VLF-Transmissions from India - new transmission site
Which VLF-transmissions take actually place from INS Kattabomman in India? When you look on Wikimapia, you will see, that south of the multi-mast antenna situated at 8.387002 N 77.752816 E two new VLF-masts were built, which may have according shadow comparasions to the existing masts ( the central mast of the multi-mast antenna is according http://indiannavy.nic.in/about-indian-navy/ins-kattabomman 301 metres tall, the shadows of the new masts are 1.5 times longer than that of the central mast) a height of 450 metres. Re: VLF-Transmissions from India - new transmission site
For which service are these new masts used? How tall are they really?
Posted by John Davis on June 06, 2014 at 00:44:28.
In reply to VLF-Transmissions from India - new transmission site posted by Thornut on June 05, 2014
That is a good question. I can't get a picture from Wikimapia, but with I see them with Google. My first guess would be that they are probably intended as enhancements to the existing antenna, although it's not clear why a new building would be necessary for that. On the other hand, if they are part of an entirely new antenna, it would be very poor design to locate them right at the edge of the VLF antenna with their ground fields overlapping so significantly.
Very puzzling. Perhaps someone can eventually shed more light on the matter. VTX already puts quite a signal into my part of the world, nearly 12000 miles distant, a good percentage of the time.
John
Re: VLF-Transmissions from India - new transmission site
Posted by Thornut on June 06, 2014 at 13:39:54.
In reply to Re: VLF-Transmissions from India - new transmission site posted by John Davis on June 06, 2014
Could it be an ELF-antenna? It is claimed, that India plans to build an ELF-transmitter.
Has Israel a VLF-transmitter?
Posted by Franzen on June 06, 2014 at 15:41:36.
Has Israel a VLF transmitter? If yes, which frequency or frequencies does it use? Are the masts of "Dimona Radar Facility", you can see on http://wikimapia.org/#lang=de&lat=30.971611&lon=35.097284&z=16&m=b also used as VLF-transmitter? It seems so, as if one has a close look at the basements of the masts one can see something like a grounding system, which may be not necessary for a radar system.
Re: VLF-Transmissions from India - new transmission site
Posted by John Davis on June 08, 2014 at 05:50:20.
In reply to Re: VLF-Transmissions from India - new transmission site posted by Thornut on June 06, 2014
The two masts are definitely not part of an ELF antenna. There is no way to make a Marconi vertical, or even an umbrella array, work efficiently at ELF. At such enormous wavelengths, the tallest masts ever built are way too short. To tune them would require impractically large helixes and the RF voltage would be astronomical.
For ELF, one would generally want a line antenna or an earth loop, such as the one the US Navy used for Project Sanguine. These involve structures that look very much like electric power lines, dozens of kilometers long.
John
Re: Has Israel a VLF-transmitter?
Posted by John Davis on June 08, 2014 at 06:05:30.
In reply to Has Israel a VLF-transmitter? posted by Franzen on June 06, 2014
It is a virtual certainty that Israel has a VLF transmitter. I've seen some slight reference to it in a scientific paper on the ionosphere and mesospheric warming. The problem is, I haven't been able to find the station on any frequency lists yet.
We reported on this site in our club publication, The LOWDOWN, a few months ago after one of our members found the antenna masts on Google Earth. There is some resemblance with the new Indian antennas, such as the appearance of the recently installed ground radial network.
An Israeli newspaper account appears to be the source of public confusion between these towers and a radar installation. The type of radar actually deployed at Dimona is a Raytheon transportable system that uses panel antenna arrays mounted on the back of a truck.
John
Old TimeAM Radio Quite Strong Tonight 9 June, 2014
Posted by EdWSlidell,LA on June 09, 2014 at 00:58:16.
The Old Time AM Radio broadcasting seems to be back on, Jack Benny(0054UT), and quite strong, in the S5-S7 range. Roughly the same on the 22m dipole, 21 ft vertical, and the 143 ft. longwire. There doesn't seem to be much in the way of QSB, so can't quess where it might be originating. Ed WSlidell, LA EM50cg
Re: Old TimeAM Radio Quite Strong Tonight 9 June, 2014
Posted by John Davis on June 09, 2014 at 05:30:43.
