Dual mode transmitter/receiver and decoder for RF transponder tags

A backscatter transponder interrogation system, comprising:

• (a) an input for receiving a backscatter signal from a backscatter transponder due to an interrogation signal;
• (b) a multiphase mixer for mixing said received backscatter signal and a representation of said interrogation signal to produce a plurality of multiphasic outputs;
• (c) means for selecting less than all of the plurality of multiphasic outputs based on a magnitude of signal strength thereof;
• and
• (d) a decoder for decoding a sequence of symbols from the selected mixer multiphasic outputs.

An RF-ID tag interrogator, responsive to a return signal from an RF-ID tag having a semiconductor device outputting symbols which are accessed serially over time to sequentially modulate an interrogation signal at a modulation rate, comprising:

• a transmitter for transmitting a radio frequency interrogation signal, said interrogation signal having a frequency which substantially varies over time;
• a receiver for receiving a signal from the RF-ID tag which corresponds to said radio frequency interrogation signal, sequentially modulated over time based on the symbols during a period in which said interrogation signal frequency substantially varies;
• a decoder, having:
• a phase-sensitive demodulator for extracting a complex modulation pattern from said received signal, with respect to a representation of said interrogation signal;
• a symbol detector for receiving said complex modulation pattern, extracting a data clock from one of said complex modulation pattern, said interrogation signal, or a reference clock, compensating for a phrase rotation in the complex modulation pattern due to frequency variation of said interrogation signal at a rate faster than the modulation rate, and extracting said symbols from said compensated complex modulation pattern and said data clock.

A radio frequency receiving device, operating in an environment including an RF generator, generating a time-variant RF signal which propagates through space, and an RF signal modulator having a frequency modulation pattern based on data symbols stored in said device, comprising:

• an input for receiving a frequency modulated signal corresponding to said time-variant RF signal modulated by the data symbols;
• a demodulator for producing a demodulated signal by mixing a signal corresponding to said time-variant RF signal with said received signal, while preserving a phase pattern;
• a comparator for selecting a phase component having a greatest magnitude from at least two phase components having differing phase axes of said demodulated signal, said comparator having a magnitude selectivity pattern excluding selection of a component based primarily on a pattern of said data symbols;
• a detector for detecting an amplitude or relative phase change of said selected phase component to extract said data symbols;
• and
• an output for outputting information relating to said data symbols.

A device for receiving information from a remote tag, the tag having information stored in a memory and a modulator for frequency modulating an incident signal based on the stored information, comprising:

• a transmitter for transmitting a radio frequency carrier having a time varying center frequency in proximity to the tag;
• a receiver for receiving a frequency modulated, time varying center frequency carrier signal from the tag;
• a balanced mixer for receiving said frequency modulated, time varying center frequency carrier signal and said radio frequency carrier to produce at least a difference signal with at least two outputs each representing a different phase axis;
• and
• a detector circuit for receiving said at least two outputs and extracting the information from at least one of said outputs, the information being extracted during a period in which said radio frequency carrier center frequency varies.

A radio frequency receiving device, operating in an environment including an RF generator, generating a phase-continuous, time-variant RF signal which propagates through space, and an RF signal modulator having a frequency modulation based on data symbols, comprising:

• an input for receiving a frequency modulated signal corresponding to said time-variant RF signal modulated by the data symbols;
• a demodulator for producing a demodulated signal by mixing a signal corresponding to said time-variant RF signal with said received signal, while preserving a phase pattern;
• a comparator for selecting a phase component having a greatest magnitude from at least two phase components having differing phase axes of said demodulated signal wherein said comparator has a magnitude selectivity pattern excluding selection of a component based primarily on a pattern of said data symbols;
• a detector for detecting an amplitude or relative phase said selected phase component to extract said data symbols;
• and
• an output for outputting information relating to said data symbols.

An RF-ID tag reader, responsive a return signal from an RF-ID tag having an RF output modulating an interrogation signal over time in a pattern corresponding to a sequence of symbols, comprising:

• a receiver for receiving a modulated signal from the RF-ID tag which corresponds to said radio frequency interrogation signal, modulated over time based on the symbols;
• a complex demodulator for demodulating in complex space a modulated signal pattern of the received modulated signal to produce at least two phases and selectively producing an output based on a phase having a greater signal strength, to extract a modulation pattern from said demodulated signal;
• and
• an analyzer for reconstructing the symbols from the detected modulation pattern.