If the SNR is negative, how is it that you can copy any signal?
73,
Mark N5RFX
At 02:36 AM 8/21/2008, Tony wrote:
__
Sensitivity Test - Direct Path
(no ionospheric disturbance)
Minimum SNR for error-free copy
Contestia 500/32-15db
At 04:31 PM 8/21/2008, Tony wrote:
The path simulator adds Gaussian white noise to the input signal to simulate
a signal-to-noise ratio through a 3KHz band pass filter. If the SNR is less
than 0, it's below the noise level.
Tony, thanks the bandwidth is 3K for all modes that is what was
At 04:19 PM 6/27/2008, Mel wrote:
Regarding the previous post's mention of re-calibrating the sound card,
how is this done ?
There is a program in C:\Program Files\MixW called CheckSR.exe
. This program will help you calibrate your sound card. First run
your test with a sample rate of
At 12:53 PM 6/5/2008, Rick W. wrote:
Paul Rinaldo, ARRL CTO, has gone on record as claiming Hell modes to be
J2D when being transmitted from an SSB transmitter as most of us do.
Looking at the ITU Emission Classifications, it seems to me that J2C
would be more appropriate.
You are correct.
At 08:49 AM 5/14/2008, kh6ty wrote:
The problem with MFSK16, as you found, is the mistuning tolerance.
For messaging, when there is a fast series of ARQ exchanges, if one
station has uncompensated offset between RX and TX (NBEMS must work
with untrained and inexperienced operators to be
At 08:47 PM 5/7/2008, expeditionradio wrote:
In FCC's official consideration statements, FCC
specifically supports no finite limit of bandwidth for
digital data emissions for the amateur radio service.
FCC instead prefers to rely upon existing rules, and to
encourage amateur radio operators to
At 08:36 PM 3/28/2008, you wrote:
Why do I find so so many RTTY signals up side down
on the ham bands.
I think it is because many of the sound card programs give you mark
high and space low when the rig is using USB. A newbie asks which
sideband to use and someone invariably says LSB.
At 11:28 AM 12/28/2007, you wrote:
Hi Mark,
How would this kill various digital modes with a bandwidth of 1500 hertz
or less? I operate Oliva mostly at 500 hertz wide and sometimes and
1000 hertz wide.
73, tom n4zpt
If a mode's bandwidth is 1500 Hz or less, then there would be no
change in
Forwarded with the permission of G3PLX
Subject: Your excellent petition
Date: Wed, 26 Dec 2007 20:37:30 -
X-Mailer: Microsoft Outlook Express 6.00.2900.3138
Mark:
I hope I have the right email address
This is just a note to offer my congratulations and express my
admiration for the
Hey, I thought I was the only guy who labels his socks by day. :-)
This petition, if adopted, will be a huge step towards advancement of
the digital modes on the amateur bands, and a clean-up of non-amateur
modes and practices that threaten our bands.
Roger,
I had my wife take a look at that
The FCC has released
http://fjallfoss.fcc.gov/prod/ecfs/retrieve.cgi?native_or_pdf=pdfid_document=6519820340
Public Notice report 2828-Correction establishing a new comment
period for
http://fjallfoss.fcc.gov/prod/ecfs/retrieve.cgi?native_or_pdf=pdfid_document=6519008574
RM-11392.
RM11392
At 06:27 AM 12/11/2007, cesco12342000 wrote:
Here is my XYL after encoding with MELP and FDMDV
Are you trying to discredit the program by posting worst-case examples ?
No. Are you trying to embellish the program by only posting
best-case examples?
73,
Mark N5RFX
Can you measure the crest factor in function of ALC button ?
Yes the crest factor fell to 11 dB.
73,
Mark N5RFX
My own audio sounds quite similar, but i have heard some stations
with excellent audio on this codec. I think we should move the mic
further away and use a pop and hiss filter, or move the mic sideways.
Would be intresting to have original and coded audio to compare.
Here is my XYL after
Personally I feel the words high quality may overstate it.
Traditionally there has been a trade-off between bandwidth and
quality, the less bandwidth the worse the quality.
But it's free and costs nothing to try so I'm downloading my copy
and if it comes anywhere close to the quality of a 2.4
At 05:29 AM 7/1/2007, Roger J. Buffington wrote:
Not 28070?
Nope 28.120. There is a PropNET PSK31 beacon on 28.131 . Back
during the last peak of the sunspot cycle 28.131 was a hotbed of MT63 activity.
73,
Mark N5RFX
At 09:14 PM 6/30/2007, Andrew O'Brien wrote:
Anyone hear running Xastir ?
Andy K3UK
Yes version 1.9.1. N5RFX-8 is an IGATE connected to a Tracker 2
(N5RFX-6) in Kiss Mode. I have been thinking about switching to
DIGI_NED so that I can bring in a 9600 baud 440 MHz APRS channel.
