Campbell Scientific RF401-series and RF430-series Spread Spectrum Data Radios/Modems - Manual (Page 58)

Appendix B. Advanced Setup Menu
LONG HEADER TIME
Sets long header duration in tenths of a second. The default is 7 (for 0.7
seconds). If changed from the default of 7, this number should be set to the
“Max. Response Delay” indicated in TABLE B-1 for the standby mode you are
using plus 200 milliseconds (0.2 seconds). For example, if your standby mode
delay is 2 seconds, set the long header time to 2.2 seconds. The valid number
range is from 0 to 255. The longest long header time you should ever need is
8.2 seconds.
B-6