Gained count, lost range after antenna/unit moved up

[voyteke]

Noob here, I’ve installed dump1090, FlightAware and fr24 on RPi with nooelec SDR about 3 weeks ago, working good in my living room, ground floor.
On Saturday, moved the unit 8 floors up, internally.
On Sunday, re positioned antenna on building roof, open air.
I’ve gained count of aircraft, as expected, but, I seem to have lost range?
What am I doing wrong? Sydney airport, we don’t fly nighttime…
7 days:

24 hours:

Ahem, I know it’s not the way to mount…
As this is temporary, antenna is held by brick on cable, with plastic bag over antenna/mount…could that be part of my problem…? for completeness I better include this:

[tomvdhorst]

The plastic bag doesn’t do your reception good. Also I suspect you will be having more external interference on the roof then when it was inside. The building provided some kind of shielding against it and now the antenna is in the open. Lastly you are running it on max for receiving and this can make the antenna deaf for longer range signals. Try to reduce the gain and check if the situation improves.

[voyteke]

thanks, appreciate your help. I’ll remove the plastic bag today or soon, also, need to ‘secure’ base, maybe a strip of metal to make it attach…?

$ sudo systemctl status dump1090-fa -l
● dump1090-fa.service - dump1090 ADS-B receiver (FlightAware customization)
Loaded: loaded (/lib/systemd/system/dump1090-fa.service; enabled; vendor preset: enabled)
Active: active (running) since Sun 2023-07-09 20:45:10 AEST; 1 day 20h ago
Docs: PiAware - ADS-B and MLAT Receiver - FlightAware
Main PID: 379862 (dump1090-fa)
Tasks: 3 (limit: 3933)
CPU: 5h 48min 15.996s
CGroup: /system.slice/dump1090-fa.service
└─379862 /usr/bin/dump1090-fa --quiet --device-type rtlsdr --gain 60 --adaptive-range --fix --lat -33.xxx --lon 151.yyy --max-range 360 --net-ro-po>

Jul 09 20:45:10 rpi2 systemd[1]: Started dump1090 ADS-B receiver (FlightAware customization).
Jul 09 20:45:10 rpi2 dump1090-fa[379862]: Sun Jul 9 20:45:10 2023 AEST dump1090-fa 8.2 starting up.
Jul 09 20:45:10 rpi2 dump1090-fa[379862]: rtlsdr: using device #0: Generic RTL2832U OEM (Nooelec, NESDR SMArt v5, SN 00000001)
Jul 09 20:45:10 rpi2 dump1090-fa[379862]: Found Rafael Micro R820T tuner
Jul 09 20:45:11 rpi2 dump1090-fa[379862]: rtlsdr: tuner gain set to about 58.6 dB (gain step 29) (tuner AGC enabled)
Jul 09 20:45:11 rpi2 dump1090-fa[379862]: adaptive: using 50% duty cycle
Jul 09 20:45:11 rpi2 dump1090-fa[379862]: adaptive: enabled adaptive gain control with gain limits 0.0dB (step 0) … 58.6dB (step 29)
Jul 09 20:45:11 rpi2 dump1090-fa[379862]: adaptive: enabled dynamic range control, target dynamic range 30.0dB
Jul 09 20:45:11 rpi2 dump1090-fa[379862]: Allocating 4 zero-copy buffers
Jul 09 20:45:21 rpi2 dump1090-fa[379862]: adaptive: reached upper gain limit, halting dynamic range scan here

partial/relevant values form /etc/default/dump1090-fa

Initial receiver gain, in dB. If adaptive gain is enabled (see below) the actual gain
may change over time
RECEIVER_GAIN=60

Adjust gain to try to achieve optimal dynamic range / noise floor?
ADAPTIVE_DYNAMIC_RANGE=yes
Target dynamic range in dB (leave blank to autoselect based on SDR type)
ADAPTIVE_DYNAMIC_RANGE_TARGET=
Reduce gain when loud message bursts from nearby aircraft are seen?
ADAPTIVE_BURST=no
Gain range to allow when changing gain, in dB (empty = no limit)
ADAPTIVE_MIN_GAIN=
ADAPTIVE_MAX_GAIN=

[geckoVN]

@voyteke

I’ll remove the plastic bag today or soon, also, need to ‘secure’ base, maybe a strip of metal to make it attach…?

