VLF Experiments in Newfoundland

The only known VLF transmitter in Newfoundland and Labrador. Others welcome!
F=8.0-8.3 kHz, Wavelength ~36 km. P ~30 watts, Efficiency < 0.000001

Authorised ERP 10 mW. Licence renewed by ISED Canada: January 2017, Sep. 2017.
Paul Nicholson VLF RX
VLF milestones
Roger Lapthorn's VLF site
VE2IQ VLF grabber


2017


December. W4DEX is welcomed to 8270.0 and makes a good showing on Paul's new and more sensitive spectrogram. DF6NM makes a brief appearance on .0025 completing a VLF pileup on the 3rd. There is snow on the ground and wx changes so coil current is peaked and power are adusted to keep the aerial current near 0.25A.

VLF Pileup.

Dex and yours truly on Paul's spectrograms. 12th. Letter S sent to Stefan is received by Paul instead. This is the fist EbNaut message transmitted using SL here. Syntax: " echo 'S' | ./ebnaut -et -N1 -p 16K21A -k 8 > psk.txt " and put it column format for Spectrum Lab. Paul copies the S but not Stefan. 15th. peaked -20.2 dB S/N in 1 Hz at 0440 on pn spectrogram but no trace after 0830. Dex was there too. 16th. Phase inversions at 6m40s (period) 0000 - 1000 ut. 17th. Phase inversion at 5 min intervals (period =10m). 1400ut. problem with notebook operating system or soundcard. Since 1500 ut. using ne07m in frequency mode instead of SL to generate carrier on 8.2700075 kHz. but uint32_t limits set to integral frequencies?? but "double freq = atof( ARG_f); if( UBX_set_frequency( h, 0, freq, 0, 0, 0, 0, 0.5, 1)) printf( "set output frequency %.6f Hz\n", freq); " suggests uHz resolution so leave it for a while! 18th. No trace of sigs seen on Paul's VLF spectrogram.
November
1st. Continuing with carrier GPS conrolled via SL. 250 mA RF. Paul sends several reports noting absence of signal during daytime and periodically. 4th. Aerial raised at far end again. From Paul:
4th/5th H-field 10.46 dB 0.09 fT -106.5 deg
E-field 10.34 dB -107.8 deg
Combined 14.62 dB EbNaut transmission started 16K19A 2300 utc and decoded by Paul with 1.8 dB Eb/N0 and 40 % BER.
5-6th. 5 Character message sent and received by Paul. Eb/N0 = +1.8 dB, BER 40.5%
8th-9th. 8 character message sent. Received by P. Nicholson: Eb/N0 = -0.5 dB, constant reference phase, BER 41.1% 9th (~1800 utc) : A pickup wire is connected to the soundcard to correct phase for aerial/coil fluctuations with SL. 12th. Peaked I_A by increasing L a bit. Heard CW sigs at 1.7 km using the crude DC RX.
20th Far end of low RL increased 50 percent. 22 Nov. The pickup wire (for SL phase stabilisation) was disengaged earlier today 23 Spectrogram of signals reported by Paul who suspects they might be from here. http://abelian.org/vlf/fbins.shtml#p=1511402400&b=100&s=sp DF6NM reminds the op on correct SL usage ie: it will correct phase shifts whether they are intentional or not! 24th. Mains was out so there was no carrier from morning to 2200 utc today. Continuing with carrier 8.2700075 kHz.
25th. Phase stabilised by E field feedback to Spectrum Lab starting ~2200 ut. The notebook pc is synchronised by GPS NMEA and 10 mS PPS. TXN to DF6NM,DK7FC for SL tips and Paul's UBX code for the NEO7M. 8270.0075 Hz, 10 uW + a little bit due to the aerial being raised on 1 Nov.
October
4-6th Good reception of carrier on 8270.00709 Hz by P. Nicholson. 10 µW to low RL with new xfmr (1:5) 144,70,100,17 mH coils. 30 watts from G1/SC amp. Exciter: DDS60 (AD9851 + 8088 amp). Paul's field strengths and S/N were 0.06, 0.084 and 0.042 fT and 13 14 and 11 respectively in 34.72 uHz "(8 hours 23:00 to 07:00 UT) using combined E-field and H-field." 7th. Heard VLF CW beacon at 1km using homebrewed rx.
Report from P. Nicholson:
Overnight signals 23:00 to 07:00 UT:

