Do I Need A Filter?

[mtflightfeeder]

Yep. I did that and the T620 is worse than all my Pi’s. I’m pretty sure it’s because my Pi’s run RadarBox SDRs that are filtered and amplified.

I went with the Nano 3 SDRs because they are small and I can fit them inside on the 620’s two internal USB ports. I drilled a hole on the front and mount the antenna mast there. That way there isn’t a bunch of junk sticking out of the 620 like Frankenstein’s Monster.

It would seem that the Nano 3’s are the weak link. That’s why I was thinking that an amp would be helpful. But would I want to filter and amplify? Depending on the size of the LNA and filter I may still be able to keep everything inside the 620’s case too.

Thanks

[zs6bv]

When you amplify you also amplify the noise, so amplify and filter together rather.

[mtflightfeeder]

I understand an amplifier will amplify noise. But, wouldn’t the tuned SDRs only receive 978 and 1090 anyway?

Thanks

[jimMerk2]

@mtflightfeeder

But, wouldn’t the tuned SDRs only receive 978 and 1090 anyway?

Except that any signal at 1090 MHz for example will still have noise on it. Think of it that way.

[wiedehopf]

The nano sdrs aren’t as good for ADS-B and yes you’re also missing an LNA / filter in front.

There is a pretty good combine filter / LNA by uputronics or from rtl-sdr, consider either of those.

And consider just not using a nano if you want best performance i think.

[wiedehopf]

@mtflightfeeder

I understand an amplifier will amplify noise. But, wouldn’t the tuned SDRs only receive 978 and 1090 anyway?

The noise isn’t the issue, interference is from strong emitters is.
The LNA / SDR can get overloaded from other frequencies causing noise on the frequency you want to receive.

[mtflightfeeder]

Does anyone have any experience with this filter? I like it because it may be small enough where I can keep it inside the T620.

Amazon.com: Stratux 1090 MHz + 978 MHz Splitter and Saw Filter : Electronics

Thanks

[mtflightfeeder]

Well, if no one has any experience with the Stratux filter…

Which filter do people like?

Thanks

[Flipkaan]

Hello,

This wont work for me with Bullseye OS, cannot install python. Can anyone help please?

[abcd567]

@Flipkaan

Hello,

This wont work for me with Bullseye OS, cannot install python.

sudo apt update  

sudo apt install rtl-sdr  

sudo apt install python3     

sudo apt install python3-pil   

sudo wget https://raw.githubusercontent.com/keenerd/rtl-sdr-misc/master/heatmap/heatmap.py

sudo chmod +x heatmap.py 

sudo systemctl stop dump1090-fa piaware   

sudo rtl_power -f 800M:1200M:100k -i 30 -c 50% -e 30m -g 30 -F 9 >scan.csv  

Wait till scan finishes (15 to 30 minutes)
 

sudo reboot  

sudo ./heatmap.py scan.csv scan.png  

 

 

[Flipkaan]

Thank you, i just did this and giving me ‘No supported devices found’. I’m using the airspy mini

test@raspberrypi:~ $ sudo rtl_power -f 800M:1200M:100k -i 30 -c 50% -e 30m -g 30 -F 9 >scan.csv
Number of frequency hops: 286_power -f 800M:1200M:100k -i 30 -c 50% -e 30m -g 30 -F 9 >scan.csv
Dongle bandwidth: 2797202Hz
Downsampling by: 1x
Cropping by: 50.00%
Total FFT bins: 9152
Logged FFT bins: 4576
FFT bin size: 87412.56Hz
Buffer size: 16384 bytes (2.93ms)
Reporting every 30 seconds
No supported devices found.

[abcd567]

@Flipkaan

Thank you, i just did this and giving me ‘No supported devices found’. I’m using the airspy mini

This wont work on AirSpy.
It worka on RTL based dongles such as DVB-T, Flightaware Prostick and Flightaware Prostick Plus, etc.

[Taxom]

Yes!

[abcd567]

@Taxom

Yes!

 

How good/bad this filtered LNA is?

 

[rugomol]

What is SQ61D chip?
No datasheet

[geckoVN]

Took a while, but the best I’ve come up with is a 4.8V low noise LDO.
A Ricoh RP130K481A

rp130x-series_ricoh.pdf

Any guesses for the amp?

Edit:
No it’s not.
It looked good, but the “SQ” isn’t the SOT23-5 package

[rugomol]

3M9009 is TQP 3 M 9009 amp

[Taxom]

I use it now, it seems to work fine.

Maxim Pi ADS-B Feeder Statistics - FlightAware

[martinpolu]

Hi! I do the test.

RTL SDR + Antenna “5 dBi” (https://es.aliexpress.com/item/1005003628094587.html?spm=a2g0o.order_list.order_list_main.83.cb54194ddX2nSj&gatewayAdapt=glo2esp).

I was thinking of buying a filter but in my country filters are difficult to obtain and import from other countries. Is it worth buying an uputronics?

I use 29.7 db Gain

[abcd567]

 

Having a filter is preferable, but if filter is very costly, you may servive even without it.

Also try following scan which shows intensity of interfering RF noise also:

Spektrum - How-to Speedily Scan RF Noise in band 24MHz ~ 1800MHz