Re: Codec2

Tom Azlin N4ZPT <tom@...>

I would add that there has been a lot of work done looking at tandeming vocoders. Conclusion a noticeable loss in audio quality measured in the mean opinion score. If you could find a way to bridge between the two vocoders that would avoid the existing patents that would be good. So I will stick with D-STAR where I have the most invested. Maybe cross link co-located FM repeaters in a way to set up headers in a meaningful way.

73, tom n4zpt

On 5/23/2012 12:53 PM, Tyrell Berry wrote:

When dealing with music, I consider myself an audiophile. When I buy a
CD, I rip it to my home server in the FLAC format; No, I don't carry
loss less audio around on my portable devices... But I like AAC when my
player supports it, and MP3 when it doesn't. My primary concern with
storing my primary source in either lossy format is that if I convert
between the two, it's going to lose MORE data/quality with each
conversion... Lossy on top of lossy is bad.

The same is true of these vocoders... They are all lossy formats... And
at such low band widths, they don't leave much left over to be lost
again. My point is this: A transcoder between any two formats that use
different vocoders will significantly degrade the audio quality...
Maybe it will still be legible, but I doubt it will be a pleasant

In light of that, going from one digital mode to another may or may not
be considered worse than going from FM to digital, depending on the real
world performance of that double (or potentially triple in a poorly
optimized network) lossy conversion.

On May 23, 2012 9:32 AM, "Tim Hardy AF1G" <hardyt@...
<mailto:hardyt@...>> wrote:

I'm not opposed to linking different protocols, but there is value
in some of the objections to linking specific networks. If the
objections or concerns can be mitigated, then fewer people would resist.

The most often heard objection to linking FM systems to D-Star seems
to be that D-Star users don't want all the white noise from a weak
FM station digitized and retransmitted on D-Star, and I agree with
this objection. Find a way to limit the retransmission of FM signals
onto the D-Star network to only good, mostly full-quieting signals
and you will probably overcome these objections.

Echolink and IRLP were a match because they both use the same mode, FM.

Linking one type of digital system to another won't have this
specific problem, so I don't see why we couldn't develop this option
as long as protocols in each system are satisfied. For example,
D-Star sends the callsign of the transmitting station through the
network. Make this happen from the non-D-Star system and the D-Star
network would probably be satisfied. Otherwise, there will continue
to be objections.

Tim, AF1G

---- "Tony Langdon wrote:

At 11:51 AM 5/23/2012, you wrote:
>"this is something that should have been done ten years ago"
>Unfortunately it wasn't, and that the biggest issue I have with the
>development of D-Star. Having said that, Amateur Radio is already a
>splintered hobby with many niches, so it's nothing new.

D-STAR was developed a long time ago, technology has moved on since,

>What concerns me more is the (political) resistance to allowing
>interoperability/gateways between systems. The transcoding, gateways
>and transports themselves are all relatively minor feats in
>comparison. All it takes is "someone" saying they won't allow gating
>from IRLP to Echolink, Echolink to D-Star, or P25 to whatever, and a
>segment becomes isolated. We're our own worst enemy and we'll pay
>for it in real dollars.

Agree totally. To me, the ultimate aim is to have a

>I don't want to have to take three HT with me when I leave the
>house, or have a rack of three mobile rigs in the car. I also don't
>want my investment in D-Star to become worthless.

I had the same issue back in 2002, when I was running IRLP and
Echolink on a single antenna, which meant that two of the 3 ports on
my triplexer were taken up with links! As I was the main user, there
had to be a better way. I wasn't the only one who thought this, and
a few people put their heads together and came up with EchoIRLP,
which allowed the same analog endpoint to be used for both
networks. With digital, there's no common medium until you get to
the end user radio itself, so you either need a multiprotocol radio,
or you need infrastructure which can route across networks (and
willing network administrators!). At least with digital, it should
be possible to transparently carry IDs from end to end, leaving only
the need to cross from network to network, and transcoding the audio
where necessary.

If the gateways can be built out of something like the UDR, then that
could push the protocol conversion as close to the edge of the
network as possible, which might scale better, as well as minimising
issues of "We don't want XXX on our network!".

73 de VK3JED / VK3IRL

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