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IQ Vector Scope

The IQ Vector Scope block shows the digital modulation as a vectorscope displaying I and Q as X-Y plot:

IQ Vector Scope Block

Left hand side Input:

  • IQ


The IQ Vector Scope block offers the basic Sample Delta modes (bypass, sub, add, mul, rotate and adjustable emphasize), different drawing modes (Sample/Hold, Average, Maximum Hold and Minimum Hold). In addition you can add a fully scalable Modulation Grid Overlay for QAM (BPSK, qpsk, 16qam, 64qam, 256qam, 1024qam, 4096qam) and Radial:

IQ Vector Scope Settings

A 16QAM signal decoding as vector scope:

IQ Vector Scope Screenshot

16QAM Vector Scope Demo Mission Screenshot

Typical Missions:

IQ Vector Scope Typical Missions

UPDATE: We have added an automatic or manual Phase Shift Correction feature to the IQ Vector Scope block: Under Main -> Phase Shift you can select from

  • bypass (no changes)
  • manual (change the phase shift within 0,1 Degree by hand)
  • quadpower (automatic phase shift correction)

A phase shifted 16QAM without correcting the phase shift: It is way of the constellation diagram:

IQ Phase Shift Correction Feature

After correcting the phase shift (around 30 Degrees) the 16QAM fits into the constellation grid:

Manual IQ Phase Shift Correction


UPDATE: We have added an "Autotune" feature. It slightly changes the frequency to stabilize the signal:

IQ Vector Scope Autotune Feature

You can select from

  • bypass
  • manual
  • phaseshift
  • powerskew
  • centerphase
  • quadphaseshift
UPDATE: We have again improved the IQ Vector Scope block and added an IQ output:
IQ Vector Scope Block gets IQ Output
We added an automatic adaption to the signal. The low pass filter will now atomaticaly adjust to the variance of the signal.
For a noisy signal it will now take a bit longer until the frequency adjustment is done but you get a much more stable signal.
The auto adaption will now be available for the new IQ output and will take place to all docked blocks.

The IQ Vector Scope now gets circle shape constellation grids instead of quares, which is much more realistic:

IQ Constellation Diagram

Check out the latest video showing how to operate the block: