If you feed ADS-B, your receiver already sees everything nearby, but unless you set up readsb's heatmap or globe history, tar1090 only shows a short track history. I built Velocity to keep all of it: point ADSB_FEED_URLS at your tar1090's aircraft.json and every position gets recorded to your own disk, so you can scrub back to any moment later. The variable replaces the default list, so you choose exactly which sources it reads: just your receiver, or your receiver plus community aggregators like adsb.lol.

It also does ships from public AIS feeds, area alerts to Discord, a webhook or ntfy, and replay of the public readsb heatmap archives back to 2024.

What's rough: anything beyond your own receiver is only as good as the public feeds, and the 3D globe wants a decent GPU (there's a 2D map). I built it with a lot of help from Claude Code and review every change.

AGPL, docker compose: https://github.com/AndrewCTF/velocity

Curious whether people here would rather have it record raw Beast/SBS output instead of aircraft.json.

Has anyone here looked at Altierre / Agile Displays electronic shelf labels, specifically the ETAG 250W or eTAG 210E?

I own several and want to retrieve their displayed price, product description and barcode over radio, without changing anything on the tags. Either passive listening or a known read-only query would be fine.

The 250W FCC report lists 2402–2480 MHz, GFSK and frequency hopping. I haven’t confirmed the exact radio parameters of the 210E. I have no original base station, so there’s currently no normal update traffic to capture.

Available hardware is a Raspberry Pi 5 and an nRF52840-MDK USB dongle. No captures or teardown yet.

Does anyone know of an existing decoder, capture, wake-up sequence or related project? Would the nRF52840 be worth investigating, or would a 2.4 GHz SDR be the more useful starting point? Budget-friendly suggestions welcome.

I’m also wondering whether the tags ever transmit their content, rather than just IDs and battery/status information. Photos attached.

40mhz*

if you want to skip to the pictures of the setup, click here

I've been an ATC nerd for years (ever since I used to listen to it on commercial flights when they allowed that) and an RTL-SDR just helped me complete a project I've been wanting to tackle for a long time: recording a bunch of ATC audio and mixing it with lofi so I can have some awesome background music for work or whatever else. So when I had a week off work recently, I rented a Fiat 500, stuck an airband antenna up on the roof, and spent a day driving to three Chicago airports with my laptop in the passenger seat.

At O'Hare I was in the cell phone lot, at Midway I was on top of a parking garage and at KPWK I was able to get right up next to the runway in the viewing area. One thing I didn't realize was that you can use the SDR to capture the entire frequency at once and then split out the individual calls later (like I said, new at this whole thing...).

Once I was home, ended up with thousands of individual transmissions that I could layer over the background music.

The chain I ended up using was:

• Bingfu 20–1300 MHz mag-mount scanner antenna
• Gpio labs airband filter
• RTL-SDR v3 dongle

For software I used Software SDR++ tuned for each airport and used Claude Code to help with the actual backend processing.

If you want to hear the final result, the tracks are at finalapproach.fm (completely free) or anywhere you get your streaming music under Final Approach Radio.

Happy to answer anything about the rig, the channel splitting, or what I'd do differently next time (I've got SFO and the NYC airports up next on my list)!

Well lets see if this all survives reddit formatting. I also made a pastebin of the contents.

https://pastebin.com/rYVVctnA

Used

https://github.com/alphafox02/iridium-sniffer

https://github.com/frankea/adsbtrack

Note the Libresdr searched 10MHz wide at the same time.