Those are indoor antennas and are not waterproof. Once water enters the coax, your performance will deteriorate.
I disagree the bag will make any detectable difference, but sticking the magnet to a metal surface (ground plane) will make a vast improvement.

[tomvdhorst]

I would start with disabling Adaptive_dynamc_range ( change from yes to no).
Set the Recieiver_gain=60 at 49 and slowly ( check once per day) to see if increasing or lowering the gain improves the situation.
Slow steps give you a better overview

Other option is to deploy a filter for 1090 between the dongle and the antenna cable. This will reduce the amount of noise coming into your dongle.
When applying a filter you might want to compensate for the input loss of 2,5-3 dB by increasing the gain.

[voyteke]

thanks!
I’ll look for a small metal sheet, maybe just make a hole in the bag, so it’s just over base, yes, water ingress was worrying me… maybe run some silicon over base and cable…?
or, better, find a outdoors antenna/base…

[voyteke]

thanks, changed these two lines to

RECEIVER_GAIN=47
ADAPTIVE_DYNAMIC_RANGE=no

restart:

Jul 11 19:11:35 rpi2 systemd[1]: Started dump1090 ADS-B receiver (FlightAware customization).
Jul 11 19:11:35 rpi2 dump1090-fa[1115400]: Tue Jul 11 19:11:35 2023 AEST dump1090-fa 8.2 starting up.
Jul 11 19:11:35 rpi2 dump1090-fa[1115400]: rtlsdr: using device #0: Generic RTL2832U OEM (Nooelec, NESDR SMArt v5, SN 00000001)
Jul 11 19:11:35 rpi2 dump1090-fa[1115400]: Found Rafael Micro R820T tuner
Jul 11 19:11:35 rpi2 dump1090-fa[1115400]: rtlsdr: tuner gain set to 48.0 dB (gain step 27)
Jul 11 19:11:35 rpi2 dump1090-fa[1115400]: Allocating 4 zero-copy buffers

[tomvdhorst]

Here’s an outdoor antenna in AU

1090MHz ADS-B Antenna - 66cm / 26in for Mode S and ADS-B data from FlightAware...

That’s a decent antenna and is used in combination with an SMA and N connector cable.

[voyteke]

I think I’m going backwards, changed around 1 hour ago, around ~19:15
I guess no point waiting longer?
What value to try next, sorry, I’m totally out of my comfort zone…
Thanks for antenna suggestion!

[tomvdhorst]

Re-enable autogain with a value of 60

Adaptive_dynamc_range ( change from no to yes).
Set the Recieiver_gain=60.

The dongle you are using has no filtering or amplification built in so there’s not much you can tweak with it.
Maybe an external filter will improve the situation but that’s up to you.

I have a lot of different dongles to test with but not a Nooelec one.

My standard setup (I have multiple sites) consist of a FA blue dongle (amplifier and filter built-in), FA dark blue filter(external filter) and a external antenna ( ranging from 5.5 dB to 11 dB amplification).

[voyteke]

thanks again for your assistance, changed just now:

I’ll try to fix/improve position/ground plane next day or two (not that simple to climb up…), will also try antenna inside again, will think about proper antena
this was just a spur of the moment thing, (oh, can get a $50 dongle to collect aircraft data, why not)
Jul 11 19:11:35 rpi2 dump1090-fa[1115400]: rtlsdr: tuner gain set to 48.0 dB (gain step 27)
Jul 11 19:11:35 rpi2 dump1090-fa[1115400]: Allocating 4 zero-copy buffers

