Touchstone-Pro

A wideband RF spectrum analyzer. Choose a frequency range and watch the signal strength across it, live — the classic “what’s on the air right now?” view. The Wireless Toolbox does the measuring with an attached receiver, and you watch from any browser.

Live trace with automatic peak detection, so the strongest signals are called out.
Waterfall — a scrolling history that shows how the spectrum changes over time, making bursty or intermittent signals easy to catch.
Adjustable range for a wide survey or a close look at one signal.

Use it to find what is transmitting in a band, hunt down a source of interference, or confirm that a frequency is clear.

Touchstone-Pro comes in two versions on the menu, one for each receiver. They look and work the same; this page covers both, and a box like the one below marks every place they differ.

Which receiver?

Touchstone-Pro for RF Explorer — a calibrated analyzer. Levels are true dBm. The frequency range depends on the RF Explorer model and its active radio module.
Touchstone-Pro for RTL-SDR — a low-cost USB receiver covering 24–1766 MHz. It is uncalibrated: levels are approximate (see Amplitude below).

Getting started

Plug the receiver into the Wireless Toolbox, then open the tool from the menu. There is nothing to set up on your phone or computer. Once the receiver reports, a tag appears in the title bar — the RF Explorer's model (e.g. [WSUB1G]), or [RTL-SDR].
Set the range with START (MHz) and STOP (MHz), then press Start (top-right). Press Stop to pause.
START, STOP and THRESHOLD are locked while scanning — press Stop first to change them, then Start to sweep the new range. Scanning only ever begins on the Start button; the keyboard's Go key just closes the keyboard.

Scanning & frequency range

Touchstone-Pro opens on 470–600 MHz — the usual UHF range for wireless pro-audio gear. The span must be between 5 and 150 MHz, and inside the range the receiver supports (shown as MIN FREQ / MAX FREQ in the status bar). On Start the range is checked and a warning is shown if it is invalid.

To cover a span wider than the receiver can take in at once, Touchstone-Pro uses retune-and-stitch: it steps the receiver across a row of overlapping sub-scans, keeps the clean core of each, and joins them into one continuous trace. A cyan scan line sweeps left to right as each sub-scan is captured. Trace cleaning (median smoothing and noise-bias correction) is always on.

Amplitude

RF Explorer. Levels are calibrated dBm. The SNR button switches the display to dB above the noise floor.

RTL-SDR. The receiver is uncalibrated, so levels are shown in dBm relative to a nominal −100 dBm noise floor — approximate, not a traceable measurement. Each sweep's noise floor is set to that −100 dBm, so the y-axis reads roughly how far each signal rises above the noise, on the same dBm scale the RF Explorer reports and that Wireless Workbench imports. Use it to compare levels and to tell clear from occupied, not as an absolute power reading. There is no SNR button.

Resolution (AUTO / HIGH) — RF Explorer only

The RESOLUTION button sets how finely the span is measured — that is, how many sub-scans are stitched together. The status bar's EST RBW (resolution bandwidth) shows the spacing between measured points; smaller is finer.

Mode	What it does
AUTO RES	Default. Uses 8 sub-scans — fast, with ample resolution for a general look.
HIGH RES	Uses as many sub-scans as needed (up to 60) to reach an EST RBW of about 25 kHz (0.025 MHz). Wireless-audio channels sit on 25 kHz boundaries, so this is the resolution to use when hunting for clear white space between them.

HIGH RES is slower. Finer resolution means many more sub-scans — a wide span (130 MHz needs about 48) can take over a minute to build the first settled trace. Use a narrower span to speed it up, or scan in AUTO for a quick overview and then switch to HIGH to zoom in. Resolution starts at AUTO each session.

The RTL-SDR version has no resolution button.

Display controls

The left-panel buttons change how the data is shown — green = on, grey = off. All are off when the tool opens.

