[aprssig] Understanding packet

[Andrew Rich]

Gudday

I have a few questions concerning packet radio.

+ I think from memory that packet does not simply use 1200 = high or 2200 =
low.

+ Does it keep flicking between tones to "keep the energy up" in the
detector ?

+ And a non flick is a state change ?

+ From what I have been reading 0x7e or 011111110 is the start or txdelay ?

+ What is the bit stuffing i hear about ? why is that so ?

+ I have noticed an MX614 does tone changes at the zero point, what are the
distanvantages then of using xr2206 xr2211 that do not do this ?

+ Does packet use a CRC method ? is that what the passall command is in a
tnc ? show now crc chucksum valid packets ?

+ From what I can see on my bench testing, one cycle of 1200 Hz and two
cycles of 2200 Hz fits nicley into 1200 baud ? coincidence ?

Regards

Andrew

VK4TEC


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