Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on lipkowski.org X-Spam-Level: X-Spam-Status: No, score=-2.3 required=5.0 tests=FREEMAIL_FORGED_FROMDOMAIN, FREEMAIL_FROM,HEADER_FROM_DIFFERENT_DOMAINS,HTML_MESSAGE,RCVD_IN_DNSWL_MED, SPF_PASS,T_DKIM_INVALID,T_KAM_HTML_FONT_INVALID autolearn=ham autolearn_force=no version=3.4.0 X-Spam-DCC: : mailn 1480; Body=2 Fuz1=2 Fuz2=2 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by lipkowski.org (8.14.4/8.14.4/Debian-8+deb8u1) with ESMTP id v3N9xpGW004921 for ; Sun, 23 Apr 2017 11:59:52 +0200 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1d2EG2-0003BN-O0 for rs_out_1@blacksheep.org; Sun, 23 Apr 2017 10:56:42 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1d2EG2-0003BE-04 for rsgb_lf_group@blacksheep.org; Sun, 23 Apr 2017 10:56:42 +0100 Received: from resqmta-ch2-05v.sys.comcast.net ([2001:558:fe21:29:69:252:207:37]) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.89) (envelope-from ) id 1d2EFv-0006Sd-NP for rsgb_lf_group@blacksheep.org; Sun, 23 Apr 2017 10:56:40 +0100 Received: from resomta-ch2-17v.sys.comcast.net ([69.252.207.113]) by resqmta-ch2-05v.sys.comcast.net with SMTP id 2EFkdGCjIzz3d2EFqdrh3V; Sun, 23 Apr 2017 09:56:30 +0000 X-DKIM-Result: Domain=comcast.net Result=Signature OK DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=comcast.net; s=q20161114; t=1492941390; bh=Bfkm1FF+ruNn6L/Zf9/uv5WWbFvBpA7hpZ246C+0xXA=; h=Received:Received:From:To:Subject:Date:Message-ID:MIME-Version: Content-Type; b=DnxrCQCmFl2uSiklDbGglw57soKW0CLDF+3GWa71f36Q7oXnNWqeWiDZvrReXXudj yoe11acZyln5w5MjhDq8PaAQy0610ZHf0mvlcfU2tQYOdH9sUEqoT9Of2iV3KSmYVF 3tLUjkLrJxeMuUvpGnazdAp6i3ATqIJaIHWjTlPNZ349Gy+W04pqFsQtq71XsbZpwL JJwsHUZZiTSnB+E+HPklwucpd5k12wzhf8E+Po2ZNueyVbjiKLK9LCgF2xqd8cN7JA JkEerzY7ybLzACELX67vDpcL3deZ82JB2BI8mO1YGgolgEKGUnxe5em+Bqnz8qaA9G etwjlmIr98CUQ== Received: from Owner ([IPv6:2601:140:8500:7f9f:c15a:e6c9:ed63:2886]) by resomta-ch2-17v.sys.comcast.net with SMTP id 2EFpdfRe6bkqI2EFpdkXk1; Sun, 23 Apr 2017 09:56:30 +0000 From: To: References: <5872C893.80807@abelian.org> <58755576.6000702@posteo.de> <58E2383D.9040206@posteo.de> <58FB61B8.1070107@posteo.de> <58FB622F.2090708@posteo.de> In-Reply-To: <58FB622F.2090708@posteo.de> Date: Sun, 23 Apr 2017 05:56:13 -0400 Message-ID: <000901d2bc17$dfab9780$9f02c680$@comcast.net> MIME-Version: 1.0 X-Mailer: Microsoft Outlook 14.0 Thread-Index: AQH/WG6HdSYzf25Z+mzXJ05L2KR3RANKfGNdAsYsalYBMQ+OFQHuBbJHAwUsF9mhF7/+YA== Content-Language: en-us X-CMAE-Envelope: MS4wfDQxArACuqRda/a80Au0dqTlItiiUol7BzVUBf7NiK4M0A5bQrFQz9GQpCudz/HWy96DfFFWiHt6Ge9FmNf0SDZKxkaqGLDTT4TyJNueGxidtz7yYTLJ gJ3aGP05fiXOaJuU2jFZgJSX/SDX6zF+As8= X-Scan-Signature: 546a8e24375f07bde9da698a2561afcb Subject: RE: ULF: Crossed 14.4 km on 970 Hz / 309 km band Content-Type: multipart/alternative; boundary="----=_NextPart_000_000A_01D2BBF6.589C4170" X-SA-Exim-Scanned: Yes Sender: owner-rsgb_lf_group@blacksheep.org Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rs_out_1@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false X-Scanned-By: MIMEDefang 2.75 Status: RO X-Status: X-Keywords: X-UID: 11439 This is a multipart message in MIME format. ------=_NextPart_000_000A_01D2BBF6.589C4170 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Stefan, =20 Congratulations on reaching 29% of far field at 970 Hz. An exciting new = frontier. =20 Thanks also for the details including maps; this is an exceptionally = interesting experiment. Narrowband signal propagation is poorly = understood at 970 Hz at this and longer sub-megameter distances, but = propagation at 970 Hz should be significantly more stable over time and = much more predictable over distance/frequency than at 2970 Hz. In many = ways probably more stable over time and more predictable over = distance/frequency than frequencies 2970 Hz through 30kHz; but = accurately predicting nominal SNRs for your next two or three receiver = locations would be difficult; so your experiments may once again provide = first useful reference points. =20 An example: your message below includes: =E2=80=9CCan there be some QSB, = i.e. groundwave-skywave interaction even in 14.4 km distance?=E2=80=9D. = I would guess yes. Conversely, with a (hypothetical) 100-meter tall vertical transmit = antenna and wavelengths of level soil around the receive antenna I would = guess =E2=80=9Cvery little groundwave-skywave QSB=E2=80=9D.