New Year 2020: Excellent inversion over Poland

Ten wpis jest dostępny także w języku polskim: Nowy Rok 2020: Rekordowa inwersja nad Polską

This year’s winter in Poland is very mild and it does not resemble such a season in our country at all. In fact, it looks like late autumn with possible light frosts. The forecasts for the most part of January are still in line with current weather, so this month should be definitely warm. Starting from the end of December 2019, subsequent high pressure systems began to move to Poland from west. Such a weather favors good propagation, which can significantly increase the range of radio emissions. An inversion in the troposphere can enhance the reception in a wide frequency range, starting from the lower VHF (typically 50-70 MHz), through broadcast radio, television, microwaves and even… optical waves.

My DX equipment consists of RocketDish 5G31-AC antenna with DBII F52N-PRO radio on the top of a 18 m mast with a rotor near Płock, Poland (114 m ASL).

30.12.2019 – German and Czech 5 GHz Wi-Fi networks

The first episode of a tropospheric propagation occurred on the night of December 29 and 30, 2019. Fair propagation conditions were already present earlier, but nothing indicated what could happen at night, just before the Monday morning. To my surprise, in the late evening, my 5 GHz Wi-Fi DX setup detected a network from Koskowa Mountain at a distance of 315 km (SSID: HyperNET_Koskowa_Lanckorona). It was just a single received packet though. I checked the overnight propagation forecasts and accordingly configured automatic antenna rotation to azimuths between 160° and  260°. Then I went to sleep.

It was a great surprise when I checked the logs in the morning. The list of received networks was mostly red, which means that the distances had reached values of over 300 km and more. Unfortunately, this time I disabled sound notification, because I had to get a good night’s sleep. Looking through the list I noticed some German words: SchillRu (AP1-Zuse Hochhau). So… finally, I logged a very first Wi-Fi network from this country ever.

Tropo started at 4 UTC with signals from Zielona Góra (300 km) and  developed towards south over time. In total, I counted at least four German Wi-Fi networks.

BSSID Freq SSID Radio name S↑ UTC Tentative location [km]
64D15410C98E 5560 OL22.wdsl.ol.de OL21.2 KMD – NC OL22 -74 04:40 ÷ 05:21 Kottmarsdorf 247° 393
744D288A6983 5805 WET2SIE AP-WetroHochhaus -85 04:45 ÷ 04:56 Wetro 251° 402
CC2DE0B760FD 5640 SchillRu AP1-Zuse Hochhau -86 05:00 Hoyerswerda 256° 397
4C5E0C7398C4 5640 WDSL-OL-NET OL57.2 LWD AP ND -88 05:16 ÷ 05:20 Lawalde 248° 392

The first one named OL22.wdsl.ol.de was present for more than 40 minutes and reached a signal of -74 dBm at peak, which is an excellent result for a such distance. This is also my new record of level versus distance. None of the above networks are available in Wigle.net geolocation database, so the only way of identification is a manual analysis of all received signals. What’s interesting, internet service provider company WDSL-OL provides a map of their base stations.

Initially presumed network locations:

  • OL22.wdsl.ol.de (OL21.2 KMDNC OL22) is very likely a point-to-point link between KottMarsDorf and NiederCunnersdorf.
  • WET2SIE (AP-WetroHochhaus) looks like a point-to-point link between Wetro oraz SIE… (?).
  • SchillRu (AP1-Zuse Hochhau) is probably Zuse Hochhaus, Virchowstraße 60, Hoyerswerda.
  • WDSL-OL-NET (OL57.2 LWD AP ND) seems to be LaWalDe.

As can be seen in the map above, German signals were not the farthest ones during that troposhperic propagation opening. The ODX title goes to Czech network RW-DC-SNEZ-PPB1. The location was determined with Wigle.net, but the network’s name itself also suggests it: Děčínský Sněžník (438 km). Well… this is the farthest network, that I have ever received from Czech Republic, but the overall record was not broken, which is still Ukraine (464 km) from year 2018. I also logged another network at the same azimuth, namely total. Perhaps it’s got to be also around here somewhere.

BSSID Freq SSID Radio name S↑ UTC Tentative location [km]
6C3B6BD0DEB9 5200 total tota -88 04:55 ÷ 05:21 ?? 245° ??
CC2DE08EF43D 5500 RW-DC-SNEZ-PPB1 SNEZ-PPB1-070X -85 04:56 Děčínský Sněžník 245° 438

The distant signals were showing up from a quite narrow range of western azimuths (240 – 260°). My antenna was rotating back and forth much more widely (160 – 260°), making the tropo reception possible only for 20% of the total time. I believe that narrowing the azimuth range to the tropospheric ducting area only would give much better results, especially in relation to quantity of German networks.