In reply to Old TimeAM Radio Quite Strong Tonight 9 June, 2014 posted by EdWSlidell,LA on June 09, 2014
Interesting observations, Ed. It was gone quite a while there; I thought perhaps forever.
I'd love to listen for it tonight myself, but I might get stuck wading through "Lake Inferior" trying to get to my tower. ;) We've still got another couple days of heavy rains and localized flooding possible.
John
Re: Has Israel a VLF-transmitter?
Posted by Franzen on June 10, 2014 at 13:00:42.
In reply to Re: Has Israel a VLF-transmitter? posted by John Davis on June 08, 2014
Is however the erection of a VLF-transmitter in a desert a good idea? I believe grounding may be poor.
emi line filter with sdr
Posted by marky on June 10, 2014 at 18:09:11.
I'm going to use rtlsdr to receive LF. There seems to be an interference problem from AM BC stations. Some reading shows that older line filters (FCC standards, not EU standards) had a cutoff frequency of about 250 kHz. Sounds like they might be a good fit for this application. Has anyone tried using FCC line filters with RTLSDR as cutoff filters?
Thanks
Re: Has Israel a VLF-transmitter?
Posted by John Davis on June 10, 2014 at 19:03:39.
In reply to Re: Has Israel a VLF-transmitter? posted by Franzen on June 10, 2014
A desert would not be the ideal place for situating a ground system. However, there may not be many other choices.
Unless you have ample coastline, locating a VLF installation near the sea could cause it to be too near populated areas and/or make it difficult to keep secure. (The combination of salt and humidity would also greatly increase maintenance costs.) Israel has no broad, marshy plains inland, which would otherwise be the preferred choice. Fertile agricultural regions generally have good soil conductivity. But in a small nation, such land may be too valuable for raising food to use it for other purposes, and it would also be inconveniently close to population centers.
Fortunately, at VLF, there are factors which mitigate the consequences of less desirable transmitter locations. VLF waves are much less attenuated by poor soil than higher frequencies are, so whatever power manages to get radiated will propagate fairly well anyway.
Thus, it is principally necessary to make the antenna itself reasonably efficient. Losses in the immediate vicinity of a VLF antenna are more critical than the earth over which the far-field signal travels. The trick is, therefore, to make the ground system as good as possible directly under the antenna, so that the near-field energy stored in the vicinity of the towers will not be lost as heat in the soil.
Plenty of ground radials are the first step, with additional wires branching from those if possible. Ground rods can also be effective at VLF because the skin depth of the soil is greater for lower frequencies. The earth itself can be treated with moisture absorbing salts or other conductive materials to improve conductivity in the vicinity of the ground radial network. And, of course, there should be a substantial ground screen around the base of the tower to minimize resistive loss where the current flow is greatest.
I have no way to know which of these techniques may have been applied at Dimona, but I would almost be willing to bet all of them have been used there to some degree or another.
John
Re: emi line filter with sdr
Posted by John Davis on June 10, 2014 at 20:32:06.
In reply to emi line filter with sdr posted by marky on June 10, 2014
Some American type line filters might work OK, but I suspect there are many whose characteristics do not conform very closely to the average cutoff that you read about. The source and load impedance for which they were designed may also not be very close to 50 or 75 ohms. However, it wouldn't hurt anything to try one or more if you have access to them.
Alternately, here are a few loop antenna articles in which the preamps contain simple low-pass filters that are fairly easy to construct, and which are designed for around 50 ohms:
http://lwca.org/library/articles/kf5cq/lfconvtr.htm
http://lwca.org/library/articles/gregg/CompactRcvgLoop.pdf
http://members.shaw.ca/ve7sl/burhans.html
The latter design can be tuned to notch a particularly troublesome AM station, if need be.
John
Re: emi line filter with sdr
Posted by John Andrews, W1TAG on June 11, 2014 at 01:47:32.
In reply to Re: emi line filter with sdr posted by John Davis on June 10, 2014
Another receiving filter, although fairly complicated:
9th Order 518 kHz Elliptical Low Pass Filter
The goal was to "get rid" of a station on 580 kHz, while still being able to use 510 kHz and down. Works neat.
John, W1TAG
Wednesday HiFERs
Posted by John Davis on June 11, 2014 at 23:13:14.