=20 =20 With a non-vertical transmit antenna (higher radiation angle, some = horizontal polarization), 0.3 wavelengths to 0.8 wavelengths TX-RX = separation, non-level ground within a quarter wavelength of the receive = antenna, variable conductivities at and below surface within a quarter = wavelength of the receive antenna, I think that SNR at distances 0.3 = wavelength to 0.8 wavelengths could be sensitive to ionospheric = variations, especially if the receive antenna is a loop. A number of = fascinating experimental results and analyses on the above were = published in the 1950=E2=80=99s through 1960=E2=80=99s, for frequencies = 2 kHz through 30 kHz, but the aggregate of those experiments only prove = the concept (susceptibility to variations in measured amplitude and = phase at the receiver under one or more of the above conditions given an = antenna substantially different than ideal vertical). Tests at your next = two or three 970 Hz receiver locations may provide some highly = interesting and unique insights.=20 =20 Thanks for these new and most interesting results. =20 73, =20 Jim AA5BW =20 =20 =20 From: owner-rsgb_lf_group@blacksheep.org = [mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of DK7FC Sent: Saturday, April 22, 2017 10:01 AM To: rsgb_lf_group@blacksheep.org Subject: Re: ULF: Crossed 14.4 km on 970 Hz / 309 km band =20 PS: Another image, showing the whole recording from 0...5 kHz, without = filters and blankers... 73, Stefan Am 22.04.2017 15:59, schrieb DK7FC:=20 Dear friends of the Ultra Low Frequencies, Yesterday a new experiment was done on the 309 km band. With the setup = bescribed below, still running just 5 kV / 15 mA on 970 Hz, i crossed a = distance of 14.4 km which is twice the distance of the last experiment. = A plain carrier was sent on 970.005 Hz, at least this was the plan. This is the location: = http://no.nonsense.ee/qth/map.html?qth=3DJN49KL09AB And this is the path: = http://no.nonsense.ee/qth/map.html?qth=3DJN49KL09AB = = &from=3Djn49ik00wd I recorded 196 minutes at 24000 kS/s starting 15:33:03 UTC. As expected in the near field, the signal is much weaker than just 6 dB, = rather 16 dB! But it is still there! A weak but doubtless trace in 3.8 = mHz. The signal was peaking 18 dB SNR in 424 uHz. There were some strange problems on the transmitter side. For the first = recording hour there was no carrier. I had to walk 45 minutes to reach = the next village to get some mobile internet to remotely restart the = transmission. After 80 minutes the carrier disappeared again and came = back 30 minutes later on 970.000 Hz. That was not intended but it acts a = bit as a keyed carrier, a better ID which is well visible in 3.8 mHz. It is very interesting just to listen to the recording (using a 6 kHz = low pass filter). I like the sound of the sferics which are propagating = well below 500 Hz, not only down to 4 kHz. It all helps to better = understand propagation from DC to VLF. BTW there were many whistlers = that evening and i catched many of them. It is a quiet location but i = still think that the antenna has not the maximum possible sensitivity = arround 1000 Hz.=20 Some pictures in the attachment (i still need to work out a comfortable = dropbox alternative). Now, that was the next step, 29 % of the far field border is crossed. I'm planning a next experiment in 25 km distance, which would be 50% of = the far field distance. Maybe i can do some QRO or i need to do a very = long recording. The the current signal strength there should still be no = problem in 47 uHz. This time i'm planning to use a larger E field = antenna. On the end of the 3.8 mHz spectrogram the signal became significantly = stronger. Can there be some QSB, i.e. groundwave-skywave interaction = even in 14.4 km distance? Or was it just constructive QRM/N? It will be = interesting in the next (longer taking) experiment to see if there are = some diurnal signal level changes. Maybe the band turns out to work much = better during a certain time period... 