Despite the fact that a synchronous network is the most power friendly option, there are some use cases that do not have the benefit of the time required to synchronize communications between nodes. ANT has an asynchronous channel option called the scanning mode. Basically the scanning mode is not a channel as the receiver configuration is on constantly. Continuous current consumption of 18mA demands a higher power source like a USB port or large battery capacity. No other receive or transmit functions are possible during the scanning mode as the complete radio is dedicated to this function. The back channel can be used to acknowledge and respond to the transmitters as they pass through the RF range of the scanning node.