Trial Run Results for Three Types of Whip Antennas

[AnirbanSen]

As a side note, and not a part of this thread, a paper on ADS-B spoofing that you and ABCD should be aware of. And perhaps think of ways it can be defeated. I'd leave it up to you to post on other forums if need be.
Link: https://aanjhan.com/assets/ils_usenix2019.pdf

 

[wiedehopf]

See last 6 hours.

Most likely that's just variation in the amount of traffic (less traffic at night).

The number of tracks is not a good number to look at, it's kind of random and a higher number doesn't necessarily mean better reception.
If a plane fades in and out of view in the correct interval it will be counted as multiple tracks.

Maybe you also changed gain somehow when you restarted at 6:00

 

[wiedehopf]

ADS-B spoofing

Nothing for me to worry about
Maybe for the guys at planefinder or the other flight trackers.

 

[Stealth]

Nothing for me to worry about
Maybe for the guys at planefinder or the other flight trackers.

Its nothing to do with ADS, its all about ILS. Nothing new, just another paper just for the sake of publishing a paper.

 

[AnirbanSen]

Its nothing to do with ADS, its all about ILS. Nothing new, just another paper just for the sake of publishing a paper.

I don't know, but was referred to in some security related newsletter. Just wondering if the data off ADS-B can ever tell if an aircraft is following a legit ILS directive/signal sort of like a pre-curosr alert. If the Mode S protocol is further amended to include some more information. Just thinking aloud.

 

[Stealth]

I don't know, but was referred to in some security related newsletter. Just wondering if the data off ADS-B can ever tell if an aircraft is following a legit ILS directive/signal sort of like a pre-curosr alert. If the Mode S protocol is further amended to include some more information. Just thinking aloud.

Some automated data monitoring of ADS that could produce a course deviation warning might be feasible, but few transport aircraft rely solely on ILS these days anyway. Unfortunately as there are more and more universities being built, and more and more people having to publish papers to get 'qualifications', we'll see more and more papers of this sort.

 

[AnirbanSen]

I wasn't getting a signal. Finally when I went to check the antenna, it seems someone had cut the cable ties and yanked off 2 of the radial wires and bent it out of shape.
I straightened them as much as I could and replaced the 18guage radials with 22 gauge radials which I had. The wires are still not entirely straight but the signal is back, although noise is a lot more.

Is it possible for Graphs1090 to also plot at 3hrs and the 12hr mark?

 

[wiedehopf]

Is it possible for Graphs1090 to also plot at 3hrs and the 12hr mark?

You would have to make those changes yourself i'm quite fine with the graphs as they are.

sudo /usr/share/graphs1090/graphs1090.sh 12h

This will produce 12h graphs.
They will be placed in /run/graphs1090

The website is not meant for 12h graphs so you will have to modify the URL for each picture to access it.
(replace 24h with 12h)

http://pi/graphs1090/graphs/dump1090-localhost-local_trailing_rate-24h.png
http://pi/graphs1090/graphs/dump1090-localhost-local_trailing_rate-12h.png

Those graphs won't be updated automatically though.
You can take a look and try to understand this file:

/etc/cron.d/cron-graphs1090

That's where the graphs are generated

 

[AnirbanSen]

Just an update:

I tried the above method for adding the 12hr, but the buttons were still showing the original timespans. I actually wanted to ADD the 12hrs to spot any tampering with the antenna. I then tried to substitute the 48hr with the 24 hr; and the 24hr with the 12hr. Still no -go.

In the meantine, the dealer had sent the coax I had ordered a little soon. The core was aluminium covered in copper. However, the plastic jacket was of a very rigid, I could not insert more than 2 radials in the coax even after dipping the end in boiling water (wrapped in a plastic bag). Finally, I ended up attaching the radials with zipties directly to braided wire after removing the insulation and covering it up with foil and tape. However, I did not get a proper signal despite multiple tries. I have therefore returned the wire to the dealer and plan on purchasing an RG6 after the filters, LNAs and stuff from Aliexpress arrives.

 

[wiedehopf]

I wrote that you need to access the files via their specific URL.
If you want buttons and stuff you need to change the files in /usr/share/graphs1090/html

If the core isn't copper then the likelihood of the coax being bad quality is high i'd say.

 

[AnirbanSen]

I wrote that you need to access the files via their specific URL.
If you want buttons and stuff you need to change the files in /usr/share/graphs1090/html

Ah, I didn't understand that part. I did access the files via those URLs, but obviously the timespan would not record everything. I'll work in sometime.

If the core isn't copper then the likelihood of the coax being bad quality is high i'd say.

It was too cheap as well. But worth trying when return is guaranteed.

 

[AnirbanSen]

The Satellite amplifier (950 ~2050 Mhz) does need a bias-t and a12v~15v dc power supply.


Setup of Satellite amplifier and bias-t

https://forum.planefinder.net/threads/ads-b-diy-antenna.23/post-210


DIY bias-t

https://forum.planefinder.net/threads/ads-b-diy-antenna.23/post-5093

The Satellite Amplifier (950 - 2050MHz version) has not yet arrived in mail. However, if I want to use this LNA (https://www.aliexpress.com/item/1-3...-Amplifier-Module-UHF-HF-VHF/32952717426.html) which works on 12V and is NOT coax powered, what is the best way to take the power from the coax to power the LNA and feed the other side? This LNA boasts of a 18db gain at 1090MHz.
I am thinking I'll need another bias-t (A filter capacitor to the RF in of the LNA and an inductor to the +12V of the LNA).
Ideally, the same components. Agree?

