Pulse or digital communications – Repeaters – Testing
Patent
1991-12-08
1994-03-08
Kuntz, Curtis
Pulse or digital communications
Repeaters
Testing
375 59, 375 75, 34082554, H04B 138
Patent
active
052933997
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to identification remote control and, in particular, it consists of an interrogator/receiver and a passive transponder. This group allows the univocal identification of a still or moving object, animal or person by producing a coded identification signal in answer to a signal sent by the interrogator/receiver that is inductively coupled with the transponder.
2. Description of Prior Art
Some remote control identification systems have already been proposed and used in which an interrogator acts to generate an A.C. clock signal that also acts as a power signal. By means of an inductive coupling, a transponder receives said signal and uses it as its power supply, thus generating a coded reply signal that is picked up by the interrogator/receiver. The coded signal is characteristic to that transponder, thus the object, animal or person, to which the transponder is associated can easily be recognized by the interrogator.
Particularly, in the device described in the patent application WO 85/03831, the clock signal sent by the interrogator and received by the transponder by means of the inductive coupling is at first reduced in frequency, then its frequency is further divided (for instance by eight or ten). An alternate current signal is thus produced having a frequency varying between two values; any variation from a frequency to another represents a value of "zero" or "one".
The encoding of this signal is obtained by means of a Manchester encoder, while its modulation is carried out by means of FSK system (frequency shift keying). The modulated signal returns to the interrogator by means of an inductive coupling, it is filtered through bandpass filters which partially eliminate the background noise, then it is sent to a FSK demodulator capable of recognizing the frequency variations of the signal. Then a microcomputer extracts the identification code and is able to transfer it to a monitor, a printer, a disk or other storage systems or to another computer.
The main disadvantage of this device is the need to use, for isolating the signal sent by the transponder, bandpass filters having a frequency band width at least equal to the difference between the two frequency values of the signal. In this way the background noise having a frequency comprised between the modulated signal frequency values, is allowed to pass through the filters and the recognition of the identification signal is sometimes difficult, particularly in a highly electromagnetically disturbed environment. Thus only the reduction of the maximum allowable distance between the interrogator and the transponder allows a sure identification.
Moreover, the device employs unalterable memories therefore its use is limited to simple identification systems.
SUMMARY OF THE INVENTION
Object of this invention is, therefore, that to increase the maximum distance between interrogator and transponder with no power increase and to allow transmissions to occur also in bad conditions.
A further object is that to extend the utilization field of the device.
The main object has been achieved by providing a device of the kind mentioned above, that is made of an interrogator/receiver and passive transponder inductively coupled, in which the former generates a power signal of a predetermined frequency that is received by the latter that utilizes it as a clock signal for generating a codified reply signal, said signal being phase modulated between two predetermined values such that each phase shift from a value to the other corresponds to a "zero" or a "one" of the binary identification code. Then the modulated signal is sent again to the interrogator by means of an inductive coupling, filtered through bandpass filters, demodulated and decoded; the identification code is thus identified.
From the aforeasaid it will be noted that in the proposed device bandpass filters can be used having a very narrow frequency band width (less than one thousandth of the modulated signal frequency) , thus allowi
REFERENCES:
patent: 4129855 (1978-12-01), Rodrian
patent: 4463353 (1984-07-01), Kuzara
patent: 4724427 (1988-02-01), Carroll
patent: 4730188 (1988-03-01), Milheiser
Bocure Tesfaldet
Kuntz Curtis
Linn Richard
R. Audemars SA
LandOfFree
Identification system does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Identification system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Identification system will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-158683