So I took an hours worth of Iridium and wrote it to output.bits

iridium-sniffer -i soapy:driver=tezuka,tezuka_format=CS8 --soapy-gain=71 --no-gpu > output.bits

I then processed the file to extract only acars data:

cat output.bits | python3 /usr/local/src/iridium-toolkit/iridium-parser.py -g | python3 /usr/local/src/iridium-toolkit/reassembler.py -m acars

*****

2026-10-19T15:38:52Z [hdr: 0301010100000001] Dir:DL Mode:2 REG:N604SB ACK:0 Label:_? (Demand mode) bID:Z

2026-10-19T15:39:05Z [hdr: 0301010100000001] Dir:DL Mode:2 REG:N604SB ACK:1 Label:_? (Demand mode) bID:X

2026-10-19T15:39:48Z Dir:DL Mode:2 REG:N568FX ACK:1 Label:_? (Demand mode) bID:Y

2026-10-19T15:40:00Z [hdr: 0301010100000001] Dir:DL Mode:2 REG:N617AZ ACK:7 Label:_? (Demand mode) bID:Z

2026-10-19T15:48:03Z [hdr: 0301010100000001] Dir:DL Mode:2 REG:N414AL ACK:5 Label:_? (Demand mode) bID:Y

2026-10-19T15:48:21Z [hdr: 0301010100000001] Dir:DL Mode:2 REG:N414AL ACK:6 Label:_? (Demand mode) bID:Z

2026-10-19T15:48:38Z [hdr: 0301010100000001] Dir:DL Mode:2 REG:N414AL ACK:7 Label:_? (Demand mode) bID:X

2026-10-19T15:48:45Z [hdr: 03d5010100000001] Dir:DL Mode:2 REG:N954AK ACK:6 Label:_? (Demand mode) bID:S

2026-10-19T15:49:11Z [hdr: 0301010100000001] Dir:DL Mode:2 REG:N414AL ACK:9 Label:_? (Demand mode) bID:Z

2026-10-19T15:49:27Z [hdr: 0301010100000001] Dir:DL Mode:2 REG:N414AL ACK:0 Label:_? (Demand mode) bID:X

2026-10-19T15:49:42Z [hdr: 0301010100000001] Dir:DL Mode:2 REG:N414AL ACK:1 Label:_? (Demand mode) bID:Y

2026-10-19T15:50:12Z [hdr: 0301010100000001] Dir:DL Mode:2 REG:N414AL ACK:3 Label:_? (Demand mode) bID:X

2026-10-19T15:50:22Z [hdr: 039a010100000001] Dir:DL Mode:2 REG:N707KS ACK:3 Label:_? (Demand mode) bID:D

2026-10-19T15:57:16Z [hdr: 0338010100000001] Dir:DL Mode:2 REG:N8309C ACK:5 Label:_? (Demand mode) bID:K

2026-10-19T15:57:25Z [hdr: 03cb010100000001] Dir:DL Mode:2 REG:N8929S NAK Label:H1 (Message to/from terminal) bID:O [- #M1FPN/FNSWA4374/RP:DA:KSMF:AA:KSAN:D:FTHIL3.FRA:F:FRA,N37063W119357..EHF,N35291W119058..HUULK,N34355W118362:A:COMIX2.HUULK57F2\r\n]

2026-10-19T16:06:28Z Dir:DL Mode:2 REG:N351UP ACK:0 Label:_? (Demand mode) bID:Y

2026-10-19T16:06:29Z [hdr: 03ef010100000001] Dir:DL Mode:2 REG:N8798Q ACK:5 Label:_? (Demand mode) bID:E

2026-10-19T16:06:31Z Dir:DL Mode:2 REG:N727TW ACK:3 Label:_? (Demand mode) bID:Z

2026-10-19T16:25:48Z Dir:DL Mode:2 REG:N221FX ACK:1 Label:_? (Demand mode) bID:Y

2026-10-19T16:43:22Z [hdr: 03ee010100000001] Dir:DL Mode:2 REG:N559FX ACK:3 Label:_? (Demand mode) bID:B

2026-10-19T16:43:29Z Dir:DL Mode:2 REG:N360UP ACK:3 Label:_? (Demand mode) bID:X

2026-10-19T16:45:23Z [hdr: 0335010100000001] Dir:DL Mode:2 REG:N852VR ACK:1 Label:_? (Demand mode) bID:X

2026-10-19T16:45:30Z [hdr: 0301010100000001] Dir:DL Mode:2 REG:N852VR ACK:1 Label:_? (Demand mode) bID:Z

Kept 4893/28125 (17.4%) lines

125 valid packets assembled from 278 fragments (1:2.22).