73,
Mark
I will be operating Field Day as N5RFX between Comanche and Rising
Star Texas. At the top of the hour I will call for NTS traffic on
14.109.5 (dial frequency). You can send your field day section
manager report to this field day station. I will calling for
traffic in MT63/MFSK and Olivia
I will be operating Field Day as N5RFX between Comanche and Rising
Star Texas. At the top of the hour I will call for NTS traffic on
14.109.5 (dial frequency). You can send your field day section
manager report to this field day station. I will calling for
traffic in MT63/MFSK and Olivia
440 MHz has had a authorized bandwidth of 100 kHz for nearly 20
years. The repeaters and other operations there seem to work just
fine. Just because the authorized bandwidth is 100 KHz doesn't mean
that the whole band will be filled with 100 Khz signals.
73,
Mark N5RFX
WALT ... THINK
Bruce,
I will work it out when 6 is OPEN world wide and not interfere
with repeaters on 2 meters because I will continue to follow the
clause that says no amateur operator shall willfully or maliciously
interfere with or cause interference to any radio communication or
signal . How does
The ARRL has no clue . and do not care .
I respect your opinion.
When open 6 meters is packed solid from 50.105 to 50.5
with ssb there are AM users on 50.400 and PSK-31
between 50.5 and 50.7 RIGHT NOW the band is closed but
it will not be in 2 to 3 years the only open spot is
between
I think this is true in the part 90 world, but not in part 97. There
really is no FCC mandate with respect to the ARS for spectral efficiency.
73,
Mark N5RFX
In a time period shorter than most of us realize, most of the VHF and
UHF bands will be all digital. The FCC is moving all other users
Bruce,
We have had PSK and RTTY and APRS users for DECADES
and because they take up similar space they do not
cause a problem AND they have place themselves AWAY
from most other users .
This is what bandplanning, gentlemen's agreements, and cooperation
give us. Your example shows how a 32
The root cause of the complaints can be traced to the way that Pactor
III was introduced to the amateur bands. Most hams today consider
the appropriate bandwidth of a signal in the RTTY/Data subbands to be
500 Hz. Wider bandwidth modes have been tolerated, but they
typically are limited to
Rick,
This is certainly lost on the Pactor III group.
73,
Mark N5RFX
having many small bandwidth users means more throughput for more
users than one large bandwidth user at a time.
Dave,
You can use a sound card program like MTTY or MixW which lets you set
up the com port on a PC for FSK to your rig. Here is one way
http://www.aa5au.com/rttyinterface.html
The best way in my opinion is to use an opto-isolator something like
this http://www.qsl.net/k0bx/soundcard.htm
You
Maybe they should have tried this approach instead of petitioning the FCC.
73,
Mark N5RFX
At 09:24 AM 12/15/2006, you wrote:
Only from the League's lawyer, silly. That's as good as it gets.
Anyway, does anyone really want a response directly from the FCC, for Cat's
sake?!
Not I, dear sir.
Walt,
I think there is no doubt that this is true. The question I have
been struggling with is how much is enough/too much. I guess what I
am looking for is a curve showing bandwidth vs. throughput for
parallel tone modems, or maybe more precisely where is the point of
diminishing returns?
Rick,
I have been working on such a plan. This plan keeps things organized
the way they are now, but adds the multimedia playground 25kHz below
the top of each band. Let me go through a summary, then you can look
at the chart, and comment.
160 meters, no change from what it is now.
80
ERRATUM
Released: November 27, 2006
By the Chief, Mobility Division, Wireless Telecommunications Bureau:
1
Federal Communications Commission DA 06- 2379
2
1. On October 10, 2006, the Commission
released a Report and Order (FCC 06- 149)
in the above-
I think you are correct. Text emissions have some sort of code which
indicates the character to be transmitted. Such codes are Morse,
Baudot, ASCII, and Varicode to name a few. Digital facsimile is
pixilated and the pixel's intensity is represented numerically as in
bitmap images. Pixels
I disagree. You can send images as long as the bandwidth is 500 Hz
or less. That is what J2C is all about. A transmission can have
more than one emissions designator as you have pointed out. You may
start by sending J2B, then during the course of the QSO switch to J2C
without ever changing
Roger,
I will let Bonnie respond, but let me add my 2 cents. Paragraphs 15
through 19 address the rule changes which allow image
emissions. Paragraph 19 has most of us confused because while it
says we will revise our rules to clarify that the 500 Hz limitation
applies only to the emission
Jim,
Yes, MT3 at 500Hz bandwidth may have an occupied bandwidth greater
than 500 Hz. My spectrum analyzer has a hard time with bandwidths
less than 500 Hz. I used to not have that problem with it, but I
have changed something. I will have to check. I went through the
resolution bandwidth
Joe,
I think your interpretation is correct, but there is much
misinformation about this, mainly from
http://www.arrl.org/news/stories/2006/11/15/100/?nc=1 .
73,
Mark N5RFX
My interpretation, which is as good as any at this point, is that
telegraphy is plain text to be read and interpreted
Yes you are correct about regulation by emission designators. The
question really is when is the third symbol of the emissions
designator a D? 97.3(c)(2) says that data is Telemetry, telecommand
and computer communications. The third symbol of an emissions
designator identifies the content
First to the list, I am sorry about the fonts and
alignment of that post. I am not sure what happened.
