Digital Smart SolutionsJan Stürkat

Manual

RF Lotse, User Manual

Quick start

RF Lotse turns an RF Explorer into a tool for wireless coordination at events. It shows the live spectrum with a waterfall, finds free frequencies and calculates an intermodulation-free frequency plan. It imports the frequency plan already in use across all rooms, checks it for conflicts and finds a replacement for a channel that is being interfered with, then verifies it by measurement. Scans from Shure or Sennheiser receivers can be overlaid for comparison. It watches individual frequencies and logs every dropout with a timestamp. A database with about 1060 frequency bands from 27 manufacturers is built in, plus Wi-Fi, Bluetooth, wireless DMX and cellular bands, together with the allocations for Germany, Spain, France, Italy and the United Kingdom.

The name: a "Lotse" is a harbour pilot, the person who guides ships through difficult waters. RF Lotse is your RF pilot for wireless coordination.

Requirements

Installation

macOS and Windows usually include the USB driver for the RF Explorer (Silicon Labs CP210x). If no device appears on Windows, install the driver from Silicon Labs.

Connecting the antennas

The two SMA connectors belong to different measurement modules. Only one is active at a time, RF Lotse switches automatically.

Below 960 MHz RF Lotse automatically measures on the left connector, above it on the right one. The badge at the top right shows which connector is active ("main module, left antenna" or "expansion, right antenna").

A click on the badge fixes the antenna by hand: "Automatic" (default), "Left antenna (main module)" or "Right antenna (expansion)". This helps when working around 960 MHz, where RF Lotse would otherwise switch between the antennas. With a fixed choice the badge shows "(fixed)" and the range is that of the chosen module; a range outside it is moved there. On a 6G Combo+ both modules can measure 240 to 960 MHz. The choice lasts until the app is closed, on the next start RF Lotse measures automatically again.

RF Lotse reads the range of both modules from the device when it connects, so a 6G Combo+ with the wideband licence and firmware 3.36 or later measures up to 7.5 GHz without further setup. If the antennas are swapped, the UHF band reads 20 to 30 dB too low.

Input power limits

Never connect the RF Explorer directly to a transmitter output. Switch the LNA off near transmitting antennas (IEM combiners, video transmitters). Source: RF Explorer User Manual, page 47.

Starting and stopping

1. Connect the RF Explorer via USB and switch it on.
2. Start RF Lotse. It opens its own window.
3. A badge at the top right shows the source: "RF Explorer WSUB1G+ + 6G+" with the device connected, "Simulator" without it.
4. To quit, close the window. Measurement stops and the USB port is released. RF Lotse restarts the RF Explorer so that it leaves remote mode ("Remote" on its display); after about three seconds it shows its normal screen again. The same happens when switching to the simulator or playback.

If RF Lotse finds no device at startup, or another program is using the USB port, the simulator starts automatically. It generates a practice spectrum with TV blocks, wireless links and one link that drops out briefly every 23 seconds. So that nobody mistakes it for a measurement, "SIMULATOR" is written large across the spectrum, and "PLAYBACK" when a recording is played back. The source selector at the top right switches between device and simulator.

If the RF Explorer is unplugged while running, RF Lotse does not switch to the simulator. The badge shows "Device not connected" and the spectrum is cleared. As soon as the device is plugged in again, RF Lotse reconnects by itself, no restart needed. The same applies when the device is selected as source but none is plugged in.

The RF Explorer can only be used by one program at a time. While RF Lotse is running, Wireless Workbench, Touchstone or RF Explorer for Mac cannot access it.

The app opens no network port. Interface and measurement talk to each other directly, so access from other devices or from a browser is not possible.

The interface

Project commands and the manual are in the app's menu bar:

Shortcuts: ⌘N, ⌘O, ⌘S and ⌘, on the Mac, Ctrl+N, Ctrl+O, Ctrl+S and Ctrl+, on Windows. The menu bar follows the selected language at start-up, so after switching languages it changes on the next start.

Using the spectrum

The mouse wheel on its own does not zoom, so scrolling never changes the view by accident. If you prefer zooming without a key, turn it on in the settings. Zooming is damped and easy to control with a Magic Mouse.

Instead of start and stop you can enter center and span. The pair edited last applies; "Apply" or the Return key sets the range.

Frequencies are entered in MHz with a point or comma, or without a separator in kHz: a whole number of 10000 or more is read as kHz, so 508700 is 508.700 MHz. This works in all frequency fields, including markers and existing frequencies.

RF Lotse measures a range up to 900 MHz wide in a single device sweep, like the manufacturer's software. Wider ranges are split into as few segments as possible. The resolution sets the number of points:

Next to the source at the top right RF Lotse shows how many points are being measured and how long a sweep takes, also with "automatic". Every change of range costs the device a short calibration; as long as the range stays the same, it sweeps continuously.

