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Autex Packet Collisions?


Tony
 

Patrick:

I think you've done an incredible job developing Autex. I wanted let you know that I did notice a few packet collisions while participating in a round table which inevitably happens when one or more stations transmit at the same time.

Collisions will likely increase with the number of participating stations so I was wondering if Autex any has data carrier detection or some sort of busy channel method used to prevent this?

I plan on testing the mode PC-to-PC to see if I can recreate the collisions I observed on air.

Thanks,

Tony -K2MO


Patrick Lindecker
 

Hello Tony,

In an Autex net, each "Slave" station has its frequency. So there are no collisions between slaves, but a collision with the Master frame is possible.

Here is a diagram of the different possible topologies, on a bandwidth of 500 Hz around the Master frequency (MF), for Autex 4:
One Slave:
M<----->S1 (on the SF1 frequency=MF-167 Hz)

Two Slaves:
M <----->S1 (on the SF1 frequency=MF-167 Hz)
M <----->S2 (on the SF2 frequency=MF Hz)

Three Slaves (maximum):
M <----->S1 (on the SF1 frequency=MF-167 Hz)
M <----->S2 (on the SF2 frequency=MF)
M <----->S3 (on the SF3 frequency=MF+167 Hz)

Collisions will likely increase with the number of participating stations so I was wondering if Autex any has data carrier detection or some sort of >busy channel method used to prevent this?
No there is no carrier detection. The protocol permits to avoid collision, as far as possible...
The main tool used is the RS ID (Reed-Solomon Identifier) which is used to locate in time and frequency the Master message, for present and future Slaves.

73
Patrick



-----Message d'origine-----
De : main@digitalradio.groups.io [mailto:main@digitalradio.groups.io] De la part de Tony
Envoyé : mardi 27 octobre 2020 21:58
À : main@digitalradio.groups.io
Objet : [digital-mode-radio] Autex Packet Collisions?

Patrick:

I think you've done an incredible job developing Autex. I wanted let you know that I did notice a few packet collisions while participating in a round table which inevitably happens when one or more stations transmit at the same time.

Collisions will likely increase with the number of participating stations so I was wondering if Autex any has data carrier detection or some sort of busy channel method used to prevent this?

I plan on testing the mode PC-to-PC to see if I can recreate the collisions I observed on air.

Thanks,

Tony -K2MO







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