On the day before the propagation, the pressure in my location reached almost 1040 hPa, and on the evening it started to drop pretty quickly. At night, the temperature at a height of several meters oscillated around 0 °C. An atmospheric sounding performed in Wroclaw at 0 UTC presents a layer of warmer and dry air (a sharp change in the dew point temperature).

As the time was passing by, the propagation area was moving. Just before a loss of the last German network signal some southern locations appeared, such as Ustroń, Poland (325 km), and later also Zlatý Chlum, Czechia (314 km) and Havířov, Czechia and the surrounding area (~320 km). Tropo weakened greatly at around 6 UTC and the distances began to shorten.

Within two days, the high-pressure system was partially displaced by low-pressure system from the north. The level dropped by as much as 25 hPa. However, at the turn of the new year, a high pressure system began to sweep in from the west into Poland once again…

02.01.2020 – extreme inversion

Tropospheric propagation actually began a day before, i.e. January 1 on New Year. Tropo affected mainly the reception of broadcast radio frequencies. On the FM band (87.5 – 108 MHz) I logged BBC Radio 2 and 4 from Holme Moss (1443 km), as well as Dutch stations from Smilde at RDS level (899 km) and a very large number of German signals. In the evening the tropo began to shorten, and closer signals were getting stronger.

On the night of January 1 and 2, I set the automatic 5 GHz scanning to the 160 – 340° range and I went to sleep. As expected, the microwave tropo started at night, more precisely a few minutes past 3 UTC, when first distant networks were logged from the north-west (Koszalin), from the west (around Zielona Góra) and from the south (incl. Ustroń). Before 5 UTC, the maximum distance increased to 355 km to the south-west, as far as Świeradów-Zdrój.

The extraordinary microwave tropo lasted all day. In the morning I took a short nap, but to my surprise the propagation was still up and even getting stronger. The tropo peak occurred around 13:20 UTC. At that time, a new record of signal strength in relation to distance was broken. It was the MHT2-EW4N network from Ustroń at a distance of about 325 km with a level of -66 dBm, almost like with a line of sight! It is difficult to determine the exact location of this network, but the abbreviation MHT probably points to the Manhatan estate in Ustroń.

Czech signals also reached record levels of up to -68 dBm an hour later, at 14:20 UTC. The strongest Bv-Ss network is probably Sedliště, Bezručova vyhlídka (viewpoint) at a distance of 332 km. In the photo available in the Google gallery one can notice few parabolic antennas. The record  in relation to the count of logged Czech networks was also broken. This time I counted about 100 Wi-Fi networks from Czechia, received as far as here in Płock. The following table presents a list tentative and identified signals from this country …

