Displaying a Constellation Diagram (TEDS)

To display a constellation diagram for the default subcarrier(-4) using a test signal for TEDS Normal Uplink, 50kHz, 16QAM:

  1. Load the demo signal (see Loading a TEDS Demo Signal).

  2. Select TEDS demodulation (see Selecting TEDS Demodulation).

  3. In the Format tab of the TEDS (TETRA2) Demod Properties dialog box (see Displaying TEDS Demod Properties Dialog Box ), select a channel bandwidth of 50kHz. The Channel Bandwidth must be selected before a Preset to Standard can be used.

  4. Click Preset to Standard > Normal Uplink. The VSA will then set certain parameters based on a Normal Uplink slot format / 50kHz channel bandwidth. The parameter settings are listed in Using Standard Setups/Presets.

  5. In the Analysis tab of the TEDS Demod Properties dialog box (see Displaying TEDS Demod Properties Dialog Box ), select 16QAM for the modulation type (if necessary).

  6. Click within a trace, and then select Trace > Data > Channel 1 Subcarr > IQ Meas Time, followed by Trace > Format > Constellation (if necessary) to display the constellation diagram for this TEDS signal. If you do not see a corresponding constellation diagram, the constellation diagram is scattered. If the constellation diagram is too small, check your recording and parameter settings. Try Trace > Auto Scale. Make sure your recording is running. Verify you selected IQ Normalize (Advanced Tab).

    image\DispConstellDiag.jpg

  7. In the TEDS (TETRA2) Demod Properties dialog box, select the Analysis tab. Choose different subcarriers in the Analysis Subcarrier drop-down menu and notice your selections appear in the upper-left corner of your subcarrier constellation display.

  8. To zoom in on a portion of the constellation diagram, in the Toolbar click the Select Area icon (next to the Pointer icon), select the area of the diagram of interest, choosing Scale X & Y. Repeat to zoom in further.

See Also

Symbol Constellations

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