Button	What it does
SNR (RF Explorer only)	Switches the y-axis from absolute dBm to SNR — dB above the noise floor.
MAX HOLD	A red max-hold trace — the highest level seen at each frequency since Start.
DENSITY	A persistence "dot cloud" of where the trace has been. The green trace is hidden while it is on.
NOISE FLOOR	A dashed amber line at the estimated noise floor.
THRESHOLD	A reference level with a yellow line and a black/red waterfall — see Threshold below.
PEAK DETECT	Shows the detected peaks — markers on the trace plus a ranked table (top-right).
CLEAR MARKERS	Removes all markers. Momentary — it does not stay on.

Trace & waterfall

The trace plots signal strength against frequency. The green line is the settled result, cleaned for a stable display; a cyan line sweeps across as it is built. The waterfall below scrolls newest-on-top, one row per sweep — dark = noise floor, brightening blue → cyan → green → yellow → red — and lines up column for column with the trace.

RF Explorer. The top of the y-axis is fixed at −40 dBm and the bottom sits just below the noise floor, so the trace stays steady instead of jumping. The area between the noise floor and the trace is shaded green.

RTL-SDR. The y-axis ranges automatically to fill the vertical space.

Peak detection. A detector finds real peaks (not noise ripple), ranks them, and labels each HIGH / MED / LOW confidence from its SNR and how persistently it recurs. With PEAK DETECT on, each peak is marked on the trace with a coloured drop-line and circle (green = high, yellow = medium, magenta = low) and listed in a ranked table (top-right).

Threshold

The THRESHOLD control sets a reference level — type it in the box just below the button. A solid yellow line is drawn across the trace at that level, so you can see at a glance which signals rise above it.

Pressing the THRESHOLD button (green = on) also switches the waterfall to a simple two-colour view: black wherever the signal is below the threshold and red wherever it is above. Occupied and clear frequencies then stand out — handy for spotting white space for a new wireless-audio channel. The yellow line is drawn over the waterfall too. Turn the button off to return the waterfall to its normal colours.

RF Explorer. In dBm mode the threshold is an absolute level, −100 to −40 dBm. With SNR on it becomes a level above the noise floor, 0 to 70 dB — the box and its label switch units with the SNR button. Occupancy is worked out on the underlying signal, so it behaves the same in either mode.

RTL-SDR. The threshold is in dBm on the approximate scale described under Amplitude — for example −80.

Markers

Tap the trace (or the waterfall) to drop a marker: a dashed amber line with a diamond, labelled with the frequency (nearest MHz) and the level. CLEAR MARKERS removes them all.

Status bar

Field	Meaning
S/N (RF Explorer)	Serial number of the attached RF Explorer.
TUNER (RTL-SDR)	The RTL-SDR's tuner chip, e.g. R820T2.
MIN FREQ / MAX FREQ	The frequency range the attached receiver supports. For the RTL-SDR, 24–1766 MHz; for an RF Explorer, that of its active module.
EST RBW	Estimated resolution bandwidth — the spacing between measured points (span ÷ number of points). Smaller in HIGH RES.
NOISE EST (RF Explorer)	Estimated noise-floor level of the current trace.
DYN RANGE	Dynamic range — how far the strongest peak rises above the noise floor.

If the trace stops updating

If the receiver stops sending data while a scan is running, Touchstone-Pro says so on the page. Switch the RF Explorer off and on with its own power switch, or unplug the RTL-SDR and plug it back in; then return to the menu and start the tool again.

Menu (⋮)

Save as PDF — see below.
Export Trace to CSV — downloads the most recent complete trace as frequency, amplitude pairs (MHz, dBm) — the format Shure Wireless Workbench imports. Available once a scan has been stopped.
About — version information.

The ☰ button (top-left) returns to the Wireless Toolbox menu.

Save as PDF

The ⋮ menu (top-right) has Save as PDF. It captures the tool exactly as shown and writes one file to your device’s Downloads folder, named with the tool and a timestamp, e.g. Touchstone-Pro 2026-08-13 14.32.05.pdf. Every save is timestamped, so nothing is overwritten.