Rf amp yes or no ?

[Col@home]

Hello all
my setup is pi3b+ running noelec nesdr mini tv28t v2.0,fr24, home brew 1/4 wave spider with 3 mtr coax and band pass filter antener aprox 7mtr above ground no obstacles range 150 nm .
question is it worth geting lna.

[abcd567]

First determine what maximum range you can get. Even with RF Amplifier, you cannot receive beyond the limit set by terrain around your location.


What is the Maximum Range I can Get?

[Col@home]

I have done that with col@home and it showed about 25nm way less than what I am getting.i just had another look if the blue ring means what I should get at 30000 ft then I don't get that far.

[abcd567]

In this case an RF Amplifier is most likely to improve your range.

[Col@home]

Thank you, I am going to make a better aireal first and raise it a 1 mtr at what I have was a quick lash up to see how it works. Will post picture of it before installing it. Going with the bottom of this pic.

[Col@home]

Thank you, I am going to make a better aireal first and raise it a 1 mtr at what I have was a quick lash up to see how it works. Will post picture of it before installing it. Going with the bottom of this pic.

Lol just noticed that it's your picture so let's hope it's good.

[abcd567]

Originally the DVB-T was designed for TV which uses 75 ohm system. The TV, the TV antenna, and the coax (RG6) has 75 ohm impedance.There are 4 variants of Spider in that picture. These four sketches are designed for 75 ohm system, which was originally used for ADSB initially about 15 years ago. The best performer for 75 ohm system is sketch number 4.

The Amateur radio and Cell/Mobile system uses 50 ohm equipment. Due to their influence, the subsequent development of dongles and coax started using 50 ohm design.For 50 ohm system, the best performer is design of sketch number 2, i.e. the one with radials slanting 45 degrees down from horizontal.

You can also make an easy low cost antenna by the method given here:

QUICK SPIDER - No Soldering, No Connector

[Col@home]

Would this be what I want? ADS-B Active SAW Filter&LNA SMA Connectors Low Noise Amplifier 21dB Convenient

[Col@home]

https://www.ebay.co.uk/itm/186575427996?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=dkywsml0sjc&sssrc=4429486&ssuid=do-D5nNjQ0u&var=&widget_ver=artemis&media=COPY

[abcd567]

Recently I tested similar Filtered Amplifier. As Amp, it is good. It's Filter does filtering, but is not very effective.


Test Setup - Mag mount Whip Antenna + Fliltred LNA + Generic DVB-T + RPi Model 4

Filtered LNA-and-DVB-T.jpg



Reception, No Filtered LNA

No-Filtered-LNA-1.jpg





Reception, With Filtered LNA

With-Filtered-LNA-1.jpg





Scan of RF Noise by "Spektrum".
Scan Range 24 MHz ~1800 MHz


No Filtered LNA

Scan - No Filtered LNA.png





WITH Filtered LNA

Scan - With Filtered LNA.png

[G4LOH]

https://www.ebay.co.uk/itm/186575427...mis&media=COPY

I checked the specification of this product and note that they do NOT specify a Noise Figure for it, also, based on the picture, the SAWF appears to be placed *ahead* of the LNA device.

So I think the noise figure is likely to be around 3dB, which is better than the dongle alone, but is far from optimal. The 21db gain is excessive when you have a short coax cable and will reduce system dynamic range.

Overall, it's *probably* going to help the range, but the actual performance will be highly dependent on your local RF environment.... are there transmitters on nearby frequencies close to you?

Here, I have strong DVB-T TV signals from a mast 15km away that completely swamped my FR24 dongle before I added a good filter. I also have strong military RADAR signals and mobile phone masts within 5km.

[Col@home]

Sorry its taken me so long to replay I now have new spider withs 45° radials at 9m above ground and the saw at per ebay listing may range exceds haywatsthat and my planes tracked has morthan doubled. Thank you for your help.
Screenshot_20240924_000759_Flightradar24.jpg
20240915_082556.jpg

[Col@home]

Well that saw lasted two weeks so have now orded amp and separate fiter, let's see how they go.
so anybody reading this the saw above is probably not a good idea.

[Col@home]

How do I get the performance chats the people keep posting had a look round but cannot find any instructions 🤔

[wiedehopf]

graphs? https://github.com/wiedehopf/graphs1090#graphs1090

would recommend readsb or dump1090-fa as a decoder. (https://github.com/wiedehopf/adsb-sc...ion-for-readsb)
if you change decoder, reinstall graphs1090.

general guide for an RPi: https://github.com/wiedehopf/adsb-wi...ADS-B-receiver
all in one image: https://adsb.im/