06108367 is referenced by 27 patents and cites 12 patents.

A two-way low-power communication system for an electronic shelf label system uses a multiplicity of labels, each of which has an antenna and a diode. Data to be received at the label is Manchester encoded and 100% AM modulated onto a spread-spectrum RF signal, emitted from a broadcast antenna in the store ceiling. Preferably the RF is around 2.4 Ghz, and the spreading is via direct sequence phase shift keying with a chipping rate at least ten times the RF frequency. A 63-bit sequence may be used. The label detects the RF energy, and a simple comparator followed by a manchester decoder extrats the digital data stream. Data to be set from the label is communicated via a selective modulation of the diode with an offset signal, preferably in the range of 1 to 10.7 Mhz. During this time the ceiling broadcast antenna is emitting a spread-spectrum signal that is not data-modulated in any way. Energy re-emitted by the label antenna is picked up by a ceiling-mounted receiving antenna, and the energy is diverted to two sidebands during times when the diode is being modulated. The received signal is spread-spectrum demodulated and band-pass filtered so that only sideband energy is processed. The label's outbound data stream is recovered by digital signal processing techniques from the sideband energy. The result is a minimization of cost and complexity in the label and an optimal exploitation of the bandwidth given the regulatory framework thereof.

Title
Low power two-way wireless communication system for electronic shelf labels
Application Number
398905
Publication Number
6108367
Application Date
December 20, 1997
Publication Date
August 22, 2000
Inventor
Noam Livneh
Yuvalim
IL
Alex Herman
County of Norfolk
MA, US
Agent
Oppedahl & Larson
Assignee
Electronic Retailing Systems
CT, US
IPC
H04L 27/30
H04K 1/00
H04B 15/00
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