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English / News / Aktualności / Tropo / Wi-Fi DX


AUTUMN 2015: EXTREME TROPO DUCT 5 GHZ WI-FI 300+ KM

by kkonrad29-10-201526-05-2018

 Ten artykuł jest także dostępny w języku polskim. / This article is also
available in Polish language.

An extremely strong propagation occurred on October 27 and 28, which made
possible detection of 5 GHz Wi-Fi network signals near Płock, Poland at
distances of over 300 km, including… Czech Republic.

In last days, thanks to a high pressure system over the central Europe, very
interesting propagation conditions occurred on the radio bands. The weather
settled down on October 26 and 27 and brought a windless night. The morning, in
line with my predictions and tropo forecasts, brought a very strong propagation
from southern Poland on the VHF-FM band. The enhanced conditions were still
remaining throughout the day, however significantly weaker than in the morning. 

In the late afternoon, around 16:30 local time, I decided to check the 5 GHz
band for some distant Wi-Fi signals. Without any enhanced propagation
conditions, the range of reception is limited here up to 10-20 km, despite a
high gain antenna (grid 90×70 cm – approx. 30 dBi). This is caused mainly by low
mast height (just around 8 m AGL + 114 m ASL). I was very surprised, as I almost
instantly found a stable signal called br_ogo2. The networks names often include
the location names or their substrings. Using my antenna with a very narrow
main-lobe together with a high resolution rotator (1° precision), I was able to
estimate the location of this transmitter. I found a village called Ogorzelnik
(in Silesian Voivodeship) that matched my rotator azimuth indication at a
distance of around 215 km. This was a pretty nice distance to begin with. Of
course, this is only my assumption – I don’t know where this network is
precisely located, as well as other.

The signal level was slowly floating up and down, however due to absence of
other networks from this direction in a longer moment I decided to rotate the
antenna slowly within 160°-200° range. In just a moment I heard a sound of new
network detection. This time the name AirplusN_Slopnice_dookolna explicitly
identified the location of transmitter (ISP name + village name + antenna type,
dookólna means omni-directional). I checked the maps and I couldn’t believe what
just happened. It was Słopnice village, near Limanowa… 325 km away from my QTH!
The ISP’s website also confirms this location. 



Update – the antenna is a sector located around 770 m ASL, not an
omni-directional one as the name suggests (source: Trzepak.pl).

Other networks appeared shortly, coming mostly from surroundings of Częstochowa,
but also from Świętokrzyskie Province. The network br_ogo2 mentioned earlier
reached a fair level of -78 dBm. Due to a significant count of new incoming
networks I was not able to determine all their locations. I was focusing mostly
on SSIDs that included an explicit place name. Another key moment was the
reception of Andrychów (approx. 305 km) few minutes past 22 local time. I
noticed networks: Ventus_Andrychow3_5G_N, Ventus_RoczynyD3_5G_N and other.



By the way – network NTL>>>KIET is located at a lattice mast, which was used in
the past for NTL television broadcasting in Amelin near Radomsko. The substring
KIET mostly likely points to a village Kietlin, whick is placed inline with my
direction, at north of Amelin. Despite a considerable distance – 170 km, I have
already received this network few times before in the summer, but usually for a
very short period of time. I believe that high antenna installation height has
an important role in this recurring DX.

The IMGW’s weather radar maps (Institute of Meteorology and Water Management),
that use the 5 GHz band (5650 MHz) for the precipitation measurement, were
evidently interfered by other transmitters. The following map was valid at 23:10
local time.



The tropospheric duct was caused by a strong temperature inversion. Such perfect
weather provided convenient conditions over a wide area, but of course the best
were situated along the lines of an equal pressure. The following map from 00:00
UTC on October 28, 2015 confirms my suspicions. The 1024 hPa isobar goes
approximately in parallel with my furthest microwave DX paths.



I was observing some historical levels of VHF broadcasting stations from Poland,
that still continued to rise. I also noticed a strong audio signal from Ukraine
on 99.75 MHz. In fact actually two of them, Kovel in horizontal polarization on
Körner 19.3 and Lozova in vertical on 2×9-el, both with 35-40dBf signal. One of
the records was made at 00:30 local time. RMF FM 97.1 from Włoszczowa reached
71dBf (-49dBm @ 75Ω, 12kW ERP @ 178km). Anyway, because of a very crowded band
with many Polish stations I was focusing mostly on the microwaves.

I was very close to the Czech and Slovak border. Unfortunately, this second
country is obstructed by some mountains, but I was pretty sure that DX from
Moravian Gate in Czech Republic is possible, taking into account what I’ve just
logged before… The propagation was quite widespread, bringing southern parts of
Poland, including Bochnia (BC_LYCHOW_PN), Kraków (G2B-InfaNET-Wisniowa 310+km),
Bielsko-Biała (eurolan-wapienica-3, SPEED-NET-Grawerska-MIMO 310+km) and
Czechowice-Dziedzice (KOLNET-AM-Walcownia-3, JKNS-Tetmajera-6v, 300km). Apart
from the south direction, I was also receivng lots of networks (actually
hundreds of them…) from the west, initially southern, but later also northern.

