Unexplained drop in tracks

[herren]

Hello,

I’ve noticed an unexplainable drop from time to time. I was able to catch it and save graphs. Do any of the forum experts have any ideas as to what’s happening?

Setup
FlightAware 1090 Antenna → N->SMA adapter > RTL-SDR LNA → LMR400 10ft cable SMA → 10inch RG361 whip → RTL-SDRv3 → Powered USB hub → old MacBook Pro w/ Debian 11 Bullseye. I’m also running another dongle for 978 on the same USB hub.

Confirmed decoder has been up since I last restarted it to adjust gain.

$ sudo systemctl status readsb.service 
● readsb.service - readsb ADS-B receiver
     Loaded: loaded (/lib/systemd/system/readsb.service; enabled; vendor preset: enabled)
    Drop-In: /etc/systemd/system/readsb.service.d
             └─bias-t.conf
     Active: active (running) since Fri 2022-02-25 21:18:39 CST; 19h ago
       Docs: https://github.com/wiedehopf/readsb
    Process: 341957 ExecStartPre=/usr/local/share/adsb-wiki/biastee/rtl_biast/build/src/rtl_biast -b 1 (code=exited, status=0/SUCCESS)
   Main PID: 342098 (readsb)
      Tasks: 8 (limit: 9185)
     Memory: 25.6M
        CPU: 3h 13min 5.986s
     CGroup: /system.slice/readsb.service
             └─342098 /usr/bin/readsb --device 0 --device-type rtlsdr --gain 25.4 --fix --ppm 0 --lat 36.**** --lon -87****.>

Feb 25 21:18:39 macbookold readsb[342098]: Using lat:   36.***, lon:  -87.***
Feb 25 21:18:40 macbookold readsb[342098]: Preparing error correction tables.. done.
Feb 25 21:18:40 macbookold readsb[342098]: 30002: Raw TCP output port            30005: Beast TCP output port
Feb 25 21:18:40 macbookold readsb[342098]: 30003: SBS TCP output ALL port        30004: Beast TCP input port
Feb 25 21:18:40 macbookold readsb[342098]: 30104: Beast TCP input port
Feb 25 21:18:40 macbookold readsb[342098]: rtlsdr: using device #0: Generic RTL2832U OEM (Realtek, RTL2838UHIDIR, SN 00000101)
Feb 25 21:18:40 macbookold readsb[342098]: Detached kernel driver
Feb 25 21:18:40 macbookold readsb[342098]: Found Rafael Micro R820T tuner
Feb 25 21:18:40 macbookold readsb[342098]: rtlsdr: tuner gain set to 25.4 dB
Feb 25 21:18:40 macbookold readsb[342098]: Allocating 16 zero-copy buffers

[wiedehopf]

@herren

I’ve noticed an unexplainable drop from time to time.

Some sort of interference / noise.

Try and correlate with some electric device being turned on.
Monitors … whatever.

[foxhunter]

@wiedehopf

Could it be a power issue as well or similar to mine the other day a weak USB-connect?
Or would this then look different?

[herren]

I live in an apartment block so I can’t deal with interference from neighbors However, I’m 80% certain I was able to resolve interference from two devices. I used my M1 MacBook Pro + CubicSDR and a third RTL-SDR + dipole kit to detect emissions and correlated with graphs1090. I tested both again, so there is a dip in the graphs again today.

1. Vizio TV formerly connected via Ethernet was switched to WiFi due to lack of ports on network device. Swapped for larger switch and got it back on WiFi.
2. A small, industrial fan sometimes propped in the window for air exchange / cooling, I moved my receivers to accommodate a coax upgrade in the last week, putting the fan next to my receivers and on top of some of the cables, fan moved to other side of window and power cable routed differently.