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Overlap resolution — recommended defaults

SCOPE.md: "Merging five inventories without curation produces four ADS-B decoders and no opinion about any of them — the opposite of what this project is for." This is the opinion.

Recommendations only. Every one of these is the maintainer's to accept or reject. Nothing here is written into a manifest.

Per PARITY-POLICY.md, a recommended default never removes working software. Alternatives stay in the catalog with the trade-off documented; the default is what an operator gets when they install a profile and express no preference.

Availability was checked against sources.debian.org and the Blend task files, so the cost of each recommendation is known rather than assumed.

1. ADS-B and aircraft tracking

Candidate Source Availability
dump1090 (FlightAware) AHRL — source build from a master zip not in Debian
dump1090-mutability Debian Blend (nonamateur) in unstable only — not in Debian 13
readsb — in Debian
Virtual Radar Server AHRL — Mono + .exe not in Debian
tar1090 (web UI) — not in Debian

Actively maintained, in Debian, and it supersedes both dump1090 forks at once — AHRL's unpinned master snapshot and the Blend's dump1090-mutability, which AHRL itself dropped in v27.

Also carry: dump1090-mutability — it is the Blend's own choice and removing it would break parity with a team-governed source for no user benefit. Note, measured 2026-08-25, that it does not install on Debian 13 either; it is in unstable. That strengthens rather than weakens the readsb recommendation, since readsb is in Debian 13 and every other target.

Recommend RETIRE: Virtual Radar Server. Mono was handed off by Microsoft in 2024, the AHRL install needs a second tarball purely to patch a runtime error, and its launcher starts a decoder and killall -9s it on exit.

Flagged cost: tar1090, the modern web UI, is not packaged. It is carried since 2026-10-02 as a pinned data unit that hammunition reference serve serves on 127.0.0.1 (D-071), which needed no new backend. The decoder half is apt-only.

2. Logging

Candidate Source Availability
cqrlog, xlog, klog, tlf, tucnak, pyqso, trustedqsl Blend logging in Debian 13
qlog, not1mm Blend logging in unstable only — not in Debian 13
fllog, flnet AHRL — source not in Debian
HAMRS 73Linux — AppImage not in Debian

Modern, actively developed, and already the agreed default in PARITY-POLICY.md.

⚠️ Corrected 2026-08-25 — qlog does not install on Debian 13. A probe of all 152 Blend packages inside a debian:13 container found qlog and not1mm present in unstable (qlog 0.52.0-1) and absent from stable. The earlier claim that this default "costs no backend work" was wrong on our primary targets, which derive from Debian stable.

The recommendation is unchanged — qlog is still the right default, and it arrives in Debian 14. What changes is what the catalog must say in the meantime:

Option Consequence
Recommend qlog; declare it unavailable on stable in the capability matrix; fall back to cqrlog ⭐ Honest, costs nothing, and is exactly what the capability matrix exists for. cqrlog is in Debian 13 and works.
Ship a source or upstream-.deb path for qlog on stable Gives everyone the default. Adds a backend obligation for one package, for a gap that closes on its own.
Change the default to something in stable Optimises for today's package archive over the software. Wrong trade.

Recommendation: the first. Per D-005, coverage counts only where it installs, and per D-019 "in the Blend" is not the same claim as "installable". Recorded rather than papered over.

These are not all the same job, and treating them as one overlap would be a mistake:

Job Recommended Why
General station log qlog Active and modern; sid-only, see above
Contest logging (GUI) not1mm Actively developed; already carried by AHRL; sid-only
Contest logging (terminal) tlf The serious contest CLI; no GUI competitor
Net control flnet Different workflow entirely — running a net, not logging QSOs
Networked shared log fllog Serves a log across machines; not a personal logger
LoTW upload trustedqsl Not a logger at all; every operator needs it

Also carry: cqrlog, xlog, klog, tucnak, pyqso. All work, all packaged, all have users.

Post-1.0: HAMRS — proprietary freemium, AppImage, and its upstream is discovered by scraping a webpage.

3. SDR receivers

Candidate Source Availability
gqrx-sdr Blend sdr; AHRL builds from source in Debian
sdrpp (SDR++) Blend sdr; AHRL builds a master snapshot in Debian
sdrangel Blend sdr in Debian
cubicsdr Blend sdr in Debian
quisk Blend sdr; AHRL source in Debian
welle.io Blend nonamateur in Debian (DAB, not general)

The most documented, most widely used, and simplest receiver to get working with a first SDR — which is the situation most users are in when they open one.

Tiered alternatives, because "SDR receiver" hides three different needs:

Need Recommended Why
First SDR, general listening gqrx-sdr Simple, documented, forgiving
Modern UI, plugin ecosystem sdrpp Actively developed, better performance
Multi-channel, transmit-capable, advanced sdrangel Far more capable and far more complex
Transceiver operation, not scanning quisk A transceiver app; different job

This resolves an unpinned snapshot for free. AHRL builds SDR++ from an unversioned SDRPlusPlus-master.zip. Debian packages it. Preferring apt removes one of the six snapshot problems in D-006 at no cost — see the same pattern in blend-inventory.md's M3 cross-reference.

