Wiki › Spectrum analyzer

Band plans

A band plan puts frequency labels right on the spectrum: FPV channels, ELRS, Wi-Fi, cellular bands or your own spans 0.9.57. This page covers the built-in collections with all their limits, how to add a band from a selection, what the strips look like, starred bands and undoing a band change, which files the app reads and writes, and what not to expect from these limits.

Where it is in the app

All the controls are in the Bands group on the Spectrum analyzer tab (Ctrl+1). The group is also described on the page The main window and controls, together with the table of the default list. The app has one list of bands. A collection is not a separate layer but ready-made content for that list: once taken, a collection can be edited row by row like everything else.

Each row of the list has a colour swatch (a click steps to the next of ten colours), the name, the lower and upper limit in MHz, a star 0.9.58 and a delete button. The app swaps limits entered the wrong way round by itself; a zero limit or a zero-width row is not accepted, and the row keeps its old limits.

Built-in collections

Pick a collection in the Collection list and press one of the two buttons next to it:

Replace

Puts the collection in place of the whole list. The active profile stays the same, so on exit this list is written to it, as with any other edit (see Files).

Add to the list

Appends the collection to the end of the list, so you can have, for example, FPV and Wi-Fi together. Rows with the same name and the same limits are not added twice.

The row names of all the collections except Defaults are written in Latin letters and are not translated.

FPV 5.8 GHz

Each channel is shown as a band of ±9 MHz around the carrier. A row is named after the table, the channel number and the carrier: A1 5865, R8 5917. Channels of different tables often overlap.

FPV 1.2 and 2.4 GHz

Also a band of ±9 MHz around the carrier. The rows are named CH1 1080, CH8 2510.

ELRS and control links

Wi-Fi

In the 2.4 GHz collection a channel is shown as a band of ±11 MHz around its centre: ch1 2412 is 2401–2423 MHz, and the centre then rises by 5 MHz up to ch13 2472 (2461–2483 MHz).

Cellular bands of Ukraine

Each band is two separate rows, for example GSM/LTE 900 UL and GSM/LTE 900 DL.

Your own band

Add a band from the selection

An item of the spectrum context menu (right click). Drag with the left button across the spectrum and choose this item: the selected span becomes a new row at the end of the list. Without a selection the item is disabled.

Add

The button below the list: a new row with the limits of the currently chosen span, the one in the range fields of the side panel header and on the overview ruler.

A new row is named new. If the lower limit of the span is not above zero (this happens with a recording with no known frequency), both actions add a 100–200 MHz placeholder for you to correct. Change the name, the limits and the colour right in the row. An empty name is not accepted: the row keeps the old one.

The strips on the spectrum

Show on spectrum

Turns all the strips on and off together, and the waterfall columns with them. On by default. The list itself does not change.

At the bottom of the spectrum

Moves the strips to the lower edge of the spectrum. Off by default: the strips stand at the top, below the marks of the receiver's own spurs.

On the waterfall too

Also draws the same bands as columns over the full height of the waterfall, 2.5 times fainter than the strips. Off by default. This is only a hint of where each band lies: the columns do not react to the mouse.

Strip height

From 9 to 28 px, 13 px by default.

Opacity

The opacity of the strips: from 10 to 80 % in steps of 5 %, 30 % by default. One value for all the strips. A strip under the cursor gets brighter.

How a strip behaves:

• The label shows as many letters of the name as fit into the width. The tooltip under the cursor gives the full name and the limits.
• A click selects the whole band, just as if you had typed its limits into the range fields: the device retunes, and a span wider than the instantaneous bandwidth starts a sweep. The app trims limits that go beyond the range of the receiver.
• When a strip takes up almost the full width of the screen (zoomed inside the band), it stays a mere label and ignores clicks.
• A strip narrower than a pixel is not drawn.
• All the strips stand in one row, so overlapping bands (for example, FPV 5.8 GHz channels of different tables) lie on top of each other.

The position, height, opacity, the checkboxes and the list itself are kept between runs — see What is remembered.

Starred bands 0.9.58

Star a band you go to often: a row of the list has a ☆ between the limits and the delete button; a click turns it into ★, another click removes it. The star's tooltip reads Starred: shown in the row at the bottom of the spectrum; a click puts the receiver on the band.

• Starred bands stand as a row of rounded "★ name" chips along the bottom edge of the spectrum, in the order of the list. The row is visible whenever at least one band is starred: also when the band strips are hidden with Show on spectrum, and also when the band itself lies outside the visible span.
• A click on a chip puts the receiver on the band the same way as a click on a strip: the device retunes, and a span wider than the instantaneous bandwidth starts a sweep. Limits beyond the receiver's range are trimmed.
• The chip of a band this receiver does not cover at all is pale and ignores clicks; its tooltip says outside this receiver's range. The chip of a band within the receiver's range shows the limits and click selects.
• With a source that does not retune (a recording), the chips are visible but a click does nothing.
• The star is part of the row: it is saved in the profile together with the name and limits (see The profile format).

