LEK - BRO Wrapup
Posted by John Andrews on February 28, 2002 at 09:18:47
Since last week, LEK has been transmitting in WOLF mode, 50 Hz above or below BRO, who has continued to send QRSS60. Both stations are in MN, on the same loop bearing for me, and at a distance of about 1100 miles.
I have been comparing the signals as recorded from 0230 to 0630 EST (0730-1130 UTC), which has been the best time period for that path over the last year. I have only rarely copied either station during the evening (pre-midnight) hours. Lyle has observed that the E/W paths tend to be less productive than N/S paths, and that pretty much squares with my experience.
In reading a QRSS signal with software like Argo (which I used), the brain becomes a big part of the process. On seeing a broken line exactly on 182.200 kHz, I can reasonably assume that I'm seeing BRO, and then try to figure out what's being sent. Since Bryce has been sending "BRO", I only have to guess one of three letters. Sometimes that's not possible -- only fragments are present. You "know" you are copying BRO, but it would be tough to prove it to others.
On the face of it, WOLF is less vulnerable to a runaway imagination. Unless the signal is being correctly decoded, you only see endless permutations of the alphabet. I have in fact seen some of the words I spoke aloud on realizing that conditions were really bad! But there are a lot of clues in the numeric data in the WOLF output, the most important of which is the apparent frequency. Just as with BRO, I KNOW that LEK is on frequency. I'm not going to waste my time looking farther than 0.1 Hz from Lyle's announced spot. And once having correctly decoded LEK, I can watch for that particular frequency on later files. This allows you to say that the signal "is there," even though WOLF isn't decoding it correctly.
With a few exceptions, during the last 6 nights, if I could say that BRO "was there," LEK was also, using the above criteria. The exceptions probably trace to interference. WOLF occupies a much larger bandwidth than QRSS60, and while you benefit from the mini-spread-spectrum nature of it, WOLF can be clobbered by a signal that your brain would ignore in QRSS mode.
There were a number of instances where BRO could be legitimately copied with clearly readable characters, and LEK just wasn't decoding. As many have observed before, there is a threshold for WOLF. I've found that the "q" values are a big help in anticipating what's going to happen. Copy is likely with values above -3, though last night there was one file where it was at -2 with no luck.
When WOLF copy is possible, you get 15 characters. If you only got one correct line in the full 27 minute, 10 seconds it can handle, you would only have received 13 more characters than you would for a QRSS60 signal. If you receive multiple lines, as is common, you have lead-pipe-cinch confirmation of correct copy.
QRSS -- 60, in this case, would be my choice both for simplicity, and for the ability to identify a station as being receivable. With our 2 or 3 letter call signs and a reasonbly active imagination, it would be the weak signal mode of choice for most current Lowfer activity.
WOLF has a clear advantage for moving more information in the same amount of time, and should be workable at the same signal levels that produce "correct" QRSS60 copy. If it only decoded in real-time, it would be much more valuable mode for 2-way QSOs. As it stands, with fast computers at each end, and a short transmit/receive switchover, QSOs with "real" information should be possible. Dex and I attempted it once, but my transmit antenna was not up to the task. Note that with my new 1.6 GHz P4, a full-length WOLF file takes 1 minute, 50 seconds to decode. Neat.
Thanks to Lyle and Bryce for the signals. If anyone has any opinions, pro or con, please weigh in!
John Andrews, W1TAG
Re: LEK - BRO Wrapup
Posted by lloyd chastant on March 01, 2002 at 07:42:25
John I haven't been making overnite captures at tries on LEK and BRO--rather I have tried at 9-11 PM before quitting for the night.I have been getting LEK wolf very nice during that time period for last several days but rarely BRO.But last nite(Thursday nite) I had nice QRSS60 copy on BRO and then a OK copy on LEK wolf(6-7 lines last nite /10-11 other nites).
And your correct Wolf decode is very fast but still takes 25:20 minutes to collect before one sees any results..
de Lloyd W3NF
About which distance a TV set, which is turned on, can be detected?
Posted by Harald on March 01, 2002 at 11:16:44
About which distance is it possible to detect the TV line scan base fequency of a TV set which is turned on?
About which distance can I transmit with a coil as aerial using a frequency of approximately 5 kHz and 15 kHz?
What frequencies do avalanche probes for mountaineers and ski runners use? About which range are they detectable?
Re: About which distance a TV set, which is turned on, can be detected?
Posted by Bernhard on March 02, 2002 at 01:16:28
The TV set should be detectable within a range of approximately 5 to 15 meters depending on the receiving system. If you take a coil and connect it to an HIFI Amplifier it may be detectable for 30m. You may increase the distance by building a very large coil - lets say a wire that lays around your garden. I believe it's possible to get a range of several hundred meters.
As far as I know the avalanche probes run at 2275 Hz (~2kHz) and get a range of about 10m. But there is another system that works on microwave frequency somewhere in the 1GHz region.
The magnetic field of a coil which you connect to an audio frequency signal decreases with 1/r^3 that's why there's now way to get a real large range.
Bernhard
TAG PSK31 Test
Posted by John Andrews on March 02, 2002 at 15:56:51
TAG will be sending PSK31 on 178.400 kHz until at least 10 PM EST on Saturday. I'm not sure how long the buffer will take to unload, and I'll be unable to watch it for part of the time.
The PA stage is non-linear, so the signal is pretty wide. I'm interested to see if the northeast guys can copy this.
John Andrews, W1TAG TAG Status: http://webpages.charter.net/w1tag/
Re: PBJ 13.55787 mhz COPY
Posted by Ken Brown on March 02, 2002 at 16:26:14
I also copy this station daily, does anyone know of the location for PBJ?
Ken N4SO n4so@juno.com
Re: Seen my 1st 22 meter QRSS signal HIFer
Posted by Ken Brown on March 02, 2002 at 16:34:18
Stan,
Be glad to listen for your Beacon when you get it going.
