HFU HF Underground
Loggings => DGPS => Topic started by: skeezix on August 30, 2017, 2327 UTC
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Bjargtangar Lt
Wednesday, August 30, 2017 07:15:58
Horta
Wednesday, August 30, 2017 19:02:29
Count ID ref1 ref2 kHz Baud City Country Lat Lon km Deg
1 117 434 435 318.0 100 Sagar Island Lt India 21.662 88.059 12,601 358
579 879 258 259 286.0 100 Upolu Point, Hi Hawaii 20.257 -155.885 6,285 266
1 342 484 485 308.0 200 Horta Azores 38.533 -28.617 5,280 74
1 412 624 625 300.0 100 Bjargtangar Lt Iceland 65.503 -24.531 4,614 36
110 891 282 283 295.0 100 Level Island, AK Alaska 56.467 -133.098 3,014 309
1 944 342 343 310.0 200 Cape Norman, NL Canada 51.509 -55.831 2,842 62
870 942 340 341 288.0 200 Cape Ray, NL Canada 47.636 -59.241 2,621 71
174 885 270 271 292.0 100 Cape Mendocino, CA United States 40.447 -124.405 2,563 270
25 909 300 301 309.0 200 Alert Bay, BC Canada 50.589 -126.93 2,554 296
12 808 016 017 314.0 200 Card Sound, FL United States 25.442 -80.452 2,468 147
2 881 262 263 302.0 100 Point Loma, CA United States 32.677 -117.25 2,462 244
1 908 302 303 315.0 200 Tofino [Amphitrite Point], BC Canada 48.931 -125.545 2,456 292
12641 764 210 211 314.0 200 Lincoln, CA United States 38.855 -121.361 2,395 263
5228 886 272 273 287.0 100 Fort Stevens, OR United States 46.208 -123.96 2,363 284
9757 907 304 305 320.0 200 Richmond, BC Canada 49.114 -123.183 2,283 292
1 936 332 333 319.0 200 Point Escuminac, NB Canada 47.075 -64.8 2,210 74
5063 871 172 173 300.0 100 Appleton, WA United States 45.792 -121.332 2,168 282
480 809 018 019 289.0 100 Cape Canaveral, FL United States 28.467 -80.554 2,162 144
3 939 326 327 295.0 200 Partridge Island, NB Canada 45.239 -66.056 2,138 80
17165 827 244 245 312.0 200 Tampa, FL United States 27.85 -82.543 2,138 149
10126 799 044 045 290.0 200 Penobscot, ME United States 44.453 -68.776 1,942 83
7900 772 198 199 306.0 200 Acushnet, MA United States 41.749 -70.889 1,852 93
13716 771 196 197 294.0 100 New Bern, NC United States 35.181 -77.059 1,765 123
191 778 192 193 292.0 100 Kensington, SC United States 33.491 -79.349 1,759 132
4226 828 246 247 301.0 100 Angleton, TX United States 29.301 -95.484 1,756 187
2906 803 006 007 293.0 100 Moriches, NY United States 40.794 -72.756 1,743 98
14156 927 316 317 309.0 200 Lauzon, QC Canada 46.821 -71.165 1,729 75
305 814 028 029 293.0 200 English Turn, LA United States 29.886 -89.947 1,709 169
12429 806 012 013 289.0 100 Driver, VA United States 36.963 -76.562 1,670 116
1443 804 008 009 286.0 200 Sandy Hook, NJ United States 40.475 -74.02 1,659 101
27865 844 094 095 324.0 200 Hudson Falls, NY United States 43.272 -73.542 1,595 90
283 929 312 313 296.0 200 St Jean Richelieu, QC Canada 45.324 -73.317 1,574 82
6236 847 058 059 301.0 200 Annapolis, MD United States 39.018 -76.61 1,538 110
1 865 160 161 320.0 200 Millers Ferry, AL United States 32.095 -87.397 1,528 158
3187 919 308 309 306.0 200 Cardinal, ON Canada 44.783 -75.417 1,417 85
28828 792 136 137 297.0 200 Bobo, MS United States 34.125 -90.696 1,233 168
16265 839 118 119 322.0 100 Youngstown, NY United States 43.239 -78.972 1,170 95
5711 918 310 311 286.0 200 Wiarton, ON Canada 44.75 -81.117 971 87
30709 838 116 117 319.0 200 Detroit, MI United States 42.306 -83.103 883 106
23799 836 112 113 292.0 200 Cheboygan, MI United States 45.656 -84.475 704 81
89661 777 218 219 304.0 200 Mequon, WI United States 43.202 -88.066 474 113
41852 831 102 103 298.0 100 Upper Keweenaw, MI United States 47.233 -88.628 446 55
51124 830 100 101 296.0 100 Wisconsin, Point WI United States 46.708 -92.025 219 30
(http://i.imgur.com/sDUiZEU.png)
CURRENT DGPS ADVISORIES FOR 30 Aug 2017
Site Name Site Id BNM # OUTAGE MESSAGE
SCHEDULED / UNSCHEDULED OUTAGES
Biorka 890 0317-17
BROADCAST SITE WILL BE UNUSABLE FROM 09/07/2017 16:00 Z TO 09/09/2017 16:00 Z.