73, Stefan Am 03.04.2017 13:55, schrieb DK7FC:=20 Hi ULF friends, Saturday night i build an active E field receiver optimised for ULF. It = is using a BF862 front-end as a source follower and a LT1028 with 20 dB = gain. There are 3 RC filter stages cutting off at 10 kHz. Furthermore = there are two isolation transformers in series, 4:1=3D>1:10. In the = center they are parallel resonated. This gives a further good low pass = filtering and some additional gain below 3 kHz. It was a quick = construction without thinking to much, soldered at night, 02 AM local = time. The antenna probe is a 1m long steel rod (for welding) with 2 mm = diameter. The antenna height above ground was just 2m. There were no = trees in a radius of 20 m. For transmitting i'm again using the modified 5 kV mains transformer. At = 970 Hz, the antenna impedance is 342 kOhm! So i can just run 15 mA = antenna current which means 3 nW ERP. The new ALC build inside SpecLab = holds the 15 mA accurately and protects the transformer that way! = SpecLab is a very well usable tool for transmitting on VLF/ULF, thanks = to DL4YHF!! The transmit frequency was 970.005 Hz. I didn't expect much, thought that this distance may be to optimistic. = The last signals were very weak on my tree grabber in 3.5 km distance. = But that tree grabber is using loop antennas and they are not sensitive = in that frequency range. So there was a certain chance to see a trace, = maybe in 212 uHz??? I drove to JN49JL00EB and built up the receiver there because it is a = quiet location, a nice region for a walk and, there is a good restaurant = not to far!!!!!! So it was easy to spend some time there and let the = Raspi (using a GPS module on the right soundcard channel, with PPS+NMEA) = record for nearly 3 hours at 24 kS/s. This is the path between TX and RX: = http://no.nonsense.ee/qth/map.html?qth=3DJN49JL00EB = = &from=3Djn49ik00wd A distance of 7.2 km, or 0.023 wavelengths or 14% of = the distance to the far field border. So it is still a near field = experiment. It is about twice the distance i've managed in the last test. Now i'm back in the shack, analysing the recording and to my surprise i = can see a strong trace of 30 dB SNR in 424 uHz!!! See attachments in 424 = uHz and 3.8 mHz. All this makes me much more optimistic to reach farer distances. I tell = you i will crack the far field border on that 309 km band! That would be = a distance of 49.3 km. There must have been some local thunderstorms not to far away, because = there was QRN in the observed spectrum. So the SNR can be improved a bit = by doing the next test in the late morning hours. Also the resonance of = the transformers seem to be a bit to low, so maybe i can reach a bit = more sensitivity when optimising that resonance. It could further help = to rise the effective height of the antenna. Flat fields rather than the = deep forest is the region to select now.... 73, Stefan Am 10.01.2017 22:43, schrieb DK7FC:=20 Hi ULF,=20 Since a few hours i'm running 15 mA antenna current on 970 Hz, the 309 = km band. This requires to apply 5 kV to the antenna. You can see a very = faint trace on the lower image at = http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_VLF_Grabber2.html=20 Just about 10 dB SNR in 424 uHz in 3.5 km distance, or in 0.011 lambda = distance. The receive antenna is a H field antenna that is not even = pointing to the transmitter. Also the preamp noise is dominating the = background noise on that frequency. So the RX is deaf on that band. = Anyway, there is something.=20 The ALC into SpecLab does a very good job, it holds the antenna current = stable during all the changes and working point drifts. The plot can be = seen at http://www.iup.uni-heidelberg.de/schaefer_vlf/VLF/TX.png=20 15 mA results in an ERP of 3 nW.=20 My new preamp circuit is waiting for a first test together with the = large loop. I hope to pick up the signal in at least 5 km distance with = that preamp which is really low noise down to the lower Hz range.=20 An E field reeiver would be a better choise for the reception from that = E field Tx antenna, at least in the lower near field. Maybe that will = give another test then.=20 With 30 kV i could reach 0.3 uW. Not sure where this could be detected? = And who knows the advantages of this part of the spectrum for our = purposes!?!=20 Since 21:20 UTC, a 2 character EbNaut message is running. It will take = 2h, 2min, 40s. Hopefully the tree grabber is available until the message = ends. It will shut down in a few hours due to lack of solar energy in = these days (an improvement of this system has already been prepared and = waits for the installation).=20 73, Stefan=20 ------=_NextPart_000_000A_01D2BBF6.589C4170 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable

Stefan,

 

Congratulations on reaching 29% of far field at 970 Hz. An exciting = new frontier.

 

Thanks also for the details including maps; this is an exceptionally = interesting experiment. Narrowband signal propagation is poorly = understood at 970 Hz at this and longer sub-megameter distances, but = propagation at 970 Hz should be significantly more stable over time and = much more predictable over distance/frequency than at 2970 Hz. In many = ways probably more stable over time and more predictable over = distance/frequency than frequencies 2970 Hz through 30kHz; but = accurately predicting nominal SNRs for your next two or three receiver = locations would be difficult; so your experiments may once again provide = first useful reference points.

 

An example: your message below includes: =E2=80=9CCan there be some = QSB, i.e. groundwave-skywave interaction even in 14.4 km = distance?=E2=80=9D.=C2=A0 I would guess yes.

Conversely, with a (hypothetical) 100-meter tall vertical transmit = antenna and wavelengths of level soil around the receive antenna I would = guess =E2=80=9Cvery little groundwave-skywave QSB=E2=80=9D. =

 

With a non-vertical transmit antenna (higher radiation angle, some = horizontal polarization), 0.3 wavelengths to 0.8 wavelengths TX-RX = separation, non-level ground within a quarter wavelength of the receive = antenna, variable conductivities at and below surface within a quarter = wavelength of the receive antenna, I think that SNR at distances 0.3 = wavelength to 0.8 wavelengths could be sensitive to ionospheric = variations, especially if the receive antenna is a loop. A number of = fascinating experimental results and analyses on the above were = published in the 1950=E2=80=99s through 1960=E2=80=99s, for frequencies = 2 kHz through 30 kHz, but the aggregate of those experiments only prove = the concept (susceptibility to variations in measured amplitude and = phase at the receiver under one or more of the above conditions given an = antenna substantially different than ideal vertical). Tests at your next = two or three 970 Hz receiver locations may provide some highly = interesting and unique insights.

