What is the point of digital voice when there are already AM, SSB
and FM for those who want to appear indistinguishable from CBers?

Perhaps it is cynicism from the manufacturers who introduce such things
as they see their traditional highly-priced corner of the market
being wiped away by SDR technologies?

On 24/02/15 12:47, gareth wrote:

What is the point of digital voice when there are already AM, SSB
and FM for those who want to appear indistinguishable from CBers?

Technical developments of new encoding techniques that reduce required
bandwidth, just as SSB improved over AM. You can get CODEC2 down to
way less than an SSB signal quite easily.

Technical developments of new encoding techniques that decrease the
S/N margin needed for successful communications.

Ability to send voice and data at the same time, over the same
channel.

Perhaps it is cynicism from the manufacturers who introduce such things
as they see their traditional highly-priced corner of the market
being wiped away by SDR technologies?

Undoubtedly some are introducing digital technologies in an attempt to
increase market share (hence them not all being compatible with each
other), but there are many other reasons.

A lot of the next generation HF rigs will have some kind of SDR onboard
anyway (even if they have nice butons and knobs to use that we are all
used to)

Not everyone is going to want to get their hands dirty and code their
own transceiver, or even hook up PA's PTT Changeover relays, preamps
etc, so it's not as if the big manufacturers are going to be wiped
out by SDR. There will still be a market for "black boxes"


73s

Iain

"Iain Young, G7III" wrote in message
...
On 24/02/15 12:47, gareth wrote:

What is the point of digital voice when there are already AM, SSB
and FM for those who want to appear indistinguishable from CBers?

Technical developments of new encoding techniques that reduce required
bandwidth, just as SSB improved over AM. You can get CODEC2 down to
way less than an SSB signal quite easily.

Those who subscribe to these digital voice apparatuses lack a single clue
about any underlying technical development

On Tue, 24 Feb 2015 16:57:04 +0000, gareth wrote:

Those who subscribe to these digital voice apparatuses lack a single
clue about any underlying technical development


I've had this dream before. Oh wait a minute, that was about Single Side
Band :-)

Charlie.

--
Hello Wisconsin!

On 24/02/2015 16:57, gareth wrote:
"Iain Young, G7III" wrote in message
...
On 24/02/15 12:47, gareth wrote:

What is the point of digital voice when there are already AM, SSB
and FM for those who want to appear indistinguishable from CBers?

Technical developments of new encoding techniques that reduce required
bandwidth, just as SSB improved over AM. You can get CODEC2 down to
way less than an SSB signal quite easily.

Those who subscribe to these digital voice apparatuses lack a single clue
about any underlying technical development

Sweeping statement.

I have used digital voice and I have built my own kit (non-ham but
basically the same as a digital voice front end) and wrote my own codecs
(both fractal lossy and various lossless codecs).
If you have trouble sleeping at night I am sure I can dig out my
dissertation and forward it. The technology is dated (I built my first
one using thick-film technology - that dates it a little) but the
underlying work is still valid.

Andy

"gareth" wrote in news:mchrrq$n83$1@dont-
email.me:

What is the point of digital voice when there are already AM, SSB
and FM for those who want to appear indistinguishable from CBers?

Perhaps it is cynicism from the manufacturers who introduce such things
as they see their traditional highly-priced corner of the market
being wiped away by SDR technologies?

Technical investigations for those with the requisite skill set. Isn't that
what you're always banging on about, OM? Inane babble (i.e. 95% of all
QSOs) is till inane babble regardless of whether it is transported by voice
or Morse code.

On 24/02/2015 12:47, gareth wrote:
What is the point of digital voice when there are already AM, SSB
and FM for those who want to appear indistinguishable from CBers?

Perhaps it is cynicism from the manufacturers who introduce such things
as they see their traditional highly-priced corner of the market
being wiped away by SDR technologies?

Bandwidth reduction for one.
If you can encode and compress speech sufficiently then you can use
less bandwidth in transmission.

Clarity. With duplex transmission it is possible to transmit clear
speech over a noisy channel assuming you use an error correcting and
retransmission protocol, self correcting codes techniques etc.

Band sharing. Multiple users can transmit on the same band assuming
adequate time-slicing and collision detection and traffic handling.

or just for the fun of doing it.

Andy

"AndyW" wrote in message
...
On 24/02/2015 12:47, gareth wrote:
What is the point of digital voice when there are already AM, SSB
and FM for those who want to appear indistinguishable from CBers?