66/278 (23.7%) broken fragments.

193 dupes removed.

SBD: 3 short & 67 single messages. (97.2%).

SBD: 1 successful multi-pkt messages.

SBD: 0/2 fragments could not be assembled. (0.0%).

********

I just wanted the aircraft registrations so I asked Gemini for a means to:

"linux program to find "REG:" and output characters afterward up to the

space character"

with reply

grep -oP 'REG:\K[^ ]+' input.txt

cat output.bits | python3 /usr/local/src/iridium-toolkit/iridium-parser.py -g | python3 /usr/local/src/iridium-toolkit/reassembler.py -m acars | grep -oP 'REG:\K[^ ]+'

N604SB

N604SB

N568FX

N617AZ

N414AL

N414AL

N414AL

N954AK

N414AL

N414AL

N414AL

N414AL

N707KS

N8309C

N8929S

N351UP

N8798Q

N727TW

N221FX

N559FX

N360UP

N852VR

N852VR

OK I didn't specify that I was going to pipe into it but I knew to just

drop the "input.text"

********

Lots of duplicates but I know how to use the sort command.

cat output.bits | python3 /usr/local/src/iridium-toolkit/iridium-parser.py -g | python3 /usr/local/src/iridium-toolkit/reassembler.py -m acars | grep -oP 'REG:\K[^ ]+' | sort -u

N221FX

N351UP

N360UP

N414AL

N559FX

N568FX

N604SB

N617AZ

N707KS

N727TW

N8309C

N852VR

N8798Q

N8929S

N954AK

Create a file of the registrations:

cat output.bits | python3 /usr/local/src/iridium-toolkit/iridium-parser.py -g | python3 /usr/local/src/iridium-toolkit/reassembler.py -m acars | grep -oP 'REG:\K[^ ]+' | sort -u >registrations.txt

