Bandline: RF Signal ID

Heard a signal you can't identify? Bandline is an offline signal
identification tool for radio listeners — enter a frequency, hold
your phone to the receiver, or match a waterfall shape by eye. It
narrows 520 known signals down to a handful, using what you can
actually measure.

Built for SDR users, licensed amateur radio operators, shortwave
listeners, scanner enthusiasts and anyone poking at 433 MHz or
868 MHz sub-GHz gear. No account, no connection required.

— THREE WAYS IN —

BY FREQUENCY
Type any frequency and see the full allocation stack: primary and
secondary service, national applications, footnotes, licence class
and power limits. Then see which known signals actually live in
that band, ranked by how commonly they're heard.

BY EAR (the interesting one)
Hold your phone near the receiver's speaker, or plug in a line-in
cable. Bandline records a short sample and measures:

- occupied bandwidth (−26 dB)
- autocorrelation peaks (ACF, in milliseconds)
- tone count and tone spacing for MFSK
- estimated symbol rate
- burst length, duty cycle, on/off periodicity
- modulation class (AM, FM, SSB, PSK, FSK, OFDM-like)

Each measurement becomes a filter. The candidate list narrows as
you go — 520, then 12, then 3. Drop a chip if a reading looks off.
Every measurement shows a confidence indicator, because measuring
through a phone mic is honest work but not laboratory work.

BY SHAPE
Browse a visual grid of reference waterfalls, filtered by band and
category. You already know what CODAR and STANAG look like — this
is faster than reading a list.

— SIGNAL CARDS —

Name and aliases, category, active status, frequency ranges,
modulation, bandwidth, ACF, symbol rate and mode. A reference
waterfall you can pinch-zoom and compare side by side with your own
capture on a matched frequency axis. A playable audio sample with a
live spectrogram. Protocol notes and links to specifications and
decoder software.

— FREQUENCY ALLOCATIONS —

Switzerland, Germany, France, the UK and the USA at launch, from
official national tables and the European ECA/EFIS data. IARU
amateur band plans included. Auto-detects your region, or set it
manually.

— BUILT FOR FIELD USE —

Fully offline once your library is downloaded. Dark theme with an
optional red night mode. Monospace numerics throughout. Density
over whitespace — the numbers stay on screen.

— WHAT THIS ISN'T —

Bandline is an instrument and a reference, not a receiver. It does
not connect to SDR hardware; it works alongside whatever radio you
already own.

It identifies signal types, never message content. No decryption,
no descrambling, no guidance on intercepting protected
communications — by design, permanently.

— PRO —

A single one-time in-app purchase, no subscription, ever. Removes
ads, unlocks all offline packs, plus unlimited saved captures,
waterfall export and a private custom signal library.

Useful if you search for: signal identification, unknown signal,
waterfall spectrum, SDR companion, shortwave utility monitoring,
scanner frequencies, band plan, modulation reference, ACF lookup,
433 MHz, 868 MHz, sub-GHz.

Signal reference informed by the community work at sigidwiki.com.
Corrections welcome from every card.