At mid afternoon, all I could see were USC, EH, and NC, though NC and EH had drifted into a collision. The lower frequency of NC was barely half a Hz above the top frequency of EH, and it may have been on top of 7P. The lower frequency of EH also appeared to be atop another signal, but it wasn't always present so I couldn't tell who it was.
Farther up the dial, I could see PBJ (but with deep enough fades to break up dashes into false dots). I have not heard MTI for at least a week now, but there has been a steady carrier about where it should be.
I then attempted to find any of the signals above mid band, but the white noise level got very high for a time. Afterward, nobody was audible for a good while. This apparently coincided with an M-class flare, now that I'm back in town and looking at NOAA's SWPC page.
Around 5 PM CDT I tuned in 22 meters again. USC was still steady, NC had drifted above EH a little bit, and I could see the lower frequency of EH was firmly planted on the resting frequency of SIW slant mode, which was then starting to fade in. Higher up, I could still see PBJ and the steady carrier. At AJO's slot, Argo showed the broken trace of the DAID, but the signal was not audible to me. GNK came in sporadically.
I'll check again before dark.
John
Re: Old TimeAM Radio Quite Strong Tonight 9 June, 2014
Posted by Lee on June 11, 2014 at 23:34:47.
In reply to Old TimeAM Radio Quite Strong Tonight 9 June, 2014 posted by EdWSlidell,LA on June 09, 2014
What freq do you hear Old Timey Radio.
Re: Old TimeAM Radio Quite Strong Tonight 9 June, 2014
Posted by EdWSlidell,LA on June 12, 2014 at 00:30:04.
In reply to Re: Old TimeAM Radio Quite Strong Tonight 9 June, 2014 posted by Lee on June 11, 2014
Hi Lee. My little Icom IC-706MkII radio showed it as about 13560.65 KHz. However, John D advised that has has seen it move up and down a few hundred Hz over time. I don't hear it at the present time--0018UT/12 June, 2014. As the general noise centered on 13560.0KHz is fairly strong here, I couldn't hear the LSB side the first few times, but this last time it was strong enough to easily copy both USB and LSB portions of the AM signal. Odd that it was about the same S5-S7 signal strength on three different antennas, with very little apparent QSB. The only signal I recognize at the present time is GNK on ~13564 KHz, with some gurglely signal slightly above it. Ed WSlidell, LA EM50cg
Re: Wednesday HiFERs, 2
Posted by John Davis on June 12, 2014 at 02:15:19.
In reply to Wednesday HiFERs posted by John Davis on June 11, 2014
USC was nice and steady just before sunset, SIW was gone, EH was fair, 7P barely recognizable, and NC alternated about a minute and a half strong, then about a minute and a half invisible. PBJ was still present but broken, and the steady carrier that might be MTI was not to be seen. Just a slight trace of GNK from time to time and maybe bits and pieces of FRC, but it was hard to tell.
No sign of our old timey pirate at ~13560.650 either session today.
John LF: MP going QRT for a bit
Posted by Mitch Powell on June 12, 2014 at 02:17:22.
Hi all:
Will be shutting down today for a couple of weeks - as some of the storms
go through, and can also get some work done on cables, etc.
See you all shortly.
73 and thanks to all for the continuing reports --
73 Friday ME Hifers
Mitch VE3OT
Posted by John Andrews, W1TAG on June 13, 2014 at 23:44:34.
Results of tuning around on a rainy day in southern Maine:
MTI in CW on 13,557.52 at 1552Z
PBJ in QRSS3 on 13,557.55 at 1603Z
GNK in CW on 13,563.98 at 2002Z
USC in DFCW on 13,555.37/38 all day
The SIW's in QRSS (13,555.43) and slant (13,555.44) all day.
NC as usual all the time wandering down as the day went on.
Nothing else seen/heard -- tried the regulars. The western stuff might show up later.
John, W1TAG/1 Raymond, ME FN43sv
Re: Friday ME Hifers
Posted by John Davis on June 14, 2014 at 02:58:50.
In reply to Friday ME Hifers posted by John Andrews, W1TAG on June 13, 2014
Nice results, John. Down here in Kansas, I finally made it to the field right at sunset and took a quick look & listen for HiFERs before switching to 630 meters. USC, EH, and NC were each pretty strong (sometimes two or more audible at the same time), and 7P managed to sneak in occasionally.