        

A moment before 2 o’clock I got two networks with similar names: www.rydy.eu
RAC401 X2 and www.rydy.eu_ORL15R2. The ISP’s website pointed me
to Rydułtowy city, literally 15 km from the Czech border! Two minutes later
another network shown up with SSID PKdirect-MESTO at 197° azimuth. So, the
impossible became possible? Czech word “mesto” means “city” in English. My joy
lasted shortly, as I haven’t found anything related to the “PKdirect” keyword on
the Internet. I decided to keep the same azimuth and wait for other networks
with more distinctive names. About 10 minutes later, another SSID appeared on
the list with a characteristic name: inera.cz_vyhl_wc->170. The following
recording shows the 5GHz band scanning during reception of both Czech networks:



At this point I was pretty sure that I was getting Czech Republic. A moment
later, at 2:16 local time, the tropospheric ducting brought another
network: hasici (means “fire brigade” in English) AP Martinka5-K, as can be
seen on the following recording. A serial console is displayed at the right side
of video and it was used to set an antenna azimuth.



Maybe I got more foreign networks, however the identification with just a name
is rather impossible. A bit longer video (about 20 minutes) is available
here: https://vimeo.com/143992097. Full log of received networks is linked at
the end of this article. I was also checking the radio reception from Ostrava
and the surroundings in parallel to WiFi DX. Interestingly, Hošťálkovice were
remaining at stable 30dBf level, i.e. such like during quite weak, typical
tropo.

The following list contains all identified Czech networks:

Freq Ch Address SSID Radio name Sig Time (CET) Azi 5220 20/an 0027225A5828
PKdirect-MESTO NAR-LAS -87 01:50 ~ 02:04 197° 5500 20/an 000C424EB614
inera.cz_vyhl_wc->170 000C424EB614 -89 02:01 ~ 02:03 197° 5580 20/an
DC9FDB0C4338 hasici AP Martinka5-K -88 02:16 ~ 02:17 200°

The WiFi DX distances were getting shorter as the time was passing and the duct
itself was moving slightly west. The signal levels of broadcasting radio
stations at shorter distances (100-200km) strengthened up even more and I logged
some records of all the time. I can say it clearly that it was not a regular
tropospheric ducting, but something like a waveguide. I thought that the starry
sky replaced itself into… a metal sheet that was reflecting a signal.

 * 91.0 RMF FM / Raszyn: 80 dBf / -40 dBm (75Ω) 120kW @ 96km
 * 99.2 PR Łódź / EC-4: 84+ dBf / -36 dBm (clipped with tuner AGC!!), 30kW @
   95km
 * 101.4 PR Kielce / Św. Krzyż: 80 dBf / -40 dBm, 120kW @ 212km

Taking this opportunity, I also estimated the signal level of an intermodulation
on 106.8 (107.3 PR4 + 107.8 PR1), which likely comes from a vertical antenna
system on EC-4 chimney in Łódź. As far as I remember, this signal is present all
the time and it is definitely not being created in my tuner itself.

 * 107.3 PR4 74dBf @ 1500W ERP
 * 106.8 intermodulation 37dBf (!)
   Let’s calculate the factor with 74 – 37 = 37dB signal difference: 10^(37/10)
   = 5012x. Therefore, the ERP (effective radiated power – together with antenna
   gain and cable losses) of this intermoduation is something like 0,3
   W (300mW).

In the morning the microwave duct quickly faded away. Few minutes past 7 I was
still receiving networks from Kalisz (~150km) and surroundings but this was
definitely the end of such extraordinary conditions.

Here is a list of the most interesting and furthest networks that I have
initially identified (approximate distances):

