Chart of HDTV freqs?
 

Sal M. Onella wrote:
By the old TASO standards, you need over 40 dB s/n to get a nice picture,
which requires a lot more peak RF power. By comparison, the digital signal
needs only about 17 dB s/n.

What happens at a 12 dB s/n for both? That's probably
what happened here during Hurricane Ike.
--
73, Cecil http://www.w5dxp.com

Chart of HDTV freqs?
 

Cecil Moore wrote:

...
I hear digital voice used on HF amateur radio has the
same problem.

Amateur digital communications have one real and serious problem, they
have not adopted Ogg Vorbis as their standard digital
encryption/coding/decoding/error-checking "mode"--indeed, an actual
"superset" of Ogg Vorbis is needed for radio duplex communications ...
amateurs, in general, need be the "final designers"--that won't happen
until larger numbers are involved.

Ogg Vorbis is open source, free to use/implement in your own software,
it just doesn't get the blessing of the arrl and it can't be used as an
excuse to inflate prices ... :-(

Until that is established as a standard, Ogg Vorbis, (or, a "mode"
invented/designed/implemented with the same
redundancy/efficiency/fool-proof-ness), these problems will be of a
notable nature ... :-( How and when to request re-sending of error
packets, how many times these requests can be allowed, how long to hold
a packet in the buffers, how large of buffers to be used, size of the
packets allowed, etc., etc., etc will all need to be agreed upon in that
standard--so far NONE I HAVE SEEN ARE ADEQUATE--indeed, only one is on
the right track at all ... and, the standard can be designed to be
highly adaptable/upgradeable--with only firmware upgrades needed to
bring old hardware completely up-to-date (manufacturers will surely
attempt to get in control of this and be able to force the purchase of
new equip/planned-obsolescence by the denial of new "flash firmwares" or
designing new firmware upgrades in such a manner as make existing equip
unable to accept them, example, just make it too large for the present
memory(s) size(s) and disallow memory upgrades--you know, the "standard
stuff" already being done. grin)

While you and a buddy can use it between yourselves, or, you can attempt
to get your club interested ... it remains on the fringes ... I find
"digital hams" on the HF bands to be as rare as "chickens teeth", at
least ones working with decent digital transmission
software/algorithms/etc. ... :-(

There was a group of hams which broke away from all this are were going
to release open source code which would have to be accepted just because
of its' sheer efficiency and performance ... internal bickering and
outside pressures had/has brought its' progress to a crawl/halt at the
present time ... such "tinker-ings" gets the attention of high powers in
high places ... :-(

(or, is this all just my paranoia--I will allow you and the future to
decide ...) digital radio is coming ... it is just walking with a cane!
LOL

Regards,
JS

Chart of HDTV freqs?
 

The neat thing about going full digital? You no longer have any idea why
the signal breaks up. PERIOD. The Customer is no longer bothered by
interference of any kind. Either it works or not. If your QSO, Phone Call,
Mayday, Police call for backup, TV signal gets knocked off the air, you
won't have a clue why.

I have experimented with Easy Pal Digi SSTV and DRM it is neat but I can
rarely get the S/N high enough for a complete transfer. Text is more
reliable, but it is hard for me to put my faith in a signal that sounds
clean and strong to my ear but with no result. I could have passed several
photos on MMSSTV with half the S/N and knew well what they were. Sometimes
getting the information through is more important than waiting for
conditions to get better to get it perfect.

I don't mind being a network admin. but being a radio op isn't quite dead
yet.

picture breaks up and quits. At other times the same station will give a
solid 3 or 4 bars.This happens on all channels. Perhaps atmospheric
movement? Lots of dust here in the desert. Any other ideas?


Yes, ducting and "ghosting" of the signal(s) due to reflections, etc.--I
can see these as being a REAL problem. From your description(s), sounds
like "they" just took the exact-same
technology/encoding/decoding-schemes and implemented them onto broadcast

Chart of HDTV freqs?
 