Above the watering hole, I also caught MTI, but with very wide signal level fluctuations. I think there must have been a keying problem that is now fixed, because the steady carrier at that spot has disappeared and the Morse has returned. No sign of PBJ this evening, though.
No westerners so far here, but I'll look later tonight. Sometimes interesting things show up after midnight on this band...more on that in another post.
John D
Nothing could be finer/than Hi-FERs from Carolina/in the mor-r-ning
Posted by John Davis on June 14, 2014 at 19:33:19.
USC and NC were mostly all I saw at the watering hole from daybreak onward, but this capture has a couple of extras. EH (which was the only signal I saw overnight) had faded out at daybreak, but returned for a while and then was gone again when I checked back an hour later.
The most unusual feature is about midway through. Note the noise burst that disrupts EH. It takes Argo a couple of seconds to recover, and then--as if out of nowhere--there's a 14 second long enhancement of both slant mode SIW and QRSS6 SIW, both apparently in the middle of a "W" at the time. Most of the time these days, SIW is in my skip zone, so something (like sunrise or sunset) usually has to tilt the ionosphere for me to see it. I looked at the Space Weather Prediction Center data afterward, and there didn't seem to be any sudden solar activity around that time. Must have been some other high-altitude event.
Time is CDT, frequencies have been adjusted to track the tuned frequency (that is, "430" is actually 13,555.430, etc), and frequencies are accurate within +/- 1 Hz.
John
... and Georgia & Tennessee Too
Posted by John Davis on June 14, 2014 at 19:46:44.
Quite a wide range of signal strength on MTI today...sometimes blasting out of the speaker, other times hardly visible on Argo. Pretty good shot of PBJ too. It was intermittently visible earlier, fairly solid for this capture, then disappeared by an hour later.
Time is CDT. Frequencies have been shifted to be accurate within about 0.5 Hz at the end of the trace.
John
Additional Signal on 60kHz
Posted by Steve Vukusic on June 14, 2014 at 23:49:59.
Wondering if anyone is/has been receiving a signal in the vicinity of WWVB? Have an apparent level peak of S-5 at 59.8 kHz. Smallest filter BW is 2kHz...this is the best I can do. Pulse count approx 33/ minute. WWVB's sig level is approx S-3 @ 23:30 UT.
Tnx, Steve KQ7E
T QRT for a while and a second planned beacon
Posted by James-AG6YM on June 15, 2014 at 03:31:58.
Hi,
My beacon will be QRT while I move it to the attic. Part of the 30 gauge wire antenna was ripped off. As far as I can tell no one has heard my beacon (except me) yet. I suspect the XMTR, because I can work the middle of the country most days on 20m phone, with good reports, using a very similar antenna and 100W. If I build another beacon at ~13,560 will it get swamped by the old time pirate? Any advice from the experts is appreciated.
73 James-AG6YM
Re: T QRT for a while and a second planned beacon
Posted by John Davis on June 15, 2014 at 09:24:45.
In reply to T QRT for a while and a second planned beacon posted by James-AG6YM on June 15, 2014
> "If I build another beacon at ~13,560 will it get swamped by the old time pirate?"
It would more likely get swamped by the diathermy machines, RFID systems, and other noisy Part 18 users whose carriers cluster at the center of the band. At my rural location, 30 miles from the nearest of any of those, the whole span from 13,585.5-13,562 kHz is awash in buzzes and rasps. (It's a miracle that the pirate ever makes it through.)
As for the antenna, all I can suggest is to get it in the clear as much as possible. The power difference versus 100 watts at 20 meters is over 43 dB, so a degree of absorption and attenuation that is entirely acceptable for ham work may be too much for the Part 15 signal.
John
Re: Additional Signal on 60kHz
Posted by John Davis on June 15, 2014 at 09:46:12.
In reply to Additional Signal on 60kHz posted by Steve Vukusic on June 14, 2014
This may be QRM from increasingly common household devices. I had a similar signal from a satellite TV receiver once. Some of the earliest coiled fluorescent lights in my house emit strong carriers in the vicinity of WWVB, too. I still have to make sure all of those are off at 3 AM if I want my self-setting clock to reset!
It seems odd that the consumer electronics industry sells lots of devices that supposedly depend on WWVB, then proceeds to sell others that interfere with the necessary signal.