BSSID Freq SSID Radio name S↑ UTC Azimuth Distance
B869F4D524DD 5640 Bv-Ss B869F4D524DD -68 04:41 ÷ 14:38 197° 332
CC2DE06A0853 5600 PTP-SMER-BATZ CC2DE06A0853 -71 10:41 ÷ 14:39 197° 347
000C424EB614 5500 inera.cz_vyhl_wc->170 000C424EB614 -75 10:43 ÷ 14:39 197°  
E48D8CD24D17 5540 minier APtower>havirska -77 04:34 ÷ 14:47 199° 305
DC9FDB9A8351 5580 mixorp APmanes>frysta -77 04:54 ÷ 13:34 197° 323
4C5E0C66CC4B 5580 XP_NET_W_TY_TYTY_L W_TY_TYTY_L -79 13:34 ÷ 14:22 194° 333
24A43CE29FE9 5140 PtP_GU_Kr_ZiELiNa ptp krzok to z -79 04:07 ÷ 14:25 197°  
B869F4E362C8 5680 1TRINIT1-777CT KOMIN777B -80 12:42 ÷ 13:34 194° 332
FCECDA6438C3 5680 fno_ner707_ap3 fno_ner707_ap3 -80 10:58 ÷ 14:29 197° 347
E48D8CF31953 5600 fotbalista AP Kosmonautu2-fotb.stadion -80 10:40 ÷ 14:51 197° 303
0418D60EC332 5620 XP_NET_DO_DRZURY xp dzrura -81 13:50 ÷ 14:30 194° 322
0418D654E1A9 5620 kathaz41   -82 12:45 ÷ 13:18 195° 323
64D15408C2F9 5660 Raskovice.net-183 64D15408C2F9 -82 12:37 ÷ 13:51 197° 336
D4CA6D9D0B07 5260 SFL85 AP_Javorovy_Nebory -82 13:43 ÷ 14:29 194° 336
E48D8C2F91AD 5640     -82 13:11 ÷ 13:19 200° 344
E48D8CF5CF17 5640 HOTKOSTEL APKostel-Kl-HN -82 13:02 ÷ 14:29 195°  
000C4266F90C 5580 Raskovice.net-134 Raskovice.net -82 12:41 ÷ 14:06 197°  
6C3B6B3FBF8B 5500 kopustek AP Pavlouskova5-Prchaly -83 12:30 ÷ 13:05 201°  
788A20ACA86B 5510 deseSenac ubntac -83 12:57 ÷ 14:05 201°  
B4FBE4B800D6 5665 chotnet9louky smer Louky -83 11:58 ÷ 12:56 198°  
6C3B6B01A793 5520 PRVNI-STAVEBNI-PTP PRVNI-STAVEBNI-PTP-AP -83 12:46 ÷ 14:29 197°  
0005BFCA63FA 5600 FCZ JBS Janovice SXT SA -83 14:11 ÷ 14:14 198°  
04F021183ED6 5220 Krakonos 04F021183ED6 -83 13:25 ÷ 14:25 195° 324
4C5E0CCDEC58 5630 JBT Janek-Terka 018 -83 05:25 ÷ 14:08 199°  
002722DCDB35 5650 XP_NET_LOC1 XP_NET_LOCo1 -83 14:08 ÷ 14:09 194° 322
002722B8F58B 5620 BN_GO_MR_M5_I GO_MR_M5I -83 13:34 ÷ 13:46 194° 334
CC2DE06102B1 5240 Raskovice.net-21 OMD -84 12:41 ÷ 13:52 197°  
744D285FB3A6 5540 oainsch_sec1 744D285FB3A6 -84 12:18 ÷ 13:18 196°  
D4CA6DAC55CD 5520 RW-FM-JPESINY116-APB JPESINY116-APB1-045X -84 14:14 ÷ 14:28 198°  
E48D8C3FFF09 5540 websoftsmermik1 Chlum-Kolnovice -84 03:50 ÷ 05:23 215° 280
64D154678C0E 5280 WRNVRAHKV   -84 10:48 ÷ 13:16 197° 349
B869F4E36F59 5660 1TRINIT1-Trinec666 TRINIT-KOMIN2 -84 12:47 ÷ 13:17 194° 332
6C3B6B5D7021 5715 HBF_K FeKa 027 -84 12:44 ÷ 12:44 198°  
4C5E0C8584AF 5600 PtP_ChlumMik Chlum-BSU-MIMO-Brod -84 03:49 ÷ 05:23 215° 289
802AA824B0AA 5620 www.mcnet.cz-SAFT5AC AP_KRAV-SAFT -85 12:41 ÷ 13:17 197°  
00156DECC985 5180 DSJ5-podmoravii25 AP-DSJ5-podmor -85 08:38 ÷ 13:18 197° 350
7483C2541848 5300 kraj3 kraj-ap3 -85 12:43 ÷ 12:45 198° 325
CC2DE0AC0754 5560     -85 10:20 ÷ 12:59 199° 344
D4CA6DAC54B3 5560 RW-FM-JPESINY116-APA JPESINY116-APA1-320X -85 14:24 ÷ 14:27 198°  
002722A42C55 5620 www.mcnet.cz_FRMI.SLUN.SZ ap_fm_slunecna -85 14:24 ÷ 14:29 198° 335
6C3B6BB49563 5680 www.huranainternet.cz 6C3B6BB49563 -85 13:10 ÷ 13:56 195.5°  
B869F42EF15D 5220 PLOVOUCKA B869F42EF15D -85 12:31 ÷ 13:10 194°  
DC9FDB56655B 5700 BN_GU_KI_ROC_1111 BN_GU_KI_WDS_G -85 13:34 ÷ 13:55 194°  
DC9FDB4C5EDD 5500 P2P-CEZ P2P-MASTER -85 12:46 ÷ 12:46 201° 322
64D154FF1FEE 5700 MikroTikkkl 64D154FF1FEE -85 12:25 ÷ 13:30 197° 341
64D15470ADC2 5520 PTP-MOH-MAL-DD5 64D15470ADC2 -85 13:07 ÷ 14:14 198°  
E68D8CED6E4F 5540 FCZ HBS2 (R) Ste SA 070 -85 12:46 ÷ 13:17 197° 329
0418D6A65BC1 5700 XP_NET_DUPA_BLADA Bupa Blada -85 12:45 ÷ 13:33 198° 328
00156D3C69A5 5560 BN_GU_KR_M5_HN BN_GU_KRI -86 04:10 ÷ 14:20 194° 334