Ken N4SO@juno.com
PBJ info 13.557.87 HiFer band
Posted by Ken Brown on March 02, 2002 at 16:49:19
Does anyone know the source of the PBJ beacon on
13.557.87 in the HiFer band?
I need to send him a confirmation.
Please send his name, callsign, or e-mail address.
Ken N4SO@juno.com
Re: PBJ info 13.557.87 HiFer band
Posted by Jim Smith on March 02, 2002 at 18:50:34
PBJ beacon owner:
KD4PBJ CHRISTOPHER L WALDRUP
4713 MEADOW LAKE DRIVE APEX NC 27502 USA
Re: PBJ info 13.557.87 HiFer band
Posted by Webmaster on March 02, 2002 at 19:14:59
Hi Ken,
Be sure to check out the LowFER/MedFER link at the top of the LWCA page. It can give you all this sort of information and/or sources to find it.
John
Re: About which distance a TV set, which is turned on, can be detected?
Posted by John Davis on March 02, 2002 at 20:26:02
Bernhard explains the limitations of transmitting by induction at VLF quite well.
There is one other factor which contribute to television sets being heard over longer distances by LF radio receivers, though, and that is conduction of harmonics of the sweep frequencies outside the set by way of the AC power cord and the antenna connection.
Signals which are radiated by these conductors travel a significantly greater distance than the fields being emitted from the sweep coils (yoke) or the flyback transformer.
John
TAG now running Jason
Posted by John Andrews on March 02, 2002 at 20:57:19
Just wanting to confirm that my exciter is OK, I have switched TAG over to Jason 0.92 mode on 178.400 kHz, and will leave it that way overnight.
John Andrews, W1TAG TAG Status: http://webpages.charter.net/w1tag/
Re: PBJ info 13.557.87 HiFer band
Posted by Chris Waldrup on March 03, 2002 at 01:15:45
Thanks to all who have sent me reception reports so far. PBJ has been heard in NC, SC, MA, MD, TX, AL, and Ontairo Canada.
Chris Waldrup Apex, NC KD4PBJ@att.net
Re: About which distance a TV set, which is turned on, can be detected?
Posted by Harald on March 03, 2002 at 01:47:43
How far do you think can the signal of the ELF - transmitter "Teddybaer" in Berlin, if it exists (it is said to use as aerial an underground line loop with an approximate diameter of 3 kilometres around the airport Berlin - Tempelhof and a transmission frequency of 80 Hertz) be received, if the line has two turns and the current in the line is 1000 A?
New LOWFER Beacon on 186.1 KHz (from Northwest NJ):
Posted by John Bogath on March 04, 2002 at 10:25:39
This new CW-beacon has the call "NWNJ" and is now operational Sunday nights from 6 - 10 PM ET, or by request. I plan to increase operational hours in the future. The ground-radial system is still being improved on at present.
And now running CW!
Posted by John Andrews on March 04, 2002 at 12:22:13
TAG will be running in 6 wpm CW mode for a couple of days, as I assess how it's being heard in the northeast. Frequency is 178.400, and reports are welcome.
John Andrews, W1TAG
And now running QRSS3
Posted by John Andrews on March 05, 2002 at 18:16:59
Having conclusively proven that nobody can hear TAG in 6 wpm CW mode, the next test is to drop to QRSS3, and see what happens.
TAG is currently operating on 178.400 in QRSS3 mode.
John Andrews, W1TAG TAG Status: http://webpages.charter.net/w1tag/
TH, WA, VD, LIP & BRO in one night
Posted by Dexter McIntyre, W4DEX on March 06, 2002 at 01:35:57
Twas a great night for LF reception from the South East. Q5 copy on TH in CW mode, captured WA and VD QRSS togeather, Picked up LIP QRSS6 for a new one and found BRO comming in strong. TH: http://www.gostanly.com/w4dex/TH/TH.wav WA and VD: http://www.gostanly.com/w4dex/Argo/VDandWA.jpg LIP: http://www.gostanly.com/w4dex/Argo/LIP00002.jpg
Dexter,
W4DEX
http://www.gostanly.com/w4dex
Re: TH, WA, VD, LIP & BRO in one night
Posted by lloyd chastant on March 06, 2002 at 06:38:44
TH(CW) was very strong tonite in Maryland also and had very good captures on WA and VD(QRSS30) here also Been trying for LIP but thats a good haul from MD.. Also got a WOLF copy on LEK de Lloyd W3NF
And now off the air
Posted by John Andrews on March 06, 2002 at 18:25:16
Time to do some receiving.
John Andrews, W1TAG TAG Status: http://webpages.charter.net/w1tag/
Re: TH, WA, VD, LIP & BRO in one night
Posted by Bill Ashlock on March 06, 2002 at 22:47:26
Ah, big deal! Some guys will go to any lengths to get a little free publicity!
NC Jason
Posted by lloyd chastant on March 06, 2002 at 22:51:30
Jason copy on NC tonite was a bit erratic--only getting a few words per line.Pretty broken up -guess conditions just not too good at least during evening.
de Lloyd W3NF FM19MH(Maryland)
NC JASON adds two new stations to reception list
Posted by Dexter McIntyre, W4DEX on March 07, 2002 at 09:48:16
Last night's JASON transmission was received with near perfect copy by two additional stations. David, WD4KPD, FM15MM in eastern NC, 194 miles and Nick, W1ATT, FN31LT, 602 miles. That makes a total of 12 reports for NC in JASON mode. Thanks for all the reports and thanks Alberto for the software.
Dexter
http://gostanly.com/w4dex/
Wanted! A cheap and if possible transportable reception aerial for ELF
Posted by Harald on March 07, 2002 at 11:38:06
It is very easy to build a VLF aerial for the PC. As you can see on http://www.vlf.it/harald/strangerec.htm a roll(or a serial connection of several rolls) insulated copper wire can be used.
