
1355:. Because these are military transmissions they are almost always
3762:
3748:
3058:
3018:
2719:
2163:
The high-latitude ionosphere and its effects on radio propagation
1320:
1133:, and long-distance radio communication stations switched to the
1118:
648:
552:
524:
368:
358:
348:
307:
294:
2513:. 6th International Forum on Engineering Education (IFEE 2012).
1175:
system used frequencies from 10 to 14 kHz, as did Russia's
750:(triatic) antennas. For low-power transmitters, inverted-L and
722:
High power VLF transmitting stations use capacitively-toploaded
3786:
3781:
3771:
3743:
3738:
3733:
3704:
3633:
3048:
2979:
2969:
2221:"NASA's Van Allen Probes Spot Man-Made Barrier Shrouding Earth"
1375:
The frequency range below 8.3 kHz is not allocated by the
1364:
1142:
888:
introduced by the receiver circuit and determines the receiver
539:
363:
343:
320:
315:
289:
279:
274:
2446:"Some recent milestones with amateur radio experiments at VLF"
1293:, which transmits on 23.4 kHz with a power of 800 kW
408:
3628:
3524:
3438:
2911:
2069:
1352:
1328:
1058:
1032:
948:
651:, which transmits on 24.8 kHz at a power of 1.2 MW.
511:
mechanism. The Earth is surrounded by a conductive layer of
3623:
3618:
3124:
3109:
3004:
2999:
2941:
2812:
1642:
1620:
1348:
1191:
944:
2767:
1201:
574:
VLF waves at certain frequencies have been found to cause
3643:
3129:
2989:
2916:
2124:
999:(CW), Interrupted Continuous Wave (ICW), or On-Off Keying
964:
of the antenna. The huge capacitively-loaded antenna and
516:
439:
52:
2741:"Very low wave reception with ferrite antennas 5-50 kHz"
1637:
Frequency for horizontal deflection of electron beam in
1615:
Frequency for horizontal deflection of electron beam in
1206:
Naturally occurring signals in the VLF band are used by
1347:
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
2757:
1431:
is required to retrieve the weak signals from beneath
1152:
2465:
1214:
are employed to infer the physical properties of the
555:") is high in the band, including such phenomena as "
2762:
776:
is required at the antenna feed point to cancel the
2835:
Internet based VLF listening guide with server list
2159:
1796:Used for submarine communication, 1 megawatt.
2334:
2332:
2330:
975:, which stores oscillating electrical energy. The
27:The range 3–30 kHz of the electromagnetic spectrum
2724:(in German). Meckenheim, DE: Siebel Verlag GmbH.
1443:. Useful received signal strengths are as low as
3906:
2775:Definition of frequency bands (VLF, ELF... etc.)
2508:
2425:"Sub 9 kHz spectrum in the Amateur Service"
2218:
2160:Hunsucker, R.D.; Hargreaves, John Keith (2002).
1463:typically between 1 and 100 bits per hour.
1315:which transmits on 24 kHz with 1.8 MW.
1271:frequencies are used for deeply submerged subs.
958:(MSK) is used. This is required due to the high
2327:
2110:
609:"Trideco" antenna tower array at the US Navy's
30:"VLF" redirects here. For the car company, see
2720:Klawitter, G.; Oexner, M.; Herold, K. (2000).
2542:
2540:
2538:
2536:
2534:
2299:
2297:
2295:
1098:stations that transmitted text information by
493:
3407:
3156:
2860:
1242:
992:that have been used in VLF transmitters are:
519:in the upper atmosphere at the bottom of the
389:
3421:
1514:
1085:
880:in the band. At VLF frequencies atmospheric
734:radiators, and the horizontal cables form a
717:
2604:"Shortwave HF VHF UHF utilities monitoring"
2531:
2494:: CS1 maint: numeric names: authors list (
2292:
2195:Electromagnetic theory and wave propagation
2166:. Cambridge University Press. p. 419.
2155:
2153:
2151:
2149:
3483:
3414:
3400:
3163:
3149:
2867:
2853:
2792:NASA live streaming ELF -> VLF Receiver
2715:(in Italian). Albino, Italy: SANDIT S.r.l.
2710:
1254:
396:
382:
2572:
2522:
2515:Procedia - Social and Behavioral Sciences
2055:
2039:
2022:
2003:
1981:
1961:
1943:
1925:
1907:
1892:
1877:
1863:
1848:
1835:
1815:
1799:
1780:
1761:
1747:
1728:
1711:
1692:
1666:
1648:
1626:
1604:
1588:
1572:
1556:
1540:
871:
832:
454:as the wavelengths range from one to ten
3170:
2874:
2146:
1470:
1069:
704:
407:
2509:Mardina Abdullah; et al. (2013) .
2303:
2278:. John Wiley and Sons. pp. 55–58.
2271:
2187:
2185:
2183:
1451: volts/meter (electric field) and
1274:Examples of naval VLF transmitters are
1202:Geophysical and atmospheric measurement
14:
3907:
2738:
2546:
2358:Holtet, J.A., ed. (17–27 April 1974).