8th/9th 0.046 fT S/N 9.1 dB, noise 0.016 fT;
9th/10th no signal detected, high noise;
10th/11th no signal detected, high noise;

Daytime 10:00 to 18:00 UT:

8th: 0.033 fT S/N 15.1 dB very low noise: 0.0057 fT
http://abelian.org/vlf/tmp/171011a.gif
9th: 0.022 fT S/N 8.8 dB noise 0.0083 fT
10th: no signal detected, noise 0.012 fT

Reports of spectrogram traces on right frequency from Laurnece KL7L and Markus reporting on DL0AO in Amberg also on the 10th. These traces were unlikely to have originated from here.

More reports from Paul: Overnight signals 23:00 to 07:00 UT:

8th/9th 0.046 fT S/N 9.1 dB, noise 0.016 fT;
9th/10th no signal detected, high noise;
10th/11th no signal detected, high noise;

Daytime 10:00 to 18:00 UT:

8th: 0.033 fT S/N 15.1 dB very low noise: 0.0057 fT
http://abelian.org/vlf/tmp/171011a.gif
9th: 0.022 fT S/N 8.8 dB noise 0.0083 fT
10th: no signal detected, noise 0.012 fT

After much mucking around with a neo7 and using SL ini files from Stefan and Markus, Paul reports a "nice sharp line on 8270.0075 " and "
Night: 19th/20th 13.9 dB phase 3.0 deg 0.065 fT H-field only
Day: 20th 10.5 dB phase 101.4 deg 0.034 fT H-field only
Night: 20th/21st 12.1 dB phase 8.0 deg 0.058 fT H-field only
10.8 dB phase 0.0 deg E-field only
14.4 dB E-field and H-field combined
Day: 20th 12.3 dB phase 104.8 deg 0.038 fT H-field only
10.1 dB phase 100.3 deg E-field only
15.2 dB E-field and H-field combined

Daytime phase and amplitude repeats very well."
And so our quest (for coherence, stability and accuracy) is at an end.
21 October. Start periodic phase inversions at ~2100 utc on 8.2700075 kHz. Neo7m gps module pps to notebook running SL with DF6NM vlf ini, vo1fr audio preamp, vo1bl rca patch cord, vo1na cw key cord to back of group one/sc amp, birch breadboard with knurled nuts, shunt resistor, meter, lamp, DPDT reversing relay keyed with raspi3, etc. then to helix hut via 2 pairs of 3 parallel wires to the new 1:5 xfmr, ammeter in ground lead, helix with 24x0.08mm wires, 100m RL at 12m high and much help and coaching from DF6NM and DK7FC.
22 constant phase 0750 ut, EbNaut starting 2300, 3 characters, 55 second symbols, 8K25A, 8.2700075 kHz, repeating every 12 hours.
23 October Email from P. Nicholson:
" CRC was 16 bits.
Copied 'VLF' with constant reference phase.

H-field: Eb/N0 = +1.4 dB, phase 155.7 deg
E-field: Eb/N0 = -0.2 dB, phase 152.5 deg (new RX)
Combined: Eb/N0 = +3.0 dB, phase 154.4 deg

First sub-9kHz message Canada to UK."
25th. Aerial raised a bit. tx still running.


September
7th The aerial is earthed following a forecasted lightning threat. Paul again overcomes the instability and weakness (8uW) of signal...

