IQ Vector Scope

#1 · 04/03/2021, 13:00

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:

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

Oleksii Planida has reacted to this post.

#2 · 07/03/2021, 12:33

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

#3 · 11/03/2021, 11:25

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

You can select from

bypass
manual
phaseshift
powerskew
centerphase
quadphaseshift

#4 · 15/03/2021, 09:53

UPDATE: We have again improved the IQ Vector Scope block and added an 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.

#5 · 20/08/2021, 09:47

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

IQ Constellation Diagram

#6 · 08/02/2022, 10:53

Check out the latest video showing how to operate the block: https://youtu.be/xxWVaU1Vkg4