2357:
2265:
2250:
2248:
2246:
2244:
2242:
2240:
2238:
1367:since the amount of text is so small.
3395:
3144:
2848:
2798:World Wide Lightning Location Network
2547:Fidani, Cristiano (8 December 2011).
2351:
2191:
1997:Used for submarine communication, at
1744:Frequently inactive for long periods
1466:
1377:International Telecommunication Union
1249:through-the-earth mine communications
165:EU / NATO / US ECM
2808:University of Louisville VLF Monitor
2254:
2180:
2127:. Rec. ITU-R V.431-7. Archived from
1394:
2818:Mark's Live Online VLF Receiver, UK
2235:
1483:VLF signals are often monitored by
1459: tesla (magnetic field), with
1339:Modern receivers use sophisticated
1153:Navigation beacons and time signals
24:
3466:
2704:
2036:Used for submarine communication.
1427:to digitise the signal. Extensive
1117:In the 1920s the discovery of the
478:(broadcasting time signals to set
25:
3931:
2751:
2517:. Vol. 102. pp. 80–85.
2404:"Geonics Limited - VLF Receivers"
2304:Johnson, Richard C., ed. (1993).
1682:Only active at special occasions
1231:VLF signals can be measured as a
3375:
2219:Susannah Darling (17 May 2017).
1507:signal received can vary with a
896:are usually used for reception.
808:. VLF antennas have very narrow
656:
635:
619:
602:
2813:Larry's Very Low Frequency site
2660:
2642:
2622:"Naval base link to jet plunge"
2614:
2596:
2502:
2459:
2438:
2417:
2396:
2378:
1065:
829:, and arcing from the antenna.
438:(RF) in the range of 3–30
2630:. Sydney, AU. 14 November 2008
2472:Radio Society of Great Britain
2466:Renato Romero, IK1QFK (2008).
2361:ELF-VLF Radio Wave Propagation
2275:Introduction to RF Propagation
2212:
1519:For a more detailed list, see
1509:sudden ionospheric disturbance
1499:simultaneously in the form of
1370:
13:
1:
3079:Quasi-Zenith Satellite System
2803:Stanford University VLF group
2313:(3rd ed.). McGraw-Hill.
2103:
2087:Communication with submarines
1958:Time signal transmitter Beta
1719:various locations, including
1298:Jim Creek Naval Radio Station
899:
2559:(1) (published 2012): 3–25.
2524:10.1016/j.sbspro.2013.10.716
2307:Antenna Engineering Handbook
1831:Time signal transmitter Beta
1280:Skelton Transmitting Station
1141:at Grimeton near Varberg in
7:
3515:Ultra-high-energy gamma ray
2080:
1334:Buoyant Cable Array Antenna
1265:communicate with submarines
1186:broadcasts. In the US, the
1184:standard time and frequency
853:in series with the antenna
593:
494:Propagation characteristics
412:A VLF receiving antenna at
10:
3936:
3510:Very-high-energy gamma ray
2574:10.3390/geosciences1010003
1955:various locations (Russia)
1871:various locations (Russia)
1827:various locations (Russia)
1755:various locations (Russia)
1580:various locations (Russia)
1564:various locations (Russia)
1548:various locations (Russia)
1487:using simple homemade VLF
1385:GPS disciplined oscillator
1309:Cutler Naval Radio Station
1243:Mine communication systems
1108:single-sideband modulation
780:of the antenna to make it
611:Naval Radio Station Cutler
509:Earth-ionosphere waveguide
416:, Antarctica, operated by
29:
3868:
3795:
3724:
3652:
3604:
3546:
3523:
3500:
3429:
3371:
3179:
3087:
3069:Global Positioning System
3039:
3013:
2950:
2882:
2722:Langwelle und Längstwelle
2627:The Sydney Morning Herald
2272:Seybold, John S. (2005).
2198:. CRC Press. p. 89.
1793:, Western Australia (AUS)
1515:List of VLF transmissions
1429:digital signal processing
1341:digital signal processing
1086:Early wireless telegraphy
931:. In military networks
746:" antennas, or multiwire
742:such as the "delta" and "
718:VLF transmitting antennas
676:it was dismantled in 1998
59:
44:
3423:Electromagnetic spectrum
2840:List of VLF-transmitters
2830:IW0BZD VLF TUBE receiver
2763:Radio waves below 22 kHz
2758:Longwave club of America
2255:Watt, Arthur D. (1967).
1978:submarine communication
1534:Location of transmitter
1521:List of VLF-transmitters
1267:near the surface, while
1139:Grimeton VLF transmitter
1079:Grimeton VLF transmitter
567:VLF waves can penetrate
2739:Friese (January 2006).
2092:OMEGA Navigation System
1402:earth-ionosphere cavity
1255:Military communications
1039:usually have different
668:Omega navigation system
3471:
2787:Gallery of VLF-signals
2782:PC-based VLF-reception
2656:. Military Facilities.
1777:Many operation modes.