 

[Stealth]

For running the LNA at the mast head you will need to inject the 12V into the coax and then extract the 12V at the antenna end for the LNA to operate, so yes you will need two bias devices, plus the patch lead to connect the LNA to the antenna.

I can't look at the link you give as I don't have a Aliexpress accout, so what I've said assumes that there isn't already something in the LNA to tap the power from the coax.

 

[ab cd]

This amplifier is too much wide band and pick FM, TV, Mobile phone signals, overloading the dvb-t front end and consequent poor reception.


About power insertr, please see this diagram. Both power inserters are identical (each has one capacitor and one inductor, and their values are same in both). The one used as dc blocker does not need an inductor, only a capacitor. Since these in diagram are factory made as injector they both have a capacitor and an inductor.

 

[wiedehopf]

I'm sure aliexpress has some 1090 MHz SAW filters you can buy.
Maybe even use 2 in series (after the LNA)
Might still overload the LNA if you're unlucky but hopefully not.

Without good filtering the LNAs won't help too much with reception.

To transfer the power you will need two bias-t devices, one to insert the power and another one to extract it.

 

[AnirbanSen]

This amplifier is too much wide band and pick FM, TV, Mobile phone signals, overloading the dvb-t front end and consequent poor reception.


About power insertr, please see this diagram. Both power inserters are identical (each has one capacitor and one inductor, and their values are same in both). The one used as dc blocker does not need an inductor, only a capacitor. Since these in diagram are factory made as injector they both have a capacitor and an inductor.

View attachment 2858

What about https://www.aliexpress.com/item/0-1...A-Broadband-Module-Gain-30dB/32972147890.html
This LNA is up to 2GHz.

Thank you for the picture above. You had shared it earlier and you have a lot of posts on this. But in the pic, the in-line amplifier is coax powered. I am specifically looking at any amplifier which is not coax powered thus requiring 2 Bias Tees.

Method 1: Use the diagram you supplied earlier and take the DC from Inductor, where "Leave Unconnected" is marked and use it to power the LNA.
Method 2: The 2nd Power Inserter (working as the block) would put between the LNA and the DC Power Inserter. Again, the other end of the Inductor would supply power to the LNA. Additionally, in this case, would a filter capacitor 200pf (between LNA and antenna) would still be required just in case there is any DC leakage in the LNA?

 

[AnirbanSen]

I'm sure aliexpress has some 1090 MHz SAW filters you can buy.
Maybe even use 2 in series (after the LNA)
Might still overload the LNA if you're unlucky but hopefully not.

Without good filtering the LNAs won't help too much with reception.

A Bandpass filter got delivered few days ago. I plan to connect this straight to the antenna.

For SAW filter, I saw this https://www.aliexpress.com/item/100...1-09-SAW-Filter-1090-MHz-SMD/32806265560.html, but from the picture I am not sure even how to connect this.

I'll be having a) a coax spider, b) a SO-239 4-legged spider, and c) a PCB based 1090MHz Antenna.

Under a bit of work pressure and some travels next week, so I doubt I'll be able to test out the rigs before 27th. Add to that, daytime temperature hit an unprecedented 48C. So working on the roof has to be at odd hours.

To transfer the power you will need two bias-t devices, one to insert the power and another one to extract it.

Yep, the extraction is what I am slightly in doubt about.

 

[wiedehopf]

you'll need a SAW filter on a board with connectors.

Yep, the extraction is what I am slightly in doubt about.

Speaking in DC terms:
The bias-t just connects one side of the coax with the output on the side.
So it doesn't matter which way you use it.

Basically the line from receiver to LNA looks like the following:
bias-t <---- coax ---> bias-t

Orient them correctly and both ends of this contraption will carry no DC voltage.
You can put DC in at one bias-t and you can read a voltage at the other bias-t.

Look at that picture:
https://upload.wikimedia.org/wikipedia/commons/6/6c/Bias_t.png

You orient the bias-t devices so that towards receiver and LNA you have the RF only part (no DC).

Now you just connect the DC out of the remote bias-t with the LNA DC input terminals.

 

[AnirbanSen]

you'll need a SAW filter on a board with connectors.

Aliexpress prices are close to USD 40 each. But the basic filter is inexpensive. Have asked seller to share more detailed pictures.
Not sure if the size would permit 2 SAW filters to be put inside the splitter casings in case I want to go that way.

Speaking in DC terms:
The bias-t just connects one side of the coax with the output on the side.
So it doesn't matter which way you use it.

Great, so that is clarified.

 

[wiedehopf]

This LNA is proven and has 3 filters on board: https://rtl-sdr.com/new-product-rtl-sdr-blog-1090-mhz-ads-b-lna/

It's 27$ including shipping, with 3$ added for slightly better shipping.

But putting that on the roof in those temperatures where vandalism has already take place is of course problematic.
If you could install somewhere inside it would work i guess.

Anyway just pointing out options, your current filter might be sufficient.

No matter if you use a filter in front of the LNA, i would highly recommend using one behind the LNA.
(no matter the type)
If you are confident you can solder the SAW filter to 2 connectors while keeping the losses acceptable, go ahead.
But at GHz frequencies such undertakings require knowledge about the subject.