0418D60EC1F3 5720 BN_GO_MR_GRID_I godula smer ve -86 13:44 ÷ 13:45 194°  
788A20A4EEB0 5660 Hasicarna-Dolina RT HZ Zukov smer dolina -86 12:51 ÷ 12:51 193° 328
788A20A4C942 5855 KoprStrambMestoFA ubntac -86 12:56 ÷ 12:56 199°  
788A2010EE11 5700 HN-SU-Mi SU-Mistrovice -86 12:32 ÷ 12:53 194.5° 329
64D15466BEC7 5735 Palkovice.NET_YA ->Metyl… -86 13:52 ÷ 13:52 199°  
F09FC250D734 5540 kv .. -86 12:46 ÷ 13:00 200° 326
64D154AF0CFB 5815 Raskovice.net-74 R-Houme.net -86 12:34 ÷ 13:30 197°  
744D280A1F2A 5520     -86 10:39 ÷ 12:16 199° 342
6E3B6B5D7021 5715 HBF_K (R) FeKa 027 -86 12:44 ÷ 12:44 198°  
DC9FDB18A9C7 5200 NJBulharska6 Bulharska 6 S -86 13:16 ÷ 14:04 201° 352
00156DECC93E 5240 DSJ-teranet-interhotel-07 AP-DSJ5-interh -86 10:49 ÷ 13:18 198° 350
E48D8CF2D707 5620 websoftsmermik Chlum smer Sirok -86 03:49 ÷ 05:04 215° 308
4C5E0C0DACFF 5680 RORYS.CZ_Dehylov_So_S_8 Dehylov_So_S_8 -86 12:46 ÷ 12:50 201.5° 322
6C3B6B57BB6F 5680 FCZ K509 Kota 509 050 -86 14:12 ÷ 14:13 198°  
744D285199C8 5240 PROFILAN-NET1 APNiemecJavor -86 03:52 ÷ 13:55 192°  
E48D8CED6E4F 5540 FCZ HBS2 Ste SA 070 -87 10:42 ÷ 13:18 199° 329
F09FC2E83EAA 5300 Sed_vyhlidka_AP1 Sed_Vyhl AP1 -87 14:27 ÷ 14:27 197° 333
002722DCE347 5500 BN_NE_WA_PA1 BN_NE_WA_PA1 ( -87 13:32 ÷ 13:32 197°  
00C0CA19E9DD 5580 Raskovice.net-86 00C0CA19E9DD -87 13:15 ÷ 13:17 197°  
0418D6882BAD 5580 HN-M5-SMIL Pszczolka smer -87 12:47 ÷ 13:17 193°  
FCECDA90E15C 5340 www.mcnet.cz-GALDA LiteBeam 5AC 23 smer GALDA -87 12:44 ÷ 13:16 197°  
B4FBE4BEF832 5560 SLEEP SLEEP -87 12:13 ÷ 12:24 197° 315
6C3B6BD22B75 5220 HDNET-SNEZKA-POMEZKY-V HDNET-SNEZKA-POMEZKY-V -87 04:57 ÷ 04:57 237° 340
64D154460624 5520 Corelia.cz_Bobr1a 64D154460624 -87 13:02 ÷ 13:11 201° 317
64D154678C0B 5220 WRNVRAHKS   -87 10:48 ÷ 10:49 197° 349
4C5E0C50FC68 5660 lhotka.net_AB 4C5E0C50FC68 -87 14:22 ÷ 14:22 200° 347
788A20A4CB85 5750 5gskalkyneru ubntac -87 14:04 ÷ 14:04 201°  
744D2814BAC6 5745 PR-LAN-GUT-STRI APGuty2Stritez -87 13:29 ÷ 14:06 194°  
744D2814B9EC 5320 PR-LAN-GUT-NEB APGuty2Niebory -87 04:11 ÷ 13:34 195° 333
000C42C2D5F6 5680   XP_NET_HR_Kop_W -88 12:51 ÷ 12:51 194° 329
000C42CDCE0B 5220     -88 12:58 ÷ 12:59 200° 350
64D1547C3B9B 5765 Kaliste3_112017 64D1547C3B9B -88 12:33 ÷ 12:33 195.5°  
6C3B6B3C3631 5825 P2P-Hlucin-Darkovicky03 6C3B6B3C3631 -88 12:46 ÷ 12:46 200°  
4C5E0C1FC3B3 5560 WRNVRAH6   -88 08:31 ÷ 08:31 200° 352
6C3B6B4D6141 5320 vedloja_sec2 6C3B6B4D6141 -88 12:41 ÷ 12:41 197°  
6C3B6B5D9DE4 5520 bukzovska 6C3B6B5D9DE4 -88 12:12 ÷ 12:12 197°  
24A43C9EEC2E 5605 d17senov ubnt -88 14:04 ÷ 14:04 201°  
24A43CECB6B3 5540 MC_Lhoty_Visnovka_5G2 NanoStation M5 -88 12:49 ÷ 12:49 197°  
4E5E0CCFC815 5715 FCZ BR1 (R) ZD SH90 030 -88 12:50 ÷ 12:50 198°  
D4CA6DABADA4 5745 PR-LAN-Jav-Old APJavorO2Oldrich -89 14:15 ÷ 14:15 192.5° 322
00156DF697DB 5540 trojanvicenet.cz_okr_skol_ap okraskol M5 -89 13:31 ÷ 13:31 197° 349
002722BE8CB5 5520 PORUBY ubnt:poruby-ap -89 13:30 ÷ 13:30 197°  
24A43CEA2E27 5540 UHRANICE ubnt:uhranice- -89 13:09 ÷ 13:09 193°  
CC2DE052D465 5500 koj_jez_sds Kojkovice_AP49 -89 13:09 ÷ 13:09 193°  
64D1547B817E 5520 AP_NetSys_UQ 64D1547B817E -89 10:09 ÷ 10:09 199° 341
00156D1829E7 5520 CEPECEK AP-CEPECEK-942 -89 12:49 ÷ 12:50 197° 315
64D1546FAB62 5240 WRNVRAHZ   -89 13:11 ÷ 13:11 201° 350
802AA86A9D69 5520 VELOPOLSKA ubnt:velopolsk -89 12:48 ÷ 12:48 194° 329
802AA87EA8AD 5800 kopr1151FAfranc ubnt -89 13:11 ÷ 13:11 199°  
4C5E0C88EEAF 5240 P2P_MARTKR OVANET -90 12:52 ÷ 12:52 200° 325
CC2DE0030F5C 5745 hduinr_sec3 CC2DE0030F5C -91 12:47 ÷ 12:47 196°  

