Updated ESSL - tower in the woods 2021

[ludlo]

Here is some feed setup pictures from the ESSL feed. The tower is located a bit south of Linköping. Antenna is located about 45m up the tower. Cable used is LMR900. Computer runs 4 Nooelec RTL-SDR dongles and a i7 debian box.


Antenna in the tower





Preparing LMR900



Computer interior and exterior

[andypandy]

I have been listening to the ESSL feed on and off before and lately basically every day. Always imagined that it was an antenna on someones house roof or something. Very cool setup. Thanks a lot! Is this still the current setup or has it changed?

[ludlo]

Glad you like it! I have done some changes since the first setup, now 2 airspy hf+ is used as receivers. Also a RPI 5 is used instead of the computer. The same location is used for both ESSL and ESSP feeds. They are practically the same, just the TWR freq is different.

I actively manage and maintain the feed. I visited the location last weekend to add a UPS for better uptime.

[andypandy]

I have to say, I am very surprised by getting an answer to a several year old post that quickly, pleasantly surprised! I am now in the process of preparing my own outdoor ADS-B antenna setup at home. It is not so fancy, its only on my balcony I live locally in Linköping so if you ever need any help with the setup give me a shout. I don't have much experience with radio and wont climb up the tower, but keep it in mind anyways. Just send a message if you want any contact details.

How does the tower setup work? I assume someone owns it and has given you access? Seems like a fantastic location based on the images and it obviously works great based on the distance to the aircraft I can listen to.

[ludlo]

Thanks a lot, will keep in mind! 

I rent space in the tower from the tower owner, its just a bit south of Linköping. Indeed it works very well at this point, however as the environment changes, changes also need to be done to the config files of RTL Airband. Mainly the squelch levels needs continous trimming to keep the squelch from opening on random noise. Increasing the squelch level will decrease the range and vice versa. When KLM to Linköping can be heard about to enter Swedish airspace, transmitting near Copenhagen, then I know the level is about right. 

The RTLSDR sticks that was first used, did not work nearly as well as the airspy hf+. The weak and strong signal handling of the hf+ is amazing. Also the preamp is switched to https://www.antennas.us/lnau-0122-648-Airband-Preamplifier.html

[andypandy]

Nice! Yeah I like to listen to KLM coming in, when they just enter Sweden its a bit scratcy but certainly possible to listen to. Also quite a bit up toward the Stockholm area. I have not been able to find any maps regarding how the ATC zones etc look like here in Sweden. But some Sweden control is crystal clear while there is some that are either barely audible, just noise or you only hear the aircrafts side of the conversation and never the controller. I am assuming that different zones of "Sweden control" transmits from different locations and that is why?

Are you using the RTLSDR-Airband project directly or using the docker project? I hang out in the SDR Enthusiasts discord server and have seen some discussions regarding Airband, seems a bit tricky to setup. I myself only listen for ADS-B which is much easier to setup, especially now with all the well-made docker containers.

Anyways, thanks for the work. And have a good weekend.

[ludlo]

Here is some maps
https://aro.lfv.se/Editorial/View/13884/ES_ENR_6_3-1_en
https://aro.lfv.se/Editorial/View/13885/ES_ENR_6_3-3_en
https://aro.lfv.se/Editorial/View/13006/ES_ENR_6_3-4_en

Transmitters of sweden ctrl is remotely controlled, mostly from Arlanda. The transmitter used....cant find any more logic than the one near the region of the aircraft is selected by the controller.
On weekends and holidays, more sectors are combined into fewer frequencies which if we are lucky can produce more talk on the radio.

I dont use the docker project, i build it and run it "as is". Have a good weekend 

[andypandy]

I have been having some stream issues the last few days. I noticed that transmissions was sometimes cut off in the middle or skipping or missing beginning of transmissions. When I listend via my phone I seem to be disconnected more often than before and while listening on VLC on my computer it looks like it "buffers" or something similar when it happens. There is a orange/yellow loading bar for a second when it happens, then it continues. It does look like some kind of connectivity/stability issue, but its hard to be sure. I assume that since the stream is delivered to me via LiveATC it would indicate a problem on their end and not on your setup? I'm listening to the ESSL stream. If you listen for a few minutes with radio activity you will quickly notice it.

[ludlo]

Yes indeed, I have noticed and we are actively troubleshooting that right now 
The buffering part, maybe not so much in the feeder endpoint, but the clipping is for sure in the reciever.
Hopefully we will come to a resolution in a near future.