Amplitude Modulation of NTSC requires a LOT of signal to be noise free since
even a small amount of noise is visible.

We have no basis for comparison with ATSC other than by level, since we
don't have a way to discern between multipath, power line noise, deliberate
or any other kind of interference. How are we supposed to point the
antenna? With a stupid meter that takes 10 seconds to average? All I can
think of is to put it on a rotor and nudge it 2 degrees every 10 seconds
until the picture pops in. It is amazing what gets left out in the rush to
market.

"Cecil Moore" wrote in message
...
Sal M. Onella wrote:
By the old TASO standards, you need over 40 dB s/n to get a nice
picture,
which requires a lot more peak RF power. By comparison, the digital
signal
needs only about 17 dB s/n.

What happens at a 12 dB s/n for both? That's probably
what happened here during Hurricane Ike.
--
73, Cecil http://www.w5dxp.com

Chart of HDTV freqs?
 

JB wrote:
The neat thing about going full digital? You no longer have any idea why
the signal breaks up. PERIOD. The Customer is no longer bothered by
interference of any kind. Either it works or not. If your QSO, Phone Call,
Mayday, Police call for backup, TV signal gets knocked off the air, you
won't have a clue why.


Actually, NOT. Even the simple bars on a cell phone tell you if
communication is possible or not. The software running on an up-to-date
rig can describe the exact reason to you, if your rig interfaces to your
computer screen ... not to mention broadcast HDTV is in its' infancy,
taking its' first baby-steps ... even if you give the avg. American TV
viewer this information, do you think he would know what to do about it?
For "those dummies" you will pretty much have to have the software
handle the problems ... or make simple recommendations, perhaps "MOVE
THE ANTENNA DUMMY", or "RAISE THE ANTENNA DUMMY", or "BUY A DECENT
EXTERNAL ANTENNA DUMMY", or "POSSIBLE SIGNAL REFLECTIONS ARE OCCURING,
MOVE/REPOSITION THE ANTENNA DUMMY", etc. ROFLOL!

I have experimented with Easy Pal Digi SSTV and DRM it is neat but I can
rarely get the S/N high enough for a complete transfer. Text is more
reliable, but it is hard for me to put my faith in a signal that sounds
clean and strong to my ear but with no result. I could have passed several
photos on MMSSTV with half the S/N and knew well what they were. Sometimes
getting the information through is more important than waiting for
conditions to get better to get it perfect.


If the binary signal just clears the noise floor, and not by much mind
you (I am hesitant to quote an exact figure here) a perfect signal is
quite possible ... that is simply the nature of digital.

I just don't know why anyone would claim that digital signals are not
MUCH superior to analog -- remember the old analog cell phones -- who
would ever wish to "go-back-there???" ... the only software I have used
with HF/VHF/UHF digital processing is open source ... I immediately made
modifications to the decoding/coding scheme (Ogg Vorbis), "packet hold
time" and size of the buffers and implemented my own CRC checking
(faster algorithm) ... however, others must get a copy of it from me and
we both share it or no communications are possible. I see amateur
software in the same light I see amateur antennas -- build your own or
have another amateur elmer/tutor/instruct/assist/share-with-you ... it
is just traditional and the true spirit of amateur radio ...

I don't mind being a network admin. but being a radio op isn't quite dead
yet.


I actually worked at the college I attended in the 1990's when I
returned to go "full into computers" (my previous degree was as in
electronic engineering), and before I began an intern position in my
field of study. My last few months, before receiving my diploma, the
actually created a new position for me, "Student Programmer", I was
actually quite proud of it--even though the "big boys" seen it as a
joke! LOL Being both a programmer and a network admin. assistant made
the job seem like "money for nothing", what other sys admins seen as
major problems and were on the phone to Digital Equipment Corp. (DEC)
over, for the VAX, I usually had fixed by the time the techs got there
.... made me rather "hated", really ... however, most finally came around
and asked for the perl-scripts and C programs I used to automate every
task I could find! ... common computer users worshiped us ... "some of
us" let this go to their heads ...

picture breaks up and quits. At other times the same station will give a
solid 3 or 4 bars.This happens on all channels. Perhaps atmospheric
movement? Lots of dust here in the desert. Any other ideas?


