Topographic map
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- Regular
- Posts: 58
- Joined: 03 Oct 2020, 20:46
- Location: Hampshire
Topographic map
Hi,
Found this and thought I'd share it. If you're looking for a good height dx point, this map can be scrolled and zoomed all over the place.
Have fun...
https://en-gb.topographic-map.com/maps/b9/England/
Found this and thought I'd share it. If you're looking for a good height dx point, this map can be scrolled and zoomed all over the place.
Have fun...
https://en-gb.topographic-map.com/maps/b9/England/
One person in ten understands binary, the other one doesn't.
- Stronty
- Veteran
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- Location: Up North
Re: Topographic map
Very handy, have used Hey What’s That over the years https://www.heywhatsthat.com/profiler.html
Can give you an idea of what’s around you.
Can give you an idea of what’s around you.
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- Regular
- Posts: 58
- Joined: 03 Oct 2020, 20:46
- Location: Hampshire
Re: Topographic map
Looks interesting, there goes another evening!
One person in ten understands binary, the other one doesn't.
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- Legend
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- Location: Bristol-ish
Re: Topographic map
Finally zoomed in to my town (took a while to keep loading), to find we're about 25-30m above sea level here. Seeing as we're quite close to the coast it's not too bad. However, the neighbouring towns of Portishead and Clevedon are both gone if the ice caps melt or there's a big tsunami!
- Mitch
- Radio Addict
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Re: Topographic map
If (when?) the ice caps melt, here's the one for that: http://flood.firetree.net/
The perfect face for radio.
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- Legend
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Re: Topographic map
Cheers Mitch.Mitch wrote: ↑08 Aug 2022, 21:29 If (when?) the ice caps melt, here's the one for that: http://flood.firetree.net/
Ooo... as suspected, Nailsea survives intact (just) but nearby Clevedon and Portishead are partly submerged...glug glug.
- Mudslinger
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- Location: Oxfordshire
Re: Topographic map
Google earth pro displays elevation too, if you hover the pointer it shows the height above sea level at that location.
There is more to finding a good spot than simply height though. Some of the best DX I have had were when the car was parked near the sea.
There is more to finding a good spot than simply height though. Some of the best DX I have had were when the car was parked near the sea.
Mudslinger - Simon
26TM274
26CT612
There is no such thing as a Fidelity 1000 which is too good to scrap.
26TM274
26CT612
There is no such thing as a Fidelity 1000 which is too good to scrap.
- Stronty
- Veteran
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- Location: Up North
Re: Topographic map
That's it in a nutshell, height is a lot of it but if you are trying for a certain point Hey Whats That compliments the elevation and let's you see where you are in respect to where you want to hit with your signal. However, its not the most intuitive, well at least I don't think so, but its handy once you get to know it.There is more to finding a good spot than simply height though. Some of the best DX I have had were when the car was parked near the sea.
From me to you near Portishead
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- Legend
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Re: Topographic map
Well we might be moving near Weston-super-Mare next year to be closer to my wife's parents, so I'll check if we might be underwater there and buy some scuba gear well in advance
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Re: Topographic map
Being up a hill should increase your low angle radiation. When you TX and RX radio waves what hits our antennas is a combination of direct sky wave and reflected ground waves. The sloping ground creates a favourable TX and RX in that direction. A lot of the DX from outside of Europe on 11m band (95pct) is coming in between 1 and 10 degrees off the horizon. Pretty low eh ? I was surprised to learn this as well.
The reason is that sloping ground makes the reflections more favourable at low angles. When there are 2 waves (one direct and one reflected combining together), in part they cancel each other and in part they reinforce each other. This is known as the phase of the waves. So the slope means there is greater reinforcement at lower angles than flat ground would allow.
This following image shows a ground reflection but for a line of sight contact, not propagated by the ionosphere. However the principle is the rather the same.
Phase of 2 waves they either add or subtract at different points of the combining. These are just example phases.
Low angles generally create the longest possible DX paths (when those paths are open).
At the seaside you get about 9dB extra gain on your TX and RX in the sea's direction. This is because the salt water reduces the "ground" losses associated with the summed reflections on tx and rx. It also increases the strength of your low angle radiation. Some research has suggested that you do not even need to be right on the beach to get some benefits.Though this is more likely at lower frequencies (with longer wavelengths) Read the first paragraph for more information:
http://www.on5au.be/Cebik-2/ThePseudo-b ... isited.pdf
I know a couple of CBers (also hams) went to the seaside to activate a location for an event on 11m and I was on a hill, I could here them just about. Sadly for some reason they had a bad day DX and I was doing quite well on the hill... in the same hours.
