thanks guys will see what I can do
After buildig it, the final step “tuning” (i.e. adjusting length of top wire) plays a major role in performance. When length of top wire is adjusted to optimum, performance is very good. Few mm more or less, performance drops substantially.
Same hardware, no changes.
I also tried to recreate the connection of the cable, soldering the SMA connector as I use a 10mm coax cable made from an Italian company (messi.it)
What about the rest I made?
You have strong interference from mobile at GSM800 and GSM950.
You need Flightaware Dark Blue filter.
Either you are connecting tripple filtered lna in reverse direction, or the biast is connected in reverse direction, or the power supply to biast is connected with reverse polarity.
If all connections are OK, then it is too much gain. Reduce gain.
Thanks for the reply. I’ll give another try with the filter connected both ways to be sure connection is ok.
I ran the command
sudo systemctl status dump1090-fa -l
to check my gain and it shows:
/system.slice/dump1090-fa.service
└─506 /usr/bin/dump1090-fa --device-index 0 --gain -10 --ppm 0 --max-range 360 --fix --net --net-heartbeat 60 --net-ro-size 1300 --net-ro-interval
So my understanding is that my gain is at -10 not +10, isn’t it? Which “side” should I go to reduce and/or increase gain?
This is confusing indeed.
-10 means the max amount which is in reality approx a gain of 55
So you need to increase the number to go “down”.
Next levels of gain would be 49.6, 48.0, 44.5, 43.4, 42.1, 40.2
So edit your /etc/default/dump1090-fa file and change the gain to one of these values and restart it again with sudo systemctl restart dump1090-fa
you can verify your setting with your previous command.
Make sure to rem remove the minus sign before, this is valid for -10 only
after changing, leave it running for some hours
ABOUT GAIN
-
Gain should always be a positive number (except -10).
-
Using a negetive number (except -10) sets the gain to ZERO .
-
Gain’s permissible values are from 0 to 49.6
-
Gain=“max” sets gain to maximum i.e. 49.6 dB
-
Gain -10 is a special setting. It does NOT set gain to -10. It switches dongle to AGC (Automatic Gain Control) mode. As the dongle is designed for TV reception, for TV, the AGC setting acts a intended. As the TV signal at any channel is fiarly constant, AGC works as intended. However since ADS-B signal is intermittent bursts, the AGC setting malfuntions and sets the gain to more than max (49.6). It normally sets gain to 52~55 dB .
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Well you need to enable the bias-t, otherwise the LNA gets no power.
https://www.rtl-sdr.com/getting-the-v3-bias-tee-to-activate-on-piaware-ads-b-images/
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Is this (Option 1) applicable for the Pro stick as well. I would love to see my graph as I have some custom made antennas.
When I ran the ‘rtl_power’ I got the following error:
Found 1 device(s):
0: Realtek, RTL2832U, SN: 00001000Using device 0: Generic RTL2832U
usb_claim_interface error -6
Failed to open rtlsdr device #0.
Gain (or insertion loss, SNR) is not that important for ADS-B signals as people think. A small LNA is all that’s needed to compensate for any of those loses.
Free electrical path for signals is much more important, obstructions cut the signal down almost completely at 1GHz.
Also, if the receiver didn’t get saturated by the extra band signals, adding better filtering (to cut those extra signals) won’t help. It’s already extracting all the ADS-B signals that are in the sky.
YES
You have to first stop dump1090-fa by following command, then run the command rtl_power
sudo systemctl stop piaware dump1090-fa
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as for the command itself
sudo rtl_power -f 800M:1200M:100k -i 30 -c 50% -e 30m -g 30 -F 9 >scan.csv
Use: rtl_power -f freq_range [-options] [filename]
-f lower:upper:bin_size [Hz]
(bin size is a maximum, smaller more convenient bins
will be used. valid range 1Hz - 2.8MHz)
should I adjust the frequency to 1090 MHz?
NO
Dont modify the rtl_power command given in this Guide. It is designed to scan from 800 Mhz to 1200 Mhz in 100kHz hops ( -f 800M:1200M:100k). If you change 800 & 1200 to 1090, it will scan only 1090 MHz, which will defeat the very purpose of this test.
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I have one as well, very steep and narrow bandpass, low insertion loss - highly recommended. I’m pretty sure I posted some sweeps of it a couple years back, alongside that of the light blue FA filter for comparison, but I’d need to dig.
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Looks good for a high noise 900 MHz GSM environment. A test here Radio for Everyone: Test: ADS-B Cavity Filter
I bought six 1090Mhz and six 978 Mhz models that look similar to that($US120 for six). I have some spares if you want them.
Scans using software Spektrum (spektrum-win64.zip) with the Dongle plugged into Windows10 Desktop.
https://github.com/pavels/spektrum
Range of scan: 24 MHz ~ 1800 MHz
Scan 1 of 3 - FA Antenna + ProStick (Orange) - No Internal or External Filter
Scan 2 of 3 - FA Antenna + ProStick Plus (Blue) - No External Filter
Scan 3 of 3 - FA Antenna + ProStick Plus (Blue) + External FA Filter (Light Blue)
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