Aransas Pass 816 0323-17
BROADCAST SITE IS UNUSABLE AS OF 08/25/2017 21:29 Z UNTIL FURTHER NOTICE.
Angleton 828 0325-17
BROADCAST SITE STATUS IS UNCONFIRMED DUE TO NETWORK OUTAGE AS OF 08/27/2017 00:46 Z UNTIL FURTHER NOTICE.
New Bern 771 0321-17
BROADCAST SITE WILL BE UNUSABLE FROM 09/21/2017 10:00 Z TO 09/21/2017 22:00 Z.
Sandy Hook 804 0320-17
BROADCAST SITE WILL BE UNUSABLE FROM 09/05/2017 12:00 Z TO 09/06/2017 20:00 Z.
CANADIAN DGPS OUTAGES
CURRENT CANADIAN DGPS ADVISORIES FOR 30 Aug 2017
Site Name Site Id BNM # OUTAGE MESSAGE
SCHEDULED / UNSCHEDULED OUTAGES
Western Head N011-17
BROADCAST SITE IS OFF AIR AS OF 07/25/2017 15:00 Z UNTIL FURTHER NOTICE.
AFE822x v2.0 SDR with 43' Wellbrook ALA100LN loop oriented E-W
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Interesting how you only get three daytime stations, all under 500 km. I need to see what I can get here in the daytime.
I just realized how much closer to Alaska you are. The Alaskan DGPS stations are mostly around 3,000 km from you, Kodiak is 4,167 km. Upolu Point, Hi is 6,285 km, I guess that is your furthest catch?
The west coast stations are around 3,600-3,800 km from me, Alert Bay is 4,016 km. Level Island Alaska (which I have heard) is 4,415 km from me, and Kokole Point Hawaii (which I have not heard) is 7,874 km. Azores is 4,122 km, and Madeira is 5,374 km. Portugal is 5,648 km and Helgoland Germany is 6,233 km, I think my furthest catch - a brief 19 second opening with 3 decodes, on a split channel which helped I am sure. Hmm, Koblenz Germany was also received once with 3 decodes but over 12 minutes. But also on a split channel. 6,385 km.
In many ways, the Alaskan stations are a similar distance from you as the west coast stations are for me. And Hawaii for you is about the same as Europe for me. Also these both are our longest distance catches, and they are very similar in distance. Your path to Hawaii has to travel over a bit of the US first before the Pacific Ocean, I have a shorter distance to the Atlantic, but then for stations from continental Europe there is a bit of land again. You do get Hawaii more consistently than I get Europe, and with many more decodes. A lot of this is a function of what other stations the desired target has to compete with (part of my motivation to build the loop)
I find it interesting how comparable the distances are, and whether they represent the maximum range possible. There's also the transmitter power (and antenna pattern) of each of the stations. I believe Canada has coverage maps on their site. How many of these stations have omni directional antennas, how many are purposely directional, and how many are accidentally directional due to local terrain? I believe there is a west coast DXer that routinely gets DGPS from Australia. Quite a long haul, but if it is only over the ocean, that helps a lot.
I need to read up a bit on MW/LW (DGPS sits right at the intersection of the two) propagation. I wonder what distance is covered by each hop, and is roughly 6,000 km a maximum because it is several hops already, and any further is attenuated too much? Especially for the power level, I believe these stations are typically a few hundred watts. vs the megawatt (or at least hundreds of kW) that the broadcast stations use. NDBs are at roughly the same power as DGPS stations I think, although CW is going to be a more efficient mode. If only decoding of it over the entire band could be automated.
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Interesting how you only get three daytime stations, all under 500 km. I need to see what I can get here in the daytime.
I used to get more, but the U.S. Army Corps of Engineers decommissioned a few back in May-July. My favorite was St Paul, as it was strong throughout the day and when it was breaking up, I could tell bad storms or something was wrong. There were times when I thought my station might have a problem, but St Paul confirmed it was just propagation.
I just realized how much closer to Alaska you are. The Alaskan DGPS stations are mostly around 3,000 km from you, Kodiak is 4,167 km. Upolu Point, Hi is 6,285 km, I guess that is your furthest catch?
Yes, so far Upolu Point the furthest, at least that I've been able to confirm.