 

Thanks for these new and most interesting = results.

 

73,

 

Jim AA5BW

 

= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0<= /p>

 

From: owner-rsgb_lf_group@blacksheep.org = [mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of = DK7FC
Sent: Saturday, April 22, 2017 10:01 = AM
To: rsgb_lf_group@blacksheep.org
Subject: Re: = ULF: Crossed 14.4 km on 970 Hz / 309 km = band

 

PS: Another = image, showing the whole recording from 0...5 kHz, without filters and = blankers...

73, Stefan

Am 22.04.2017 15:59, schrieb DK7FC: =

Dear friends of the Ultra Low = Frequencies,

Yesterday a new experiment was done on the 309 km = band. With the setup bescribed below, still running just 5 kV / = 15 mA on 970 Hz, i crossed a distance of 14.4 km which is = twice the distance of the last experiment. A plain carrier was sent on = 970.005 Hz, at least this was the plan.
This is the location: = http://no.no= nsense.ee/qth/map.html?qth=3DJN49KL09AB
And this is the path: http://no.nonsense.ee/qth/map.html?qth=3DJN49KL09AB&from=3D= jn49ik00wd
I recorded 196 minutes at 24000 kS/s starting 15:33:03 = UTC.

As expected in the near field, the signal is much weaker = than just 6 dB, rather 16 dB! But it is still there! A weak but = doubtless trace in 3.8 mHz. The signal was peaking 18 dB SNR in 424 = uHz.

There were some strange problems on the transmitter side. = For the first recording hour there was no carrier. I had to walk 45 = minutes to reach the next village to get some mobile internet to = remotely restart the transmission. After 80 minutes the carrier = disappeared again and came back 30 minutes later on 970.000 Hz. That was = not intended but it acts a bit as a keyed carrier, a better ID which is = well visible in 3.8 mHz.

It is very interesting just to listen to = the recording (using a 6 kHz low pass filter). I like the sound of the = sferics which are propagating well below 500 Hz, not only down to 4 kHz. = It all helps to better understand propagation from DC to VLF. BTW there = were many whistlers that evening and i catched many of them. It is a = quiet location but i still think that the antenna has not the maximum = possible sensitivity arround 1000 Hz.

Some pictures in the = attachment (i still need to work out a comfortable dropbox = alternative).

Now, that was the next step, 29 % of the far = field border is crossed.
I'm planning a next experiment in 25 km = distance, which would be 50% of the far field distance. Maybe i can do = some QRO or i need to do a very long recording. The the current signal = strength there should still be no problem in 47 uHz. This time i'm = planning to use a larger E field antenna.

On the end of the 3.8 = mHz spectrogram the signal became significantly stronger. Can there be = some QSB, i.e. groundwave-skywave interaction even in 14.4 km distance? = Or was it just constructive QRM/N? It will be interesting in the next = (longer taking) experiment to see if there are some diurnal signal level = changes. Maybe the band turns out to work much better during a certain = time period...


73, = Stefan





Am 03.04.2017 13:55, schrieb DK7FC: =

Hi ULF friends,

Saturday = night i build an active E field receiver optimised for ULF. It is using = a BF862 front-end as a source follower and a LT1028 with 20 dB gain. = There are 3 RC filter stages cutting off at 10 kHz. Furthermore there = are two isolation transformers in series, 4:1=3D>1:10. In the center = they are parallel resonated. This gives a further good low pass = filtering and some additional gain below 3 kHz. It was a quick = construction without thinking to much, soldered at night, 02 AM local = time. The antenna probe is a 1m long steel rod (for welding) with 2 mm = diameter. The antenna height above ground was just 2m. There were no = trees in a radius of 20 m.