But for ELF, this aerial has only a low effiency. There are three possible ways to build an effective aerial for ELF:
- a serial connection of a lot of coils (disadvantage: expensive. How many coils would you suggest, if each one has 309 windings, a length of 0.04 metres and a diameter of 0.103 metres)
- usage of a preamplifier (disadvantage: needs an extra power supply, possibility of cross – modulation, etc.) with the existing aerial
- a ground dipole (disadvantage: digging in the ground is required when changing reception site)
What aerial type would YOU suggest?
If you have an ELF aerial please also show me your experiences in handling it and perhaps some results in form of spectrograms.
Re: About which distance a TV set, which is turned on, can be detected?
Posted by Bernhard on March 07, 2002 at 17:26:20
Hello Harald! This is a difficult question.
The radiation resistance is approximately R=197n^2(U/Lambda)^4 where n is the number of turns, U is the circumference of the loop and Lambda is the wavelength. I found this equation in the "Rothammel" aerial book. Your estimated dimension give us R=31.3nOhm! A current of 1000A at 80Hz produces an effective radiation power (ERP) of 31.3mW! I do not know how far this signal can be received. Maybe someone else can help.
What both magnetic and electric field do 31.3mW isotropic radiated power produce? By the way, the airport Berlin-Tempelhof is less than 15km from here.
Bernhard
Re: About which distance a TV set, which is turned on, can be detected?
Posted by John Davis on March 08, 2002 at 00:15:59
Interesting analysis, Bernhard. If the radiated power of 31.3 mW were ERPD, the electric field at 15 km would be about 83 uV/m. At the moment, I don't have the conversion factor for EIRP at hand, but it results in roughly a couple of decibels lower field strength values for a given power level.
This might be enough for low-speed communication purposes out to a few thousand kilometers _if_ the earth image of the horizontal loop doesn't detract appreciably from the radiation. That's likely to be a significant limitation, though, and I'm not sure how to model it accurately.
Anyone have any good ideas?
John
A tower with an observation deck – an interesting suggestion for „musicmann
Posted by Harald on March 08, 2002 at 02:53:40
Is it possible to use an effective longwave aerial on a grounded tower with an observation deck on its top? If the answer is “yes”, I would suggest such a tower for “musicmann 279”.
Such a tower would have many advantages: first it will be a tourist attraction which brings money to the owner and the authorities and I suppose it will have a very big acceptance of the people in the surrounding area, since many people like visiting towers with observation decks.
I do not believe, that this would be impossible, since the Eiffel tower in Paris carried until the fifties also an aerial for longwave and the radio tower of Berlin was used from 1925 until 1935 as suspension tower for a mediumwave T - aerial.
The best would be, if they would make on the top and/or at the foot of the tower an information centre for radio technology!
From which VLF – transmitters I can also decode the information of the signa
Posted by Udo Maier on March 08, 2002 at 06:11:07
From which VLF – transmitters I can not just survey the transmitting activity and find out the direction of the signal, but also use the information of the signal in a much more or less sensitive way?
E.g. I could imagine the usage of ALPHA for finding out the geographical coordinates of my PC. Is there software on the internet available, with which I can use the ALPHA signals in order to determine the position of my PC or perhaps for setting the clock.
(Of course, there are much better ways to do this job, but for a technical demonstration this would be still interesting!)
Is software available, with which I can use the signals of the Russian VLF transmitters “Beta” for setting the PC clock?
Although I assume, it is illegal, but the question remains: is it possible for amateurs to decode the signals of VLF - transmitters which send messages to submarines?
If the answer is “yes”, from which stations and with which software? Where is this software available?
Re: About which distance a TV set, which is turned on, can be detected?
Posted by Harald on March 08, 2002 at 06:28:48
Concerning the extreme low radiation resistance of the described loop around the airport Berlin - Tempelhof.
I suppose this value would be no problem, if the loop would be a superconductor. Perhaps is it a ssecret test of a superconducting ELF aerial?
Antennas for LF and VLF carried from (unmanned) helicopters, kites and ballo
Posted by Udo Maier on March 08, 2002 at 11:12:23
What experiences are available with antennas for VLF and LF which are carried with the help of (unmanned) helicopters, kites or balloons in the height? Which is the maximum height reached with such arrangements?
Do also some professional VLF and LF services use (unmanned) helicopters, kites or balloons in order to carry their aerial in the height?
If the answer is “yes”, which services do so?
(I assume military services with lower power perhaps)
At which places, for which service and for which frequencies were aerials carried with (unmanned) helicopters, kites or balloons in the height used?
Which was the height of the top of the aerial?
Which was the used transmission power?
Is it possible/ allowed for radio amateurs to build/ use an aerial similar that of TACAMO?
1. Under usage of a model plane?
2. Under usage of a small aircraft (e.g. a Cessna)
For the case of 2, which pilot license is necessary and is it against the law to use such an aerial arrangement over international waters?
Part 15 in 1750 Meters
Posted by William C. Walker on March 08, 2002 at 21:31:10
Hello, I am new to 1750 meters. Does anyone know if there are any 1 watt part 15 Long Wave transmitters that are capable of broadcasting voice? Do any come fully assembled?
Trio copy on 185.3
Posted by lloyd chastant on March 11, 2002 at 12:59:43
Had several copies yesterday on the trio on 185.3 here in Maryland..VD seemed to win out most times...Conditions haven't been the best but signals seemed to pick up yesterday de Lloyd W3NF FM19MH
Ultimate LOWFER Transmitter?
