[Elecraft] K3 Convergence

[VR2BrettGraham]

W4TV further continued:

> > CI-V does have collision detection, as every device can
> > see the serial bus as it sends.  That also makes a
> > checksum unnecessary.
>
>CI-V can only see the data it is sending.  Depending on the
>hardware, it is entirely possible for two devices to be
>sending on the bus at the same time with the local data
>masking the remote data.

There are no hardware differences involved - a serial bus
with one device trying to pull the bus low & another device
trying to pull the bus high will result in at least one device
not seeing what it was expecting to see on the bus.

What you describe could happen if the serial bus has been
changed, but then that deviates from how the manufacturer
intended the product to be used.

73 & HLNY, VR2BrettGraham.

> > -----Original Message-----
> > From: elecraft-bounces at mailman.qth.net
> > [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of VR2BrettGraham
> > Sent: Thursday, February 14, 2008 7:39 PM
> > To: 'Elecraft Reflector'
> > Subject: RE: [Elecraft] K3 Convergence
> >
> >
> > W4TV continued:
> >
> > > > CI-V also allows for multiple controllers, though I
> > > > have yet to see any other application that appears
> > > > to properly implement its CSMA/CD protocol.
> > >
> > >There is no carrier switching or collision detection in the
> > >CI-V protocol.  The data packets do not carry any checksum
> > >or sequence number both of which are required for CSMA/CD.
> > >CI-V is a pure aloha protocol - if the packet gets lost or
> > >damaged the originator must resend if it does not get
> > >the expected reply.
> >
> > CI-V does have collision detection, as every device can
> > see the serial bus as it sends.  That also makes a
> > checksum unnecessary.  It is intended that a controller
> > resend a command if a collision is detected, so there is
> > no need for sequence numbers, either.
> >
> > "Carrier sense multiple access with collision detection"
> > does not mean any more than that - but what I was
> > responding to was the assertion that "there is not a single
> > radio that is capable- in either hardware  or software - of
> > reliably servicing two different radio control applications".
> > Maybe there isn't, especially if one insists on not working
> > with the radio as the manufacturer intended.
> >
> > 73 & HLNY, VR2BrettGraham.