1659:Gildeskål Municipality
1493:Fast Fourier transform
1480:
1441:VLF radio atmospherics
1182:VLF was also used for
1082:
1021:Frequency-shift keying
943:data using 5 bit
933:frequency-shift keying
872:VLF receiving antennas
833:Dynamic antenna tuning
714:
587:coronal mass ejections
576:electron precipitation
484:military communication
420:
3470:
2258:VLF Radio Engineering
2048:LaMoure, North Dakota
2031:Arlington, Washington
1858:Saint-Assise (France)
1713:RDL UPD UFQE UPP UPD8
1702:VLF station (NAA) at
1474:
1073:
1029:frequency synthesizer
904:Because of the small
890:signal-to-noise ratio
708:
691:quarter wave monopole
628:Anthorn radio station
474:services, government
411:
2876:Time signal stations
2768:VLF Discussion Group
2192:Ghosh, S.N. (2002).
1437:power line harmonics
1104:amplitude modulation
1047:Minimum-shift keying
982:electrostatic energy
956:minimum-shift keying
939:is used to transmit
925:Chu-Harrington limit
778:capacitive reactance
700:radiation resistance
3556:Extreme ultraviolet
2711:Romero, R. (2006).
2565:2011Geosc...1....3F
1282:in Skelton, Cumbria
1092:wireless telegraphy
988:The three types of
736:capacitive top-load
533:transverse magnetic
476:time radio stations
442:, corresponding to
418:Stanford University
41:
3561:Vacuum ultraviolet
3472:
2823:2009-02-28 at the
2772:Tomislav Stimac, "
2134:on 31 October 2013
1481:
1467:PC based reception
1083:
859:ferromagnetic core
847:resonant frequency
715:
696:electrically short
424:Very low frequency
421:
335:Other TV and radio
39:Very low frequency
37:
3920:Radio electronics
3902:
3901:
3606:Visible (optical)
3389:
3388:
3366:
3365:
3138:
3137:
3031:Radio Data System
2731:978-3-89632-043-8
2261:. Pergamon Press.
2205:978-0-8493-2430-7
2173:978-0-521-33083-1
2098:Radio atmospheric
2078:
2077:
2062:14–25.2? kHz
1497:Nyquist frequency
1395:Amateur equipment
1389:rubidium standard
1166:navigation beacon
1137:frequencies. The
1081:, Varberg, Sweden
884:is far above the
878:atmospheric noise
851:saturable reactor
763:dielectric losses
724:monopole antennas
645:Jim Creek station
436:radio frequencies
406:
405:
159:
158:
71:
70:
16:(Redirected from
3927:
3493:
3491:
3484:
3477:
3416:
3409:
3402:
3393:
3392:
3382:Radio portal
3380:
3379:
3378:
3182:
3181:
3165:
3158:
3151:
3142:
3141:
2869:
2862:
2855:
2846:
2845:
2747:
2745:
2735:
2716:
2698:
2697:
2695:
2694:
2685:. Archived from
2675:
2664:
2658:
2657:
2646:
2640:
2639:
2637:
2635:
2618:
2612:
2611:
2600:
2594:
2593:
2591:
2589:
2576:
2544:
2529:
2528:
2526:
2506:
2500:
2499:
2493:
2485:
2481:9781-9050-8637-5
2463:
2457:
2456:
2454:
2452:
2442:
2436:
2435:
2433:
2431:
2421:
2415:
2414:
2412:
2410:
2400:
2394:
2393:
2382:
2376:
2375:
2355:
2349:
2348:
2346:
2336:
2325:
2324:
2312:
2301:
2290:
2289:
2269:
2263:
2262:
2252:
2233:
2232:
2230:
2228:
2216:
2210:
2209:
2189:
2178:
2177:
2157:
2144:
2143:
2141:
2139:
2133:
2122:
2114:
2000:
1999:2 megawatts
1843:Tavolara (Italy)
1689:
1686:Alexanderson Day
1584:Alpha-Navigation
1568:Alpha-Navigation
1552:Alpha-Navigation
1525:
1524:
1458:
1456:
1450:
1448:
1162:radio navigation
1147:Alexanderson Day
1054:continuous phase
1014:
978:
971:
963:
844:
819:
803:
789:
740:umbrella antenna
709:A "triatic" or "
687:half wave dipole
664:Umbrella antenna
660:
639:
623:
606:
472:radio navigation
434:designation for
398:
391:
384:
91:
90:
73:
72:
67:
61:Wavelength range
55:
42:
40:
36:
21:
3935:
3934:
3930:
3929:
3928:
