Wiki SDR SA PRO
The 3D tab
PRO The 3D tab draws the waterfall as a surface: frequency across, time into the depth, level as height and colour. It is meant to show frequency hopping, short bursts and the way they repeat at a glance. It is a view, not a measurement: numbers are not read off the surface — traces and markers are there for that. This page covers where the rows come from, how to turn the view, what the tab says about OpenGL, what it costs and what has not been checked yet.
Where the tab is 0.9.58
- The 3D tab is the last one in the side panel, after the Journal tab. You can also open it from the View → 3D menu or with Ctrl+8.
- Like the rest of PRO, the tab is there in every run: SDR SA PRO opens only with a valid key (see What SDR SA PRO is).
- When the window holds several stations, each has its own surface made from its own waterfall; the tab shows the surface of the active station (see Several devices: stations).
What the surface shows
- Waterfall rows. The surface is made of the same rows as this station’s waterfall — in tuned mode and in a sweep.
- Frequency runs across: 256 columns over the whole band. A column is the peak of the bins that fall into it; a row narrower than 256 bins is stretched.
- Time runs into the depth: the newest rows in front, up to the last 160.
- Level is height and colour on the waterfall’s scale, from Ref − range to Ref, in the same palette (see Scale, auto scale and waterfall). Change Ref, the range or the palette and the surface follows.
- A new band means a new surface. When the receiver band or the sweep range changes, the surface is cleared: the old rows were about other frequencies.
At the top left is a line with the band and the depth: … … … · N rows over T s. Until there are rows it says no rows yet: the surface is drawn from the waterfall once frames arrive.
Mouse and buttons
- Drag with the mouse
- Turns the view: left and right — around the surface, up and down — the tilt, from 5 to 89°. Either the left or the right button will do.
- Wheel
- Zooms in and out — from 0.2 to 5 times.
- Double click
- Brings the view back to what it was at start.
- Pause / Resume
- Freezes the surface and lets it run again. The spectrum, the waterfall and the rest of the app go on: the pause is for this tab only.
- Clear
- Removes all rows, and the surface builds up afresh.
- Reset the view
- The same as a double click.
The angles and the zoom are not saved between runs.
A view, not a measurement
The caption at the bottom of the tab says so plainly: A view, not a measurement: … — and ends with the advice to read numbers from the traces and markers. The surface helps you see; measuring is done with the tools made for it.
- The surface has no frequency or level labels, no markers and no thresholds.
- A column is the peak of several bins: a narrow signal looks wider on the surface than it is, and a weak one next to a strong one is lost in its column.
- The depth is waterfall rows, not an even scale of seconds: how fast they come depends on the mode, the sweep and the sample rate. How many seconds of air are covered is stated by the line at the top.
- For measurements use traces, trace markers and zero span.
OpenGL
The graphics card draws the surface through OpenGL — the same way as the spectrum and the waterfall. It draws only while the tab is visible and new rows have come, and no more than 30 times a second. If OpenGL fails, the field does not stay silently empty: at the top left a red OpenGL: … gives the reason.
The cost
The surface is one more picture for the graphics card. In the run of the built 0.9.58 on the developer’s machine the worst of the tabs gave 58.6 frames a second — a little below the run’s limit of 60. The tabs now include 3D, and its cost on that machine was estimated at about two frames a second. While the tab is not visible, it does not draw.
What has been checked
A run of the built program confirmed that rows reach the tab and that the surface is drawn without an OpenGL error. Nobody has looked at the surface on screen yet.
Limits
- A view, not a measurement: numbers come from traces and markers.
- 256 columns and up to 160 rows.
- A change of the band or the sweep range clears the surface.
- The pause is for the tab only, not for the receiver.
- The angles and the zoom are not saved between runs.
- The surface has not yet been checked by eye on screen.