John
Re: Additional Signal on 60kHz
Posted by Steve Vukusic on June 15, 2014 at 18:55:12.
In reply to Re: Additional Signal on 60kHz posted by John Davis on June 15, 2014
Tnx Mr. John...was watching the signal for a while late last night; seemed to drop out for a while and then returned.
I believe you have a very good point...the behaviour of the signal seems to conform to the QRM signature. Since i do have a local VLF ,LF source of QRM, while broad banded,it seems to peak at approx 55kHz and is dirty and does extend beyond 55kHz. Sure enough, the QRM extended beyond 60 kHz last nightand this am, the 60 kHz qrm disappeared along with a decrease in level at
55kHz. I tracked some LF QRM to the next door neighbor's
Comcast box...now the fun begins .
Tnx for sharing your story....Steve
Re: T QRT for a while and a second planned beacon
Posted by John Andrews, W1TAG on June 15, 2014 at 19:03:05.
In reply to T QRT for a while and a second planned beacon posted by James-AG6YM on June 15, 2014
James,
Based on recent listening at our Maine QTH, I would recommend avoiding 13558.0 - 13563.5 kHz due to the industrial/medical interference that John Davis mentioned. Note that is not symmetrical on either side of 13560.
For example, if I tune the receiver to 13555.400, where much of the slow-speed activity is located, I can hear the signals of two prominent stations (by ear - USC and NC), but the meter only moves off S0 during static crashes. At 13560.0, the meter reads S6-S7 with the constant sound of a cat with his tail under a rocking chair. If you want your beacon to have a chance, I'd suggest avoiding the range above. There's some really clean territory below 13558 kHz.
John, W1TAG
Re: T QRT for a while and a second planned beacon
Posted by John Davis on June 15, 2014 at 20:46:08.
In reply to Re: T QRT for a while and a second planned beacon posted by John Andrews, W1TAG on June 15, 2014
That's good advice from W1TAG. His noise sources are apparently a bit stronger than mine and occupy more of the band, which shows that even though the details may vary somewhat from place to place, it's always going to be extraordinarily difficult copying anything near the center of the band.
Another good reason to stay below 13,558 if possible is the sideband splatter from the broadcaster on 13,570 at certain seasons of the year. I had forgotten about that, since they haven't operated there lately at the times I've been listening. When they're on, though, they wipe out the upper half of the HiFER segment most anywhere east of the Rockies...and maybe the other side as well. That's mostly in the afternoons, and there's usually some propagation from the west after they're done for the day, but it does limit opportunities considerably.
John
SL 630m Overnight Beacon
Posted by Steve on June 15, 2014 at 22:17:11.
I'll be running in QRSS mode again tonight but this time a little faster at QRSS30.
Frequency is 475.050 / sending 'SL'
25W to 170' inverted L
Steve / 73
Mayne Island, BC CN88iu
WEB - "The VE7SL Radio Notebook": http://members.shaw.ca/ve7sl
VE7SL BLOG - "Homebrewing and Operating Adventures From 2200m to Nanowaves": Re: T QRT for a while and a second planned beacon
http://ve7sl.blogspot.ca/
Posted by EdWSlidell, LA on June 16, 2014 at 00:00:44.
In reply to Re: T QRT for a while and a second planned beacon posted by John Davis on June 15, 2014
Hi all. The SW broadcaster(WINB/Red Lion, PA) formerly using the 13570 KHz spot has permanently moved down to 31 m/9 MHz SW band. Their web site shows the following: "Beginning March 1, 2014, WINB will broadcast the entire schedule on 9265 kHz". At least one problem out of the way for the presetn time. Now if I could get rid of the strong, gurgly signal right around 13564 KHz. Ed W Slidell, LA EM50cg.
Re: T QRT for a while and a second planned beacon
Posted by John Davis on June 16, 2014 at 00:03:37.
In reply to Re: T QRT for a while and a second planned beacon posted by EdWSlidell, LA on June 16, 2014
That's good news for HiFERs, Ed. Thanks!
Re: SL 630m Overnight Beacon
Posted by John Davis on June 18, 2014 at 16:20:11.
In reply to SL 630m Overnight Beacon posted by Steve on June 15, 2014
I managed several alternate views of SL Sunday night/Monday morning, in between WSPR sessions on 630 meters. To start off, here's the final view of SL that night, in both QRSS30 -and- QRSS20! (In all the captures below, 800 Hz represents 475.050 kHz.)