"a non-coherent average over 8 days of 10:00 to 20:00" is posted to the RSGB reflector. 26 DK7FC provides advice on SL and NEO7M which recently arrived. 27 Carrier on 2245 utc 8269.9975 kHz (note f*400/239 is prime) 8 uW ERP but not a hint seen by Paul the following morning. The DST took a major dip and there could be trouble with the carrier. 28 replaced pc and running sl+rsntp. Some fizzling sounds heard around the coil but no blue glow was seen.
August
Mentioned in LF column, p66 RadCom. TNX Dave G3YXM
0.25 amps to the 10x100m RL (8 µW) unmodulated and undisciplined (DOCXO) 8270.00709 Hz +- a few ppb. (24 Aug) Amazingly, the signals are copied by P. Nicholson who reports: ...two daytime signals, 25th and 26th 10:00 to 20:00,combined coherently, bin width is 27.8 uHz. S/N of the combined days is 16.0 dB. Adding the two days non-coherently gives only 9 dB." Nothing useful was extracted from the night signal.
July
0.3 Amps to the 10x100m RL via 3 pies and a solenoid wound with 24 strands of 0.08mm copper (~2 kg)
03. Detected using SL and DK7FC VLF E probe at airport(10km) and possibly at signal hill (20 km).
Paul's report: Nothing detected overnight 3rd/4th but a nice signal 4th/5th at 0.13 fT, S/N poor due to high noise - only about 10.3 dB in 46.3 uHz. 14th. Tuned aerial with 2 large and one small pie: Total 487 mH 148 ohm DC. 0.33 amps till flashover.

Spectrum peaks at 8270.0070865 +/- 0.5 uHz.

June
Dave G3YXM includes a quick mention on p66 of RadCom.
07 0.24 amps carrier 8270.007 Hz. Reports from P. Nicholson: night 13th/14th: average 0.11 fT, freq 8270.0070925 +/- 0.5 uHz; Daytime 14th: average 0.085 fT;night 14th/15th: average 0.082 fT;
16th. Continuing with 0.24 amps. while working in the back yard and winding workshop.
More reports from Paul: Daytime 15th: No signal detected; Overnight 15th/16th: Good signal, average 0.12 fT, S/N poor; Daytime 16th: Down in the noise at about 0.05 fT; Overnight 16th/17th: No signal visible, E-field down for some hours; Daytime 17th: 0.075 fT, S/N 12 dB in 23uHz, 8270.007080 +/- 0.5 uHz Overnight 17th/18th: 0.13 fT, S/N 12.7 dB in 46.3 uHz, 8270.007085 +/- 0.5 uHz
A note from Alan G3NYK showed a dip in the DST was timed with poor reception at Paul's. The tuning syetem comprised a pie (24 0.08mm conductors) 0.265 H 94 Ohm, solenoid (24 wire) ~70 mH and a 6 wire 100 mH 160 ohm pie. On the 19th, the solenoid and lossy pie were replaced with a 139 mH 57 Ω pie (24 wire) and the aerial current increased to 0.34A. Sadly, the 0.265 H pie started hissing, sparking and spewing ozone. Efforts to bring it back to life were not efficacious; a rewind is in order. The carrier is off for now.
21st 11:40 am carrier 0.34A. 139mH pie, 70mH solenoid, 120 mH pie. Announced on RSGB reflector. 23rd: tried new coil. 0.4 Amps. Back to previous arrangement and 0.34 amps. Carrier on tfn.
28 June 1108 utc tx off, aerial earthed. WX: Risk of thundershowers this afternoon.

May
23-29 EbNaut 2300 and 1100 utc 0.32A RF. There was no daytime psk on the 27,28th and 3 phase glitches. No 1100 psk 26 May, but fsk CW with groups of 5 numbers was heard on the portable VLF rx at around 1900 ut.
23rd. Paul decodes "VO!" at Eb/N0 -0.5 but BER 43% and 'PV4' at +0.9 dB, BER 39.6% but sadly, neither is correct. Jacek SQ5BPF spots a doubtful signal a bit off frequency.
21-22 Carrier. 22-23 Ebnaut starting 2300.
20-21 Ebnaut TA attempt. ERP up 2.5 dB with new helix: 123 µ Ω * (0.32A)2 = 12.6 µW
19-20 EbNaut TA trial again. Wound a new coil (186 mH 70 ohm) and got 60% more aerial current. Then a stench of O3 and a pffft sound. =>Dead coil. Now back to the lossy 6 wire 100 mH, 12 wire 80 mh and big 140 mH 59 ohm coil 30 watts 0.25 RF amps.
Paul Nicholson's reports for 16-18th, 17th/18th avg 0.045 fT and the noise was very low. The carrier 'decoded' to '***' at Eb/N0 = +1.2 dB The carrier decode registered best Eb/N0 +1.6 dB at a frequency ... of 8270.0070925 Hz [offset] + 9 uHz. Spectrum peaked at 8270.007101 Hz +/- 0.5 uHz.
16th/17th. night peak 0.05 fT average was about 0.035 fT, poor S/N. Daytime 17th was weak too, only averaging 0.025 fT but S/N was fairly good.
14 May. Ice melted in sunshine. Just under 0.3 amps EbNaut starting 2300.
13 May 2300 Ebnaut transmission. 3 Chars, 8K25A, 464 symbols, 55 seconds each. Antenna iced by morning and Paul's valiant efforts did not yield a decode.
13 May. Antenna iced. Low ERP overnight. Nil across pond. Paul's analysis shows the Forest reception to be doubtful. It has not been seen since the 8th.
12 May. QRV on EbNaut. 2 dB added to ERP. Calibrated ammeter. Reading 0.28A
Best report from Todmorden: 0.085 fT. 11/12 May.

