(frequency control tab)
The main window of spectrum lab contains the most important controls and output of the spectrum analyzer:
Other functions may be implemented in other windows, which you can open from the "View" menu (in SL's main menu).
See also: Spectrum Lab's main index.
The main window contains the main menu, the spectrum display (on the right side) and -optionally- some control elements on the left side, and some in the control bar on the bottom.
The main menu contains the following items:
This menu allows to change all settings of Spectrum Lab very quickly. There
are some predefined settings in this menu, and some user-defineable entries
which are initially empty. More about creating and adding your own set of
settings can be found here.
Some of the built-in configuration in the "Quick Settings" menu are described
further down.
There are a lot of different windows in Spectrum Lab, many of them are only used for special applications. The "View/Windows" menu allows you to switch to any of these sub-windows quickly, even if they are hidden by other windows. Some of the sub-windows are listed here:
Hint: Windows which are already opened will be checked in the "View/Windows". You can quickly switch between them, even if they are completely hidden by other windows on the desktop, by pressing CTRL-F6 ("Switch between SL's open windows"). This works a bit like the Windows task switcher (ALT-TAB), but only switches through Spectrum Lab's own windows. But a few SL windows may (or may not) be visible in the windows task bar.
Contains some topics of the help system and the inevitable "about"-box. The help system only works properly if there is an HTML browser installed on your system which supports jumps to anchors in the html documents through the command line. For example, if help about the spectrum graph shall be displayed, SpecLab invokes the browser with the command line argument "../html/specdisp.htm#spectrum_graph" (or similar).
Some typical configurations can be recalled from the "Quick Settigns" menu. In contrast to the user-defined settings (in the lower part of that menu), the following configurations are hard-coded in the program - so they don't have to be loaded from an external configuration file. Most of these settings are organized in categories (in the form of submenus), to avoid a bulky long top-level menu. The following list may be incomplete since the program still keeps growing:
See also: main menu , help index .
The spectrum display shows the spectrum of the analyzed signal as spectrum graph and/or waterfall.
Both display types are explained here in more
detail.
As an overlay for the spectrum graph, a reference
curve can be displayed.
The control elements are usually visible on the left side of the main window. You can turn them off from the main menu ("View") to increase the visible size of the spectrum display. (the different forms of the spectrum display are explained in a separate document)
Some of the controls on the left side of the main window are explained in the following sections. There is ...
Mainly used as a buffer-preview for long-term observations, there are also some controls on the bottom of the main window:
There is a tabbed control panel on the left side of Spectrum Lab's main window, showing...
(frequency control tab)
The "min"- and "max" fields define which part of the spectrum is visible
in the spectrum graph and the spectrogram on the main window.
Note: The input fields only accept possible values, depending on the
FFT- and the
audio settings (like sampling rate,
etc) !
The "Offs" field is an optional frequency which may be added to the labels on the frequency scale. It is typically used to add the VFO frequency of a receiver. For example, if the receiver is tuned to 135.8 kHz, enter that value in the "Offset" field to let the frequency scale show you the "high" frequencies instead of the audio frequencies. If you are only interested in audio frequencies instead of "radio frequencies", leave the offset zero and skip the rest of this chapter.
By default, this offset is contained in the frequency Min- and Max- fields. Alternatively, you can switch the min/max edit fields to AUDIO frequencies (which do not include the offset). To toggle between "audio"- and "high"-frequency editing, click on the underscored Offs-label in the frequency control panel. The min- and max fields will be immediately updated then.
When typing a frequency into any of these three edit fields, you can enter expressions like "135.8k" instead of 135800 if you like. After three seconds of "no activity" in the edit field, the expression is evaluated and written back (in normalized form) into the edit field. You may also use the "Up/Down" controls left of the edit fields to change the frequency range. While doing this, the frequency axis will be redrawn, and also the visible part of the waterfall will be redrawn (if the CPU is fast enough).
This is possible because the program saves the analyzed spectra in memory (a ring buffer, see "Extended Display Settings" in the Setup dialog ).
The "USB" / "LSB" radio buttons are only interesting if in combination with a single sideband receiver ("radio"). USB means upper side band, where higher radio frequencies give higher audio frequencies. LSB means lower side bands, where the audio spectrum is mirrored. To compensate this, Spectrum Lab reverses the frequency scale if the "LSB" option is selected. So lower radio frequencies will appear on the left side of the spectrum again.
Other tabs of this control panel are explained in the next chapter, and -possibly- in other documents because there may be more tabs than in the screenshot shown above.
See also: help index
The "Time Axis" panel shows the current time and the time of the latest waterfall line. It may also be used for scrolling the waterfall "back in time".
If the spectrum line buffer is large enough (larger than the number of waterfall lines on screen), you may scroll the time axis of the waterfall "back to the past". Old parts of the waterfall which have already disappeared from the screen can be made visible again, you may also zoom the old parts of the waterfall using the controls on the "Frequency Axis"-panel or change their color using the controls on the "Color Palette"-panel.
Shifting the slider on the "Time Axis"-panel to the RIGHT will scroll the contents of the waterfall back to the past. The waterfall will stop it's real-time-scrolling as long as the time-slider is not in the leftmost position. The FFT output will be recorded in the background then (but data collecting will not stop).
This situation is indicated by the "Time Axis"-panel changing its color from the usual gray to a light cyan. As long as you see the "Time Axis"-panel in an unusual color, you know that the waterfall display is not in "real-time"-mode but shows old data.
The amount of time (seconds, minutes, hours, or even days) is dictated by the waterfall scroll rate in conjunction with the spectrum buffer size. The spectrum buffer size can be modified on a special tab of the configuration screen,
Shifting the time-slider back fully to the LEFT will return to "real-time"-mode.
The "Time Axis"-panel also shows the current time ("NOW:") and the time when the latest visible waterfall line has been recorded ("VIEW:"). In "real-time"-mode of the waterfall there will only be a maximum difference of one FFT calculation interval between the "NOW"- and "VIEW"- time.
Note that the "Time Axis" panel (like all other time-indicators in this program) use UTC (=GMT) to be independent of the earth's timezones. If you don't see the correct time shown in UTC on this panel, you should check the time settings of your PC (double-click the time display in the task bar).
An alternative to the slider on the time-panel is the buffer-overview bar on the bottom of the main window.
The Cursor Position panel shows information about the current mouse (cursor) location.
The display on the cursor-panel depends on the cursor display mode, which can be switched by clicking on the frame of the cursor panel. Some of the cursor display modes and -options are:
In "simple" cursor mode, the cursor display panel shows...
If the control bar on the left side of the main window is switched off, the cursor text is displayed on the right edge of the main menu, so the cursor data can be seen even without the cursor display panel.
Note: Since May 2004, the text on the cursor panel can be selected with the mouse, and copied into the clipboard (with CTRL-C as usual). This makes it easier, for example, to transfer the peak-frequency into any other edit field, calibration table, or any text document.
For some special applications, you can retrieve the frequency , amplitude, and timestamp of the readout cursor with the interpreter function spa.cursor.xxx .
The displayed data in the cursor window can optionally be fixed to a certain frequency, no matter where you move the mouse. To achieve this, click into the spectrogram near the "frequency of interest" with the right mouse button. In the popup menu which opens, select one of the "Set Cursor To..." functions.
To switch back from fixed-cursor to mouse-cursor mode, select the function "unlock cursor" in the waterfall popup menu.
The Color Palette panel on the main window shows all colors that are currently used for the waterfall display (a kind of "color legend").
The two sliders on the "Color Palette" control panel affect the brightness (B) and contrast (C) of the waterfall colour assignment. This is an important feature if you are digging for weak signals, because it allows you to enhance the readability on the fly ! The palette looks a bit different if the waterfall runs in Radio Direction Finder mode, but the B & C controls work in both modes (in RDF/CDF mode, Contrast/Brightness only affect the luminosity but not the color hue values).
Double-clicking into the color bar starts the color
palette editor.
At the lower side of the color control panel is a scale which usually shows
some decibel values. Double-clicking into the decibel scale switches to a
certain part of the settings dialog
where you can modify the visible decibel range.
Note: Instead of cranking up the "contrast" slider to the maximum (to
dig weak signals out of the noise), you can also reduce the 'Displayed Amplitude
Range' in the spectrum display configuration as explained
here . For example,
if the "interesting" signals are all in the range -60 dB to -50 dB, don't
use an amplitude display range of -120 dB to 0 dB (instead, use -70 dB to
-40 dB ).
