function encodeTransmitOptions (options) {
  let result = 0x00
  if (options.acknoledge) result |= consts.TRANSMIT_OPTION_ACK
  if (options.lowPower) result |= consts.TRANSMIT_OPTION_LOW_POWER
  if (options.autoRoute) result |= consts.TRANSMIT_OPTION_AUTO_ROUTE