Posted by Jonathan Smick W2MXW on March 12, 2002 at 01:13:01
This was also posted by me to the QTH.NET Lowfer reflector:
Hi everyone,
A Part 15 'colleague' of mine, Keith Hamilton of Hamilton Printed Circuit Board (PCB) Design, who manufactures FCC Certified Part 15 100 mW AM broadcast transmitters recently expressed the idea that he would like to manufacture a LOWFER transmitter based on his very successful AM transmitter design. Basically he would (within reason) like to make The Ultimate LF Transmitter. His decision to do this would be predicated on being able to sell enough units to at least recoup the cost of FCC Certification (Type Acceptance) and so I am presenting this here so that you all might comment on what you would like to see in an LF transmitter that you would consider purchasing. Remember, unlike any other presently-available commercially-made LF transmitter this unit would be fully FCC Certified, which gives a measure of legal security over non-Certified equipment in that being tested for compliance it would be most likely to pass muster without nitpicking in the event of an FCC inspection.
Of course aside from legal issues it would be a full-featured, plug-n-play standalone LF unit which in and of itself would be desirable to many operators I'm sure.
The present features available on the current AM unit are as follows (not all of them would perhaps carry over to an LF unit and the LF unit we expect will have others not listed here - that is what we want your input for):
1. AM capability of 120% upward modulation (AM capability would remain in the LF setup because we anticipate some broadcast applications for this as well as LOWFER use, and because there isn't any other AM-capable LF rig besides the North Country kit available "out there"). Modulation is via transformer - as the present units are designed for Part 15.219 100 milliwatt use even though the trans. is purposely over-rated at 400 mW for extra safety factor its value would need to be increased for the 1 watt input level.
2. On-board final tank/antenna tuning network (originally designed to resonate with the 8-1/2 foot whip antennas we use in AM service) which consists of an Amidon T-106-2 toroid RF transformer (I'm thinking this core would have to be changed to #3 material for LF if this design were desired??) which is multi-tapped on its secondary with the taps shunt-jumper selectable for tuning; the secondary is hi-Z naturally for tuning the whip; the primary is fixed at 4 turns (although he could make it tapped and jumper-selectable as well) and is lo-Z for matching to the paralleled MOSFET finals. Fine tuning is accomplished with a 10 pF sapphire dielectric high-voltage trimmer across the coil secondary to ground. I suspect in an LF version this value would need to be made roughly up to 100 pF or so, perhaps using a parallel bank of fixed high voltage NPO ceramic caps which are jumper selectable. Something like a parallel bank of 50-20-10-10-5-5-2-2 pF perhaps where one can add-in as many as needed (in other words select more than one cap simultaneously, in fact all if needed, with the jumpers).
LOWFERS may also want to use their own big external loading coils so perhaps the present design with the on-board lo-Z to hi-Z toroid transformer may not be wanted (it serves the same purpose) although leaving it out would detract from the 'plug-n-play' philosophy somewhat, and while perhaps not *the* most efficient design possible compared to the HUGE Lowfer coils is still very efficient nonetheless, and a good deal more legal in the face of strict rules interpretations. That toroid coil has a pretty high Q. Would you like to see a very lo-Z output from the finals directly instead? A match from the very-lo-Z of the finals to 50 ohms nominal? Or some other design suggestions that would be popular? 3. The antenna output has a 1.5 kV gas tube arrestor to ground. This may be okay for LOWFER CW/QRSS/WOLF etc. use @ 1 watt but may need to be higher rated for AM modulation peaks at this level. There is also a static bleeder resistor across the ant. and a HV blocking cap to keep DC off the final tank. Volt rating of the latter is 3 kV and may need to be increased somewhat.
4. The finals are presently 3 paralleled Zetex MOSFETs with a combined dissipation of 3 watts (yes, Keith likes to over-engineer, his products are very reliable as a result) but for LF at a full watt may need to be made larger dissipation-wise or more added in parallel for extra safety margin. They are protected in the present AM design by a fast 40 volt Schottky diode across the drains. He can probably design the finals to operate in your choice of classes (C? D?)
Are there any 'pet finals' you would like to see?
5. There are on-board metering jacks for final current and voltage to make final input power compliance measurements, but an on-board meter itself is also possible.
6. The oscillator is normally fundamental xtal-controlled (10 ppm xtals) but these are expensive at LF and many LOWFERs might not want to be rockbound; a PLL design, or PLL/divider, or something else, are also possible. The osc. chip is presently a 4000 cmos. There is an optional trimmer for setting xtal freq. exactly. Any special taps or inputs/outputs desired in the osc. stage?
7. Buffer stages are presently 4000 cmos. Basically, the design of the whole unit is all-digital in the RF train.
8. Modulator is LM386, with on-board mod. level pot, and as mentioned the mod. transformer. This IC may need to be upgraded to a huskier model along with the transformer. Audio input is 600 ohms balanced also via a separate transformer. The audio quality of these units has gotten rave reviews from many of Keith's customers. This of course may not be an issue for strictly LOWFER use but we are keeping broadcast functionality too, remember.
9. There is an optional on-board NE570 compressor stage (which can be jumpered).
10. Power regulation for finals and all other circuitry is via separate on-board regulators; the final volts reg. is adjustable to make it easy to trim power input. The voltage for all the rest of the circuits is fixed. Regulators may need to be beefed up a tad, and/or have larger heat sinks. Power input is protected by a PolySwitch (tm) auto-resetting fuse and an MOV, and a reverse-polarity protection diode. Nominal power input in the present model is 11-15 VDC.
11. The unit is built on a double-sided plated-through-hole FR4 board. I assume that won't change. :-)
12. It comes in a nice fiberglass-epoxy weatherproof enclosure with gasketed lid and SS hardware -but this adds to the cost. I assume most LOWFERS will want just a bare board to use with their own choice of enclosure.
13. These units in the original design are capable of multi-unit synchronization- in other words, you put up a cluster of 4 or 5 units at one location, one has the xtal and is the 'master' and sends it's RF signal to the others which are "slaves", each is a separate transmitter in its own enclosure with its own antenna but all units share RF drive from the "master", power and audio. Since each unit shares a common freq. source there are no heterodynes. Each unit incl. the master has on-board provision for both coarse and fine phase delay adjustment to assure the relative phases of the radiated fields match thereby summing the radiated power without mutual cancellation. This allows one to get a 6 dB increase (double the range) over one unit and is perfectly legal. So in essence the cluster functionally acts as if it were one unit of 4 times the power.
