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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.