Abstract: 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.

Abstract: An improved system for space management in retail stores is described. The space management system includes price display labels mounted on rails along the edges of shelves in a store. A communications link between the computer and the labels permits the computer to address each label by a logical address and to determine the physical location of each label to within a resolution of typically four feet. The system prepares price audit lists and adjacency audit lists that permit economical use of the time of store personnel during the audit. The lists are generated in such a way that the items on a particular list are physically contiguous; thus once the correct general area has been located by the auditor little additional time need be spent locating the individual items. In performing an audit of product facings, the user is able to use the display hardware, including the pushbutton on each label, as a data collection system for product facing information.

Abstract: In a system for displaying prices in a retail store, an improved protocol permits improved communications between a host, or central computer and display devices. Such a protocol enables the host to effectively communicate messages to the display devices for the latter to display information to consumers and/or store personnel.