公开(公告)号：US4864158A

公开(公告)日：1989-09-05

申请号：US149609

申请日：1988-01-28

申请人： Alfred R. Koelle ,  Donald F. Speirs ,  Peter L. Hendrick

发明人： Alfred R. Koelle ,  Donald F. Speirs ,  Peter L. Hendrick

IPC分类号： G01S13/78 ,  G01S13/74 ,  G01S13/75 ,  G06K7/00 ,  H03K5/19 ,  H04Q9/00

CPC分类号： H03K5/19 ,  G01S13/758 ,  G06K7/0008

摘要： This invention relates to an improved signal reader for reading signals from transponders placed on moveable objects such as ship containers, automobiles or railroad cars. The reader sends out a continuous signal, which is modified by the information contained in the transponder attached to the moveable object. Multiple antennas, each of which receive separate signals, may be multiplexed at the reader. The improved circuit of the invention provides quick recognition of the receipt of a valid signal from a transponder or, in the alternative, the absence of such a valid signal.

公开(公告)号：US4786907A

公开(公告)日：1988-11-22

申请号：US885250

申请日：1986-07-14

申请人： Alfred R. Koelle

发明人： Alfred R. Koelle

IPC分类号： G06K7/08 ,  B61L25/04 ,  G01S13/75 ,  G01S13/82 ,  G06K7/00 ,  G06K19/07 ,  G01S9/56

CPC分类号： G06K19/07786 ,  B61L25/04 ,  B61L25/045 ,  G01S13/758 ,  G06K19/0723 ,  G06K7/0008

摘要： A reader transmits interrogating rf signals to a transponder including an antenna having a particular impedance. The signals received by the antenna are converted to a direct voltage which is introduced to a first terminal of a switch such as an emitter of a semi-conductor device having conductive and non-conductive states of operation. A second terminal of the switch, such as the base of the semi-conductor device, receives a voltage variable between first and second magnitudes in accordance with a pattern of binary 1's and 0's in a data source such as a read-only memory (ROM). This pattern of binary 1's and 0's is individual to an object identified by the transponder. The variable voltage on the base of the semi-conductor device causes the emitter-collector current of the semi-conductor device to vary between first and second amplitudes. When this current has the first amplitude, the impedance of the semi-conductor device and the ROM substantially matches the antenna impedance. When this current has the second amplitude, the impedance of the semi-conductor device and the ROM is substantially greater than the antenna impedance. Capacitance may be connected to the collector of the semi-conductor device and the ROM to store energy in accordance with the current flow through the semi-conductor device. This stored energy provides for an energizing of the semi-conductor device and the ROM. A diode may be connected between the emitter and collector of the semi-conductor device to increase the second amplitude of the current through the semi-conductor device.