As I have said, I am anxious for it to be deployed in my area ... I am
already looking into "digital to analog conversion boxes" which I can
download the firmware from to "reverse engineer" and then flash open
source firmware into ... either by hook or by crook. grin

Only God can control atmospheric conditions (but then, there is HARRP
and other such projects which do SEEM to alter them), and who can stop
that neighbor from erecting that steel storage shed, building that
wrought iron fence, installing those bars on his windows, operating that
ham rig from his stealth antenna grin, etc? :-(

Yes, ducting and "ghosting" of the signal(s) due to reflections, etc.--I
can see these as being a REAL problem. From your description(s), sounds
like "they" just took the exact-same
technology/encoding/decoding-schemes and implemented them onto broadcast


Regards,
JS

Chart of HDTV freqs?
 

JB wrote:
... All I can
think of is to put it on a rotor and nudge it 2 degrees every 10 seconds
until the picture pops in. It is amazing what gets left out in the rush to
market.


Sounds to me you are approaching the real focus of the problem ...
especially that "rust to market" part ... ahhh, capitalism and its'
little annoyances. chuckle

Regards,
JS

Chart of HDTV freqs?
 

John Smith wrote:

...
Sounds to me you are approaching the real focus of the problem ...
especially that "rust to market" part ... ahhh, capitalism and its'
little annoyances. chuckle

Regards,
JS

That "rust" thing, make it rush ...

Must have been a Freudian slip, and reflects the speed we can expect
improvements at ... LOL

Regards,
JS

Chart of HDTV freqs?
 

On Tue, 16 Sep 2008 17:41:49 GMT, "JB" wrote:

The neat thing about going full digital? You no longer have any idea why
the signal breaks up. PERIOD. The Customer is no longer bothered by
interference of any kind. Either it works or not. If your QSO, Phone Call,
Mayday, Police call for backup, TV signal gets knocked off the air, you
won't have a clue why.

Unfortunately, you're correct. I have considerable experience dealing
with various path impairment issues using various wireless
technologies, especially Wi-Fi. User will complain that they loose
connectivity, drop connections, suffer from erratic performance, and
generally see performance well below what would normally be expected.
The sources are many and varied. They're also very difficult to
identify. Quite a bit can be deduced with simple diagnostics (i.e.
ping stability, MAC layer packet loss, retransmissions) and from
determining the pattern (does it always die during meal times), but in
general, it's way beyond the capabilities of Joe Sixpack. I expect
much of the same with digital TV.

However, I'm not worried much about the RF issues. It will either
work or the customer can get cable or satellite TV. What I'm worried
about are all the added cables and incompatible technologies found on
the back of the HDTV sets and boxes. Another tangle of wires to deal
with.

Anyway, radio is magic. Maybe I should get one of those Halloween
pointed sorcerers hats with the stars and crescents.
http://en.wikipedia.org/wiki/Image:MGM_sorcererhat.jpg

--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558
# http://802.11junk.com
# http://www.LearnByDestroying.com AE6KS

Chart of HDTV freqs?
 

"John Smith" wrote in message
...
JB wrote:
The neat thing about going full digital? You no longer have any idea
why
the signal breaks up. PERIOD. The Customer is no longer bothered by
interference of any kind. Either it works or not. If your QSO, Phone
Call,
Mayday, Police call for backup, TV signal gets knocked off the air, you
won't have a clue why.


Actually, NOT. Even the simple bars on a cell phone tell you if
communication is possible or not.

That is all it can tell you.

The software running on an up-to-date
rig can describe the exact reason to you, if your rig interfaces to your
computer screen ...