Now, this feature is expensive and the phasing tricky to adjust w/out a calibrated FIM so I'm assuming it won't be wanted in LOWFER circles (and impractical for LF hobby broadcasting because of the much larger antennas compared with mediumwave), but if I'm wrong please correct me!
14. Power/audio input/ant./gnd./sync in/out are all via captive PCB screw terminal blocks. Is this good or would other connections be preferred?
Are there any special features (which could be made standard or optional) that would "put you over the top" so to speak if you were "on the fence" about purchasing this unit? Any special considerations for LOWFER modulation/keying requirements, IDers, etc? Remember this is going to be a stand-alone unit not a PC card type thing and there is no direct interface with a computer.
I cannot comment on the price as it is dependent on the features we wind up with except to say that it probably will be a couple to a few hundred dollars. This may seem expensive but remember this will be a professionally engineered, highly reliable stand-alone rig, not a kit, and will be FCC Type Accepted, (which ain't cheap! :-)
Keith will naturally try to keep the cost as low as possible, but as you can see from the specs of the present AM broadcast unit he does not sacrifice quality and reliability.
Sorry to go on for so long here but remember, YOUR input will help design this rig!
73, Jon W2MXW
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Re: Ultimate LOWFER Transmitter?
Posted by John Davis on March 12, 2002 at 03:06:31
At the risk of being a spoilsport (but at least I'll try not to be a wordy one)...
For most serious LowFERs, the _first_ requirement of an "ultimate" transmitter these days is frequency agility, and ideally FSK ability as well.
Type Acceptance on a unit is not a magic talisman. It possesses no juju. It's not going to carry much more weight during a station inspection for a suspected violation than having a police association bumper sticker on your car does if you're stopped for doing 90 in a school zone.
Furthermore, the FCC equipment authorization will be invalidated anyway by many of the suggested features. Remember, for manufactured equipment, no antenna substitutions are permitted! Only one of the exact same type provided with the unit (the same type TESTED with the unit for certification, that is) may be attached. Therefore, discussions of output coupling options are moot.
Even selling it minus the case in which it was first tested would probably void the FCC authorization.
As for the multiple amplifier concept, I also call your attention to Section 15.204, External radio frequency power amplifiers and antenna modifications, paragraph (b):
"A transmission system consisting of an intentional radiator, an external radio frequency power amplifier, and an antenna, may be authorized, marketed and used under this part. However, when a transmission system is authorized as a system, IT MUST ALWAYS BE MARKETED AS A COMPLETE SYSTEM AND MUST ALWAYS BE USED IN THE CONFIGURATION IN WHICH IT WAS AUTHORIZED. An external radio frequency power amplifier shall be marketed ONLY IN THE SYSTEM CONFIGURATION with which the amplifier is authorized and shall not be marketed as a separate product." (emphasis mine)
In other words, if he wants to market it various such versions, he will have to test it in EACH such a configuration, and sell it in exactly the configurations as tested. Sell a two-output version, get Type Acceptance for a two-output version; sell a four-output version, get Type Acceptance on the four-output version; etc.
It simply sounds like a very costly project to me, given the number of active or potentially active LowFERs; and, given what would have to be incorporated in such a unit to be considered "ultimate" by most any current LowFER's standards.
73,
John
Re: Part 15 in 1750 Meters
Posted by peter on March 12, 2002 at 12:39:21
Yes, Bill. Here's a site that I just found while searching for info on 1750M equipment. Seems this topic is getting popular of late.
http://www.northcountryradio.com/
I have not used or made any of the above offerings. Possibly others could opine of these.
Cheers, Peter
Re: Part 15 in 1750 Meters
Posted by William C. Walker on March 12, 2002 at 14:37:14
Thanks very much Peter. We are going to take a closer look at this unit and compare it with a couple others.
Does anyone have any experience with the Curry Communications EXP 1750a?
I have a friend (full fledged broadcast engineer and Ham) that is willing to build either unit but I don't want to commit until I have a few details about the reliability of these units.
Also will Curry be willing to sell just the transmitter portion without the receiver?
Re: About which distance a TV set, which is turned on, can be detected?
Posted by Bernhard on March 13, 2002 at 08:56:35
If the loop is not made of superconductor material but usual copper and the loop produces 1MW heat the Resistance is 1 Ohm. I calculated 3000m in diameter and 2 turns with 1000A. This big loop made of copper with 1 Ohm has to have an area of 335mm², if it's like a square it would be 18.3mm each edge. For this loop 6.3m³ copper are needed, this is a total weight of 56579kg or 56t. Does anyone know the price of copper on the worldmarket?
If the loop is made of superconductor material, the effiency would be much higher if course. But a superconductor has to be cooled pretty much, doesn't it?
Bernhard
Some further facts about SAQ Grimeton (Sweden)
Posted by Harald on March 14, 2002 at 04:15:29
On June 30th, 2002 SAQ Grimeton (Sweden) will be in the air again.
Although the transmitter is very well known to me, I had some interesting questions about it.
Because these questions are not answered in the books or in the internet I asked at “Telia” who belongs this facility by e – Mail. In the following section, you will find my question and the corresponding answer:
Question: In which transmission modes can SAQ on 17.2 kHz work? Only in A0/ A1? Or also in A2, F1, etc.?
Answer: It is only A0/A1 in Grimeton. In US was a similar transmitter once used for telephony. A modulator with 30 tubes gave the current to the magnetic amplifier. So A3 has been used on alternators. F1 is not possible with one generator. If the two alternators once installed had remained it had may be been possible, but one set was scrapped 1960.
Question: In which transmission modes may it work according to ITU regulations?
Answer: Only A1
Question: Which is its maximal usable bandwidth for SAQ on 17.2 kHz according to ITU regulations?
