Featured tool

Show Clock

Full-screen stage timer for FOH & backstage — countdown, schedule offset, and 3-second share to your crew's phones.

timer3 s sharePWA
Open Show Clock
support@squaresmile.de Köln, Germany
RF spectrum scanning & coordination · SDR hardware from ~€40

Find clean frequencies before the downbeat.

Spektra sweeps the UHF wireless-mic band in seconds on an SDR from around €40 — live spectrum with waterfall, clear free/occupied verdicts, and a Frequency Advisor that turns the measured gaps into an intermod-safe, printable coordination plan in one click.

Works offline at the venue Double-click app · no Python, no drivers Interactive demo · free account, no dongle 7 languages · 8 regulator regions
spektra · live · 470–700 MHz
SCANNING
Free channels
14 clean
Occupied ranges
5 in use
Tightest margin
0.42 MHz
Signal level
Free
Occupied
Noise threshold
Live preview — synthetic data
128
Coordinated channels max
27+
Equipment device families
8
Analyzer families auto-detected
7
Interface languages
Everything for coordination

One tool from scan to soundcheck

Spektra covers the whole pre-show RF workflow — sweep the band, read what's free, lay out your channel plan, and hand off clean numbers to the stage.

Live spectrum + dual waterfall

Full 470–700 MHz UHF sweep in a few seconds, ~1-second cold start, band presets for DECT and 2.4 GHz — hardware permitting up to 6 GHz. A live waterfall on IQ-capable devices plus a timestamped sweep-history strip on every analyzer.

Frequency Advisor

4–128 coordinated, intermod-safe suggestions placed inside the actually measured free windows — full 2-tone/3-tone IM3 checking, Robust and High-density profiles, and deterministic results: a reprinted plan always matches the printed one.

8 analyzer families, one picker

RTL-SDR (from ~€40), tinySA & tinySA Ultra, RF Explorer, HackRF One, Airspy and SDRplay — auto-detected on plug-in. No hardware yet? Demo mode generates a synthetic spectrum for training.

Smart 3-state occupancy

Not a dumb threshold: Spektra distinguishes your own carriers (green) from contention on your channel (amber) and unknown interference (red) — with a suggest-threshold helper for the noise floor.

27+ device families & regulation

Shure, Sennheiser, Lectrosonics, Sony and budget channel-wheel gear — group/channel picks resolve to exact MHz. Regulation overlays for 8 regions tint TV whitespace and give each device a license verdict.

Listen, snapshot & hand off

FM-demodulate and listen to any parked frequency with squelch and level meter. Save and compare sweeps, export scans as CSV/JSON — and hand guest crews the Advisor's coordination CSV or printable A4 PDF with spectrum snapshot.

Up and running in minutes

How Spektra works

No rack of gear, no lab analyzer, no install marathon. A dongle and a double-click.

1

Plug in & launch

Connect any of 8 supported analyzers — Spektra auto-detects it and cold-starts in about a second. Everything is bundled in one double-click app: no Python, no drivers.

2

Scan the band

Sweep the UHF band in seconds, watch the waterfall, and read the 3-state verdicts: your carriers green, contention amber, intruders red — every usable gap listed.

3

Coordinate & go

One click on the Frequency Advisor places 4–128 intermod-safe frequencies inside the measured gaps — print the A4 coordination sheet and hand it to the stage.

Built for any crew

Speaks your language. Suits your venue.

The interface ships in seven languages and switches instantly — no reload. Dark mode for the FOH position, light mode for daylight load-in, with a tunable accent so it fits your rig.

EnglishDeutschFrançaisEspañolItalianoNederlandsPortuguês
Dark
Light
Why Spektra

Pro-level coordination, without the pro-level invoice

Get the essentials that matter on show day for a fraction of the cost of dedicated suites and lab hardware.

Capability Spektra
Best value
Pro coordination suite Lab spectrum analyzer
Typical cost€49 + €40 dongle€1,000–4,000€2,000–10,000+
Live RF scanning + waterfall
Automatic free-channel detection
Intermod-safe coordination (IM3), up to 128 ch
Own-carrier vs. interference detectionPartial
Printable coordination sheet (PDF)
Multi-region regulatory overlays
On-frequency audio monitoringSome
Runs on a low-cost USB dongle
Pocket-sized & portableLaptop + receiverBench unit
What you need

Minimal kit. Maximum coverage.

An SDR or analyzer

From a ~€40 RTL-SDR to tinySA, RF Explorer, HackRF, Airspy or SDRplay — 8 families, auto-detected. Or start in demo mode with no hardware at all.

A Mac, one double-click

Ships as a ~23 MB macOS app (Apple Silicon) with everything bundled — no Python, no Homebrew, no driver installs.

Nothing else

100% local and private: binds to localhost only, no telemetry, no account, no cloud. Works fully offline at the venue.

One-time license

Buy Spektra once on Gumroad for €49, download instantly, and get updates for the version you own. No subscription.

Questions, answered

Frequently asked

What hardware do I need to run Spektra?
Any of 8 supported analyzer families, auto-detected on plug-in: RTL-SDR Blog V3 (the ~€40 reference device) and generic RTL2832U dongles, tinySA and tinySA Ultra, RF Explorer WSUB1G and 3G Combo, HackRF One, Airspy, and SDRplay RSP models. No hardware yet? A built-in demo mode generates a synthetic spectrum so you can learn the app first.
Which bands and regions does it cover?
The default sweep covers the 470–700 MHz UHF wireless-mic band in a few seconds, with presets for DECT (1880–1900 MHz) and 2.4 GHz — and capable hardware can tune up to 6 GHz. Regulation overlays for 8 regions (DE, UK, EU/CEPT, US, FR, AU, JP, CA) tint TV whitespace and give each registered device a license verdict: license-free, registration required, or forbidden.
Does it replace professional coordination software?
For the pre-show workflow, it closes the whole loop: sweep the band, read what is genuinely free, and let the Frequency Advisor generate 4–128 intermod-checked frequencies inside the measured gaps — then print the plan as an A4 PDF. What it does not do is remote-control receivers the way manufacturer suites do for their own gear.
How do I buy and download it?
Purchase a one-time license through Gumroad. After checkout you get an instant download link plus future updates for that major version. Spektra ships for macOS as a double-click app — no Python, no driver installs, everything bundled in about 23 MB.
Can I use it without internet?
Yes. Spektra is 100% local: it talks to your analyzer over USB, binds to localhost only, and sends no telemetry. No account, no cloud — ideal for festival sites and venues with no connectivity.
What languages and themes are supported?
Seven interface languages — English, German, French, Spanish, Italian, Dutch and Portuguese — with light and dark themes and a tunable accent color.

Stop guessing. Start scanning.

Walk into your next show knowing exactly which frequencies are clean.

€49 one-time license · instant download · updates for your major version · or try the interactive demo free (just an account, no dongle)

The Squaresmile suite

More tools on Squaresmile — one free account

Every browser tool below is free the moment you sign up. Create one account and the whole toolbox follows you from gig to gig — no installs, no app store.