Sub 9kHz amateur radio

Although far from perfect, I try to keep up with the latest news about amateur radio below 9kHz. Quite a lot is happening.

Surprisingly, large antennas are not needed for receive and all the software you need is free.

This is one of the true frontiers in our hobby and access is easier and far less expensive than you might think. A perfectly fine RX setup can be made for a few cups of coffee in a café.

Most activity is just below 8.3kHz, which remains unallocated in many countries.

See https://sites.google.com/site/sub9khz/

Dreamer's Band (sub 9kHz amateur radio)

This is the new frontier. As Paul Nicholson pointed out, it is inexpensive and fun. It is much easier than many think.

"Perhaps the perception is that it is difficult?  Surely not.
Don't believe all those stories you hear about how hard it is
to radiate, or how difficult it is to find a location to
receive from!

Let's see -

- Low cost. You don't need expensive SDRs or test equipment.
  Your PC soundcard is signal generator, spectrum analyser,
  and SDR, all in one.  Transmitter is just an audio amplifier,
  even a low quality one.  The most expensive thing you'll buy
  is a load of wire for a loading coil.

- GPS timing?  £18 quid for a NEO-7 module and you know your
  frequency to the micro Hertz.  Buy two, you'll use them!

- Easy to build.  Just audio frequency signals, nothing critical
  about layout.   VLF is great for the homebrew enthusiast.

- You don't need a huge ERP.  10uW and you're on the air.  Your
  LF antenna will probably do better than you think at VLF.

- UK Notice of Variation?  No problem, a simple application form,
  and if enough apply, maybe the regulators will make that easier.

- Where else can you operate at the cutting edge with such
  simple equipment?

In case you think my location here is specially good, it certainly
isn't.  The mains here at the top of the Calder Valley is very
rough, terrible sidebands.  All the properties around here get
their power by overhead lines at 12kV and one of the two 33kV
lines feeding Todmorden is only a km away.  The nearest 12kV
line is just 120m from the E-field antenna. 140mV RMS of 50Hz
on the E-field probe and a lot of harmonics.  Reception here is
bad!   You can probably do better in the suburbs.

How many times per century does amateur radio find a green field
to explore?  Not just a new band but a whole new frequency range.

Don't miss out on this one!

--
Paul Nicholson"

Continuing radiated tests on VLF from Holland

Henny PA3CPM continues to fire up his VLF system on  8.270kHz from time to time. Henny has a very small antenna, just a top loaded 14m long sloper but he manages to get 0.6A antenna current and his signal is now regularly copied several hundred kilometres away by people with suitable antennas, preamps and software. Unlike my own VLF earth-mode transmissions, Henny's signals propagate by radiation. He is a shining example of what can be done with a modest set-up on the so-called "Dreamer's Band".  It is no mean feat to radiate a decent signal on VLF with such a small antenna. I have asked Henny for photos of his VLF TX, antenna and loading coil.

More VLF activity from Germany

DJ8WX has been experimenting with a new GPS locked frequency source and is trying to put a signal out on 8.9700000kHz.  The signal has been received strongly by several stations including Paul Nicholson in Todmorden and at PA1SDB. This is the signal at PA1SDB over the last few days. Note the timescale on Peter's grabber covers several DAYS. Such is the world of amateur VLF!

Signal from DJ8WX now on 8.970000kHz (was 8.970022kHz)

Amateur activity on VLF in the last few days

Several amateurs in Europe have reported strong signals on 8970.022Hz VLF, a frequency used in the past by DJ8WX near Hamburg. It is some months since there has been any amateur "dreamers band" activity, so this is very welcome. This is the signal as seem in the Czech Republic on the OK2BVG grabber. Note the timescale on the grabber picture. It is necessary to watch the signal for very many hours to see the signal appear. Hence, very stable transmissions are needed, and a receiving system that is able to hold to a few uHz for hours and hours on end. Just listening on VLF and you will have ZERO chance of detecting such signals.
Amateur VLF reception is usually a "whole new ballgame" compared with listening for the strong MSF signals sending to submarines which are very strong.

VLF amateur signal, believed to be DJ8WX yesterday seen on Lubos, OK2BVG's grabber

Busy amateur VLF weekend

G3ZJO's reception of DK7FC on 8.97kHz

Yesterday's test by DK7FC from his fixed location was a resounding success with reception all over Europe by many stations including G3ZJO, G3WCD and G3KEV, and what is believed to be the first transatlantic reception of an amateur VLF signal by a station in the Eastern USA. Results are being checked as I write.

