Continuous preamble transmission
Sometimes a continuous standard preamble comes in handy for testing purposes.
With RevC2A chips it is possible to internally modulate with an infinite square wave pattern. Basically, we use the PN9 modulation mode but load up a ‘1010…’ seed pattern into the LFSR and then just circulate it forever.
(There was a bug in RevB1B chips that prevented this from working directly)
The following batch lines can be added to the end of a WDS generated CW batch:
(Remember to remove the original MODEM_MOD_TYPE setting)
# Set PN polynomial = 16-bit circulator
'SET_PROPERTY' 'PKT_WHT_POLY_15_8' 80
'SET_PROPERTY' 'PKT_WHT_POLY_7_0' 00
# Set PN Polynomial seed value = 0xAAAA (1010... pattern)
'SET_PROPERTY' 'PKT_WHT_SEED_15_8' AA
'SET_PROPERTY' 'PKT_WHT_SEED_7_0' AA
# Switch to PN9 mode (must be set after polynomial & seed)
'SET_PROPERTY' 'MODEM_MOD_TYPE' 13
'START_TX' 00 00 00 00