code: function Signal(properties) {
          if (properties)
              for (var keys = Object.keys(properties), i = 0; i < keys.length; ++i)
                  if (properties[keys[i]] != null)
                      this[keys[i]] = properties[keys[i]];
      }
docs: Properties of a Signal.
  @exports ISignal
  @interface ISignal
  @property {number} [percent] 信号强度
  desc: 信号强度百分比
  unit: %
  range: [0, 100]
  @property {Signal.Type} [type] 类型
  desc: 连接方式类型
  range: [ UNDEFINED, OTHER, TELE2G, TELE3G, TELE4G, TELE5G, BAND24GHZ, BAND58GHZ]
  @property {string} [protocal] 协议
  desc: 链路协议，大多数情况下仅当选择具体频率或Other时有效
  examples: ["Lightbridge 2","NB-IoT","ZigBee"]
  @property {number} [rssi] RSSI
  desc: 接收信号强度指示
  unit: dBm
  range: (-∞, 0]
   
  Constructs a new Signal.
  @exports Signal
  @classdesc Represents a Signal.
  @constructor
  @param {ISignal=} [properties] Properties to set