Freq Address SSID Radio name Sig km Lokalizacja? 5540 24A43CF456E7
AirplusN_Slopnice_dookolna AirplusN_slopn -89 325 Słopnice 5240 4C5E0C823519
BC_GIRER_2_DUO 4C5E0C823519 -86 295 Bochnia 5300 4C5E0C80E8EB BC_LAP_PN
4C5E0C80E8EB -88 295 Bochnia 5520 4C5E0C80ECBF BC_LYCHOW_PN 4C5E0C80ECBF -86 295
Bochnia 5560 D4CA6DFE738B BC_SEK_DEB3_DUO D4CA6DFE738B -89 295 Bochnia 5600
D4CA6DE1EDB4 BC_SEK_KAR_DUO_2 D4CA6DE1EDB4 -87 295 Bochnia 5320 000C42DFEA28
BC_SZK_MUCH_1_PZ 000C42DFEA28 -85 295 Muchówka 5260 24A43CE89776  eurolan-mar
0790_Mar->TRW -89 300+ Bielsko-Biała? 5280 00272252A75E eurolan-wapienica-3  
-91 300+ Bielsko-Biała? 5640 4C5E0CFEEE5B fiberway.pl_chelm_s1   -86 292 Chełm,
Kraków 5280 E48D8C164A67 G2B-InfaNET-Wisniowa G2B1 -90 310 Wiśnowa, Kraków 5580
DC9FDB0C4338 hasici AP Martinka5-K -88 300+ Czechia 5500 000C424EB614
inera.cz_vyhl_wc->170 000C424EB614 -89 300+ Czechia 5540 000C42DF34D1
JKNS-Tetmajera-6v 000C42DF34D1 -89 300 Czechowice-Dz. 5320 0418D6EAE582
KOLNET-AM-Walcownia-3 Walc. AM3 -87 300 Czechowice-Dz. 5180 D4CA6DBC9E1F
MS-NET-gr-miet D4CA6DBC9E1F -85 270+ Kraków 5280 24A43CFE1326
multi-bb-trz1-bestwina bb-trz1-bestwi -86  300+ Bestwina 5580 0418D6C848EC
multi-szy1-sq-czd szy1-sq-czd -89  300+ Szyndzielnia 5280 4C5E0C5DE9C7
OLIMPLAN_mysl->bysiAC_K 4C5E0C5DE9C7 -90  305 Myślenice 5220 0027225A5828
PKdirect-MESTO NAR-LAS -87 325 Havířov, Czechia 5180 002722329EDF
SPEED-NET-Andersa-1 SPEED-NET-Ande -88 300+ Bielsko-Biała 5240 0418D6EC3939
SPEED-NET-Grawerska-MIMO SPEED-NET-Graw -88 300+ Bielsko-Biała 5260 4C5E0C82F95C
Ventus_Andrychow3_5G_N   -88 305 Andrychów 5320 000C42DF8D41 Ventus_Kety5_5G_N  
-82 300+ Kęty 5280 000C42DFEA9A Ventus_Nidek6_5G_N   -91 300 Nidek 5640
4C5E0C886367 Ventus_RoczynyD3_5G_N   -89 305 Roczyny 5620 002722A69108
www.rydy.eu RAC401 X2 BRT_RAC401R1 -86 290+ Rydułtowy 5240 24A43C6CF28E
www.rydy.eu_M5_orl19B BRT_ORL019R1 -87 290+ Rydułtowy 5520 DC9FDB2EEA99
www.rydy.eu_ORL15R2 BRT_ORL015R2 -88 290+ Rydułtowy

Because of a significant count of received networks I haven’t investigated all
of them yet. Perhaps I logged something further than Słopnice (~325km). Czech
networks are good candidates. One of them points at the fire brigade building
(“hasici”) and Martinka 5 street. I should check maps and google street view –
maybe I will be able to spot an antenna…?

Full log of received networks contains almost 600 entries and is available
here (without locals – which are available everytime, regardless of current
propagation). My DX setup, located near Płock in central Poland, consists of a
grid Poynting antenna (31dBi in horizontal), 8m agl + 114m asl and Metal 5SHPn
radio.

Conclusions: As one can see, the distance over 300km was achieved several times.
Of course, it is possible to establish a connection during tropo. It is just a
matter of ACK Timeout adjustment (or disable). With poor signals it is possible
to link at the lowest modulation available (6Mbps data rate – BPSK, FEC 1/2) and
push a megabit or two. Additional signal improvement, at the expense of the
throughput, can be achieved with channel width narrowing from stock 20MHz to 10,
5 or even 2.5MHz (the last one is supported with AR92xx chipsets). The signal
levels of some closer networks reached up to -65dBm (SSID: Xtreme61). Now, I’m
waiting for a WiFi DX over 400km. Although it may be a problem, as the mountains
effectively block all signals…

Forecasts of this propagation were issued as follows (W. Hepburn & F5LEN):





Update (Jan 2015) – two atmospheric soundings from Legionowo near Warsaw and
Wrocław:

  

This is one of three articles about tropo from October 27th to November 6th.
Read more:

 1. Extreme tropo ducting 5GHz WiFi 300+km (Oct 27th – Oct 28th) – current
    article
 2. October 2015: UKR, FIN, HOL ducting (Oct 30th – Nov 1st)
 3. November 2015: extreme autumnal tropo (Nov 2nd – Nov 6th)




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ONE THOUGHT ON “AUTUMN 2015: EXTREME TROPO DUCT 5 GHZ WI-FI 300+ KM”

 1. Techydiy says:
    15-06-2016 at 00:12
    
    Very cool, I had never thought about wifi dx.
    
    Reply
    


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