Waterfall

By default the waterfall reaches back 12 hours, adjustable to 1, 4, 12 or 24 hours (Settings). It is kept while zooming and panning. Older lines appear in the new view as far as they cover it.

The last 4000 sweeps keep full precision. Older lines are stored in steps of just over 0.5 dB. If sweeps come faster than needed, RF Lotse merges neighbouring lines and keeps the maximum, so short peaks are not lost. 24 hours take about 60 MB of memory.

The times on the left edge belong to the line next to them, so you can see when a signal appeared or disappeared.

Colour scale

The vertical bar on the right edge of the waterfall shows which level gets which colour. The white framed window in it sets the range: levels below the window stay dark blue, levels above it red. Set well, the lower edge sits just below the noise, so the noise stays dark and every signal stands out.

The setting is kept after a restart. The tooltip of the bar shows the range in dBm.

Line at the bottom

With a narrow zoom on the main module (below about 20 MHz span) the noise is often below the measuring range of the RF Explorer. The device then reports only a few fixed values around −140 to −147 dBm, many points in a row the same. The spectrum shows this as a line at the bottom; the level axis then extends to −150 dBm automatically, and a note says there is no signal here. A real signal still appears as a peak above it.

Presets

The ＋ button next to the preset list saves the current range as your own preset under a name. Custom presets appear under "Custom" in the list and can be removed there with "✕ Delete custom preset".

Wi-Fi channels

With "Wi-Fi channels" in the toolbar the spectrum shows the channels like the TV channels: channels 1 to 13 at 2.4 GHz, each with its own light or dark 5 MHz stripe around its centre (the non-overlapping 1, 6 and 11 additionally as a thin bracket across their full width), channels 36 to 177 at 5 GHz and the Wi-Fi 6E and 7 channels at 6 GHz, each 20 MHz wide.

Once the RF activity has been evaluated (next section), the channel numbers are coloured accordingly: green quiet, yellow moderate, red a lot of RF.

RF activity in Wi-Fi bands

The "RF activity in Wi-Fi bands" section in the sidebar shows how much RF is present in each Wi-Fi channel and names the quietest one. This helps to decide where your own link in the 2.4 or 5 GHz band should go, for example a Hollyland video link, Shure GLX-D or wireless DMX. Those devices are disturbed by exactly the energy the RF Explorer measures.

What the RF Explorer cannot do: it is a spectrum analyser and measures energy only. It does not see Wi-Fi packets, network names, clients or traffic. How loaded a Wi-Fi network is, and which channel an access point belongs on, can only be seen with a Wi-Fi analyser that decodes the packets. The percentages here are therefore not Wi-Fi utilisation.

1. Click "2.4 GHz", "5 GHz" or "6 GHz". The view jumps to the band and the Wi-Fi channels are shown.
2. Let it measure for a few minutes. The longer, the more meaningful; the last ten minutes are evaluated.
3. Under "Width" choose the channel width of the planned link: 20, 40 or 80 MHz. At 2.4 GHz RF Lotse always uses 20 MHz.
4. Read the list. The quietest channel is named at the top. Clicking a channel zooms in.

How RF Lotse calculates: for each sweep it determines the noise of that sweep and counts which share of the channel width is more than 12 dB above it. The average over all sweeps is the RF activity. A channel with something transmitting across its full width all the time gets close to 100 %, a channel with occasional short bursts a few percent. Because the noise is determined per sweep, zooming in does not distort the result. With equal activity RF Lotse prefers channels without DFS and without the SRD limit.

Limits: a sweep takes about one second and each frequency point is looked at only briefly. The numbers are a sample and tend to be too low rather than too high. The RF Explorer cannot tell whether a signal is Wi-Fi, a video link or a wireless camera; the shape in the waterfall is the best clue. At 6 GHz the RF Explorer 6G Combo Plus without the extension measures only up to 6100 MHz, i.e. channels 1 to 25.

Manufacturer database and allocations

The database holds the frequency bands of wireless microphones, in-ear systems, wireless video links and intercoms: about 880 entries from Shure, Sennheiser, Lectrosonics, Wisycom, Sony, AKG, Audio-Technica, beyerdynamic, Hollyland, Teradek, DJI, Riedel, Clear-Com and others.

It also covers the radio systems that share the spectrum at events or interfere with it:

For cellular, band 20 matters most: phones in the audience transmit from 832 MHz, right above the duplex gap used by wireless microphones.