Now let's go back in time to when I first put WSPR on hold and began watching SL, a little after 12:30 AM CDT on Monday morning. This is nearly an hour and 45 minutes' worth:
As you see, by 2:30 AM CDT it had become quite strong...strong enough to allow the receiving end to overcome a problem Steve had elsewhere mentioned in connection with the transmitter.
>>> ...will probably add another chip to it so I can use my DDS and get rid of the chirp.
Or else simply wait until the signal becomes strong enough to view it in QRSS3--then the chirp becomes totally insignificant! :)
This was the identifier cycle immediately following the very bright one at the end of the preceding trace.
>>> As a stand alone CW TX it would be a great little rig as Rudy (N6LF) down in Oregon could hear it audibly quit well just after sunset.
It took a little longer here in Kansas, but when the signal was at its most solid in QRSS3, it was also audible here too...principally during the 'S' and the first half of the 'L' though not during the second half. Very cool.
73 VLF Colossus Info
John
Posted by EdWSlidell,LA on June 20, 2014 at 16:00:39.
Hello all. Was looking for info on the Colossus system used by the German Navy in WWII. John's recent posts regarding the 9 KHz activity across the Atlantic, as well as questions about a few VLF antenna systems seen on satellite had me wondering. I had not found much more than general information on the Colossus system, and indications were that it worked down to 10 KHz, suitable for reception below 25 m of water. The following site seems to have a grat deal of technical info on the site and its capabilities. It is in Cherman, but the tables seem pretty straightforward. The listed frequency range is 15-60KHz, with very low antenna resistance on the lower end, but still nearly 50% efficiency. http://aobauer.home.xs4all.nl/Goliath.pdf Re: VLF Colossus Info
Ed WSlidell,LA EM50cg
Posted by John Davis on June 20, 2014 at 20:07:51.
In reply to VLF Colossus Info posted by EdWSlidell,LA on June 20, 2014
Thanks for bringing up Klaus Herold's excellent Goliath article, Ed. It even includes schematics, in case anyone wants to build their own megawatt VLF transmitter. :)
If anyone has difficulty accessing the document (I tried six times and couldn't get it to completely download from xs4all), here's another source: http://www.cdvandt.org/Goliath.pdf
This is one of the documents I used recently for fact-checking when I was translating a German navy brochure on VLF history to accompany an article by LWCA member Harry Weber. Harry's article appears in the upcoming July issue of our publication, The LOWDOWN.
John
home brew vlf converters
Posted by Robert Rode W9ESX on June 24, 2014 at 01:05:58.
I wonder the latest vlf converters being made still xtals, all chips,..what is going on ?thanks, Robert
Re: Old TimeAM Radio Quite Strong Tonight 9 June, 2014
Posted by Robert Rode W9ESX on June 24, 2014 at 01:18:16.
In reply to Re: Old TimeAM Radio Quite Strong Tonight 9 June, 2014 posted by EdWSlidell,LA on June 12, 2014
..ah, ha, Pirate Broadcasters Galore,..week ends about 0200 Z, 6.945 and lower, usually 45 min to 1 hr several on..Radio Free Whatever, The Crystal Ship. a bunch, most often on holidays many show up, Kinda a hobby within the hobby, relay stations,take requests and reports via e mail, usually usb, some AM...have fun.
Re: Old TimeAM Radio Quite Strong Tonight 9 June, 2014
Posted by John on June 24, 2014 at 05:03:37.
In reply to Re: Old TimeAM Radio Quite Strong Tonight 9 June, 2014 posted by Robert Rode W9ESX on June 24, 2014
Anyone heard RadioTrueNorth lately.. last heard here on April 12th on 6950 and 6955 kHz
SAQ on Sunday
Posted by John Davis on June 25, 2014 at 00:37:14.
The Alexanderson alternator will operate on 17.2 kHz for a commemorative transmission this coming Sunday morning, and again on Wednesday, 2 July. See the full story as we have it at this time on the Longwave Home Page.
John
WTB: Palomar, Quantium Pro LW Heads
Posted by Bill Marvin on June 25, 2014 at 01:13:55.