Answer: I don't know. I think it is 0.1 kHz.
Question: Which is its maximal usable bandwidth for SAQ on 17.2 kHz according to its existing six - tower - aerial at Grimeton including its tuning coils?
Answer: I have seen old oscillograms with a speed of 90 words/minute. At that speed where dots considerably rounded.
I know that US used one 200 kW alternator for telex to Greenland during the "cold war". So that transmitter (at a slightly higher frequency) could transmit at 50 baud.
Demodulator program for the W & G Pegelmesse
Posted by Alberto di Bene, I2PHD on March 14, 2002 at 04:52:29
Many LF enthusiasts have a Selective Level Meter, generally made by Wandel & Golterman. Some of these units have a demodulated output, others don't, instead providing a last IF output at 10 kHz on the rear panel.
For this last kind of equipment I have written a sort of last IF stage in software, which accepts as input a frequency between
40 and 20000 Hz, and extracts the AM, USB or LSB modulation it may have, playing it through the PC sound card.
The program sports also a graphical Phase Meter, which works only when AM is selected, and measures the incoming carrier phase referred to the program 'BFO' phase. It can be used for a very superfine tuning. A frequency difference of 1 Hz between the incoming signal and the BFO produces a whole revolution every second, so frequency differences of 10 mHz are easily appreciated.
The program does not touch the audio mixer, so it's up to the user to set it correctly. Basically you have to set the Recording panel so that only Line In is selected, and the Playback panel so that only Wave is selected. Make sure that Line In is *deselected*
for Playback.
Of course you will have to connect the 10 kHz output of your Selective Level Meter to the Line In of the sound card.
The program has a very serious problem, as the played audio lags the input by almost a second, so tuning is quite difficult.
This is due to the processing of the signal, and to the MME system of Windows. There are ways to improve this, and maybe I will pursue this, depending on my spare time and the acceptance of the program.
Bear in mind that this is just a first cut, more an alpha version than a beta, so do not have excessive expectations.... I wrote it more as an exercise, using some routines I had already written for the version 0.93 of Jason (to be released).
Of course any criticism, suggestions, bug reports are welcome.
The program can be downloaded from :
http://www.weaksignals.com/bin/radiopak_090.exe
73 Alberto I2PHD
If you have downloaded PHD Radio...
Posted by Alberto, I2PHD on March 14, 2002 at 08:45:52
If you have downloaded PHD Radio 0.90, please download 0.91 V 0.90 has been removed from the Web site.It contained a couple of bugs, introduced during some experiments performed just minutes before uploading it. Then I forgot to undo the changes done for the tests...
http://www.weaksignals.com/bin/radiopak_091.exe
Sorry for the inconvenience.
73 Alberto I2PHD
Re: Antennas for LF and VLF carried from (unmanned) helicopters, kites and ballo
Posted by Udo Maier on March 14, 2002 at 10:55:58
From Paul w0rw (e - Mail: W0rw@aol.com) i got the following message by e - Mail: i helped fly a 'paraballoon' to 6000 feet for VLF.
Also laid out 4 radials for a nice ground plane.
Ran 1000W into it.
It was at Edwards Air Force Base in 1960's.
Paul w0rw
Fwd: LF: ZL6QH tests 23 March
Posted by Bob Vernall (via Webmaster) on March 15, 2002 at 01:01:21
Subj: LF: ZL6QH tests 23 March Date: 3/14/02 10:11:25 PM Eastern Standard Time From: vernall@xtra.co.nz (Vernall)
To: rsgb_lf_group@blacksheep.org
ZL6QH TESTING 23 MARCH
ZL6QH will be transmitting on 23 March for all hours of local darkness. ZL2 sunset is nominally 0628 UTC, and sunrise nominally 1831 UTC (more details in the list at the end of the notice).
Dual frequency keying will be used, with 120 second dots, with 0.4 Hz and sending QQQQQQ. as hi, hi, lo, hi, gap. One Q takes 10 minutes.
hi = 137.7890 kHz
lo = 137.7886 kHz Each Q will start on the hour and be maintained close to 10 minute multiples throughout each hour, so absolute timing may be useful for analysis of difficult reception situations.
SUNRISE AND SUNSET TIMES (UTC)
DX stations can decide on their best times for monitoring. The following list is a sequence of sunrise and sunset times for 23 March, for various countries, by call sign prefix:
I sunrise 0508 UTC DL sunrise 0530 UTC F sunrise 0548 UTC G sunrise 0601 UTC EA sunrise 0613 UTC GM sunrise 0614 UTC IE sunrise 0623 UTC
ZL2 sunset 0628 UTC VE1 sunrise 1012 UTC W4 sunrise 1136 UTC W6 sunrise 1359 UTC VE7 sunrise 1410 UTC KH6 sunrise 1630 UTC I sunset 1711 UTC DL sunset 1733 UTC F sunset 1752 UTC G sunset 1806 UTC EA sunset 1816 UTC GM sunset 1819 UTC EI sunset 1827 UTC
ZL2 sunrise 1831 UTC
It would seem that European listeners miss out on dark paths with ZL before their sunrise, but there are dark paths at and after European dusk.
Reception reports can be emailed to vernall@xtra.co.nz
Good luck to all prospective listeners.
73, Bob ZL2CA
Re: possible design of the ELF - transmitter in Berlin, if it exists
Posted by Harald on March 15, 2002 at 02:59:28
This is true. But there are other technical devices which have to be cooled to such deep temperature, e.g. the external tank of the Space Shuttle or the telescope of infrared research satellites. The superconductor loop has if it made of high temperature superconductors cooled to a temperature of at least -190 degree Celsius. I suppose this would be possible with liquid nitrogen.
Around the conductor which has direct contact to the cooling liquid the cover for electrical insulation will follow. Many covers of thermal isolation material will follow, perhaps even a vacuum ring as in a can for keeping drinks cool. I do not know how thick such an arrangement has to be, but I ould lay it in an experimental system in a walkable tunnel, if repairs are necessary.