Both will often have 1 single major advantage, low noise floor. You will hear so much more with a low noise floor.
This is worth a look:
Low incidence angles can travel longer distances, longest is about 2,500 miles per hop from what is known as the F2 layer.
And in the early morning (say between 7am and 11am when conditions allow) you can make long path contacts to Aus and New Zealand
using a slightly different propagation called Chordal hop. (this is only theorized) A type of propagation where your radio waves become trapped
in the upper atmosphere due to a expansion/distortion of the layers which allow the waves to becomes ducted in the F2 layer. This is normally associated with the grey line. The grey line is a line around the planet where the sun is rising and setting in a distant location. Unique properties
at this time allow such "chordal" contacts. Rather than come back down with multiple lossy bounces it remains in the layers of the atmosphere themselves.
Have a read here:
https://www.pa9x.com/long-path-or-short ... opagation/
CB'er s are amateur radio people as well. It is just you are not called amateurs.
Even if you don't want to be a ham you can still learn a lot and it will help your dx chances.
The reason is that sloping ground makes the reflections more favourable at low angles. When there are 2 waves (one direct and one reflected combining together), in part they cancel each other and in part they reinforce each other. This is known as the phase of the waves. So the slope means there is greater reinforcement at lower angles than flat ground would allow.
This following image shows a ground reflection but for a line of sight contact, not propagated by the ionosphere. However the principle is the rather the same.
Phase of 2 waves they either add or subtract at different points of the combining. These are just example phases.
Low angles generally create the longest possible DX paths (when those paths are open).
At the seaside you get about 9dB extra gain on your TX and RX in the sea's direction. This is because the salt water reduces the "ground" losses associated with the summed reflections on tx and rx. It also increases the strength of your low angle radiation. Some research has suggested that you do not even need to be right on the beach to get some benefits.Though this is more likely at lower frequencies (with longer wavelengths) Read the first paragraph for more information:
http://www.on5au.be/Cebik-2/ThePseudo-b ... isited.pdf
I know a couple of CBers (also hams) went to the seaside to activate a location for an event on 11m and I was on a hill, I could here them just about. Sadly for some reason they had a bad day DX and I was doing quite well on the hill... in the same hours.
Both will often have 1 single major advantage, low noise floor. You will hear so much more with a low noise floor.
This is worth a look:
Low incidence angles can travel longer distances, longest is about 2,500 miles per hop from what is known as the F2 layer.
And in the early morning (say between 7am and 11am when conditions allow) you can make long path contacts to Aus and New Zealand
using a slightly different propagation called Chordal hop. (this is only theorized) A type of propagation where your radio waves become trapped
in the upper atmosphere due to a expansion/distortion of the layers which allow the waves to becomes ducted in the F2 layer. This is normally associated with the grey line. The grey line is a line around the planet where the sun is rising and setting in a distant location. Unique properties
at this time allow such "chordal" contacts. Rather than come back down with multiple lossy bounces it remains in the layers of the atmosphere themselves.
Have a read here:
https://www.pa9x.com/long-path-or-short ... opagation/
CB'er s are amateur radio people as well. It is just you are not called amateurs.
Even if you don't want to be a ham you can still learn a lot and it will help your dx chances.
- Mitch
- Radio Addict
- Posts: 600
- Joined: 02 Nov 2012, 21:26
- Call Sign: M1TCH
- Location: Leicestershire UK
Re: Topographic map
The perfect face for radio.
- Stronty
- Veteran
- Posts: 2798
- Joined: 24 Sep 2007, 17:48
- Location: Up North
Re: Topographic map
Nice!Mitch wrote: ↑13 Aug 2022, 17:13 Here's one that might be useful for next week:
https://www.lightningmaps.org
Here's another one! i even find this one nice to look at
https://earth.nullschool.net/#current/w ... 12,-52.248
- Mitch
- Radio Addict
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- Joined: 02 Nov 2012, 21:26
- Call Sign: M1TCH
- Location: Leicestershire UK
Re: Topographic map
The perfect face for radio.
- Stronty
- Veteran
- Posts: 2798
- Joined: 24 Sep 2007, 17:48
- Location: Up North
Re: Topographic map
Ohhhh! Trippy that oneMitch wrote: ↑13 Aug 2022, 19:04
^ How about this one in colour, with options:
https://www.ventusky.com