nope .. its the second
first is/was mchf (and now its cloned from china)
i brought david and our programming group together ... rest is
history :-)
the guy with the laptop on very right is me ;-)
i have often used freedv with pc on shortwave and i have found
out that the freedv hardware solution .. smartmic .. sm1000 .. has
an stm32 chip and the mchf also has that stm32 inside ... then i
brought david rove in contact of our user group
dg9bfc sigi
Am 27.03.2023 um 01:35 schrieb Ashhar
Farhan:
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The digital voice mode that could possibly replace
ssb is freedv. It is actually two things that work together.
First, the voice is converted into a stream of
very few bits per second. A usual voice stream like that of
telephone uses about 64,000 bits per second. Freedv codec
reduces it to 700 bits per second. This is at the cost of
reduced quality. However, it is much better that SSB on 80
meters.
The second thing is an HF modem that can work at
700 bits per second. This is a weird one. On HF as signals
bounce off the ionosphere and arrive at the rx antenna, you
can have a situation where the same signal can arrive taking
different paths and hence at different times , overlapping
itself. This reduces the number of times you can rapidly
change the frequency of the signal. This is why FT8 works so
well, it is so slow that fading, et al doesnt affect it. So,
what the freedv modem does is that it transmits a number of
parallel ft8 like signals as separate tones within the same
audio which when added up give you higher bandwidth. There is
a very impressive name for it that escapes me now.
Our plan is to add freedv into the sbitx, making
it the the first radio to support it natively.
- f
Gordon:
Either RadComm or Sprat had
an article how students in England were fascinated by
Morse code. When asked why, they replied that "voice"
(SSB) didn't interest them because they could do that
with their cell phone. But Morse was "better" because
their parents couldn't understand what was being said.
Any port in a storm...
Jack, W8TEE
Well, for several years now we have observed
some thing very fascinating among middle schoolers
in our local school.
They are not interested at all in
walkie-talkies
They are not interested at all in HF radios
Don¡¯t even get me thinking about digital.
What they absolutely go crazy over, what they
will grab onto and play with until you have to
pull them away kicking and screaming with their
parents,
Is a Morse code key!!!
At every school open house that we hold we
now always provide multiple Morse code keys and
it is a big draw.
We will provide them at this year¡®s field day
The news media always want a picture of
someone sending Morse code
We have two 6th graders in a very small
school that are already doing about 10 words per
minute. I sent 30 minutes worth of code to them
two weeks ago?
It is astonishing the attraction that Morse
code has for these middle schoolers
Meanwhile, across town, at the school devoted
to future police and fire high schoolers, they
have an extremely active contesting high school
I am radio club and I am told that their best
operator can do over 30 words per minute and
they routinely make hundreds and hundreds of
contacts at voice and CW in contests. ?
Our local ham radio club would have a hard
time beating them!!!!
So I wouldn¡¯t quite give up yet. ?human
nature is the same. And there are certain number
of us who really love the auditory and tactile
tickling that only Morse code gives¡. And by the
way it is the first digital, the only digital
that can be decoded by the human brain without
much else.? End it enjoys an order of magnitude
or two advantage over voice In terms of
threshold signal to noise ratio!!!?
On Mar 26, 2023, at
13:23, Dan Eggers N7DE <N7DE@...>
wrote:
?
Thank
you?for the
information.? I see you and I are both CW old
timers.? So far we have lost about half of the
CW people without any real replacements coming
along, but you and I came along during a
certain era.
Best wishes.? ? ? ?73,
Dan
Eventually there will be something that
replaces analog single side band voice. But it¡¯s
not yet here. ? And I think I have been doing CW
for 55 years or more. ?
That¡¯s my thought
Gordon Kx4z?
On Mar 26, 2023, at
11:51, Dan Eggers N7DE <N7DE@...>
wrote:
?
I have been
sending Morse code now for 57 years,
and I will just continue to send Morse
code, but since you seem to be very
knowledgeable is there a digital voice
modulation system that will eventually
replace SSB?
Thank you.? ? ?
? ? 73, Dan, N7DE?
Single side band typically requires a 10
DB signal to noise ratio for useful
communications in a disaster.? That is,
the efficient transfer of information
My contrast, using the same base
noise in that bandwidth, data
communications of moderate speed can
tolerate SNR into low single digits,
and still move efficient
communications far faster than voice
Low data rate redundant digital
communications can tolerate signal to
noise ratios a couple orders of
magnitude lower SNR
These comparisons are widely
available
It¡¯s no secret why people who are
very involved in the (voice) national
traffic system often have kilowatt
amplifiers. ?
And people who are into JS8 ?don¡¯t
need them
So there are different requirements
for different parts of our hobby
On Mar 26,
2023, at 11:33, Dan Eggers N7DE
<N7DE@...>
wrote:
?
I used
20 watts for a long time, and
I have had a number of people
refuse to talk to me, because
my signal was too week, so
more power is needed.? I have
written a booklet about solar
cells, and maybe you use solar
cells and power conversion,
and that is also a very
interesting area, but I also
want to be able to talk to
people.
? ? ?
73, Dan, N7DE? ?
With respect, Dan, "need"
isn't an actionable or useful
concept, especially in QRP land.
I live on a sailboat and am
currently in Tampa Bay. With a
couple of meters of tinn
On Sat, Mar 25, 2023 at 01:55
PM, Dan Eggers N7DE wrote:
20
w is -7 dB, and that is
too far down.? it is
getting close to -10 dB
down.? You need to be at
50 w, and that is only -3
dB down.? What I have used
for low cost has been an
MRF455 in an EB63A board
from Communications
Concepts, and it works
very well.
?
However,
the Chinese are selling a
100-w amplifier with a
heatsink that has had the
level set, and they also
sell a lowpass filter
board XDT LPF200 for 3 -
30 MHz at a reasonable
price that works very
well, so these days there
really isn't any reason to
"build your own"
amplifier.?
?
The
main thing I am saying is
that you need more power
so that you can be heard.?
I went through enough
Electrical Engineering
courses that I am now an
Electrical Engineer, but I
do not think I am going to
try design amplifiers from
scratch myself.
?
I
am very grateful for all
of the people who helped
produce the UBITX 6,
because I think that has
been the only low cost
real general coverage
transceiver that is out
there.? ? ? ? ? ? ?73,
Dan, N7DE
?
Hi Ted
Thanks. Incidentally the FET
is? IRFP150? And Not IRF150
, sorry for the typo.
I will edit at the end of
the video..
The FET i have used is
Harris IRFP 150
It works great with not much
heat at 35 V .
Regards
Sunil vu3sua
--
Jack, W8TEE
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