[aprssig] ARPS physical layer

[Jack Cavanagh]

Derek Love wrote:
> I have been scouring the interweb and have so far not found a definitive
> description of the physical layer / air interface of the APRS system. All
> the published info seems to revolve around the Link layer (AX-25) which is
> all well and good, but doesn't let me design a new TNC. Can someone point me
> in the direction of a suitable source of information, please?
>    
Try:
http://www.tapr.org/pdf/AX25.2.2.pdf
> This document defines a protocol used between two amateur radio 
> stations in a point-to-point or networked
> communications environment. The protocol specifies only link layer and 
> physical layer functions. It is not
> intended to specify any upper-layer protocol other than certain 
> interface requirements to and from other
> layers.

73,
Jack
KB4XF