Article surveillance system receiver using synchronous demodulat

Details Article surveillance system receiver using synchronous demodulat Article surveillance system receiver using synchronous demodulat

1985-09-17

1987-02-17

Grimm, Siegfried H.

Demodulators

Amplitude modulation demodulator

Having specific distortion, noise or other interference...

329105, 329124, 340572, G08B 1324, H03D 1300

Patent

active

046442863

ABSTRACT:
An article surveillance system includes a generator of a first inductive magneticc field having on and off duty cycle portions. The generator derives the first magnetic field at a predetermined AC frequency during the on duty cycle portions. The articles to be detected includes a structure which responds to the predetermined frequency of the first magnetic field to derive a second inductive magnetic field at a predetermined frequency. The second field is derived as a pulsed wave having a starting time at the expiration of each on-duty cycle portion and a predetermined carrier frequency. A receiver for the predetermined frequency of the second inductive magnetic field derives first and second different responses while an article including the structure is and is not in a detection region magnetically coupled to the receiver and transmitter. The receiver includes a synchronous detector for detecting first and second orthogonal components of the carrier frequency of the pulsed wave relative to a reference wave having a reference phase at the carrier frequency. The responses are derived independently of the amplitude of the carrier frequency components in the pulsed wave. The first and second responses are separately integrated over a predetermined interval, in synchronism with the occurrence time of each pulsed wave. The presence of the pulsed wave is indicated in response to either of the first or second responses having an absolute value in excess of a predetermined value during the interval.

REFERENCES:
patent: 4135184 (1979-01-01), Pruzick
patent: 4215342 (1980-07-01), Horowitz
patent: 4551712 (1985-11-01), Fockens

Affiliated with

Also associated with

Rating

Article surveillance system receiver using synchronous demodulat does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Article surveillance system receiver using synchronous demodulat, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Article surveillance system receiver using synchronous demodulat will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-1939492