Jul 11 21:16:13 rpi2 dump1090-fa[1148448]: rtlsdr: tuner gain set to about 58.6 dB (gain step 29) (tuner AGC enabled)
Jul 11 21:16:13 rpi2 dump1090-fa[1148448]: adaptive: using 50% duty cycle
Jul 11 21:16:13 rpi2 dump1090-fa[1148448]: adaptive: enabled adaptive gain control with gain limits 0.0dB (step 0) … 58.6dB (step 29)
Jul 11 21:16:13 rpi2 dump1090-fa[1148448]: adaptive: enabled dynamic range control, target dynamic range 30.0dB

[voyteke]

Yesterday I slightly re positioned antenna around 17:30, there is a large stainless plate bolted on the roof, I’ve repositioned antenna on the plate, secured with cable ties (stainless, magnet didn’t work), removed plastic bag, let’s see results today, seems to be getting better.
Should the plate be explicitly grounded, should I run a wire to some metal point?

This morning’s result so far promising:

[geckoVN]

@voyteke

Should the plate be explicitly grounded,

Not necessary - such is the voodoo of RF!
A 1/4 wavelength radius is the useful minimum, but once the metal plate is greater than a wavelength or so, it becomes indistinguishable from an infinite plane.

[voyteke]

Thanks again, encouraging results obtained!
Due to need of using existing slots in plate to secure antenna base, antenna is fairly close to plate edge, not in centre, also, plate has a step up, above the concrete base, might try to reposition closer to centre of plate, and, maybe on the raised section.

[voyteke]

@tomvdhorst

The dongle you are using has no filtering or amplification built in so there’s not much you can tweak with it.

sorry to be a nag, does this allow me any additional control?

rpi2:~ $ rtl_test -t
Found 1 device(s):
0: Nooelec, NESDR SMArt v5, SN: 00000001

Using device 0: Generic RTL2832U OEM
Found Rafael Micro R820T tuner
Supported gain values (29): 0.0 0.9 1.4 2.7 3.7 7.7 8.7 12.5 14.4 15.7 16.6 19.7 20.7 22.9 25.4 28.0 29.7 32.8 33.8 36.4 37.2 38.6 40.2 42.1 43.4 43.9 44.5 48.0 49.6
[R82XX] PLL not locked!
Sampling at 2048000 S/s.
No E4000 tuner found, aborting.

unrelated question:
if I wanted to pick up AIS traffic, I’d need an additional SDR device, it’s not possible to run both application on single SDR device ?

I’m not sure if/how much AIS traffic I could pick, I’m not near coastline, about 15km, with hills/city buildings in between
I might install Android AIS app on tablet, unplug SDR device from RPi, try on Android device for few minutes?or , try installing AIS stuff on RPi…?

Jul 15 09:20:45 rpi2 dump1090-fa[2482780]: Sat Jul 15 09:20:45 2023 AEST dump1090-fa 8.2 starting up.
Jul 15 09:20:45 rpi2 dump1090-fa[2482780]: rtlsdr: using device #0: Generic RTL2832U OEM (Nooelec, NESDR SMArt v5, SN 0>
Jul 15 09:20:45 rpi2 dump1090-fa[2482780]: Found Rafael Micro R820T tuner
Jul 15 09:20:45 rpi2 dump1090-fa[2482780]: rtlsdr: tuner gain set to about 58.6 dB (gain step 29) (tuner AGC enabled)
Jul 15 09:20:45 rpi2 dump1090-fa[2482780]: adaptive: using 50% duty cycle
Jul 15 09:20:45 rpi2 dump1090-fa[2482780]: adaptive: enabled adaptive gain control with gain limits 0.0dB (step 0) … 5>
Jul 15 09:20:45 rpi2 dump1090-fa[2482780]: adaptive: enabled dynamic range control, target dynamic range 30.0dB
Jul 15 09:20:45 rpi2 dump1090-fa[2482780]: Allocating 4 zero-copy buffers
Jul 15 09:20:55 rpi2 dump1090-fa[2482780]: adaptive: reached upper gain limit, halting dynamic range scan here

[tomvdhorst]

Good question,

Any SDR is in principle a wideband reciever. When using one that amplifies the signal it will enable you to receive signals from a greater distance and that enhances your range. Due to the wideband capability you are likely to receive signals from frequency bands nearby. Using a filter eliminates those nearby signals so there will be less noise for the SDR to deal with. So both functions can contribute to a better station.

When I use an RTL-SDR to receive ADSB traffic (no filter and no amplifier) it will perform less then a FA Prostick Plus that has the 2 functions built in.

In regard to AIS, you will need a 2nd dongle. You can only use 1 frequency on 1 dongle, only one program (adsb or ais) can claim the hardware, not both at the same time.
I don’t use it so I can’t give you advice on that setup but other in these forums can

[voyteke]

Thanks again for your help, and, explanations!
Tried briefly AIS using a demo version of an app on a tablet, hot unplugged SDR, plugged into tablet, run the app, couldn’t figure out if I was getting anything useful, so hot plugged back into RPi.

RTL_AIS_driver in demo mode said this:

00:20 ------------------
00:20 11:00:20 eu.ebctech.rtl_sdr_ais_driver Version= 1.1.9 VersionCode= 33
00:22
00:22 #####RequestStartofDriver
00:23 #rtl_sdr_ais_driver Device StartParam:
fd:90 usbfs_path:/dev/bus/usb/001/002 left_freq_hz:161975000 right_freq_hz:162025000 sample_rate:24000 output_rate:48000 dev_index:0 gain_percent:-100 ppm:0 bandwidth:300000 ais_port:10110 ais_host:127.0.0.1 sec_for_decoder_stat:30 edge:0 add_sample_num:0 dc_filter:0 agc:0 show_nmea:1 show_levels:0 show_waterfall:0 demo:1
00:23 Edge tuning disabled.
00:23 DC filter disabled.
00:23 RTL AGC disabled.
00:23 Add Sample Index disabled.
00:23 AIS decoder seconds for stat = 30.
00:23 Buffer size: 163.84 mS
00:23 Downsample factor: 64
00:23 Low pass: 25000 Hz
00:23 Output: 48000 Hz
00:23 Opening device with rtlsdr_open2 deviceidx 0 fd 90 at /dev/bus/usb/001/002
00:23 Found Rafael Micro R820T tuner
00:23 init_ais_decoder
00:23 Log NMEA sentences to console ON
00:23 AIS data will be sent to host 127.0.0.1 port 10110
00:23 ais_host=127.0.0.1 ais_port=10110,show_levels=0,debug_nmea=1,addsample=0,waterfall=0
00:23 Set TUNER GAIN to AUTO GAIN:
00:23 set ppm_error to 0
00:23 set (midle)frequency to 162000000
00:23 set sample rate to 1600000
00:23
Demod Thread start…
00:23 CPU WakeLock acquire
00:23 Cpu wake lock. OK
00:23 Driver Start OK
00:24 !AIVDM,1,1,A,37Ok<vgPCE:lHtWd<sR81h0170,05E
00:37 !AIVDM,1,1,B,37Ok<UPPC8bkmm1dNg3kjw<20v@,0*4F 00:43 !AIVDM,1,1,,A,17PGTB0P00:l5e5d:OtKwwp0PRr,00C