In addition, Police near Szczecin (IPEC networks) appeared at a distance of 364 km, which set the maximum distance on that day.

Just before 15 UTC the furthest signals (300+ km) disappeared. It was just after fantastic sunset show. I will not forget this view for a long time…

The extraordinary propagation continued, but the obtained distances were generally getting shorter and shorter. At moments, there were short flashes with interesting locations, such as many Wi-Fi networks from Jastarnia, Poland (Hel Peninsula) just before 20 UTC as well as Władysławowo (260 km).

In accordance with forecasts, the propagation weakened and faded away to the east. Late in the evening several more networks were logged from Biała Podlaska (240 km) and the surrounding areas. And just like that, the strongest microwave tropospheric ducting, I’ve ever seen, ended. In total, I logged 5671 networks (69% identified) and this is of course a new quantitative record of Wi-Fi DX throughout one single day.

The list of logged networks is available there: https://wifi.fmdx.pl/logs/20200102gigatropo

(click to see an interactive map of identified networks)

The inversion was very clearly visible in the atmospheric sounding. The chart below shows a measurement from Legionowo, near Warsaw, Poland.

The results of December 30, 2019 and January 2, 2020 were recorded in the The Best of Wi-Fi DX summary.

By the way, at the very beginning I mentioned about inversion and optical phenomenon. It turned out that this day was also record-breaking for lovers of distant observations. Check out some amazing photos of mirages produced by the troposphere:

I wonder if I also could see something from beyond the horizon :)

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