1. Type a manufacturer, series or band into the search field, e.g. G56, EW-DX, Mars or Bolt. Several words narrow the search.
2. Use the selector next to it to filter by type: microphone, in-ear, video, intercom, network, cellular.
3. Click a result. The view jumps to the band and the band is highlighted. Backspace or "Back" returns to the previous range. If you do not want the jump, turn it off in the settings. The band is then only shown, and clicking its name in the list of shown bands jumps to it. For devices with fixed channels, such as Teradek Bolt or FPV Raceband, the channels appear as dashed lines.
4. Any number of bands can be shown at once. The first twelve get a colour of their own, after that the colours repeat. From twelve bands on, the shading in the spectrum gets lighter so the trace stays readable. "Source" opens the manufacturer document the values come from.

Allocations by country

The checkbox "Show allocations" adds the regulatory ranges in grey: wireless microphones, video links, mobile networks, DECT, WLAN, television and public safety radio. The selector next to it sets the country. EU and CEPT rules are always shown. Hovering over an entry shows its conditions and source.

All values come from manufacturer documents or official regulator publications. Entries marked "unverified" could not be fully confirmed. Check the source before relying on them; the regulator of the country concerned is always authoritative.

Database texts such as notes are in German.

Existing frequencies

This section holds the frequency plan already running on site, for all rooms together. RF Lotse checks it for conflicts, draws it into the spectrum and includes it in every replacement search.

Importing

New entries are added to the list, identical ones are not duplicated. The list is kept after a restart. "Clear" starts over, "CSV" saves the current list with the previous values in a separate column.

Check

Right after importing, conflicts are listed above the list:

Channels with a conflict have a red dot in front of the name.

Editing

Finding a replacement frequency

For a channel that has a foreign transmitter on it or is assigned twice:

1. Set the range to search, e.g. "Shure G56". If a database band containing the channel is selected, only that band is searched.
2. Let it measure for one or two minutes so the max hold collects everything.
3. Under "Frequency plan", choose what the search is "Based on": own measurement, loaded scan or both.
4. Click "Replace" next to the channel in the list of existing frequencies.
5. RF Lotse suggests five frequencies (A1 to A5, dashed in the spectrum) and verifies them in turn, about 8 seconds each, until three are clear. An occupied candidate moves down and the next one is measured. The view jumps briefly to each candidate and returns afterwards.
6. The table shows "clear", "occupied", "not measurable here" or "not verified", with the margin above the noise floor. Clear candidates are at the top, occupied ones at the bottom.
7. "Apply" changes the frequency in the list. The check runs again.

With the same number of IM3 hits, frequencies close to the old channel come first, because the device can tune there safely. With many transmitters, e.g. 50 across several rooms, 3-transmitter products cannot be avoided anywhere; the number is then only for comparison.

"Stop verification" ends the verification, "Measure again" repeats it. The max hold restarts afterwards.

Scans from other devices

Shure receivers (e.g. AD4Q, ULX-D) and Sennheiser receivers (e.g. EM 6000, D9000, EW-DX) scan the UHF band themselves and are more sensitive there than the RF Explorer. Their scans can be overlaid on the own measurement as a green curve.

1. In RF Lotse choose "Load scan …" above the spectrum or drop the file onto the spectrum.
2. Device and start time of the scan appear next to the checkbox. Several antennas or data sets are merged into one curve.
3. The scan is kept until removed with ✕.

A loaded scan can be the basis of the replacement search (see above). This is worthwhile when weak TV is present: the AD4Q shows it, the RF Explorer often does not.

The import has been tested with a real .sdb3 file from an AD4Q. The .sdb2 and WSM CSV formats are implemented from published descriptions and open-source converters and have not yet been tested with real files. If WSM stores levels in "dB" instead of "dBm", RF Lotse reads them as dBµV and converts to dBm; this is not confirmed.

Frequency lists from WSM ("Export list …", frequencies in kHz) and plain lists with one frequency per line can be imported under "Existing frequencies".

Frequency plan

RF Lotse searches the measured spectrum for new frequencies that are free and compatible with each other.

1. Set the range you want, or pick a band from the database.
2. Wait for a few sweeps. The plan is based on the max hold, so the longer you measure, the safer the plan.
3. Set the number of channels and spares, channel spacing, tuning step and the threshold for "free".
4. Under "Range" choose the visible range or the last selected database band. For a band, its tuning step is used.
5. "Calculate". Channels appear in green in the spectrum, spares as dashed yellow lines.

The frequency plan only uses the own measurement and checks the new channels against each other. For a single channel in an existing plan, the replacement search is the better tool, as it takes all existing frequencies into account.

Channel spacing recommended by manufacturers:

"CSV" saves the plan as a table, e.g. for Wireless Workbench. "Watch all" starts watching every channel. "Hide" removes the plan from the spectrum.

