We　propose　a　simplified　scheme　for　measuring　the　entangled　state　of　the　motional　and　electronic　degrees　of　freedom　of　an　ion　trapped　in　a　one-dimensional　harmonic　potential.　The　scheme　is　based　on　the　polychromatic　excitation　of　the　ion　by　three　lasers　tuned　to　the　carrier,　the　first　lower,　and　the　upper　vibrational　sidebands,　respectively.　The　method　directly　yields　the　elements　of　the　Wigner　characteristic　function　matrix　in　the　electronic　basis.　The　scheme　can　be　easily　generalized　to　the　two-dimensional　case.