Friday, 19 January 2018

Great new semi-/P operating location.

Many years ago, as a teenager interested in astronomy, I was given kind permission to use an old water pump building in the middle of a big field to store and act as a base for my telescope(s).  Until then, I had to carry the whole instument in pieces in my little Ford Fiesta, often attracting a stop from police at 1am!

After some years, I had an observatory at home, and stopped using the field.

My 280mm and 158mm Newtonians in the field, about 1990.
Recently, with a mind to freeing myself from the home QTH, I thought it would be very useful to have access to that field and its pump house again for more scientific fun.  The person from whom I gained permission, which was granted so long as I needed it, died many years ago.  So the new owner or renter may be surprised and not like me turning up again, all of a sudden.

Anyhow, I visited the pumphouse this afternoon, and found that I had left the door padlocked, although I was sure I had left it unlocked when I stopped using it in the early 2000s.  Taking a photo through a very small opening with my phone's camera and flash, I could see parts of the old telescope cover and a small desk were still inside, just like I left them nearly 20 years ago!

Time capsule - very odd to see this still there (including the car battery and an old jamjar magnetometer (magnet and mirror on a thread in a coffee jar!)

The field is very wet, being essentially a marsh where water levels rise to a temporary lake in winter.  It's ideal for radio, because it is very open, with an almost flat horizon all around.  It is also far away from any RFI, being one of the most isolated spots on the island.

Terrain profile from the marsh to USA (280 degrees)

Terrain profile from copper mine site to USA (280 degrees)

My dad, now 85 years old and who helped me build a base and cover for my telescope mount all those years ago, knows just about every landowner on Anglesey.  So I called in for a cup of tea and asked who owned the field.

Turns out the person who gave me permission was only renting the field, so couldn't really, at least in the strict legal sense, have given valid permission for someone else to access it.  Still, I never caused any problems, and so it was no issue.  My dad knew who the landowner was, a man from a semi-aristocratic family who came to Anglesey without any Welsh language at the age of 10, but who now sounds just like a native, albeit with a hint of aristocratic English underneath it all!

Within seconds of explaining why I had turned up on the farm on a bitterly cold day, and who's son I was, I had hand-waving 'of course you can' permission to enter the land and use the pumphouse again.  That's the very best hospitality of Wales, though increasingly a rare thing in today's litigious society.

The new grid is IO73th, grid square SH47. 

The possibilities are now very good, and there are even a few mature trees from which to hang larger verticals or v-beams. With a basic but perfectly weather-proof building to shelter in, it will be easy to run laptops and such like with little difficulty.  Maybe I'll ask if I can put a solar panel or two up in a little while, or perhaps even grab an old Honda generator!

MW6PYS now transmitting from the new site on WSPR (14MHz).

UPDATE:

WSPR site comparison tests at 14MHz from mid-afternoon onwards after installation at the marsh show essentially neck-and-neck performance between two identical verticals, one at the copper mine, the other at the marsh (pictured above).  This, despite the sea not being visible and the site in a slight depression at the marsh.

Open marsh (MW6PYS, red) vs. Copper mine (MW1CFN, blue)


Signal/noise at the receiver when all distances are taken into account, comes out at the marsh site being very slightly (0.5dB) better than the copper mine site.  I have an issue with DXPlorer's use of arithmetic mean, though, because the median is better for the type of outliers one sees with signal propagation.  Using the median of 60 spots, the outcome is 0dB - no difference at all between the two.  I expected the copper mine to have done better as the signal angles reduced, but this doesn't happen in practice, perhaps hinting at a practical limit to 'takeoff' angles, even when the ground is elevated and sloping towards the visible sea, as it does at the copper mine.

For this discussion, though, I am not really interested in spots from Europe, so I am focusing on the DX performance.

All distances, with arithmetic mean computation.


When limiting the spots to those beyond 4600km, the situation changes markedly, with the marsh site 1.95dB better using the mean, 2dB better on median.  Again, I'm amazed.

Spots beyond 4600km.

All spots on the first afternoon to evening run:


Second day's (longer) WSPR run.

In the period of mid-morning to late afternoon (21/01/18), at DX distances beyond 4000km, the marsh site was up to 3.5dB (on arithmetic mean) better than the copper mine site.  This reflects the data from day 1, and we can settle on a consistent difference of at least 2dB for DX spots in favour of the marsh site for much of the day.

In terms of relative power, a 3.5 dB increase over 200mW amounts to the signal 448mW would give - a factor of over two times.

7.5hours of range data.  Marsh site (red), copper mine (blue).

The range graph shows a small but significant increase in DX range for the marsh site, and also a greater maximum range.

Considering (below) all 208 simultaneous spots, over all distances over the 7.5 hours of the test, the marsh site is 2.7dB better than the copper mine site. 



Beyond 4000km, the situation (below) is even better: a difference of 3.5dB.


Overall, then, and although there is a small change with time of day in the degree of advantage for the marsh site, it is always better, falling typically between 0.5 and 3.5dB.  I think I can be very happy with the new site!

Day 3 - morning run.

Last evening saw an extremely sharp cut-off in spots from much of anywhere.  At about 19UT, I looked at WSPRnet and was only being heard by two Italian stations.  With a change in the wind direction and strength, and having stays that only supported the antenna from the opposite direction, I was worried the system had fallen over!

Having trudged in the dark through an extraordinarily wet field and sinking to my shins at one point, I reached the antenna to find it was perfectly fine.  Having checked all the connections and reset the WSPRlite, all looked fine.  When I got home and looked at the magnetogram in Sweden, it was clear that a significant disturbance in the geomagnetic field had occurred, wiping 20m propagation clean away.

This morning, then, with very sbudued propagation on the recovery from last evening's disturbance, I gathered morning comparison data from about 07 until 12UT.

The range persists as significantly better for the marsh site (red):


The reported SNR advantage across all distances for the marsh site is the highest yet seen, at 4dB (2.5 times) better than the copper mine site:

Beyond 2400km, the SNR advantage is 2.4dB better for the marsh site:



Before I finish, I have to compare the marsh site with other WSPR stations.  I stress that the stations chosen are merely those with a decent number of spots, and which have been checked against many other stations to ensure they provide a typical comparison.  No stations came close to the performance of the marsh site.

First, here's someone running 5W.  The marsh matches the range using over 12dB less signal - just 0.2W.



Next, here's a station also running 200mW, with spots limited to good DX (more than 4000km) - a benefit for the marsh of over 4dB.  All data, by the way, is over just under 3 days in total:



The mean and peak range were considerably better for the marsh site at all times of day:


1 comment:

  1. A remote operating site, how cool. Great blog, keep it up. Mi0YPT.

    ReplyDelete