Anyone operating HF digital telephony?
 

I am interested in this mode of operation, but don't know anything about it
on amateur radio, such as where do folks hang out on this mode? Is one band
preferred over another? How is low power operation using this mode? And just
about any other questions concerning this mode. TIA

Ed, NM2K

Anyone operating HF digital telephony?
 

If you mean "digital voice", I have heard some on and around 14.235 - 14.236
There are a few programs around that will decode it. It requires a very
clean signal, but when it gets it, it sounds crystal clear! There are some
other bands that people play on, but that should get you started.
kk5h
"Ed Cregger" wrote in message
...
I am interested in this mode of operation, but don't know anything about it
on amateur radio, such as where do folks hang out on this mode? Is one band
preferred over another? How is low power operation using this mode? And
just about any other questions concerning this mode. TIA

Ed, NM2K

Anyone operating HF digital telephony?
 

"robo tech" wrote in message
news:mGtmk.286981$yE1.241550@attbi_s21...
If you mean "digital voice", I have heard some on and around 14.235 -
14.236 There are a few programs around that will decode it. It requires a
very clean signal, but when it gets it, it sounds crystal clear! There
are some other bands that people play on, but that should get you started.
kk5h

-------------

Thanks. I've give 14.235 a gander.

I was hoping that it wouldn't take a really terrific signal to decode. I'm
still hopeful, but the added overhead of a digital encryption scheme just
about guarantees either the need for more bandwidth for the same quality as
the analog signal, or a degradation of the analog signal while at the same
bandwidth.

I have both the box and the programs. Now to find someone to play with. G

Ed, NM2K

Anyone operating HF digital telephony?
 

Ed Cregger wrote:
"robo tech" wrote in message
news:mGtmk.286981$yE1.241550@attbi_s21...
If you mean "digital voice", I have heard some on and around 14.235 -
14.236 There are a few programs around that will decode it. It requires a
very clean signal, but when it gets it, it sounds crystal clear! There
are some other bands that people play on, but that should get you started.
kk5h

-------------

Thanks. I've give 14.235 a gander.

I was hoping that it wouldn't take a really terrific signal to decode. I'm
still hopeful, but the added overhead of a digital encryption scheme just
about guarantees either the need for more bandwidth for the same quality as
the analog signal, or a degradation of the analog signal while at the same
bandwidth.

In addition, I believe you have to be listening at the start of a
transmission for the signal to be heard. HF digital won't be the sort of
thing that we randomly tune across a band listening for a CQ. I suspect
for it to catch on, HF will almost need to be channelized. That won't
get rid of the strong signal issue. I'm not really sure of the
advantages of Digital HF over analog, unless it is a simple "Digital is
always better" thing.

A similar situation exists in digital SSTV. The mode can send pictures
of just about any size, but if the receiving transceiver doesn't get the
signal right, it prompts the transmitter to retry. Sometimes the message
just doesn't get through because of noise, QRM, etc.

It's enough of a problem that many suggest not even trying it unless you
are running serious power.


- 73 de Mike N3LI -

Anyone operating HF digital telephony?
 

"Michael Coslo" wrote in message
...
Ed Cregger wrote:
"robo tech" wrote in message
news:mGtmk.286981$yE1.241550@attbi_s21...
If you mean "digital voice", I have heard some on and around 14.235 -
14.236 There are a few programs around that will decode it. It requires
a very clean signal, but when it gets it, it sounds crystal clear!
There are some other bands that people play on, but that should get you
started.
kk5h

-------------

Thanks. I've give 14.235 a gander.

I was hoping that it wouldn't take a really terrific signal to decode.
I'm still hopeful, but the added overhead of a digital encryption scheme
just about guarantees either the need for more bandwidth for the same
quality as the analog signal, or a degradation of the analog signal while
at the same bandwidth.

In addition, I believe you have to be listening at the start of a
transmission for the signal to be heard. HF digital won't be the sort of
thing that we randomly tune across a band listening for a CQ. I suspect
for it to catch on, HF will almost need to be channelized. That won't get
rid of the strong signal issue. I'm not really sure of the advantages of
Digital HF over analog, unless it is a simple "Digital is always better"
thing.

A similar situation exists in digital SSTV. The mode can send pictures of
just about any size, but if the receiving transceiver doesn't get the
signal right, it prompts the transmitter to retry. Sometimes the message
just doesn't get through because of noise, QRM, etc.

It's enough of a problem that many suggest not even trying it unless you
are running serious power.


- 73 de Mike N3LI -

-------------

Well, I have a kilowatt to try and use digital phone with a low inverted
vee.

If I understand it correctly, HF digital is using FEC (Forward Error
Correction), which would contribute to the characteristics that you are
describing. It's been a while since I messed with Amtor/Pactor and other
digital modes. I'm sure some of it will come back in time.

Maybe I'll give it a shot with the commercial box I have and then sell it if
I'm not pleased with it. Selling is something that I do quite often anyway.
I like to try lots of modes, like many other hams.

Ed, NM2K

Anyone operating HF digital telephony?
 

I remember 14.235MHz being used for slow scan television. I don't know if
this has changed over the years.

Pete

"robo tech" wrote in message
news:mGtmk.286981$yE1.241550@attbi_s21...
If you mean "digital voice", I have heard some on and around 14.235 -
14.236 There are a few programs around that will decode it. It requires a
very clean signal, but when it gets it, it sounds crystal clear! There
are some other bands that people play on, but that should get you started.
kk5h
"Ed Cregger" wrote in message
...
I am interested in this mode of operation, but don't know anything about
it on amateur radio, such as where do folks hang out on this mode? Is one
band preferred over another? How is low power operation using this mode?
And just about any other questions concerning this mode. TIA

Ed, NM2K

Anyone operating HF digital telephony?
 

"Pete KE9OA" wrote in message
. ..
I remember 14.235MHz being used for slow scan television. I don't know if
this has changed over the years.

Pete


The most common 20 meter frequences for sstv is now on 14.230 and 14.233.
Set the transmitter for this on usb and make contact on voice. The
transmitter will then be on the correct frequency for the audio frequencies
of sstv.