3926:
3925:
3924:
3905:
3904:
3903:
3898:
3864:
3791:
3766:
3752:
3720:
3648:
3600:
3542:
3519:
3496:
3489:
3482:
3475:
3473:
3425:
3420:
3390:
3385:
3376:
3374:
3367:
3362:
3359:
3358:300 GHz/1 mm
3357:
3347:
3344:
3342:
3332:
3329:
3327:
3317:
3314:
3313:300 MHz/1 m
3312:
3302:
3299:
3297:
3287:
3284:
3282:
3272:
3269:
3268:300 kHz/1 km
3267:
3257:
3254:
3252:
3242:
3239:
3237:
3227:
3224:
3223:300 Hz/1 Mm
3222:
3212:
3209:
3207:
3197:
3194:
3192:
3175:
3169:
3139:
3134:
3083:
3035:
3009:
2946:
2932:TDF time signal
2878:
2873:
2825:Wayback Machine
2754:
2743:
2732:
2707:
2705:Further reading
2702:
2701:
2692:
2690:
2677:
2676:
2666:
2665:
2661:
2648:
2647:
2643:
2633:
2631:
2620:
2619:
2615:
2608:Random Abstract
2602:
2601:
2597:
2587:
2585:
2545:
2532:
2507:
2503:
2487:
2486:
2482:
2464:
2460:
2450:
2448:
2444:
2443:
2439:
2429:
2427:
2423:
2422:
2418:
2408:
2406:
2402:
2401:
2397:
2390:plasmon.elte.hu
2384:
2383:
2379:
2372:
2356:
2352:
2344:
2338:
2337:
2328:
2321:
2310:
2302:
2293:
2286:
2270:
2266:
2253:
2236:
2226:
2224:
2217:
2213:
2206:
2190:
2181:
2174:
2158:
2147:
2137:
2135:
2131:
2120:
2116:
2115:
2111:
2106:
2083:
2014:Oso, Washington
1998:
1902:Rosnay (France)
1683:
1631:15.734 kHz
1609:15.625 kHz
1598:Rosnay (France)
1577:14.881 kHz
1561:12.649 kHz
1545:11.905 kHz
1517:
1489:radio receivers
1469:
1461:signaling rates
1454:
1452:
1446:
1444:
1412:, and coherent
1397:
1373:
1319:Since 2004 the
1302:Oso, Washington
1257:
1245:
1236:electromagnetic
1226:electromagnetic
1204:
1155:
1096:radiotelegraphy
1088:
1075:Flattop antenna
1068:
1012:
1006:radiotelegraphy
997:Continuous Wave
976:
969:
959:
902:
874:
842:
835:
817:
801:
787:
720:
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:
3933:
3923:
3922:
3917:
3915:Radio spectrum
3900:
3899:
3897:
3896:
3891:
3886:
3881:
3875:
3873:
3866:
3865:
3863:
3862:
3857:
3852:
3847:
3842:
3837:
3832:
3827:
3822:
3817:
3812:
3807:
3801:
3799:
3793:
3792:
3790:
3789:
3784:
3779:
3774:
3769:
3764:
3760:
3755:
3750:
3746:
3741:
3736:
3730:
3728:
3722:
3721:
3719:
3718:
3713:
3708:
3686:
3681:
3658:
3656:
3650:
3649:
3647:
3646:
3641:
3636:
3631:
3626:
3621:
3616:
3610:
3608:
3602:
3601:
3599:
3598:
3593:
3588:
3583:
3578:
3573:
3568:
3563:
3558:
3552:
3550:
3544:
3543:
3541:
3540:
3535:
3529:
3527:
3521:
3520:
3518:
3517:
3512:
3506:
3504:
3498:
3497:
3495:
3494:
3461:
3456:
3451:
3446:
3441:
3436:
3430:
3427:
3426:
3419:
3418:
3411:
3404:
3396:
3387:
3386:
3372:
3369:
3368:
3364:
3363:
3350:
3348:
3343:30 GHz/10 mm
3335:
3333:
3320:
3318:
3305:
3303:
3298:30 MHz/10 m
3290:
3288:
3275:
3273:
3260:
3258:
3253:30 kHz/10 km
3245:
3243:
3230:
3228:
3215:
3213:
3208:30 Hz/10 Mm
3200:
3198:
3185:
3180:
3177:
3176:
3172:Radio spectrum
3168:
3167:
3160:
3153:
3145:
3136:
3135:
3133:
3132:
3127:
3122:
3117:
3112:
3107:
3102:
3097:
3091:
3089:
3085:
3084:
3082:
3081:
3076:
3071:
3066:
3061:
3056:
3051:
3045:
3043:
3037:
3036:
3034:
3033:
3027:
3025:
3011:
3010:
3008:
3007:
3002:
2997:
2992:
2987:
2982:
2977:
2972:
2967:
2962:
2956:
2954:
2948:
2947:
2945:
2944:
2939:
2934:
2929:
2924:
2919:
2914:
2909:
2904:
2899:
2894:
2888:
2886:
2880:
2879:
2872:
2871:
2864:
2857:
2849:
2843:
2842:
2837:
2832:
2827:
2815:
2810:
2805:
2800:
2795:
2789:
2784:
2779:
2770:
2765:
2760:
2753:
2752:External links
2750:
2749:
2748:
2736:
2730:
2717:
2706:
2703:
2700:
2699:
2659:
2654:GlobalSecurity
2641:
2613:
2595:
2530:
2501:
2480:
2474:. p. 77.