For transmitting i'm again using the = modified 5 kV mains transformer. At 970 Hz, the antenna impedance is 342 = kOhm! So i can just run 15 mA antenna current which means 3 nW = ERP. The new ALC build inside SpecLab holds the 15 mA accurately and = protects the transformer that way! SpecLab is a very well usable tool = for transmitting on VLF/ULF, thanks to DL4YHF!!
The transmit = frequency was 970.005 Hz.

I didn't expect much, thought that this = distance may be to optimistic. The last signals were very weak on my = tree grabber in 3.5 km distance. But that tree grabber is using loop = antennas and they are not sensitive in that frequency range. So there = was a certain chance to see a trace, maybe in 212 uHz???
I drove to = JN49JL00EB and built up the receiver there because it is a quiet = location, a nice region for a walk and, there is a good restaurant not = to far!!!!!! So it was easy to spend some time there and let the Raspi = (using a GPS module on the right soundcard channel, with PPS+NMEA) = record for nearly 3 hours at 24 kS/s.
This is the path between TX and = RX: http://no.nonsense.ee/qth/map.html?qth=3DJN49JL00EB&from=3D= jn49ik00wd  A distance of 7.2 km, or 0.023 = wavelengths or 14% of the distance to the far field border. So it is = still a near field experiment.
It is about twice the distance i've = managed in the last test.

Now i'm back in the shack, analysing = the recording and to my surprise i can see a strong trace of 30 dB SNR = in 424 uHz!!! See attachments in 424 uHz and 3.8 mHz.

All this = makes me much more optimistic to reach farer distances. I tell you i = will crack the far field border on that 309 km band! That would be a = distance of 49.3 km.

There must have been some local = thunderstorms not to far away, because there was QRN in the observed = spectrum. So the SNR can be improved a bit by doing the next test in the = late morning hours. Also the resonance of the transformers seem to be a = bit to low, so maybe i can reach a bit more sensitivity when optimising = that resonance. It could further help to rise the effective height of = the antenna. Flat fields rather than the deep forest is the region to = select now....

73, Stefan



Am 10.01.2017 22:43, = schrieb DK7FC:

Hi ULF,

Since a few hours i'm = running 15 mA antenna current on 970 Hz, the 309 km band. This requires = to apply 5 kV to the antenna. You can see a very faint trace on the = lower image at http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_VLF_Grabber2.ht= ml

Just about 10 dB SNR in 424 uHz in 3.5 km distance, or in = 0.011 lambda distance. The receive antenna is a H field antenna that is = not even pointing to the transmitter. Also the preamp noise is = dominating the background noise on that frequency. So the RX is deaf on = that band. Anyway, there is something.

The ALC into SpecLab does = a very good job, it holds the antenna current stable during all the = changes and working point drifts. The plot can be seen at http://= www.iup.uni-heidelberg.de/schaefer_vlf/VLF/TX.png
15 mA results = in an ERP of  3 nW.

My new preamp circuit is waiting for a = first test together with the large loop. I hope to pick up the signal in = at least 5 km distance with that preamp which is really low noise down = to the lower Hz range.
An E field reeiver would be a better choise = for the reception from that E field Tx antenna, at least in the lower = near field. Maybe that will give another test then.

With 30 kV i = could reach 0.3 uW. Not sure where this could be detected? And who knows = the advantages of this part of the spectrum for our purposes!?! =

Since 21:20 UTC, a 2 character EbNaut message is running. It = will take 2h, 2min, 40s. Hopefully the tree grabber is available until = the message ends. It will shut down in a few hours due to lack of solar = energy in these days (an improvement of this system has already been = prepared and waits for the installation).


73, Stefan =


------=_NextPart_000_000A_01D2BBF6.589C4170--