Low power two-way wireless communication system for electronic shelf
labels
    8.
    发明授权
    Low power two-way wireless communication system for electronic shelf labels 失效
    低功率双向无线通信系统,用于电子货架标签

    公开(公告)号:US6108367A

    公开(公告)日:2000-08-22

    申请号:US995454

    申请日:1997-12-20

    摘要: 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.

    摘要翻译: 用于电子货架标签系统的双向低功率通信系统使用多个标签,每个标签具有天线和二极管。 在标签处接收的数据是曼彻斯特编码的,并且在商店天花板中从广播天线发射的扩频RF信号被100%AM调制。 优选地,RF约为2.4Ghz,扩展通过直接序列相移键控,切片速率至少为RF频率的十倍。 可以使用63位序列。 该标签检测RF能量,一个简单的比较器后面跟着一个曼彻斯特解码器来解码数字数据流。 要从标签中设置的数据通过具有偏移信号的二极管的选择性调制来传送,优选在1至10.7Mhz的范围内。 在此期间,天花板广播天线正以任何方式发射不进行数据调制的扩频信号。 由天线安装的接收天线拾取由标签天线再发射的能量,并且在二极管被调制的时间期间能量转移到两个边带。 接收到的信号进行扩频解调和带通滤波,以便仅处理边带能量。 通过数字信号处理技术从边带能量恢复标签的出站数据流。 结果是标签的成本和复杂性最小化,并且考虑到其管理框架对带宽的最佳利用。