Hi Group I am looking to buy a Palomar LW Head (150-500 KHz) and a Quantium Pro 15 inch Longwave LW head.
Many Thanks!
Bill KB9IV
The ELF-transmitter of India?
Posted by Arktur on June 26, 2014 at 16:13:30.
Is it correct, that India is building an ELF-transmitter? If yes, where exactly and what type of antenna will it use? Are first transmissions already observed, if yes, on which frequencies?
Is a ground-dipole the only possible type for an ELF-transmitter? Would a horizontal dipole of suitable length installed on normal powerline towers also work?
VLF-Transmitters in Africa and South America
Posted by Arktur on June 26, 2014 at 16:15:25.
Which VLF-transmitters exist or existed in Africa and South America? Were the OMEGA-stations the only VLF-transmitters, which existed there? Have or had Brazil and South Africa a VLF-transmitter? If yes, where?
Re: The ELF-transmitter of India?
Posted by John Davis on June 27, 2014 at 02:51:38.
In reply to The ELF-transmitter of India? posted by Arktur on June 26, 2014
There has been all sorts of speculation online about this alleged station, fueled in large part by a post appearing on several Web sites that quote what is supposed to be a portion of a short article by James Hardy, taken in early March of this year from the Janes Defence website. I haven't been successful in finding the full article myself, and cannot confirm its authenticity.
In the part that is so widely quoted, however, it is stated that the presumed site will not be commissioned until next year. Therefore, if this project truly exists, it has probably not transmitted its first signal yet, nor been received by anyone.
The quoted text claims that evidence of the site's construction turned up in Digital Globe satellite photos in January, at the existing Indian Navy installation at Vijaya Narayanam. The text states that the station will have nuclear hardened bunkers, and claims "Russia is closely associated with the research and development for the facility, which is expected to be similar to Russia's own ELF transmitter at the ZEVS facility near Murmansk."
The only problem is, the new construction visible at Vijaya Narayanam thus far is clearly not a hardened bunker, and nothing about the new antenna system system that we can see on satellite photos bears any resemblance to the Russian ZEVS installations. What that new construction really is, remains a mystery to me at this point.
For further information on ZEVS, there is an excellent article by Trond Jacobsen that I highly recommend at the vlf.it site.
As for low horizontal dipoles, they would make terrible antennas at VLF and ELF. The horizontally polarized radiated wave would, in effect, be "shorted out" by its own interaction with the earth. That's why vertically polarized antennas are preferred for virtually all frequencies below the HF bands.
There is also the practical difficulty of constructing an antenna long enough to behave as a halfwave dipole, even if it would work. In Trond's article, you may notice that a half wavelength at 82 Hz (for example) is in excess of 1829 kilometers! He compares that to the distances beween major cities on various continents, to emphasize the point to the reader.
John
Re: VLF-Transmitters in Africa and South America
Posted by John Davis on June 27, 2014 at 03:10:51.
In reply to VLF-Transmitters in Africa and South America posted by Arktur on June 26, 2014
Within the last half century, at least, the only VLF transmitter in Africa appears to have been OMEGA.
My information on VLF sites in South America dates back to about the year 2000. At that time, Chile had an allocation at Santiago on 26.6 kHz, and Brazil had two allocations: Belem (25.0) and Recife (30.0 kHz). I have no idea whether those are still on, what traffic they carried, or whether other stations have since been added. Perhaps someone else will have a more recent list.
John
Grimeton rebroadcast ?
Posted by Robert Rode W9ESX on June 27, 2014 at 07:55:38.
..any info available on Grimeton/saq rebroadcast on hf freqs. ?
Re: Grimeton rebroadcast ?
Posted by John Davis on June 27, 2014 at 23:39:40.
In reply to Grimeton rebroadcast ? posted by Robert Rode W9ESX on June 27, 2014
No rebroadcasts on HF as such, just the amateur club station activity before and after the VLF transmissions, as reported on our home page. (Note that the time of the second transmission has been corrected to 8 AM EDT.))
Coordinates of mutual VLF-stations in Brazil
Posted by Arktur on June 28, 2014 at 17:20:38.
In reply to Re: VLF-Transmitters in Africa and South America posted by John Davis on June 27, 2014
Which are the coordinates of the mutual VLF-stations in Recife and Belem?
potrzebie