What is the shortest frame/packet that can be sent and still received?

[WhiteHare]

So, is that the recommended number of preamble bits for 300kbps?  4 bytes worth?  I seem to be getting pretty good results with just one byte of preamble.

It sounds like one rounds up from the desired number of bits to the nearest number of bytes?  For instance, if the DS says the preamble is 12 bits (which is obviously not an even multiple of 8-bit bytes), then when setting the preamble length, do I need to make it 2 bytes?  That part I'm still unclear about.

[perky]

Well it's 12 bits plus the TS_RE time minimum, and since you can only select the preamble in units of bytes (i.e. 8 bits) you have to round up.

Edit: My maths I think is wrong, the Trssi times are part of the preamble itself (see figure 18 in the sx1231h spec), so it's actually TS_RE plus 8 bits, which actually makes it 3 bytes minimum for the preamble.

Mark.

[joelucid]

Experimentally 3 bytes are required at 300kbit even without AGC.

[WhiteHare]

Thanks, guys, for your great input on this.  Makes sense.  I'm now sold on using a longer preamble and more sync bytes.