2458:
2437:
2416:
2395:
2377:
2370:
2350:
2326:
2319:
2291:
2285:978-0471743682
2284:
2264:
2234:
2211:
2204:
2179:
2172:
2145:
2108:
2107:
2105:
2102:
2101:
2100:
2095:
2089:
2082:
2079:
2076:
2075:
2073:
2063:
2060:
2054:
2053:
2051:
2045:
2042:
2038:
2037:
2034:
2028:
2025:
2021:
2020:
2017:
2011:
2008:
2002:
2001:
1995:
1989:
1986:
1980:
1979:
1976:
1969:
1966:
1960:
1959:
1956:
1953:
1950:
1942:
1941:
1939:
1933:
1930:
1924:
1923:
1921:
1915:
1912:
1906:
1905:
1903:
1900:
1899:21.75 kHz
1897:
1891:
1890:
1888:
1885:
1882:
1876:
1875:
1874:rarely active
1872:
1869:
1866:
1862:
1861:
1859:
1856:
1853:
1847:
1846:
1844:
1841:
1840:20.76 kHz
1838:
1834:
1833:
1828:
1825:
1822:
1814:
1813:
1811:
1805:
1804:20.27 kHz
1802:
1798:
1797:
1794:
1788:
1785:
1779:
1778:
1775:
1769:
1766:
1760:
1759:
1758:Rarely active
1756:
1753:
1750:
1746:
1745:
1742:
1736:
1733:
1727:
1726:
1724:
1721:Matochkin Shar
1717:
1714:
1710:
1709:
1707:
1700:
1697:
1691:
1690:
1680:
1674:
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1532:
1529:
1516:
1513:
1501:spectrogrammes
1485:radio amateurs
1468:
1465:
1396:
1393:
1372:
1369:
1351:or 8 bit
1317:
1316:
1305:
1294:
1283:
1256:
1253:
1244:
1241:
1203:
1200:
1171:The worldwide
1168:transmitters.
1154:
1151:
1123:high frequency
1087:
1084:
1077:towers of the
1067:
1064:
1063:
1062:
1050:
1044:
1024:
1018:
1000:
947:or 8 bit
921:radiotelephony
901:
898:
886:receiver noise
873:
870:
834:
831:
719:
716:
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:
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328:
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309:
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296:
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287:
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262:
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232:
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202:
197:
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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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124:
119:
113:
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107:
102:
97:
87:
86:
80:
79:
69:
68:
63:
60:
57:
56:
48:
45:
32:VLF Automotive
26:
9:
6:
4:
3:
2:
3932:
3921:
3918:
3916:
3913:
3912:
3910:
3895:
3892:
3890:
3887:
3885:
3882:
3880:
3877:
3876:
3874:
3871:
3867:
3861:
3858:
3856:
3853:
3851:
3848:
3846:
3843:
3841:
3838:
3836:
3833:
3831:
3828:
3826:
3823:
3821:
3818:
3816:
3813:
3811:
3808:
3806:
3803:
3802:
3800:
3798:
3794:
3788:
3785:
3783:
3780:
3778:
3775:
3773:
3770:
3768:
3761:
3759:
3756:
3754:
3747:
3745:
3742:
3740:
3737:
3735:
3732:
3731:
3729:
3727:
3723:
3717:
3714:
3712:
3709:
3706:
3702:
3698:
3694:
3690:
3687:
3685:
3682:
3679:
3675:
3671:
3667:
3663:
3660:
3659:
3657:
3655:
3651:
3645:
3642:
3640:
3637:
3635:
3632:
3630:
3627:
3625:
3622:
3620:
3617:
3615:
3612:
3611:
3609:
3607:
3603:
3597:
3594:
3592:
3589:
3587:
3584:
3582:
3579:
3577:
3574:
3572:
3569:
3567:
3564:
3562:
3559:
3557:
3554:
3553:
3551:
3549:
3545:
3539:
3536:
3534:
3531:
3530:
3528:
3526:
3522:
3516:
3513:
3511:
3508:
3507:
3505:
3503:
3499:
3492:
3488:
3481:
3469:
3465:
3462:
3460:
3457:
3455:
3452:
3450:
3447:
3445:
3442:
3440:
3437:
3435:
3432:
3431:
3428:
3424:
3417:
3412:
3410:
3405:
3403:
3398:
3397:
3394:
3384:
3383:
3370:
3361:
3360:3 THz/0.1 mm
3356:
3355:
3349:
3346:
3345:300 GHz/1 mm
3341:
3340:
3334:
3331:
3330:30 GHz/10 mm
3328:3 GHz/100 mm
3326:
3325:
3319:
3316:
3315:3 GHz/100 mm
3311:
3310:
3304:
3301:
3296:
3295:
3289:
3286:
3283:3 MHz/100 m
3281:
3280:
3274:
3271:
3266:
3265:
3259:
3256:
3255:300 kHz/1 km
3251:
3250:
3244:
3241:
3240:30 kHz/10 km
3238:3 kHz/100 km
3236:
3235:
3229:
3226:
3225:3 kHz/100 km
3221:
3220:
3214:
3211:
3206:
3205:
3199:
3196:
3193:3 Hz/100 Mm
3191:
3190:
3184:
3183:
3178:
3173:
3166:
3161:
3159:
3154:
3152:
3147:
3146:
3143:
3131:
3128:
3126:
3123:
3121:
3118:
3116:
3113:
3111:
3108:
3106:
3103:
3101:
3098:
3096:
3093:
3092:
3090:
3086:
3080:
3077:
3075:
3072:
3070:
3067:
3065:
3062:
3060:
3057:
3055:
3052:
3050:
3047:
3046:
3044:
3042:
3038:
3032:
3029:
3028:
3026:
3024:
3020:
3016:
3012:
3006:
3003:
3001:
2998:
2996:
2993:
2991:
2988:
2986:
2983:
2981:
2978:
2976:
2973:
2971:
2968:
2966:
2963:
2961:
2958:
2957:
2955:
2953:
2949:
2943:
2940:
2938:
2937:Time from NPL
2935:
2933:
2930:
2928:
2925:
2923:
2920:
2918:
2915:
2913:
2910:
2908:
2905:
2903:
2900:
2898:
2895:
2893:
2890:
2889:
2887:
2885:
2881:
2877:
2870:
2865:
2863:
2858:
2856:
2851:
2850:
2847:
2841:
2838:
2836:
2833:
2831:
2828:
2826:
2822:
2819:
2816:
2814:
2811:
2809:
2806:
2804:
2801:
2799:
2796:
2793:
2790:
2788:
2785:
2783:
2780:
2777:
2776:
2771:
2769:
2766:
2764:
2761:
2759:
2756:
2755:
2742:
2737:
2733:
2727:
2723:
2718:
2714:
2709:
2708:
2689:on 2011-09-27
2688:
2684:
2683:ludb.clui.org
2680:
2673:
2669:
2663:
2655:
2651:
2645:
2629:
2628:
2623:
2617:
2609:
2605:
2599:
2584:
2580:
2575:
2570:
2566:
2562:
2558:
2554:
2550:
2543:
2541:
2539:
2537:
2535:
2525:
2520:
2516:
2512:
2505:
2497:
2491:
2483:
2477:
2473:
2469:
2462:
2447:
2441:
2426:
2420:
2405:
2399:
2391:
2387:
2381:
2373:
2371:9789401022651
2367:
2363:
2362:
2354:
2343:
2342:
2335:
2333:
2331:
2322:
2316:
2309:
2308:
2300:
2298:
2296:
2287:
2281:
2277:
2276:
2268:
2260:
2259:
2251:
2249:
2247:
2245:
2243:
2241:
2239:
2222:
2215:
2207:
2201:
2197:
2196:
2188:
2186:
2184:
2175:
2169:
2165:
2164:
2156:
2154:
2152:
2150:
2130:
2126:
2119:
2113:
2109:
2099:
2096:
2093:
2090:
2088:
2085:
2084:
2074:
2071:
2067:
2066:Karachi coast
2064:
2061:
2059:
2056:
2052:
2049:
2046:
2044:25.2 kHz
2043:
2040:
2035:
2032:
2029:
2027:24.8 kHz
2026:
2023:
2018:
2015:
2012:
2010:24.6 kHz
2009:
2007:
2004:
1996:
1993:
1992:Cutler, Maine
1990:
1987:
1985:
1982:
1977:
1974:
1970:
1968:23.4 kHz
1967:
1965:
1962:
1957:
1954:
1951:
1948:
1944:
1940:
1937:
1934:
1932:22.2 kHz
1931:
1929:
1926:
1922:
1919:
1916:
1914:22.1 kHz
1913:
1911:
1908:
1904:
1901:
1898:
1896:
1893:
1889:
1886:
1884:21.4 kHz
1883:
1881:
1878:
1873:
1870:
1868:21.1 kHz
1867:
1864:
1860:
1857:
1855:20.9 kHz
1854:
1852:
1849:
1845:
1842:
1839:
1836:
1832:
1829:
1826:
1824:20.5 kHz
1823:
1820:
1816:
1812:
1809:
1806:
1803:
1800:
1795:
1792:
1789:
1787:19.8 kHz
1786:
1784:
1781:
1776:
1773:
1770:
1768:19.6 kHz
1767:
1765:
1762:
1757:
1754:
1752:18.9 kHz
1751:
1748:
1743:
1740:
1737:
1735:18.3 kHz
1734:
1732:
1729:
1725:
1722:
1718:
1716:18.1 kHz
1715:
1712:
1708:
1705:
1701:
1699:17.8 kHz
1698:
1696:
1693:
1687:
1681:
1678:
1675:
1673:17.2 kHz
1672:
1670:
1667:
1663:
1660:
1657:
1655:16.4 kHz
1654:
1652:
1649:
1644:
1641:televisions (
1640:
1636:
1633:
1630:
1627:
1622:
1619:televisions (
1618:
1614:
1611:
1608:
1605:
1600:
1597:
1595:15.1 kHz
1594:
1592:
1589:
1585:
1582:
1579:
1576:
1573:
1569:
1566:
1563:
1560:
1557:
1553:
1550:
1547:
1544:
1541:
1536:
1533:
1530:
1527:
1526:
1523:
1522:
1512:
1510:
1504:
1502:
1498:
1494:
1490:
1486:
1478:
1473:
1464:
1462:
1442:
1438:
1434:
1430:
1426:
1422:
1417:
1415:
1411:
1407:
1403:
1392:
1390:
1386:
1380:
1378:
1368:
1366:
1363:
1358:
1354:
1350:
1345:
1342:
1337:
1335:
1330:
