This sets how many packets pass before the modem does a full refresh of its payload compression algorithm's internal dictionary and state. Because payload compression algorithms build up a dictionary of repeated data patterns over successive packets, periodically refreshing that state rather than letting it grow indefinitely recovers cleanly from any lost packet that would otherwise desynchronize the compressor and decompressor. A value of 600, the maximum, refreshes the compression state only once every 600 packets, maximizing compression efficiency but taking longer to recover if a state-carrying packet is lost over the satellite link.