Markers and watch list

A click into the spectrum sets a marker, "+ Marker" adds one in the middle of the view and opens its frequency for typing. There is no limit, from the thirteenth marker on the colours repeat. Markers are kept when the app is closed and saved in the project with name and colour. In the sidebar each marker shows the live level and the max hold at its frequency. Hovering over the marker list shows the spacing between the last two markers in kHz.

Finding dropouts

The watch list is meant for links that keep dropping out briefly. RF Lotse measures the frequency on every sweep and compares the level with a threshold. The threshold starts 15 dB below the measured level and can be changed per watched frequency.

• The graph shows the last five minutes, the dashed line is the threshold.
• When the level falls below the threshold, a red line appears under "Events" with the time, the level and how long the signal had been present.
• When the signal returns, a green line follows with the length of the dropout.
• The dot in front of the frequency shows the state: green for signal present, red for dropout.

Tip: zoom in with "Focus" first, then watch. With a narrow range RF Lotse measures several times per second, so short dropouts are caught reliably. Watching only works while the frequency is within the visible range.

All events are also saved to a daily log file (see "Files and folders").

Projects

A project collects everything that belongs to one venue: range and resolution, markers, existing frequencies, the frequency plan and its settings, the loaded scan, database entries shown, country and allocations, and the watch list.

The commands are in the menu bar under "File".

The name of the open project appears in the window title, and saving again suggests the same name. The file is plain text (JSON) and can be emailed to colleagues.

When opening a project, RF Lotse checks every entry for the expected type. Unsuitable entries, such as text in place of a frequency, are skipped, and text from the file is never run as program code. A project file from an unknown source therefore cannot do any harm, although like any project file it replaces the current state.

Recording and playback

"Record" writes every sweep with a timestamp to a file, so you can review a measurement from the night before at leisure or show it to a colleague.

Recordings are kept when the app is closed. The "Recordings" section in the sidebar lists them with date, time, frequency range, duration and size:

If a recording is running when the app is closed, RF Lotse continues it in a new file on the next start. Recordings can still be played from the source selector at the top right as well.

Settings

The gear icon at the top right opens the settings, as does ⌘ and comma on the Mac or Ctrl and comma on Windows. In the menu bar they are under "RF Lotse" > "Settings …" on the Mac as usual, and under "File" on Windows. Every change applies immediately and is saved.

"Reset all settings" needs a second click and restores all defaults, including colour scale, window split, collapsed sections and Wi-Fi channel width. Markers, existing frequencies, the loaded scan and your own presets are kept.

Files and folders

In the Mac App Store version the same files are kept in the app's sandbox: ~/Library/Containers/de.dss-info.rflotse/Data/Documents/RF Lotse/ and …/Data/Library/Application Support/RF Lotse/.

Existing frequencies, loaded scan, view, country and language are saved in einstellungen.json: on the Mac in ~/Library/Application Support/RF Lotse/, on Windows in %APPDATA%\RF Lotse\.

Limitations and notes

• RF Lotse does not replace an official frequency assignment. The built-in allocations reflect the state of research; the publications of the regulator in the country concerned are binding.
• Measurements are taken at one location. Levels at the receiving antennas may differ.
• The RF Explorer reports levels below −127.5 dBm as an overflow. In some ranges this appears as a wide plateau of −15 to −47 dBm, on the main module around 500 to 514, 544 to 565 and 582 to 598 MHz. RF Lotse detects this and corrects the values. Very low values around −130 dBm and below simply mean: nothing to measure.
• The RF Explorer's noise floor varies by up to 60 dB depending on frequency. RF Lotse therefore decides whether a frequency is clear by comparing it with its surroundings.
• The RF Explorer does not reliably detect weak TV a few dB above the noise. When in doubt, load a receiver scan.
• For ranges across 960 MHz RF Lotse switches between the modules, which takes about 1.5 seconds each time.
• At high resolution the main module sometimes returns several identical values in a row. The curve then shows short flat sections; this is a property of the device, not a measuring error of RF Lotse.

Legal

• RF Lotse comes without warranty. Frequency suggestions and built-in allocations are planning aids, not a licence. Whoever uses a frequency is responsible for making sure it is permitted in the country concerned.
• RF Explorer, Shure, Wireless Workbench, Sennheiser and WSM are trademarks of their owners. RF Lotse is not affiliated with them; the names only describe which devices and files the program works with.
• RF Lotse sends no data to the internet and has no user account. Measurements, frequency lists, scans and logs stay on your own computer. The app opens no network port.
• Third-party libraries and their licences are listed under "Licences" at the bottom of the sidebar.

Open items

Next steps

1. Collect feedback from the first jobs.
2. Distribute the program to colleagues.
3. Keep adding devices and allocations to the database.