Paul's spectrum with the Fourier transform bins aligned to 8270.0070625 Hz +/- 0.5 uHz.

Matching transformer,current probe and tuning helix used for VLF transatlantic transmission 7-8 May 2017.

08 May. Paul Nicholson reports a peak in Todmorden 46.3 uHz above the posted frequency. The maths puts the carrier high by 92.6 and the ref osc is likely low by 5-6 ppb. Paul's LWPC models FS as 0.069 fT,(0.021 uV/m) in agreement with his measurement, and verifies that the signal was from the west. It looks like the sigs crossed the pond.
Paul's info: signal peak 8270.0070625 Hz +/- 0.5 uHz. (about 3.6 ppb low) S/N 13.9 dB in 46.296 uHz. r=3545 km. Daytime (08:00 to 11:00 8 May 2017) 0.04 fT.
A peak is detected in Virginia on the RX operated by Mike KE3RJQ at r=2442 km.

07 May. ~10 uW carrier on 8270.007 Hz. Watching VE2IQ grabber. Using new big pie: 128 mH 59.3 ohms and 2 smaller ones 80 mH, 116 mH L=470 mH. Heard at 1 mile with portable dc receiver.

24 Apr. Crossband VLF-CW/VHF-FM QSO on 8.277 kHz/147.77 MHz.

18 Apr. Detection of anthropogenic 36 km fraunhofer photons (r=7km)

Coloured lines are 'flexible curves' with inverse cubic roughly fitted to data. Note the anomaly between 1 and 2 km.

Remote reception site. Note the small iceberg behind the DK7FC VLF e-probe. Looking towards England, 3500km away.

SL config file Tnx to all! Helix at 200 mA since 1000 utc. P_rad=123uOhm*(0.2A)^2= 5 uW

16 Apr. 100x12m(h) aerial is up again. Current probe reading:22 (about 1A of primary current, 0.2A secondary). Running vlf8277_2b.usr/SL/pan pc at r=1km then helix arced!

15 Apr. Both aerials are on the ground or treetops thanks to ice and wind. Experimenting in the shack with DL4YHF SL, PA0RDT MW and DK7FC VLF probe and a carrier generated by a DDS60.

14 Mar. Higher current to the new coil. Primary current: 12 on probe (~.25A) secondary = 0.25/5 = 0.05 ma. Prad=123 * (0.05)**2= 0.31 uW, assuming the probe is 2A full scale. Amp o/p was 'dirty'. Heard at 1.5km using dc rx.

8 March. Repaired Traynor amp. QRV again. 6 uA probe primary (uncalibrated). {10 uA probe reading for speakers or 16 ohm loads, 20 v p/p. (3 watts)} i=v/r = 7/16; primary= 6/10 * 7/16 = 0.3A ; secondary = p/5= 0.06A Aerial 10h x 100m Rotated L (RL). H_eff~10m assumed uniform current distribution.
R_rad=(40Heff/ λ)2=123.4567890 uOhm. P_rad=0.4 uW. Heard with dc rx + mw at 0.93 km.