1325:
1322:
1314:
1313:Cutler, Maine
1310:
1306:
1303:
1299:
1295:
1292:
1288:
1284:
1281:
1277:
1276:
1275:
1272:
1270:
1266:
1262:
1252:
1250:
1240:
1237:
1234:
1229:
1227:
1223:
1222:Geophysicists
1219:
1217:
1216:magnetosphere
1213:
1209:
1208:geophysicists
1199:
1197:
1193:
1189:
1185:
1180:
1178:
1174:
1169:
1167:
1163:
1160:
1150:
1148:
1144:
1140:
1136:
1132:
1129:atoms in the
1128:
1124:
1120:
1115:
1113:
1109:
1105:
1101:
1097:
1093:
1080:
1076:
1072:
1060:
1055:
1051:
1048:
1045:
1042:
1038:
1034:
1030:
1025:
1022:
1019:
1015:
1007:
1004:
1001:
998:
995:
994:
993:
991:
986:
983:
974:
973:tuned circuit
967:
962:
957:
952:
950:
946:
942:
941:radioteletype
938:
934:
930:
926:
922:
919:
915:
911:
910:audio signals
907:
897:
895:
894:loop antennas
891:
887:
883:
879:
869:
867:
863:
860:
856:
852:
848:
840:
830:
828:
824:
823:air breakdown
815:
811:
807:
806:tuned circuit
804:
796:
794:
790:
783:
779:
775:
770:
768:
764:
760:
755:
753:
749:
745:
741:
737:
733:
729:
725:
712:
707:
703:
701:
697:
692:
688:
677:
673:
669:
665:
659:
650:
646:
638:
629:
622:
612:
605:
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:
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:
334:
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:
248:
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:
163:
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:
82:
81:
78:
75:
74:
64:
58:
54:
49:
43:
33:
19:
3844:
3474:
3373:
3352:
3351:
3337:
3336:
3322:
3321:
3307:
3306:
3300:300 MHz/1 m
3292:
3291:
3285:30 MHz/10 m
3277:
3276:
3270:3 MHz/100 m
3262:
3261:
3247:
3246:
3233:
3232:
3231:
3217:
3216:
3210:300 Hz/1 Mm
3202:
3201:
3195:30 Hz/10 Mm
3187:
3186:
2773:
2721:
2713:Radio Natura
2712:
2691:. Retrieved
2687:the original
2682:
2671:
2662:
2653:
2644:
2632:. Retrieved
2625:
2616:
2607:
2598:
2586:. Retrieved
2556:
2552:
2514:
2510:
2504:
2468:Radio Nature
2467:
2461:
2449:. Retrieved
2440:
2428:. Retrieved
2419:
2407:. Retrieved
2398:
2389:
2380:
2360:
2353:
2340:
2306:
2274:
2267:
2257:
2225:. Retrieved
2214:
2194:
2162:
2136:. Retrieved
2129:the original
2112:
2019:192 kW
1945:RJH63 RJH66
1887:Hawaii (USA)
1817:RJH63 RJH66
1706:, Maine (US)
1601:400 kW
1518:
1505:
1482:
1477:loop antenna
1433:interference
1421:loading coil
1418:
1398:
1381:
1374:
1362:one-time pad
1346:
1344:operations.
1338:
1326:
1318:
1273:
1258:
1246:
1230:
1220:
1205:
1181:
1170:
1156:
1116:
1089:
1066:Applications
987:
968:form a high
966:loading coil
953:
903:
875:
866:permeability
857:. This is a
855:loading coil
836:
797:
774:loading coil
771:
767:Counterpoise
756:
735:
721:
684:
583:solar flares
537:
504:ground waves
497:
480:radio clocks
451:
447:
427:
423:
422:
109:
3889:Medium wave
3566:Lyman-alpha
3548:Ultraviolet
3487:wavelengths
3480:frequencies
3444:Ultraviolet
2634:14 November
2553:Geosciences
2138:20 February
2094:, 1971–1997
1988:24 kHz
1973:Rhauderfehn
1952:23 kHz
1949:RJH77 RJH99
1821:RJH77 RJH99
1371:Amateur use
1291:Rhauderfehn
1261:nuclear war
1233:geophysical
1188:time signal
882:radio noise
728:radio masts
535:(TM) mode.
523:called the
456:myriameters
444:wavelengths
77:Radio bands
3909:Categories
3870:Wavelength
3726:Microwaves
3538:Hard X-ray
3533:Soft X-ray
3502:Gamma rays
3434:Gamma rays
2693:2009-07-13
2668:"20–25kHz"
2588:14 January
2320:007032381X
2104:References
2072:(Pakistan)
1531:Frequency
1425:sound card
1285:Germany's
1278:Britain's
1159:hyperbolic
1131:ionosphere
1100:Morse code
1037:sine waves
1003:Morse code
990:modulation
937:modulation
900:Modulation
814:variometer
754:are used.