*******

Look up registrations using adsbtrack

cat registrations.txt | xargs -I {} uv run python -m adsbtrack.cli

registry lookup --tail {}

Registered aircraft

Tail: N221FX

ICAO hex: a1e54b

Serial: 21080

Registrant: EXETER AVIATION LLC

Address: C/O FLEXJET LLC 26180 CURTISS WRIGHT PKWY

CLEVELAND, OH 441431453

Country: US

Cert issued: 20260513

Last action: 20260513

Airworthy date: 20250903

Expiration: 20330531

Status code: V

MFR/MDL code: 1390044

Registered aircraft

Tail: N351UP

ICAO hex: a3ea54

Serial: 37874

Registrant: C C & E I LLC

Address: ATTN: QUALITY ASSURANCE MGR 1400 N HURSTBOURNE PKWY

LOUISVILLE, KY 402234015

Country: US

Cert issued: 20120504

Last action: 20230512

Airworthy date: 20120419

Expiration: 20280531

Status code: V

MFR/MDL code: 1385212

Registered aircraft

Tail: N360UP

ICAO hex: a40e1c

Serial: 37946

Registrant: C C & E I LLC

Address: 1400 N HURSTBOURNE PKWY ATTN QUALITY ASSURANCE MGR

LOUISVILLE, KY 40223

Country: US

Cert issued: 20130730

Last action: 20230818

Airworthy date: 20130729

Expiration: 20290731

Status code: V

MFR/MDL code: 1385212

Registered aircraft

Tail: N414AL

ICAO hex: a4e307

Serial: 9359

Registrant: WILMINGTON TRUST CO TRUSTEE

Address: 1100 N MARKET ST

WILMINGTON, DE 198901805

Country: US

Cert issued: 20200225

Last action: 20231007

Airworthy date: 20200131

Expiration: 20300228

Status code: V

MFR/MDL code: 3940051

Prior deregistration record also on file

Registered aircraft

Tail: N559FX

ICAO hex: a7216d

Serial: 21054

Registrant: FLEXJET LLC

Address: 26180 CURTISS WRIGHT PKWY

CLEVELAND, OH 441431453

Country: US

Cert issued: 20260211

Last action: 20260211

Airworthy date: 20250318

Expiration: 20330228

Status code: V

MFR/MDL code: 1390044

Registered aircraft

Tail: N568FX

ICAO hex: a74535

Serial: 21057

Registrant: JC INVESTCO LLC

Address: C/O FLEXTJET LLC 26180 CURTISS WRIGHT PKWY

CLEVELAND, OH 441431453

Country: US

Cert issued: 20260109

Last action: 20260218

Airworthy date: 20250401

Expiration: 20330131

Status code: V

MFR/MDL code: 1390044

Registered aircraft

Tail: N604SB

ICAO hex: a7d7ad

Serial: 5569

Registrant: KHOSLA VENTURES LLC

Address: 2128 SAND HILL RD

MENLO PARK, CA 940256903

Country: US

Cert issued: 20220407

Last action: 20230728

Airworthy date: 20040128

Expiration: 20290430

Status code: V

MFR/MDL code: 1390009

Prior deregistration record also on file

Registered aircraft

Tail: N617AZ

ICAO hex: a808d7

Serial: 30575

Registrant: AMAZON.COM SERVICES LLC

Address: ATTN LEGAL DEPARTMENT 410 TERRY AVE N

SEATTLE, WA 981095210

Country: US

Cert issued: 20210111

Last action: 20230414

Airworthy date: 20010525

Expiration: 20280131

Status code: V

MFR/MDL code: 1385101

Registered aircraft

Tail: N707KS

ICAO hex: a96f81

Serial: 5581

Registrant: HR TOP GUN LLC

Address: 3835 CYPRESS DR STE 110

PETALUMA, CA 949546966

Country: US

Cert issued: 20210315

Last action: 20240305

Airworthy date: 20190312

Expiration: 20280331

Status code: V

MFR/MDL code: 1390009

Prior deregistration record also on file

Registered aircraft

Tail: N727TW

ICAO hex: a9bf4b

Serial: 30340

Registrant: DELTA AIR LINES INC

Address: DEPT. 595 AIRCRAFT REGISTRATIONS 1775 MH JACKSON SERVICE RD

ATLANTA, GA 30354

Country: US

Cert issued: 20200131

Last action: 20230930

Airworthy date: 19991201

Expiration: 20300131

Status code: V

MFR/MDL code: 1384908

Registered aircraft

Tail: N8309C

ICAO hex: ab5bf0

Serial: 36985

Registrant: SOUTHWEST AIRLINES CO

Address: 2702 LOVE FIELD DRIVE #HDQ 4GC

DALLAS, TX 752351908

Country: US

Cert issued: 20120601

Last action: 20230519

Airworthy date: 20120515

Expiration: 20280630

Status code: V

MFR/MDL code: 138440A

Prior deregistration record also on file

Registered aircraft

Tail: N852VR

ICAO hex: abb0b1

Serial: 87126

Registrant: TVPX AIRCRAFT SOLUTIONS INC TRUSTEE

Address: 39 E EAGLE RIDGE DR STE 201

NORTH SALT LAKE, UT 840542533

Country: US

Cert issued: 20260907

Last action: 20260907

Airworthy date: 20260603

Expiration: 20330930

Status code: V

MFR/MDL code: 3980221

Registered aircraft

Tail: N8798Q

ICAO hex: ac1b44

Serial: 67786

Registrant: SOUTHWEST AIRLINES CO

Address: 2702 LOVE FIELD DR # HDQ-4GC

DALLAS, TX 752351908

Country: US

Cert issued: 20230317

Last action: 20230317

Airworthy date: 20230308

