Mark Kramer wrote:
In article ,
Derry Hamilton wrote:
I'd prefer to make one myself, except I'd have to buy an AMBE chip from
DVSI.

I'd like to make a lot of things for myself but I have to buy patented
chips from the license holders. AM radio isn't a proprietary protocol,
but a lot of the parts used to make an AM radio are patented. You buy
them only from people the licensee has approved.

Hi Mark,

Could you elaborate on the relationship of electronic parts to
proprietary codecs for radios?


I think there is a little confusion here regarding proprietary aspects
of electronics and radio concepts.

Any patents held on electronic components are patents to safeguard the
makers methods of making them - not the concept of the parts. The
resistors, diodes and other parts are basic electronic building blocks,
and anyone can make those.

I could make a nicely functioning radio out of pencils, microscope
slides, aluminum foil, scrap wire, an old oatmeal box, and If I really
wanted to get involved, I could construct my own vacuum tubes and design
and build a superheterodyne radio.

As long as I built them according to my own methods, and did not
infringe on the methods used by a manufacturer, not one patent, nor
intellectual property would be violated.

Another way of looking at this, is that I can go to the local Radio
Shack, and buy a handful of components to build say, a blinking light.
Maybe an IC-type 555, an op amp or two, and their needed peripheral parts.

My finished device is not owned by the companies that made the parts. If
it is my original design, I can claim copyright on it.

Now on to the intellectual property of the D-Star codec.

D-Star uses this Codec, and it is proprietary.

If you do not use the Codec, you will not be able to use the D-Star
repeater.

If you can use the repeater, you have the Codec.


This differs in many important ways from normal repeaters, and normal
Codecs in use by Amateurs.

Examples of non proprietary Codecs are(randomoly picked except for D-Star:

SPEEX- lossy but good ro IRLP

FLAC - lossless


Proprietary codecs:

AMBE

The D Star Codec.

The ramifications of using each are important.


Amateur Radio has traditionally used open source whenever possible,
because we also have a tradition of working on and improving those
things that we work with. Examples are the PSK31 and RTTY modes.
Amateurs are continually providing new and improved software for those.
There are even multi PSK channel data transmission softwares out there.
A lot of PSK signals fit within the bandwidth taken up by one SSB voice
transmission.

My experimenting with a particular PSK engine is usually based on going
to the web, and downloading it. Most applications are free, but even
those that have to be purchased, the whole sum is going to the developer.

Hypothetically, say a group of hams came up with a digital repeater
using the SPEEX Codec. (SPEEX is used for illustration purposes only, it
might not be the best choice)

Most of us would be able to either build or purchase an interface that
would allow us to interface our radios to the computer, as software
would be easily available to run them.

Hand helds would be easily adaptable, as there is no specific need for a
computer, just the necessary software and hardware to turn an audio
stream into a digital stream, in the same manner as cell phones do (they
use a different codec, but the principle is the same.

I would note that there has not been a huge amount of work done by
Amateurs in the VHF and up region as related to Digital voice. A lot of
this can be ascribed to the fact that an SSB channel is already pretty
narrow, so there aren't orders of magnitude gains to be made in
conserving bandwidth. Another issue is that with digital signals,
multipath can be a severe problem. Anyone who does doppler direction
finding (I do) can tell you that at VHF and up, Multipath is a major
problem. What might be a little whoosh or garble on FM without upsetting
readability can sometimes just keep the digital system nice and quiet.

Now let us turn to our D-Star equipped repeater.

What will communicate with it:

Icom D-Star Equipment
Kenwood ( a rebranded Icom, sold only in Japan
Moetronix Can hear and talk D-Star on the internet.

That is a pretty short list. One for all practical purposes You buy the
equipment and you use it.

Do you know what the price for the AMBE Chip is in quantities of one? It
may not even be realistic for an amateur to attempt to build one of
their own.

Mike