Campbell Scientific RF401-series and RF430-series Spread Spectrum Data Radios/Modems - Manual (Page 65)

Appendix D. Setting Up RF401-to-CR206(X) Communications
FIGURE D-2. This graph represents a transmitting radio that uses a
long header and a receiving radio that is in a sleep cycle. The
length of the wake-up initializer exceeds the time interval of cyclic
sleep ensuring that the receiver detects the wake-up initializer and
receives the payload (i.e., transmitted data).
FIGURE D-3. This graph represents a radio that transmits a wake-up
initializer that is shorter than the cyclic sleep of the receiving radio.
The receiver does not detect the wake-up initializer and remains
asleep—missing the data transmission.
1. Any radio that is transmitting to a sleeping radio must have a
long header that spans the sleep duty cycle.
2. When a CR206(X) (or RF401) transmits to another CR206(X)
(or RF401), the receiving radio knows when the originally
transmitting radio is awake and not duty cycling. This allows the
radio to only transmit a long header when it is needed.
NOTES
D-3