Expiration: 20300331

Status code: V

MFR/MDL code: 13844FZ

Prior deregistration record also on file

Registered aircraft

Tail: N8929S

ICAO hex: ac5066

Serial: 42578

Registrant: SOUTHWEST AIRLINES CO

Address: 2702 LOVE FIELD DR # HDQ-4GC

DALLAS, TX 752351908

Country: US

Cert issued: 20240710

Last action: 20240710

Airworthy date: 20240702

Expiration: 20310731

Status code: V

MFR/MDL code: 13844FZ

Prior deregistration record also on file

Registered aircraft

Tail: N954AK

ICAO hex: ad438d

Serial: 44104

Registrant: ALASKA AIRLINES INC

Address: 19300 INTERNATIONAL BLVD C/O LEGAL SEAZL

SEATTLE, WA 98188

Country: US

Cert issued: 20221214

Last action: 20230922

Airworthy date: 20221208

Expiration: 20291231

Status code: V

MFR/MDL code: 138469A

You see, when the vehicle was weighed on the Dharma weighing scale, before loading the vehicle it was zero, when the vehicle was unloaded it showed -20 kg, in this way was the weight of 2 tonnes added to it?

This is Part 2 of our SDR digital-communication receiver series. We investigate how a Costas Loop pulls a continuously rotating QPSK ring — caused by residual carrier frequency offset — into four stable clusters, measured on real hardware.

📌 Key takeaways:

1. A QPSK constellation that looks like a spinning ring is not noise — it is residual carrier offset rotating the constellation in complex baseband
2. Costas Loop = phase detector → loop filter → NCO update, closed every symbol. It needs no knowledge of the transmitted bits — the error comes from QPSK symmetry
3. Loop bandwidth trades off:
   • Wider bandwidth → faster acquisition, more steady-state jitter
   • Narrower bandwidth → smoother lock, slower pull-in
4. Measured on dual P201Pro: the rotating ring collapses into four clean QPSK clusters
5. Honest limit: the loop stops the rotation but cannot tell the four quadrants apart — the 90° ambiguity, fixed later in the series

🔧 Test environment: Ubuntu Linux + GNU Radio 3.10, dual P201Pro transceiver OTA setup, Fc = 1 GHz.

Next video: Part 3 — finding the optimal sampling instant with the Gardner timing-recovery loop.

Full written article : https://www.reddit.com/r/PuzhiPZSDR/s/4PQFt1vV6g

Timestamps: Intro — the spinning ring What carrier offset does to QPSK Costas loop architecture, step by step Measured convergence: ring → 4 clusters Loop bandwidth trade-off The 90° ambiguity, previewed

#SDR #GnuRadio #RF #SoftwareDefinedRadio #HamRadio

Edit: ended up running SDR++ as a server on my VM. After installing SDR++ on the VM, I ran sdrpp —server in the console, then went to my main pc and connected to the VMs IP address with the default port in the SDR++ software itself. Works like a charm!

Sorry if this isn’t allowed, I copied my post from [r/Proxmox](r/Proxmox) in hopes that someone here is doing something similar and may be able to help.

I'm running a Nooelec RTL-SDR v5 via SDR++ in a Fedora 44 KDE VM on my main Proxmox host with 2.5gb networking between all machines.

My main PC also runs Fedora 44 KDE.

My main issue is that I cannot get audio to passthrough to my main PC when remoting into the VM, either through the Proxmox GUI (VNC doesn't support audio, this much I know) or using KRDC with RDP. The VM can see all my other audio devices (hard wired) on the network, such as my AVR, ATV4K and WiiM player, but the audio output through those is extremely choppy and horrible quality when I try to use them. I'd like to get this working as well, so I can listen to ATC and/or FM radio in the future without having to access a PC.

I saw something about using SPICE, but, I am a brand new Linux user of less than 6 months and still barely know enough to cause damage. Hell, I just built my first gaming PC 2 months ago. Saying all that, please treat me like a special needs student with your explanations of things, lmao.

I'd appreciate any help I can get!

Hello i am going on a cruise in a few weeks and i plan to take my rtl sdr v4 along with me with a couple antennas:

1 quarter groundplane for ads-b

1 quarter groundplane for ais, flexible conductors held straight with 3d printed parts so i dont go carrying around solid half meter sticks of metal around

1 rubber duck for ais (didnt take a pic)

I am aware that i cant bring trasmitters onboard but there aint no rules for bringing radios onboard

Its an msc cruise.

