[App_rpt-users] App_rpt-users Digest, Vol 85, Issue 58

Steve Wright info at meshnetworks.co.nz
Wed Mar 30 19:54:29 EDT 2016

On 31/03/16 11:46, Joe Leikhim <rhyolite at leikhim.com>wrote:
> What is the problem with the RTCM and simulcast?

RTCM Transmit simulcast "doesn't work", we were told.  I haven't tried it.

RTCM Receive voting works famously.

> Analog simulcast may never sound as good as a single site, because it
> does experience/cause time differential interference and noise and
> therefore requires some very specific design constraints. However, for
> some applications it still is the way to go.

How difficult for Hams?  RTCM TX Simulcast is a very good idea, but it 
seems to be on the back burner.

> Moving forward 5-10 years,
> two slot DMR with IP connectivity will be the way to go. Before I get
> flamed, TETRA never got a foothold in the US and because FCC eliminated
> most 25KHz channels, getting TETRA to play in the US is reserved for
> those few who have the contiguous spectrum.

We're Hams though, and we can do as we choose within our own 
regulations, and our propensity to negotiate new rules.  I don't like 
4800baud audio, and if we don't want to do something, then we don't have 
to do that.  There's no need to focus on the commercial world and their 
limitations and rules, but we just don't have to.

> [....] commercial products are very pricey and complex. That
> being said, I see the RTCM as having some potential niche in the
> commercial LMR world.

All the commercial stuff WILL go digital.  That's my prediction anyway.  
There's too much cleverness in the digital RF world to be ignored now - 
the benefits are just too great and the products are too disruptive.  
There won't be any analog RF before long - it'll be too slow, too 
featureless, too expensive, too power-hungry, and almost anything else 
you can think off.

Maybe Hams are stuck with that reality - that an analog RF high-site 
will be cool and quaint, like a transistor analog VFO.  Nice and 
old-world to play with, but not enough toys in the toybox.

For myself, I just can't get past the horrible 4800baud audio, and I 
don't think that we have to - not on VHF/SHF anyway.  A nice 64kbit 
channel would be lovely thanks! :p


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