In SDR SA PRO PRO the first five starred bands become the bands of a sweep by several bands with one button, From the starred bands, on the Scanner tab — see Scanner.

Undo the band change 0.9.58

The Instrument → Undo the band change menu item or Ctrl+Z puts the receiver back on the previous span — the one chosen before the last change, however you changed it: with the ruler, the range fields, the wheel over the spectrum, or a click on a strip or a starred chip. The span is chosen the same way as by hand, so going back from a narrow span to a wide one starts the sweep again.

• The app remembers up to 50 previous spans; each press goes back by one. An undone change cannot be redone: the undo itself is not added to the list.
• Only spans chosen in this session go into the list. The span the device stood on right after the launch is not there: after the very first change there is nothing to undo yet, and from the second change on you can go back to the first span you chose.
• When there is nowhere to go back to, a line over the spectrum says Nothing to undo: there was no previous band yet.
• The list lives only in this session and is not kept between launches. With a source that does not retune there is nothing to undo.
• The display zoom (Ctrl+wheel, Ctrl+= and Ctrl+-) does not retune the receiver and does not go into this list.

Bands on several stations 0.9.58

When the window holds several devices (stations), every station has its own band list and stars, although at startup they all read the same active profile. The Instrument → Shared bands switch makes them shared: an edit of the list or a star on one station is written to the active profile at once, and the other stations read it again. The app remembers the state of the switch between launches; it is off by default. On exit only the list of the first station in the column is written to the profile: without shared bands, edits made on the other stations do not reach the file.

Files

The list lives in a profile, a separate JSON file you handle like a document. The path of the active profile stands at the bottom of the group. The default profile is config\bands.json in the app's data folder (see What is in the data folder).

Open…

Reads a profile or a Spectrozir SA collection, and this file becomes the active profile. If the file cannot be read, a red line below the buttons names the entry and what is wrong with it, and the current list stays as it was.

Save as…

Writes the list to a file, and this file becomes the active profile.

Export for Spectrozir…

Writes a copy of the list in the Spectrozir SA collection format. The active profile does not change.

Defaults

Restores the default list of twenty bands.

The profile format

A JSON list; each entry is a name, limits in hertz and a colour:

[{"name": "FM broadcast", "f0": 87500000.0, "f1": 108000000.0, "color": "#8C3F5E"}]

• The name is not empty, both limits are above zero, f0 is below f1.
• The colour may be left out: the app takes one from the palette.
• A starred band 0.9.58 also has the field "starred": true. The field is optional: profiles of earlier versions are read as they are, without stars.
• The file is checked as a whole. The first error stops the reading, and the text says what is wrong: band {i}: empty name, band {i} ({name}): f0 ≥ f1, the band profile must be a JSON list.
• A profile is written atomically: a power failure leaves no truncated file.

Spectrozir SA collections

A collection of that program can be opened as it is with Open…. The name, the limits (start and stop in hertz) and the colour of each entry are taken from it:

• Entries with visible: false are not taken.
• The transparency in an entry's colour is dropped: in SDR Signal Analyzer there is one value for all the strips.
• The other fields of an entry are not read.

On export the file name becomes the name of the collection, all the entries become visible, and the limits are rounded to whole hertz. Such a file carries no stars.

Bands and your work

• A click on a strip goes to a band in one move, so keep on the spectrum the plans you really look at and remove the rest.
• To keep several plans, save each as a separate profile (Save as…) and open the one you need.
• In SDR SA PRO PRO bands are only labels on the scale. The rules that give a signal a name or raise an alarm live elsewhere: in the Scanner's frequency table and alarm zones.

Limits

• The limits of the collections are reference values: hints on the scale from well-known channel tables and band allocation plans, not a regulatory document. Correct the exact limits for your work in the list and save them to a profile.
• A strip only says what the span is according to the table. It neither measures nor recognises anything: a signal inside the GSM/LTE 900 DL strip is not necessarily a GSM or LTE signal.
• A strip colour can only be chosen by stepping through the palette of ten colours; any other shade can only be set in the profile file.
• Strips cannot be split into separate rows: overlapping bands lie on top of each other.
• The active profile is written on exit, from the list of the first station (and, with shared bands on several stations, after every edit too); if the process crashes, edits not yet written to the file are lost.
• Undoing a band change remembers at most 50 steps, within the session only, and an undone step cannot be redone.

The wiki describes version 0.9.58. Your app's version is shown in the Help menu, under About. Found a mistake? Write to us.