Feb. 2017. On the air ~20 ma with new coils (0.5 H 12x0.08 mm Cu wire)

13 Jan. 2017 VLF licence renewed by Innovation, Science and Economic Development Canada.

14 Jan. Tests with uno/ad9850 module sq out/tc4426. 8277 Hz. Range 1 metre. XH100 tone: 553.3 553.8 (using Argo on win xp pc)


2016

24 Dec. 2016 Excellent reception of SAQ on 17.2 kHz CW at 0800-0804 with 100m Rotated L ~20m high, LF10 and XH100 with SRA8 mixer. Audio clip

10 Nov. 2016 IEEE NECEC 2016 Paper: "On VLF radiation from an extremely small aerial"

7 May. Checked RF ammeter. OK. Low current was due to short in the helix. Corrected with a few pokes. L=0.37 H. 5:1 n:n xfmr primary 4.24 mH Secondary 0.1H. Primary current 0.034x14=0.471A Off air due to short in upper helix which must now be rewound.

1 May 2016. Brief test: ~20 watts to the 100m wire up ~12 metres. Poor range. Not heard at 1 km but FSK from NAA and CW from RDL were heard clearly on the direct conversion RX.

8 April 2016. Licence renewed until December.

20 Mar 2016: VE7SL is interested in getting on VLF. German and English amateurs are sending EbNaut back and forth on 8.270 kHz.


2015

20 Dec 2015: VLF test. About 30 watts were fed to a 1:5 XFMR and a 0.47H tuning coil then to the 100m wire at 10m height. CW signals were heard clearly at 2 km using a homebuilt DC RX and a PA0RDT miniwhip. The sigs could not be heard on the DC RX at 2.7 km and were much weaker though audible on the XH100/LF10 with 20m of wire strewn in the trees. This is a new distance record for audible reception at 8.277 kHz.

I_a=0.17A R_rad=1579(10/36000)^2=122 uOhhm; P_rac=I^2R=3.5uW

08 Nov 2015. Best DX so far 5 km (Spectrum Lab, PA0RDT Miniwhip and DK7FC E-probe. Today using homebrew DC receiver, heard sigs clearly at 0.5 km on 8.277 kHz.

09 Jun 2015 awaiting renewed licence.

dB on SpecLab QRSS120 vs r in km.

31 May 2015 Licence expired. Renewal requested.

09 May testing DK7FC design VLF preamp circuit.

05 May '15. Tried QRSS100 but best range 3.8km (10 dB). Nil at 4.3, 6.6 km. MW + Spectrum Lab.

29 Apr. Rewound another pie. 6*0.08mm Cu wires. 276 mH 279 ohm and put about an inch above another pie 98 mH 159 ohm. ~ 0.45H. Sigs detected at 5.2 km(0010) but not at 5.9 km(0015). (CW instead of QRSS100 was used with spectrum lab (DL4YHF) in dot 60 mode.

The sigs appear at 8277.2 Hz due to a sound card calibration error.

21 Apr 15. Wound 2 new pie tuning coils using a drill press. Very quick and convenient. Now to get past the 5764.58277 m boundary....

15 Apr. Weak 8.277 kHz CW sigs copied at 1 km with xr2206/4066/lm386 VLF homebrew DC RX and PA0RDT Miniwhip antenna.

12 Apr detection of 12 WPM cw sigs using Spectrum Lab QRSS60 and mw antenna at 4.67 km.

5 Apr. Using same setup as below -- Weak but readable CW at 2.15 km.

4 Apr 2015. XH-100 & LF10: Audible CW reception at 1.25 km. Amp set at 5 (~30 watts). New tuning coil (0.1H) wound on wc paper roll to replace old one that apparently arced. Used with XBT spool (.17H) coaxial for L=.426H 1:5 ferrite match + variac (1:2).
Nature Magazine Vol 226 20 June 1970 reports on VLF reception in NL during eclipse. It was foggy at Marconi Place 7 March 1970. Rycroft & Reeve from U Southhampton. Spectra 1-10 kHz. 3m square loop, filters for 16 17.8 100 112.6 kHz ("GBR NAA Loran and a local navigation station..") The latter presumably Decca in Shoe Cove.

