| 摘要 |
PURPOSE:To enable a ghost measurement with a high accuracy in a weak electric field with the aid of a correlative operation by using a random signal line, which is superimposed for the purpose of a ghost removal during the vertical fly-back period of a TV signal. CONSTITUTION:After an input RF signal is converted into an IF signal by a tuner 1, a carrier wave is regenerated by a regeneration circuit 3 through an IFA 2, and by means of phaseshifting 4 it by 90 deg., a regenerated carrier wave, the phase of which is orthogonal to the original regenerated carrier wave, is generated. A synchronous detection is executed at synchronous detection circuits 5, 6 by these two carrier waves intersecting orthogonally to each other. A signal sampling circuit 8 generates a gate signal for sampling the random signal line superimposed during the vertical fly back period by a timing signal which shows a random signal line superimposing period from a timing generation circuit 9, and samples the random signal line from the output of the circuit 5. It removes 7 the ghost by using this signal line, and sends to a woveform memory 10. The signal lines before and after the ghost removal are correlatively operated 11, and further, the amplitude ratio, a phase difference and delay time between a desired wave and a ghost wave are calculated 12 and indicated 13.
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