00:46 !AIVDM,1,1,A,37P1iG061q:l@FId@6B?ikH0Q1@,0*67 00:53 A: Received correct: 3 | wrong CRC: 9 | wrong size: 3 00:53 B: Received correct: 1 | wrong CRC: 7 | wrong size: 5 00:53 ------------------ 00:53 11:00:53 eu.ebctech.rtl_sdr_ais_driver Version= 1.1.9 VersionCode= 33 00:53 00:53 #####RequestStatusOfDriver 00:53 driver is running 01:12 !AIVDM,1,1,,B,17PGTB0P00:l5dsd:NLKwwp082,0*6B 01:23 A: Received correct: 3 | wrong CRC: 21 | wrong size: 10 01:23 B: Received correct: 2 | wrong CRC: 13 | wrong size: 7 01:24 !AIVDM,1,1,,B,17PGTc0P01:l5eKd:dLBOwv0d1m,03D
01:34 !AIVDM,1,1,A,17PGTc0P01:l5eSd:dLBOwv0pDe,0*4F 01:43 !AIVDM,1,1,,A,B7Oe@S000JdtPAs::4kQ3wn5oP06,0*4A 01:45 !AIVDM,1,1,,B,39N1>5000:l3o;dWm:UcoSb0Dg:,01F
01:53 A: Received correct: 5 | wrong CRC: 29 | wrong size: 17
01:53 B: Received correct: 4 | wrong CRC: 23 | wrong size: 8
01:55 !AIVDM,1,1,A,17PGTc0P00:l5eEd:h<BOwv0PR6,0*41 02:05 !AIVDM,1,1,,B,37OmClPOhBbl6NidWq5R36:210@,00F
02:21 !AIVDM,1,1,A,H7Og4GQ0E8U05AE<00000000000,046
02:23 A: Received correct: 7 | wrong CRC: 42 | wrong size: 22
02:23 B: Received correct: 5 | wrong CRC: 32 | wrong size: 16
02:32 !AIVDM,1,1,B,17PGTB0P00:l5dcd:MdKwwp0hCJ,0*5B 02:41 !AIVDM,2,1,6,B,59N1>82E1LCDiKN21<D60P5Lf2222222222216BpND:5nk0F0EH4nA,0*61 !AIVDM,2,2,6,B,888888888888880,2*21 02:42 !AIVDM,1,1,,A,17PGTB0P00:l5e9d:O<Kwwp0hI,0*79 02:44 !AIVDM,1,1,,A,B7Oe@S000:dtPEs::4oQ3wnUoP06,0*5A 02:53 A: Received correct: 9 | wrong CRC: 56 | wrong size: 28 02:53 B: Received correct: 7 | wrong CRC: 40 | wrong size: 22 02:53 !AIVDM,1,1,,A,37P1iG0tis:lBkMdD=jaB1b0P00,006
02:55 !AIVDM,1,1,B,17Oh2jPPAF:l8=wdWv2n9Tqf0D1D,01D
02:55 !AIVDM,1,1,A,37OmClP00?bl6eidWqgRu2?h20sP,032
02:59 !AIVDM,1,1,A,37OgOr?PCR:lApcd=4c=pul011@,0*07 03:02 !AIVDM,1,1,,A,17PGTB0P00:l5dwd:OdKwwp0t2L,025
03:13 !AIVDM,1,1,A,37Oh2jPOiG:l8DudWtN64lpJ00Kh,04D
03:17 !AIVDM,1,1,A,H7Og4GTTCBD:<1V19Ejij>0h731t,025
03:21 !AIVDM,1,1,A,17PGTB0P00:l5dad:PLKwwp0h=4,0*6F 03:23 A: Received correct: 16 | wrong CRC: 65 | wrong size: 34 03:23 B: Received correct: 8 | wrong CRC: 49 | wrong size: 26 03:23 ------------------ 03:23 11:03:23 eu.ebctech.rtl_sdr_ais_driver Version= 1.1.9 VersionCode= 33 03:23 !AIVDM,1,1,,A,37OgOr?PCS:lA1Od>Lc0pjd0150,0*7E
03:23
03:23 #####RequestStopDriver
03:23
Demod Thread end…
03:23 Stopping was successful!
03:24
User cancel, exiting…
03:24 OK rtl_ais_andro says bye!
03:24 Driver Exit OK
03:24 Wake lock released
03:24 close Android USBDeviceConnection

I guess I should install AIS application on RPi, briefly shut down tar1090, run AIS and see, I noticed there is a lengthy AIS thread, need to read that I think.