Ping mode is used by the hub to find an available channel; channels are unavailable if they are being used by another hub with the same SOP code, or if there is excessive noise on the channel. Upon arriving on a new channel, the hub takes 32 RSSI samples and if any sample is greater than pingRssiThreshold, the hub goes to the next channel in the subset. If one complete cycle through the channel subset occurs, then pingRssiThreshold is incremented. If the RSSI samples show a quiet channel, then the hub sends a ping request using the zero-CRC Seed. If an AutoAck is received (indicates the presence of another hub in the channel), the hub goes to the next channel in the subset. Otherwise, Data Mode is entered on the channel.