Perhaps it is cynicism from the manufacturers who introduce such things
as they see their traditional highly-priced corner of the market
being wiped away by SDR technologies?

Bandwidth reduction for one.
If you can encode and compress speech sufficiently then you can use less
bandwidth in transmission.

That's the bit I have trouble getting my head around. Back in the 1970s and
1980s digital transmissions used a much greater bandwidth than their
analogue equivalents. Sampling at 2.2 x max frequency x number of bits plus
housekeeping bits etc. etc.
A UK standard 625 line PAL video transmission would have used a bandwidth of
over 400MHz!
Times have changed and left me behind, but I've still got me beer so who
cares?
--
;-)
..
73 de Frank Turner-Smith G3VKI - mine's a pint.
..
http://turner-smith.co.uk

On 2/24/2015 11:32 AM, FranK Turner-Smith G3VKI wrote:
"AndyW" wrote in message
...
On 24/02/2015 12:47, gareth wrote:
What is the point of digital voice when there are already AM, SSB
and FM for those who want to appear indistinguishable from CBers?

Perhaps it is cynicism from the manufacturers who introduce such things
as they see their traditional highly-priced corner of the market
being wiped away by SDR technologies?

Bandwidth reduction for one.
If you can encode and compress speech sufficiently then you can use
less bandwidth in transmission.

That's the bit I have trouble getting my head around. Back in the 1970s
and 1980s digital transmissions used a much greater bandwidth than their
analogue equivalents. Sampling at 2.2 x max frequency x number of bits
plus housekeeping bits etc. etc.
A UK standard 625 line PAL video transmission would have used a
bandwidth of over 400MHz!
Times have changed and left me behind, but I've still got me beer so who
cares?

But you forget compression. For instance, unless there is a scene
change, the vast majority of a television picture does not change from
frame to frame. Even if the camera moves, the picture shifts but
doesn't change all that much. Why waste all of that bandwidth resending
information the receiver already has?

And voice isn't continuous; it has lots of pauses. Some are very
noticeable, while others are so short we don't consciously hear them,
but they are there.

And once you've compressed everything you can out of the original
signal, you can do bit compression, similar to zipping a file for sending.

There are lots of ways to compress a signal before sending it digitally.
About the only one which can't be compressed is pure white noise -
which, of course, is only a concept (nothing is "pure").

--
==================
Remove the "x" from my email address
Jerry, AI0K

==================

"Jerry Stuckle" wrote in message
...
On 2/24/2015 11:32 AM, FranK Turner-Smith G3VKI wrote:
"AndyW" wrote in message
...
On 24/02/2015 12:47, gareth wrote:
What is the point of digital voice when there are already AM, SSB
and FM for those who want to appear indistinguishable from CBers?

Perhaps it is cynicism from the manufacturers who introduce such things
as they see their traditional highly-priced corner of the market
being wiped away by SDR technologies?

Bandwidth reduction for one.
If you can encode and compress speech sufficiently then you can use
less bandwidth in transmission.

That's the bit I have trouble getting my head around. Back in the 1970s
and 1980s digital transmissions used a much greater bandwidth than their
analogue equivalents. Sampling at 2.2 x max frequency x number of bits
plus housekeeping bits etc. etc.
A UK standard 625 line PAL video transmission would have used a
bandwidth of over 400MHz!
Times have changed and left me behind, but I've still got me beer so who
cares?

But you forget compression. For instance, unless there is a scene
change, the vast majority of a television picture does not change from
frame to frame. Even if the camera moves, the picture shifts but
doesn't change all that much. Why waste all of that bandwidth resending
information the receiver already has?

And voice isn't continuous; it has lots of pauses. Some are very
noticeable, while others are so short we don't consciously hear them,
but they are there.

And once you've compressed everything you can out of the original
signal, you can do bit compression, similar to zipping a file for sending.

There are lots of ways to compress a signal before sending it digitally.
About the only one which can't be compressed is pure white noise -
which, of course, is only a concept (nothing is "pure").

Thanks, Jerry, you've explained a lot to me, and in a manner that an old
fart like me can understand.
I appreciate that, and feel I owe you a pint, (not a compressed 1cc one).
--
;-)
..
73 de Frank Turner-Smith G3VKI - mine's a pint.
..
http://turner-smith.co.uk