Note the naming trap: the Debian package is gqrx-sdr, not gqrx. A manifest that guesses will silently resolve to nothing.

4. APRS

Candidate Source Availability
xastir Blend packetmodes; AHRL apt in Debian
YAAC AHRL — Java zip not in Debian
Pi-APRS 73Linux not packaged; unlicensed (D-001)
aprsdigi Blend packetmodes in Debian
direwolf Blend; AHRL source in Debian

Mature, packaged, in the Blend, and already installed by AHRL — the only candidate that is simultaneously maintained, free of licence questions, and apt-installable.

Also carry: YAAC. It has a genuinely better map UI and an active author, and some operators strongly prefer it — but it needs a JRE and a binary backend, so it should not be the default.

Cannot carry: Pi-APRS. KM4ACK's own work in an unlicensed repository (D-001); we have no right to redistribute it regardless of merit. If the licence question is resolved this reopens.

Not competing, do not conflate: direwolf is the TNC — the modem layer underneath any of these. aprsdigi is a digipeater. Both belong in the packet profile alongside a client, not instead of one.

5. Satellite imaging

Candidate Source Availability
satdump Blend satellite; AHRL source snapshot in Debian
noaa-apt AHRL — RETIRED not in Debian
xwxapt AHRL — RETIRED not in Debian
wxtoimg — not packaged, abandoned
gpredict Blend satellite; AHRL source in Debian

The only live option — it handles the LRPT and HRPT services that still transmit, and it is already the agreed supersede target for both retired APT decoders.

There is no real overlap here to resolve. Both alternatives are retired because the NOAA APT satellites were decommissioned on 2025-11-09. This section exists so the reasoning is written down where someone looking for an APT decoder will find it.

Second free snapshot fix: AHRL builds SatDump from SatDump-master.zip while shipping an unused pinned SatDump-1.2.2.zip. Debian packages it. Prefer apt.

Not competing: gpredict is tracking — where a satellite is and when it passes. SatDump is decoding what it transmits. An operator needs both.

6. HF data modems

Added 2026-09-30 from the gap analysis (catalog-gaps-2026-09.md section B, Group 3; Q-022 #6). Unlike the five sections above, this one is decided: Mercury and FreeDATA are carried beside ardopcf in the packet profile. Availability here is the seven-target apt-cache policy sweep of that day.

Modem What it is Interface it offers What Pat uses Licence Availability
ardopcf ARDOP ARQ modem ARDOP host TCP (8515) and a web view ardop:// MIT source build, every target
mercury OFDM ARQ modem, FreeDV-derived modes VARA HF's TCP interface (8300/8301) and a KISS broadcast port varahf://, unchanged (measured peer to peer, no radio) GPL-3.0-or-later apt on Kali (1.9.13); source build elsewhere
freedata codec2 messaging and file transfer with a browser interface its own REST and WebSocket API (5000) none: not a Winlink path GPL-3.0-or-later venv from PyPI, x86-64 only
VARA HF closed ARQ modem, Windows VARA's TCP interface varahf:// proprietary not carried; post-1.0 Wine prefix, optional

No single default. The choice is decided by what the station at the other end runs, because none of these interoperate on the air: an ARDOP gateway needs ardopcf, a Mercury station needs mercury, a VARA-only gateway needs VARA. Mercury does not make a VARA gateway reachable; it makes Pat's VARA transport useful with free software at both ends. FreeDATA answers a different question, messages and files between two FreeDATA stations with no Winlink account.

What VARA still buys is the gateways that run only VARA. That is why its Wine prefix stays post-1.0 rather than being retired, and why it is now optional rather than the only HF upgrade over ARDOP (SCOPE.md).

Also overlapping, already raised

Not in this queue item, but they are the same class of problem and each already has an open question:

Overlap Where
FT8 family — wsjtx / wsjtx-improved / jtdx / mshv dispositions.md, NEEDS-DECISION
Rig control — flrig / grig / wfview / libhamlib-utils dispositions.md, SUPERSEDE #5
HamClock clients — four options Q-006
RigExpert analysers — flaa / antscope2 / aa-analyzer dispositions.md, SUPERSEDE #3

The pattern worth noticing

Four of the five recommendations above land on a package Debian already carries, and three of them (sdrpp, satdump, and the readsb supersession) eliminate an unpinned master snapshot from AHRL's inventory as a side effect.

That is not a coincidence. Preferring the packaged option where one exists is usually also the option with a maintainer, a version, and a signature — which is why SCOPE.md puts the Blend first in the staging order. The exceptions worth building a backend for are the ones where Debian genuinely has nothing: tar1090, YAAC, HAMRS.