Detecting XBee Packet Transmission

Is there a pin or LED on the XBee USB Explorer that can be observed to detect the transmission of a (Series 1) data packet, particularly ones resulting from AutoSample data transmissions?

Our rig can send a Remote AT IS command and receive the response packet, but the programmed AutoSample transmissions do not appear to be occurring.

receiving XBee will alter its received signal strength indicator (RSSI) as each packet is received. That pin on the XBee can be observed.