14 Mar Wound 2 more secondaries on the ferrite xfmr 30-32 turns 3.5 mH per winding. Juiced 1 winding and put the other 5 in series. One end to the .35 H coil, the other to gnd. Was able to measure aerial current for first time... about 6 mV across the 50 uA current probe meter/multiplier. Heard the CW ID on 8277 Hz at 0.75 km. A hawthorn tree could not be found so used a fir tree instead to test the MW and home-brew VLF RX...

DC VLF receiver & Miniwhip: CW on 8.277 kHz

9 Mar 2015 Volume level 4. Trouble measuring Iae; reception at 0.66 km. 10th procured coil.

Posted to the RSGB reflector 8 March 2015:
Yesterday an old XR2206 was discovered in the shack and it seemed this might make a nice LO for a DC RX. A 4066 was used as a mixer and an LM386 as the audio stage. The PA0RDT MW fed the mixer. A crude design for sure, not even a diplexer to follow the mixer so the 8730 Hz LO was qite loud in the speaker. It was a lovely sunny but cold day so I put the contraption against my ear held the MW above my head with the other hand and began walking. The VLF CW beacon could be clearly heard at 0.5 km but disappeared at 0.7 km. There were all sorts of strange noises heard including the Alphas For TX, about 10 watts were fed to a 1:4 xfmr and tuned to the 100m wire (15m mean height) with about 0.35 H of very lossy inductance. DL4YHF Spectrum Lab in the DC RX mode was used in earlier experiments but it seems the computer makes much QRM. For todays test, I took the computer battery pack to power the RX and left the noisy part the shack. This the best VLF DX so far from here. It is hoped to get a few km of wire for an improved tuning coil.


2014

27th Dec. 2014 Set up TX again on 8277 kHz. Heard it on 3 different receivers.

24 Dec. Good reception of SAQ on 17.2 kHz CW at 4:30 AM local. Used 100m wire, LF10 and XH100 with SRA8 mixer.

17.2 kHz Christmas Eve 2014 0806 utc

23 Dec 2014. A developmental licence is now in hand, valid for 6 months. Presently tinkering with a divider circuit to get high precision 8277 Hz signal. Getting noise from 7493 chip when something is connected to the output. Tried filtering the input with ferrite choke, bypass cap. which took out the ~10% noise. Tried shunting 0.01 uF across the 100 uF across Vcc of chip. now have a mar-3 amp to boost the docxo to 4 v p/p (2vp/p 50 ohm). Maybe feedback ?

SAQ on the air tomorrow morning. From xxxxx Mon Jun 23 17:03:33 2014 Date: Mon, 23 Jun 2014 17:03:31 -0230 (NDT) From: xxxxx To: rsgb at ba_ba_blacksheep.org Subject: VLF in Canada

Dear Group, I tried again to get an LOA for VLF. This time, the response from Industry Canada was favourable: 10 mW 8.0-8.3 kHz. Yesterday, after a few slight rf burns, and thanks to PA0RDT's miniwhip design and DL4YHF's Spectrum Lab and advice, VLF sigs on 8.277 kHz were heard at 200m from the 100m wire aerial. This was a reception outside my back yard! 10 watts from an 1970's keyboard amp (volume control set on 3) were stepped up with an xfmr to a lossy 500 ohm tuning coil peaked with a ferrite rod for maximum squeal at L=0.35 H. Is it possible for someone who is not especially enthralled by winding a mile of 0.7mm wire to use an iron core to make a VLF tuning coil?

73 Joe VO1NA


Canadian Table of Frequency Allocations:
http://www.ic.gc.ca/eic/site/smt-gst.nsf/eng/sf10759.html#t1
Below 8.3 kHz is unallocated, but footnoted:
C1 (CAN-14) Users of frequencies below 8.3 kHz shall ensure that no harmful interference is caused to the services to which the bands above 8.3 kHz are allocated.
C2 (CAN-14) Scientific researchers using frequencies below 8.3 kHz are urged to advise the Department in order that such research may be afforded all practicable protection from harmful interference.

Outside the back yard