The west coast stations are around 3,600-3,800 km from me, Alert Bay is 4,016 km. Level Island Alaska (which I have heard) is 4,415 km from me, and Kokole Point Hawaii (which I have not heard) is 7,874 km. Azores is 4,122 km, and Madeira is 5,374 km. Portugal is 5,648 km and Helgoland Germany is 6,233 km, I think my furthest catch - a brief 19 second opening with 3 decodes, on a split channel which helped I am sure. Hmm, Koblenz Germany was also received once with 3 decodes but over 12 minutes. But also on a split channel. 6,385 km.
In many ways, the Alaskan stations are a similar distance from you as the west coast stations are for me. And Hawaii for you is about the same as Europe for me. Also these both are our longest distance catches, and they are very similar in distance. Your path to Hawaii has to travel over a bit of the US first before the Pacific Ocean, I have a shorter distance to the Atlantic, but then for stations from continental Europe there is a bit of land again. You do get Hawaii more consistently than I get Europe, and with many more decodes. A lot of this is a function of what other stations the desired target has to compete with (part of my motivation to build the loop)
Very true. A couple of things:
- Hawaii is a little lower in latitude than I am, so our daylight is about the same. Over in Europe, some of them are further north which means in summer, more daylight.
- For the path MN to HI, over middle of US then over water. For MN to EU, its a more polar route. For MD to EU, its still more polar than from MN to HI.
- Then there's MN to AK. All over land, and AK is way up north, but it comes into southeast AK. Still impact from polar conditions.
- With winter on the way, this will be interesting.
Q: How much does the polar impact LW/MW propagation?
I find it interesting how comparable the distances are, and whether they represent the maximum range possible.
Unknown, unless we had stations every 0.5 km in a full grid on the earth. Far too many holes in the DGPS stations.
There's also the transmitter power (and antenna pattern) of each of the stations. I believe Canada has coverage maps on their site. How many of these stations have omni directional antennas, how many are purposely directional, and how many are accidentally directional due to local terrain? I believe there is a west coast DXer that routinely gets DGPS from Australia. Quite a long haul, but if it is only over the ocean, that helps a lot.
This is one of the biggest factors. You can see from the CCG maps a great disparity in patterns (assuming they're accurate).
And then there's there's the ground between them & us.
Water (esp salt water) helps a lot. You can see that with some coastal U.S. MW stations and their patterns.
I need to read up a bit on MW/LW (DGPS sits right at the intersection of the two) propagation. I wonder what distance is covered by each hop, and is roughly 6,000 km a maximum because it is several hops already, and any further is attenuated too much?
Good question. At ~6km , daylight can't be far away on either end, esp when in summer. If we could turn the sun off for a couple of days...
Especially for the power level, I believe these stations are typically a few hundred watts. vs the megawatt (or at least hundreds of kW) that the broadcast stations use. NDBs are at roughly the same power as DGPS stations I think, although CW is going to be a more efficient mode. If only decoding of it over the entire band could be automated.
The power of NDBs and DGPS stations are roughly the same. I think the NDBs range from 25W to 1-2kW, with modest antennas.
The NDBs- There is the carrier + LSB + USB. That would be harder to decode. They're all on 1.0 kHz spacing, with US stations the MCW is at 1030 Hz. Canada is 400, IIRC. I don't know about doing the entire band at the same time, but if you pick some target stations, listen for the LSB+USB signals. If they match, then look for something midway that could be identified as a carrier, then lock onto that thing. Measure the carrier. If one sideband is lost, no big deal, listen to the other. If both are lost, then could no longer consider the carrier as ID'd. Or something like that. Measure the strength of the carrier & the sidebands (independently).
However, trying to decode weak CW may be hard, as an H may turn into an S. Which is one reason why I think fine resolution may not be possible. Would need to listen to the CW over time and determine its true ID vs problems from fading.
That should work, until you factor in multiple stations on the same frequency. Or even adjacent freqs since the 1 kHz spacing is pretty close to the 1.03 kHz spacing of the MCW.
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Very true. A couple of things:
- Hawaii is a little lower in latitude than I am, so our daylight is about the same. Over in Europe, some of them are further north which means in summer, more daylight.
- For the path MN to HI, over middle of US then over water. For MN to EU, its a more polar route. For MD to EU, its still more polar than from MN to HI.
- Then there's MN to AK. All over land, and AK is way up north, but it comes into southeast AK. Still impact from polar conditions.
- With winter on the way, this will be interesting.
Q: How much does the polar impact LW/MW propagation?
Agreed, the actual path, whether it is mostly over land or water, matters a lot.
From the papers, there is a substantial auroral effect.
Water (esp salt water) helps a lot. You can see that with some coastal U.S. MW stations and their patterns.
Definitely.
The power of NDBs and DGPS stations are roughly the same. I think the NDBs range from 25W to 1-2kW, with modest antennas.