Coupling in of the signal would be performed by a special transformer, which has one superconductive winding for feeding the signal in the aerial and a normal winding for the signal out of the amplifier. The core would be a ferrit type. The windings relation would perhaps a value of 10000 : 1. This means for a current of 1000 A in the loop only an amplifier outout current of 0.1 A is necessary!
The radiation resistance is the only effective resistance in the loop. So no other looses would occur in the loop. Since the input current to my proposed transformer is very low ( 0.1 A), the wires leading to it may be very thin and would give therefore only a small thermal conductor! (One of the problem of superconducting device is that the electrical connections of it make the thermal insulation inefficient, since most cold runs about it out of the device!)
The amazing fact of my proposed design is, that these 0.1 A to the primary transformer could be possibly delivered from the output of a standard amplifier!
Of course all my considerations are poor speculations. I have no evidence, if the ELF transmitter under the airport Berlin - Tempelhof exists. But if someone says to me, I should build one using a loop aerial of 3 kilometre diameter and I would have the necessary money (and the necessary permissions, etc.) I would build it in this way.
Perhaps reality is of another kind. But this makes things so interesting!
Can ELF and ULF - frequencies come from space to earth?
Posted by Udo Maier on March 15, 2002 at 10:36:58
Can ELF and ULF frequencies trepasure the ionosphere?
I believe, that this should not be completely impossible, since the height of the ionosphere is not small for these frequencies in relatio to their wavelength and according to the tunneleffect it is possible for waves through a barrier for some frictions of a wavelength!
This must also happen with ELF and ULF waves coming from space. Is there a fault in my statement? If yes, where?
TAG on 185.302 in NEW Mode!
Posted by John Andrews on March 15, 2002 at 20:01:44
After (choose one of the following):
1. Months of careful research in my well-equipped laboratory,
or
2. An hour of messing around,
I am pleased to announce the development of a new mode of Lowfer communication. TAG is currently operating in that mode on 185.302 kHz. No special decoder is required. Use Argo in the 30 sec/dot mode, and be sure to have the range between 185.302 and 185.303 in view on the screen. No knowledge of the International Morse Code is required, either. The skills that you were taught in elementary school will be sufficient. Reception reports, particularly with screen shots, would be appreciated. The guys in the northeast are advised to back off on Argo's sensitivity if the signal produces "dog bones," as they will detract from the pleasantness of the viewing.
Since all new Lowfer modes have to be given an easily-remembered acronym, I propose to dub this invention, "Font Assisted Radio Transmission." I am therefore currently transmitting in FART30 mode.
I leave it to others to develop a sound-card method of generating this signal. My present implementation of FART is with a DDS synthesizer and a microcontroller programmed in assembly language. Much work remains to be done. Twenty three letters, in fact.
John Andrews, W1TAG TAG Status: http://webpages.charter.net/w1tag/
Re: Antennas for LF and VLF carried from (unmanned) helicopters, kites and ballo
Posted by Mark Andress on March 16, 2002 at 21:24:46
You might try doing a search on GWEN. This was a global warning system that could also be used with balloon and trailing airplane antennas. The frequency was 150-175 kHz. There are some web pages on it.
GWEN - which transmission modes were used?
Posted by Andreas Berger on March 17, 2002 at 13:37:43
Which transmission modes and which frequencies with which bandwidthes were used for GWEN?
In which countries did GWEN exist?
Re: GWEN - which transmission modes were used?
Posted by John Davis on March 17, 2002 at 15:43:12
GWEN, as such, only existed in the United States. It was a packet data network, and sounded not unlike amateur radio packet signals, but at somewhat higher speed. (Someone may still have more detailed specs they could share.)
Ultimately, it existed on carrier frequencies from about 155 kHz to 175 kHz, but the signals were so broad they tended to also disrupt the remainder of our 160-190 kHz LowFER band as well on days when there was a lot of traffic.
73,
John
Wireless dog fence
Posted by Jeff Baker on March 18, 2002 at 06:20:14
I have a friend who was asking me about his dogs wireless fence. He stated the transmiter was transmitting at around 10khz. Does this sound reasonable? I am not real familiar with low bands and figured it would more likely be in a higher band like a garage door opener or cordless phone. Any comments ?
Thanks Jeff Baker KG4ENR
Re: Wireless dog fence
Posted by Jacques d'Avignon on March 18, 2002 at 08:40:03
Hi:
I do not know what frequency these dog fences work, but I know that they can be very disruptive in the LF band. I have tracked one that was causing QRM to our LF listening event, and it was located about 2 miles away!!
Jacques
TAG new mode capture in Maryland
Posted by lloyd chastant on March 18, 2002 at 17:34:32
Had a one TAG capture of John's FART mode here in Maryland on Saturday evening..Wasn't roaring in but was a definite TAG pattern...de Lloyd W3NF
Re: A nice picture and some interesting facts about longwave broadcasting
Posted by Sukhbaatar on March 20, 2002 at 06:36:11
I am interested in messaging or paging service using LW transmitter. Thank you
Fading in the VLF – range
Posted by Harald on March 21, 2002 at 03:36:15
Below which frequency interference between the ground wave and the wave reflected from the ionosphere does not occur? Is there such a frequency value determinable or can under extremely rare conditions interference between ground wave and wave reflected from the ionosphere occur down to frequencies until 10 kHz and more?
Is there something like fading on frequencies below 10 kHz?
Below which frequency value the difference between the range of a transmitter at night (wave reflected by ionosphere) and day (only groundwave) will become neglieable small?
Do some longwave broadcasting transmitters use fading – reducing aerials which radiate in a flat angle (I suppose Allouis in France on 162 kHz, because I can receive the signal of this transmitter 500 kilometres away from the aerial often without fading!). If yes, which transmitters? How do such aerials look like?
