Order Tray | Contact Us | Home | SIG Lists

[aprssig] AX.25 'H' flag

AE5PL Lists HamLists at ametx.com
Mon Nov 14 16:30:19 UTC 2005

You are correct Curt.  From the v2.0 spec shown at www.tapr.org: Multiple Repeater Operation
... As a frame progresses through a chain of repeaters, each successive
repeater will set the H bit (has-been-repeated bit) in its SSID octet,
indicating that the frame has been successfully repeated through it. No
other changes to the frame are made (except for the necessary
recalculation of the FCS)...

Each repeater sets _its_ H-bit when repeating the packet.  Since each
repeater does this in serial sequence and each repeater is _not_ to make
any other changes to the frame (except for the FCS), this means that the
H-bit is supposed to be set for _every_ repeater that has repeated the
packet.  If a repeater resets the H-bit to zero for previous repeaters,
it is in violation of this portion of the specification.


Pete Loveall AE5PL
mailto:pete at ae5pl.net 

> -----Original Message-----
> From: Curt, WE7U
> Posted At: Monday, November 14, 2005 10:06 AM
> Subject: Re: [aprssig] AX.25 'H' flag
> spec.  That bit _must_ get set in order to show that the slot 
> is used up.  Havoc will reign otherwise.

More information about the aprssig mailing list