The NDBs- There is the carrier + LSB + USB. That would be harder to decode. They're all on 1.0 kHz spacing, with US stations the MCW is at 1030 Hz. Canada is 400, IIRC. I don't know about doing the entire band at the same time, but if you pick some target stations, listen for the LSB+USB signals. If they match, then look for something midway that could be identified as a carrier, then lock onto that thing. Measure the carrier. If one sideband is lost, no big deal, listen to the other. If both are lost, then could no longer consider the carrier as ID'd. Or something like that. Measure the strength of the carrier & the sidebands (independently).
However, trying to decode weak CW may be hard, as an H may turn into an S. Which is one reason why I think fine resolution may not be possible. Would need to listen to the CW over time and determine its true ID vs problems from fading.
That should work, until you factor in multiple stations on the same frequency. Or even adjacent freqs since the 1 kHz spacing is pretty close to the 1.03 kHz spacing of the MCW.
The fact that the MCW sidebands of US NDBs are almost on top of the adjacent NDB channels is frustrating. Why oh why did we do it that way? There is that nominal 30 Hz separation, which might be enough. But there's another problem - nominal. The actual NDB carrier frequencies and sidebands are all over the place. Along with the actual CW WPM speeds, and interval rates for repetition of the callsign. In a way that is good, because it means they are not always on top of each other. But it is also bad because you'd need a table of all the actual values. And I am not sure how constant they are, they could drift all over the place (both in frequency and speed/time). So you really want some sort of a smart algorithm that looks for anything that appears to be CW. Unfortunately, noise often looks like CW.
One way to extract a weak repetitive signal out of the noise is to integrate multiple receptions. If a beacon transmits its callsign every 5 seconds, you take 5 second snapshots of the audio, and effectively lay them on top of each other. The noise, being random, averages itself towards zero. I think they do this with astronomy photos calling it stacking. Works great. But, you need to precisely know the repetition rate. And it needs to be stable. I tried playing around with this a while back with actual recorded NDB audio, but did not get very far. One of those "works great in theory but not so well in practice in the real world" problems.
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The fact that the MCW sidebands of US NDBs are almost on top of the adjacent NDB channels is frustrating. Why oh why did we do it that way?
You just had to ask and now its stuck in my brain. Why?? I'm sure there's a reason. I was going to read those old propagation docs tonight, but this may have distracted me now.
Searched for a little while for historical docs on NDBs, but have yet to find anything. Which is kind of weird.
Found some online references to NDBs using 1020 Hz, not 1030. I measured PPI at 400 kHz here. On my AFE822x v3.0, the carrier was at 399.888 kHz and the lower MCW at 398.856, which is 1032 Hz. That was with SdrDx at 16384 FFT. At little margin for error (so I wouldn't take 1032 as definitive, but certainly was within a Hz or so and definitely not 12 Hz off).
There is that nominal 30 Hz separation, which might be enough. But there's another problem - nominal. The actual NDB carrier frequencies and sidebands are all over the place. Along with the actual CW WPM speeds, and interval rates for repetition of the callsign. In a way that is good, because it means they are not always on top of each other. But it is also bad because you'd need a table of all the actual values. And I am not sure how constant they are, they could drift all over the place (both in frequency and speed/time). So you really want some sort of a smart algorithm that looks for anything that appears to be CW. Unfortunately, noise often looks like CW.
Very much so... the real world interferes with theoretical.
One way to extract a weak repetitive signal out of the noise is to integrate multiple receptions. If a beacon transmits its callsign every 5 seconds, you take 5 second snapshots of the audio, and effectively lay them on top of each other. The noise, being random, averages itself towards zero. I think they do this with astronomy photos calling it stacking. Works great. But, you need to precisely know the repetition rate. And it needs to be stable. I tried playing around with this a while back with actual recorded NDB audio, but did not get very far. One of those "works great in theory but not so well in practice in the real world" problems.
Pity. That sounds like a great theoretical idea. As I was reading this, was coming up with all sorts of ideas, until the practical experience showed it was less than useful. But still...
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Found some online references to NDBs using 1020 Hz, not 1030. I measured PPI at 400 kHz here. On my AFE822x v3.0, the carrier was at 399.888 kHz and the lower MCW at 398.856, which is 1032 Hz. That was with SdrDx at 16384 FFT. At little margin for error (so I wouldn't take 1032 as definitive, but certainly was within a Hz or so and definitely not 12 Hz off).
Yes, they all seem to be using 1030 not 1020. I did find the official ICAO regulation on this, probably the same thing you found:
3.4.5.4 The frequency of the modulating tone used for identification shall be 1 020 Hz plus or minus 50 Hz or 400 Hz plus or minus 25 Hz.
But no idea of the history behind it. Those frequency tolerances are huge. Probably from back in the stone age when transmitters had tubes. The frequency was probably set by a knob. Can't trust those knobs.