ZL6QH Spring Results
Posted by Webmaster on March 23, 2002 at 23:28:52
Following are messages forwarded from the RSGB LF Group regarding reception of the March 23, 2002, 137 kHz amateur radio LF tests from New Zealand:
--------------------------------------
Subj: LF: ZL6QH seen in Massachusetts Date: 3/23/02 7:16:12 AM Eastern Standard Time From: w1tag@charter.net (John Andrews)
I know this doesn't set any new distance records, but I appear to have captured two of the DFCW "Q's" from ZL6QH this morning, on 137.789 kHz. The screen shot may be seen at:
http://webpages.charter.net/w1tag/files/ZL6QH.jpg
The shot covers the 1000 - 1100 UTC time period, with the reception occurring around 1030. This is about a half hour before my local sunrise. An attempt to record the session on another computer with a 60 sec/dot setting failed when the computer locked up overnight. The 120 second screen smears the consecutive characters, so each of the long lines is actually two "dashes."
The receiving location is in Holden, Massachusetts, grid square FN42ch. Coordinates are 42d 19m 12s N and 71d 49m 43s W. An Icom R75 receiver with a 12 turn loop was used.
I'll be out of email contact for a day or so.
John Andrews, W1TAG
--------------------------------------
Subj: LF: ZL6QH 137khz test received in North Carolina Date: 3/23/02 9:16:44 AM Eastern Standard Time From: dmcintyre@att.net (Dexter McIntyre, W4DEX)
Best Q received just after 0900 posted at:
http://www.gostanly.com/w4dex/Argo/ZL6QH/ZL6QH23mar020930.jpg
More screen shots at this directory:
http://www.gostanly.com/w4dex/Argo/ZL6QH/
ARGO screen time is UTC.
My thanks to ZL2CA and the Quartz Hill group for their efforts.
Dexter, W4DEX
--------------------------------------
Subj: LF: ZL6QH not received in Virginia Date: 3/23/02 8:57:31 PM Eastern Standard Time From: esanders@erols.com (Nan and Sandy Sanders)
Well almost. A few seconds on the right frequencies here and there at the same time W1TAG was receiving "Q's". But nothing even close. It looks like at least 3 people were trying to receive. Will try again next time.
Sandy WB5MMB
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Subj: LF: ZL6QH log Date: 3/23/02 5:10:34 PM Eastern Standard Time From: vernall@xtra.co.nz (Vernall)
Hi all,
Thanks for reports so far made. It looks like ZL6QH made it to the east coast of stateside again, but not across the next pond.
I can confirm that ZL6QH made a reasonable go of it, from well before ZL sunset to well after ZL sunrise. However, there was a 30 minute transmission outage from 2000 - 2030 UTC due to power problems, and an operating error at 0510 UTC when a frequency trim was inadvertently done when it should have been a timing trim, so there was a "bad Q" from 0510 to 0520, but good again after that. Apart from these matters, transmission was steady and frequency was thought to be within 0.1 Hz of declared frequencies.
Cheers for now,
Bob ZL2CA
--------------------------------------
Fwd: LF: California too
Posted by Bob Vernall on March 24, 2002 at 15:53:58
Subj: LF: Califorina too Date: 3/24/02 12:07:44 AM Eastern Standard Time From: vernall@xtra.co.nz (Vernall)
To: rsgb_lf_group@blacksheep.org
Hi all,
A direct QSL from Mike KB6WFC, Daly City, CA. His Argo pics confirm receiving a couple of clear Qs from ZL6QH, and other patchy reception.
73, Bob ZL2CA
Re: Fwd: LF: California too
Posted by Mike KB6WFC on March 25, 2002 at 11:30:32
Hi All,
Pic of my reception may be viewed at http://www.geocities.com/silversmj/03230200010.jpg
73 de Mike KB6WFC Daly City, CA USA CM87sq 37:40:47N 122:28:21W
"Land of the Free & Home of the Brave"
Re: A tower with an observation deck – an interesting suggestion for „musicmann
Posted by Paul Strickland on March 26, 2002 at 06:07:40
Wouldn't there be safety concerns as they would be within a few feet of a 500,000watt TX?
Re: A tower with an observation deck – an interesting suggestion for „musicmann
Posted by Harald on March 27, 2002 at 07:12:24
I do not think this would be such a big problem. In Germany there are some powerful transmitters on the longwave and the mediumwave where you can go until a distance of approximately 5 metres to the aerial (e.g. Donebach of Deutschlandfunk for 153 kHz with 500 kW and Weisskirchen of Hessischer Rundfunk for 594 kHz with 300 kW).
I would built my tower as a grounded steel or concrete tower carrying a rhombic aerial for the longwave. The observation deck I would place on the top higher then the aerial. Because of potential suiciders I would make a complete fence around the observation deck, but I would choose the width of the mashes so that an objective of a professional camera would pass through, because the tower should be "photographer - friendly".
The fence I would make of metal, so it has a bit effience of a faradic cage.
Concerning to the ground:
The mount of theaerial of the ground where the danger is that people come to close to the aerial I would enclose completely with a fence. I think there are no dangers of the 500 kW long wave radiation for people without heratbeat controller, if they do not touch the aerial or uninsulated lines leading to it. But this is a general problem of high voltage engineering.
Jason V0.93
Posted by Alberto di Bene (fwd) on March 30, 2002 at 14:52:41
Hello all,
Jason 0.93 has been just uploaded to the weaksignals Web site. The signalling format is compatible with 0.92. The main changes are :
- A different demodulation method (zero IF) has been used, which makes unnecessary the Low Speed mode. Now the program works ok on a 150 MHz Pentium, with no compromises.
- The program now remembers from session to session the various settings.
- Tweaking of the decode routine, with (maybe) a fraction of a dB in decoding gain.
- Minor adjustments to the code and bug fixes.
To download it: http://www.weaksignals.com
Reports are welcome.
73 Alberto I2PHD
www.lwca.org
potrzebie