I’ll need 5 or 6 SDRs to cover all frequencies I’m monitoring.

Currently: antenna > lmr400 > SDR v3 > laptop
Ideal: antenna > lmr400 > 5 SDRs > laptop

I wanted to share my failure (thus far) to determine why my garage door opener doesn't work when it's below ~50f and the light is on. I thought it was interference from the LED bulbs, so I replaced them. That didn't work so I bought a plug-in shop light and an adapter to turn the light socket into an outlet, so the light source can be far away from the antenna - no luck.

So I decided to get more technical. I dug out the RTL-SDR I bought ten years ago and installed SDR++. I was hoping to find interference from the light or opener in the range of the emitter, but I didn't.

First, I had to find where my two clickers emitted. That's the waterfall you see. The two blips on the left are the newer (2 years) emitter, and that mess on the right is the older (20 years) one that is usually in my car. Yeah, wtf.

Now, I'm just a chemist, but that looks sloppy as hell. Not only is it sloppy, the freq. changes when I tilt the emitter. What could cause the frequency to drift when I rotate the device? There's nothing lose in there, it's a very simple circuit.

At least I knew where to look for interference, but when I took my laptop out to my garage, I found no evidence whether the light was on or off, but I have to hold the new emitter just inches away from the antenna to get it to work when the light is on - the old one won't work at all until the light times out. This remains true even when there are no lights connected.

So I'm no closer to making the door work. I think I'll try improving the antenna, which is currently just a wire hanging from the opener.

I'm about at my wit's end with this. It all used to work and now getting back into it after a few years, all I get is this damned error

Found 1 device(s):
 0:  Realtek, RTL2838UHIDIR, SN: 00000001

Using device 0: Generic RTL2832U OEM
usb_claim_interface error -6
Failed to open rtlsdr device #0.

Kubuntu 26.04, all updated, and I've tried so many fixes found by searching the web. Nothing is working to free this up and just let me use the thing. It's been extremely frustrating and discouraging. Does anyone have any additional ideas?

So I’ve been messing around with SDRangel trying to decode ADS-B traffic, and I got that side of it to work but I can’t seem to get the map to function, and under features I can’t even find the map, I understand it’s more than likely a API issue in why it’s showing blank but I can’t even get to the settings to set up my Cesium Ion api. Anyone got any help? Much application in advance

I wanted something like a tinySA that I could carry around, but that could also listen to what it finds and tell me what a signal is. So I built SDR-Kit: a Raspberry Pi Zero 2 W with an RTL-SDR, and a web panel you open on your phone. No app, no internet needed.

What it does:

• Spectrum analyzer + waterfall, 0.5–1766 MHz, with markers, channel power, OBW, SNR, zero span, max hold, etc.

• Tap a signal to listen to it: FM, AM, WFM, USB/LSB, plus digital voice through DSD-FME (optional).

• It tries to tell you what the signal is by its shape (2/4-FSK, GMSK, AFSK, symbol rate).

• Decoders: POCSAG/FLEX pagers, APRS, EAS, 433/868/915 MHz sensors (rtl_433) and an offline ADS-B radar (dump1090).

• Scanner, memories, per-transmission recording and a 24/7 monitor with phone alerts.

• Joins your WiFi at home, makes its own hotspot in the field, or works through Tailscale.

Install is one line on Raspberry Pi OS, and updates roll themselves back if something breaks.

You can try it without any hardware: there's a demo mode that simulates real, decodable signals (pagers, APRS, FM stations…), so you can click around on a laptop first.

It's MIT licensed, receive-only, and the interface works in English and Spanish.

Repo + screenshots: https://github.com/romartak/sdrkit

I'm a medical student and this is a side project, so I'd really appreciate feedback: what's missing, what's confusing, or what breaks on your dongle.