1) The "xxx" shows the output from the receive module when the transmit module is not switched on. "Inter-packet dead interval"? NEEDS A MORE CONCISE NAME! During such periods, unless another DCDW unit nearby is transmitting, the output of the receiver will be undefined, and, shortly (define more closely?) after tx shuts down, the output from rx will start swinging (sharply?) from 0 to 1 and back again, randomly. (Nature of this random signal?) Note that if a DCDW module is connected directly to the monitoring computer, no RF link, for debugging or other reason, then during "inter-packet dead interval" state of input will be determined by the passive components, in particular a likely pull up (or pull down) resistor.