Stefan's ERP was later re-calculated as around 800uW. It is incredible that such a tiny VLF signal can be detected so far away. If confirmed, this certainly heralds the dawn of a new and exciting phase of VLF amateur work. With another 3-6dB ERP, worldwide amateur VLF DX is now a real possibility. Of course such VLF DX reception requires incredible frequency stability, very narrow RX filters and long signal integration times; signals are far too weak to hear.

Also, Marcus DF6NM ran a 8.97kHz test today using a kite antenna. G3ZJO received a good signal in IO92ng 20dB above the noise in 424uHz bandwidth. Marcus was also well received by many other stations across Europe.

In summary, this weekend has been a BUSY one on the Dreamer's Band.

Amateur VLF transmissions this week

G3XIZ as received at 45km 4.6.11

Both Marcus DF6NM and Chris G3XIZ have been active on VLF this last few days. G3XIZ was a good signal on 8.976662kHz with his improved antenna and DF6NM has been copied in Yorkshire by Paul Nicholson. Although QRN can be a problem at this time of the year there is still activity. The screen shot here shows G3XIZ's VLF signal with me today.

A busy VLF amateur band (8-9kHz)

DK7FC's 8.97kHz grabber showing 4 stations active!

This screen shot from DK7FC's grabber shows just how busy this band is now becoming and how much progress has been made in the last 12 months. Visible in the grab taken March 6th 2001 are DJ8WX, OE3GHB, DK7FC (local testing) and DF6NM. Only a year ago people dismissed experiments at sub-9kHz as dreaming whereas today stations are regularly getting reports from anything from a few km to nearly 3000km for the better equipped stations.

This is REAL ham radio at the frontiers folks - put your cheque books away, forget those black boxes and join the fun on the Dreamer's Band.

VLF Dreamer's Band video

For those interested, I've made a short video showing my current VLF receiving set-up for 8.7-9.1kHz (antenna, matching, preamp, PC) used in the recent VLF reception tests in which G3XIZ has been copied twice now (45km), DJ8WX all of yesterday (645km) and DK7FC/P twice (629km). I am not claiming it to be fully optimised, but it certainly works.

What I like is that the wire antenna and the preamp cost a few pounds, the software is free (thanks Wolf) and the results mind blowing. In the near future I will try replacing the loop and preamp with a small E-field probe.

This is the link http://www.youtube.com/watch?v=UxEAhqPFBFE

Also, G3XIZ was copied again on 9.0909kHz VLF at 45km. He was also copied by a few other UK stations including G3ZJO and M0BMU.

Austrian VLF tests this weekend

Gerhard OE3GHB hopes to be transmitting on VLF this Saturday (Jan 22nd) on 8.96995kHz (+/- 0.03Hz) starting between 0800-0900z. Although the chances of copying him are low, I will be monitoring and uploading what I see (or do not see) to my VLF grabber which will be active as long as possible this Saturday.

Dreamer's Band activity around 8.97kHz

In the last few days OE3GHB and OE5ODL have been testing close to 8.97kHz with their signals (from home QTHs) being received at considerable distances across Western Europe. DK7FC was planning his 10th kite VLF test this weekend but has had to postpone this until Jan 29/30 because of the weather. My grabber is currently looking around 8.97kHz and seeing a strong signal, although I suspect this is a locally generated interferer. See http://dl.dropbox.com/u/15047843/xbm_grab.jpg for the grabber as it updates. This is not on all the time, just when I am testing or listening.

A 4th UK station with VLF NoV

Just received this from Gary G4WGT:

"Today I received my SRP from Ofcom to carry out research and experiments on the 9kHz band. The NoV is effective immediately and expires on 10th January 2012. The allocated frequency, power and additional conditions are the same as for other UK 9kHz operators, ie. 8.700kHz to 9.100 kHz with a maximum of 100mW (-10dBW) e.i.r.p. I am not ready to transmit a signal yet but it will be quite soon. I will make an announcement through the usual channels.

73  Gary - G4WGT"

Diurnal Variation in Dreamer's Band Noise

Over the next 24 hours I am doing a test to measure the change in VLF noise floor between 0-24kHz. DK7FC has let me have a suitable .usr file for Spectrum Lab to allow this to be recorded. You can see the results on the G3XBM VLF grabber which is updating the plot every 15 minutes.

G3XIZ on 8.97kHz today

Chris, G3XIZ was testing on the Dreamer's Band again today and I was monitoring some 34km to the east. Unfortunately, this attempt was also unsuccessful with no copy here in East Cambridgeshire.

DK7FC's report on his 9th VLF experiment

DK7FC with his VLF loading coil

Stefan has summarised the results of his latest tests on VLF. This is well worth reading with best DX 2873km and lots of new stations receiving his transmissions for the first time.

This picture was taken by a friendly visitor and there are more pictures at http://mkorbit.de/2010/12/05/weltrekord-signalubertragung-auf-einer-langstwelle-vlf/

8.76kHz field testing in the snow at 1.5km

With a temperature around 0 deg C I did a field trip today TXing on 8.76kHz VLF to test two things: (1) to check the rebuilt 4-5W TX based on the TDA2003 could be copied at moderate range and (b) to try out the new tuned preamp with earth electrode receive antennas and see how these compared with a loop. The usual first test site, a National Trust car park about 1.5km from home was chosen. Today it was totally deserted with more sensible people curled up in front of warm fires. Using the 80cm receiving loop or with the earth electrode antenna (electrodes placed about 13m apart) decent

copy was achieved in QRSS3, using Spectrum Lab this time rather than Spectran on the PC.  For the earth electrodes I just used barbecue skewers pushed in about 10cm into the very cold ground. Reception was also possible with the two earth electrodes just 2m apart. The first picture shows the signal received with a loop. The second is with the earth electrode antenna on receive. The ground was covered in a thin layer of wet snow and results when the soil, and soil surface, are dry should be better on earth mode conduction using earth electrodes at each end. The roads in the Fens were too icy to try reception at a more distant point 5-6km away. Also, I need a much longer baseline earth electrode pair in the car in case this is needed at greater range.

Looking for G3XIZ on VLF this evening

G3XIZ is transmitting with 20W to his Marconi vertical on 8.9719kHz this evening from 2000-2200z. I am looking out for his signal with my loop into both Spectrum Lab and Spectran software. You can look on my VLF grabber to see if he is visible at all over here in JO02dg. At the moment all that is visible is a wobbly 50Hz related signal and my 8.760kHz QRSS3 beacon running on a dummy load. UPDATE: nothing copied and Chris had to close because of an antenna fault at 2100z.

VLF Grabber operational capturing 8-9kHz in JO02dg

I'm setting up a VLF grabber at my home QTH to take periodic screenshots of the 8-9kHz Dreamers Band and make these available online. At the moment it is taking input from my earth electrode "antenna" into Spectrum Lab and is very much a work in progress and needs a lot of improvements on the RX and antenna front. It won't be ON unless I'm in the shack and don't need the PC for other VLF stuff.  

The resulting screen grab every few minutes appears at https://dl.dropbox.com/u/15047843/xbm_grab.jpg . 

UK first transmission on the Dreamer's Band (8.760kHz)

Signal received at 5.1km from home QTH on 8.760kHz VLF

This morning 0915-1115 GMT I transmitted a QRSS3 beacon signal on 8.760kHz under the terms of my NoV recently received.  I think this is a first in the UK, legally at least.

8.76kHz TX

TX was 4W from a TDA2002 audio IC matched into earth electrodes 20m apart. The beacon signal was provided by a K1EL keyer chip and the frequency reference by dividing down an HF crystal by 512 times in a 4060 divider IC. Reception was possible 5.1km away from the transmitter location, detecting the signal with an 80cm loop fed into an E-field probe (Hi-Z input) into Spectran running on a WinXP PC. Best reception was always with the loop flat on the ground suggesting the main mode of propagation is utilities assisted earth mode. Comparing results on 8.76kHz with those at 838Hz earlier in the summer, my first impressions are that signal levels are some 6dB weaker, but more careful tests will be needed.

Preparations for Dreamer's Band Tests

This evening I modified my loop antenna and VLF preamp to better optimise them for use at 8-9kHz and also modified my E-field probe antenna. So, on the RX side I think I'm ready with the hardware. By Wednesday I hope to have the 4060 divider behind the HF crystal to give me a stable 8.750kHz source for the TX. If the weather is reasonable I should be out testing in the Fens locally by Wednesday or Thursday.