752:T antennas
670:beacon on
521:ionosphere
488:submarines
51:3–30
3884:Shortwave
3879:Microwave
3459:Microwave
3120:Radio VNG
3041:Satellite
2952:Shortwave
2583:2076-3263
2490:cite book
2386:"AWDANet"
1975:(Germany)
1528:Callsign
1357:encrypted
1251:systems.
1212:whistlers
1135:shortwave
1112:sidebands
929:bit rates
906:bandwidth
839:resonance
810:bandwidth
793:litz wire
561:lightning
557:whistlers
529:waveguide
513:electrons
468:data rate
460:bandwidth
66:100-10 km
3894:Longwave
3654:Infrared
3454:Infrared
2985:ROA Time
2884:Longwave
2821:Archived
2679:"WA3248"
2650:"Cutler"
2081:See also
1808:Tavolara
1741:(France)
1739:Le Blanc
1723:(Russia)
1679:(Sweden)
1677:Grimeton
1661:(Norway)
1537:Remarks
1336:(BCAA).
1224:use VLF-
1190:station
1011:antenna
862:inductor
782:resonant
772:A large
732:monopole
594:Antennas
569:seawater
500:diffract
154:12 (THF)
149:11 (EHF)
144:10 (SHF)
3485:longer
3478:higher
3449:Visible
3088:Defunct
3064:Galileo
3059:GLONASS
2561:Bibcode
2409:13 June
2227:11 June
1938:(Japan)
1918:Skelton
1810:(Italy)
1791:Exmouth
1772:Anthorn
1365:ciphers
1321:US Navy
1127:ionized
1119:skywave
748:flattop
744:trideco
711:flattop
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)
3787:L band
3782:S band
3777:C band
3772:X band
3758:K band
3744:Q band
3739:V band
3734:W band
3639:Orange
3634:Yellow
3614:Violet
3525:X-rays
3439:X-rays
3049:BeiDou
2980:JN53DV
2970:HD2IOA
2728:
2672:vlf.it
2581:
2478:
2451:13 May
2430:13 May
2368:
2317:
2282:
2223:. NASA
2202:
2170:
1704:Cutler
1143:Sweden
1041:phases
935:(FSK)
827:corona
759:ground
540:fading
127:7 (HF)
122:6 (MF)
117:5 (LF)
3872:types
3797:Radio
3693:Bands
3666:Bands
3629:Green
3464:Radio
3174:(ITU)
3074:IRNSS
3054:DORIS
2912:DCF77
2744:(PDF)
2345:(PDF)
2311:(PDF)
2132:(PDF)
2121:(PDF)
2070:Sindh
2050:(USA)
2033:(USA)
2016:(USA)
1994:(USA)
1971:near
1964:DHO38
1947:RJH69
1936:Ebino
1819:RJH69
1435:from
1387:or a
1353:ASCII
1329:acres
1307:U.S.
1296:U.S.
1287:DHO38
1177:Alpha
1173:Omega
1059:ASCII
1049:(MSK)
1033:ASCII
1023:(FSK)
949:ASCII
800:high
786:high
647:near
486:with
464:audio
250:IEEE
3767:band
3753:band
3711:LWIR
3689:MWIR
3684:SWIR
3624:Cyan
3619:Blue
3125:WWVL
3110:OLB5
3005:YVTO
3000:WWVH
2942:WWVB
2907:Beta
2726:ISBN
2636:2008
2590:2021
2579:ISSN
2496:link
2476:ISBN
2453:2017
2432:2017
2411:2014
2366:ISBN
2315:ISBN
2280:ISBN
2229:2024
2200:ISBN
2168:ISBN
2140:2013
2058:PNSH
1920:(UK)
1774:(UK)
1643:480i
1621:576i
1439:and
1414:BPSK
1410:MFSK
1406:QRSS
1349:ITA2
1192:WWVL
1106:and
945:ITA2
694:are
585:and
546:and
517:ions
515:and
84:ITU
3860:ELF
3855:SLF
3850:ULF
3845:VLF
3825:VHF
3820:UHF
3815:SHF
3810:EHF
3805:THF
3716:FIR
3662:NIR
3644:Red
3596:UVA
3591:UVB
3586:UVC
3581:NUV
3576:MUV
3571:FUV
3354:THF
3339:EHF
3324:SHF
3309:UHF
3294:VHF
3234:VLF
3219:ULF
3204:SLF
3189:ELF
3130:Y3S
3115:OMA
3105:NAA
3100:HBG
3095:BSF
3023:UHF
3015:VHF
2995:WWV
2990:RWM
2975:HLA
2965:CHU
2960:BPM
2927:RTZ
2922:RBU
2917:JJY
2902:BSF
2897:BPL
2892:BPC
2569:doi
2519:doi
2125:ITU
2041:NML
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