Maybe you know of a secret diagnostic menu for my DTX9900?
If I remember correctly, all they know is RSSI and data errors. Please,
tell me if there are other indications that discern multipath, interference,
or any other reception problem without either sophisticated test equipment
or an analog indication - perhaps a color coded bar graph or channel
spectra that can react faster than the stream filling the buffer. I don't
know how ATSC handles error correction, but being a broadcast stream, I
would suppose only forward error correction is possible.

If the binary signal just clears the noise floor, and not by much mind
you (I am hesitant to quote an exact figure here) a perfect signal is
quite possible ... that is simply the nature of digital.

PACTOR yes, but I don't see that with DRM or ATSC at all. How is it that an
s9 signal isn't enough? I'm truly glad to have SSB so I can tell the other
station to resend the file again. The Universe isn't digital. Certainly
not radio. The signal, no matter what modulation scheme you use to improve
recovery of usable clipped and buffered data, is still in the realm of the
analog during transmission over the air. Ok, you might not understand that
if you are only the network guy and all your traffic worries start at the
protocol level as long as the Fiber box is energized.

don't know why anyone would claim that digital signals are not
MUCH superior to analog -- remember the old analog cell phones -- who
would ever wish to "go-back-there???"

Actually the best sounding mobile phone I ever had was my full-duplex 450
Motrac linked to a mountain top site with wide area direct dialing. No one
ever suspected I was mobile. But that was because my Analog link was better
than a voice grade phone line. Digital is great if you can find the
bandwidth, but great sacrifices and compromises have often been made in
audio quality for the sake of keeping the occupied bandwidth of the RF
channel within limits. What I am seeing on DTV, are stations that are doing
one 1080i or 720p stream on one RF channel with maybe 2 more streams of 480i
(often annoyingly compressed) OR up to 6 - 480i streams not so heavily
compressed. So I hate to disappoint you, that not all channels will be
better than analog until they find a way to do better than MPEG compression
and conversion from an NTSC source.

The move to digital cellular allowed channel re-use without having the
customer hear interference from co-channel sites so that many sites could be
used to communicate with many small handsets. Do you think that will be
much of an issue on Ham radio? Ham radio's greatest protection is in the
fact that it isn't supposed to compete with other services. No privacy is
needed or allowed either. If you copy the consumer model, you have no
amateur radio anymore. So I ask you sir, wouldn't you rather be using a
digital cell phone and leave the ham bands alone? Experimentation will
continue and things will be learned, people will contest and rag chew and
chase DX, but when ham radio for free is simple enough to compete with cell
phone services or a twisted pair, there will be a problem.

Chart of HDTV freqs?
 

Jeff Liebermann wrote:

...
Unfortunately, you're correct. I have considerable experience dealing
with various path impairment issues using various wireless
technologies, especially Wi-Fi. User will complain that they loose
connectivity, drop connections, suffer from erratic performance, and
generally see performance well below what would normally be expected.
The sources are many and varied. They're also very difficult to
identify. Quite a bit can be deduced with simple diagnostics (i.e.
ping stability, MAC layer packet loss, retransmissions) and from
determining the pattern (does it always die during meal times), but in
general, it's way beyond the capabilities of Joe Sixpack. I expect
much of the same with digital TV.

However, I'm not worried much about the RF issues. It will either
work or the customer can get cable or satellite TV. What I'm worried
about are all the added cables and incompatible technologies found on
the back of the HDTV sets and boxes. Another tangle of wires to deal
with.

Anyway, radio is magic. Maybe I should get one of those Halloween
pointed sorcerers hats with the stars and crescents.
http://en.wikipedia.org/wiki/Image:MGM_sorcererhat.jpg


Yep, only buy wireless routers/switches here which allow connection to
"off board" antennas ... (i.e., external antennas)

IMHO, and humble experience, reflections only worsen with a raise in
frequency ... others mileage may vary ... and EVERYTHING you own, which
is metal/conductive, is a wavelength+ at Ghz!

Regards,
JS