See also: palette editor , visual AGC , help index
This button in the lower left corner of the main window has different functions, which will be shown as a text on this button.
The button's surface may...
Clicking on the progress button can take you to a more detailed error description, or switch to a certain part of the setup dialog.
On the left side of the main window, there are a few programmable buttons (which you can only see if the window is large enough..). These buttons are completely user programmable, both the text in the button, and the function which will be executed when the user clicks one of these buttons.
To execute the button's programmed function, click it with the left mouse key or press enter when it's selected.
To change the button's programmed function and its text, click it with the right mouse key to open the following dialog:
The field "variable String Expression for button text" defines the text on the button's face (caption). This can be a simple fixed text string (embedded in double quotes), or a combined string expression like this:
"Time: "+str("hh:mm:ss.s",now)
More about this can be found in the description of Spectrum Lab's built-in interpreter, look for "string expressions" there. If the button text is not a fixed string but a variable expression, set the checkmark "evaluate and update caption periodically".
The field "Interpreter Command(s) to be executed on click with left
button defines what shall happen when the user clicks a programmable
button. This is usually a sequence of interpreter commands which are explained
in another document, but it is also
possible to run external programs this way using the
"exec" command.
In the screenshot above, the 'capture' command is used to produce a screenshot
which contains the current date+time in the filename whenever the user clicks
on the self-defined button "Capture now". However, you can do an awful lot
of other things with the programmable buttons once you know how to use Spectrum
Lab's built-in command interpreter.
The field "Hotkey" allows you to define a hotkey for the programmable button. Pressing the hotkey will have the same effect as clicking on the button with the left mouse key (see above). An empty hotkey, or the value zero means the button can only be activated with the mouse, but not through the keyboard. The keyboard-combination must be entered as a decimal value (windows "virtual key" code, see below). The code can be easily found by clearing the hotkey field, and pressing the hotkey (on the keyboard, for example F1). If the hotkey edit field is empty, it will automatically be filled with the decimal value. A few decimal keyboard codes are shown below.
| F-Key | F1 | F2 | F3 | F4 | F5 | F6 | F7 | F8 | F9 | F10 | F11 | F12 |
| code (without SHIFT etc) | 112 | 113 | 114 | 115 | 116 | 117 | 118 | 119 | 120 | 121 | 122 | 123 |
| with SHIFT key (= code + 256) | 368 | 369 | 370 | 371 | 372 | 373 | 374 | 375 | 376 | 377 | 378 | 379 |
| with CTRL key (= code + 512) | 624 | 625 | 626 | 627 | 628 | 629 | 630 | 631 | 632 | 633 | 634 | 635 |
To open an additional control bar on the bottom of the main window, select "View/Windows"..."Control bar on bottom" in the main menu. Some of the controls in the bottom bar are explained below (but not all, because this is still "in the making"). If this control bar is visible, the bottom of the main window may look like this:
The screenshot also shows a part of the main spectrogram. The bottom control
bar below it contains an overview of the spectrum buffer (which can be configured
through a menu). It only makes sense to turn this control bar on if the spectrum
buffer covers a larger timespan than the main spectrogram. If you don't need
this control bar, turn it off using the popup menu in the lower right corner.
The narrow spectrogram in the control bar contains an overview of the buffer contents. By default, the whole buffer is visible, but you can also zoom in with the buttons on the right side. The part of the buffer which is visible in the main spectrogram is marked with a small red or green rectangle. Red colour means "the main spectrogram is scrolled back in time", green colour means "the main spectrogram shows the most recent data, it is NOT scrolled back".
To scroll back and forth, you can grab the indicator rectangle with the mouse and move it left or right. Because the overview may be zoomed, you can alternatively use the navigation buttons which are explained below.
The two buttons next to the overwiev can be used to scroll the main spectrogram through the buffer, page-by-page (the left button jumps further into the past, the right button from past to present, until the indicator turns green as explained above).
The two zoom-buttons can be used to zoom the buffer overwiew (they do NOT affect the main spectrogram !). This is helpful if the buffer contains a really HUGE amount of spectrum lines, for example an overnight recording.
The menu button in the bottom control bar opens a small popup window where you can find some options for the spectrogram overview, one of them is to open the configuration screen with the spectrum buffer settings.
Last modified: 2004-05-15 (YYYY-MM-DD)