Rick,
You notice where the J2D should be emissions A1C, F2C, J2C and J3C having an
occupied bandwidth of 500 Hz or less, and
J2D. NOT emissions A1C, F2C, J2C, J3C, and
emissions A1C, F2C,
I received a response from the FCC this morning about the J2D
issue. The response was simply its on the list. This means that
they know there is an issue.
73,
Mark N5RFX
Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org
Other areas of interest:
The MixW Reflector :
We have to be pragmatic if we want to get this done. The fact is
that bringing digital text emissions to the phone/image subbands on
HF is not a popular proposal. We have to think of ways to make this
palatable to the majority of Amateur Radio Operators. If there were
some verbiage that we
Walt,
Your examples are with like bandwidths. These channels were
assigned for the purpose that you have mentioned, so any reduction in
bandwidth would not provide any increase in efficiency. In other
words you would still occupy the entire channel. With Amateur Radio
this is not the case. We
You guys are going to have to do the math for me. I do understand
that faster throughputs mean that I will be occupying a certain amount of
spectrum for a shorter period of time, but the cost is bandwidth.
Unless the increase in throughput is greater than the increase in
bandwidth, I don't
If the protocol can send the info faster than I can type, then I
think it does make a difference.
73,
Mark N5RFX
I don't think keyboard to keyboard has anything to do with it.
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The MixW Reflector :
After some off the list discussion, I retract the statement
below. For an emission to be J2B it must be narrowband direct
printing telegraphy. Narrowband is the key word and has been defined
for us as 500Hz. The remaining question is did the FCC intend to
include J2D in the list of 500Hz
Below 30 MHz it would be a very popular step, but I agree that this
most likely was not the intention of the FCC.
73,
Mark N5RFX
It would be a huge step backward for the Amateur Radio Service in USA
if FCC were to limit Data transmissions to less than 500Hz bandwidth
Need a Digital mode
Rick,
The text in the RO indicates that the 500Hz maximum occupied
bandwidth only applies to the new emissions designators added to the
definition of data. and the affected bands are below 30 MHz. This
is what I asked for in my petition. However, the FCC did put J2D in
the list of 500Hz
Rick,
All of the modes that claim to be J2D are really J2B when sending
text. When sending images they would be J2C and fall under the 500
Hz maximum occupied bandwidth limit.
73,
Mark N5RFX
OK, Mark, then it does look like we are not going to be able to use the
wider modes in the
The answers to these questions about what is an image is simple in one
respect. The current FCC rules allow digital emissions throughout
the 160 through 10 meter bands. This is true because emissions that
have a 1 or a 2 as the second symbol of the emissions designator are
allowed everywhere.
This should read Data emissions in the Phone/Image bands.
73,
N5RFX
At 10:46 AM 10/15/2006, N5RFXwrote:
Allowing Data emissions in the RTTY/Phone bands.
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Other areas of interest:
The MixW Reflector :
Bill,
Part 2 of the FCC rules section 2.1 has definitions. Look at the link below.
http://frwebgate.access.gpo.gov/cgi-bin/get-cfr.cgi?TITLE=47PART=2SECTION=1YEAR=2000TYPE=TEXT
I was not quoting; thus the absence of quotation marks, but you can
see the definitions of Telegraphy and Facsimile
I agree, and the FCC is accepting petitions.
73,
Mark N5RFX
But I really do believe that we need to be able to move data on the
phone frequencies.
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Other areas of interest:
The MixW Reflector :
I'm not so sure of that. As I understand it, D means telemetry or
telecommand.
D - Data transmission, telemetry, telecommand
No I am not out to banish Pactor III, but I am wondering why the FCC
included J2D in the list of 500Hz maximum occupied bandwidth modes.
73,
Mark N5RFX
Need a
Is your soundcard new too? You probably have a soundcard with
drivers that don't quite have the same sampling rate for tx and
rx. The way I handle this with MixW is I generate a tone and measure
it on a frequency counter. I adjust the TX sampling rate until the
frequency is correct. For
The OTHER GUY makes sure that he transmits Mark on the higher RF
frequency and Space of the lower RF frequency with a 170 Hz
shift. You do not care whether he does this on USB or LSB. At your
end YOUR equipment requires 2125 and 2295 for Mark and Space
respectively, it is YOUR
The EU example is different from what we have been discussing. The
EU stations are transmitting Mark as the lower RF frequency. We have
been talking about transmitting the Mark as the upper RF frequency
and using USB. This is what MixW allows. If it was possible with
the older equipment, I
Your ST-6 has no idea what RF frequencies the Mark and Space
at. You tune until you get 2125 for Mark, then if the shift is
170Hz you will be looking for 2295 for Space. If the Mark is sent
with a high RF frequency with respect to the Space, then you need to
be on LSB. We have discussed
Rick,
That could be, but remember that the shift was 850 Hz. You had to
choose frequencies within the passband of the receiver audio, and
make sure that harmonics were outside of the passband. 2125 was
chosen as the Mark audio frequency. The second harmonic of 2125 is
well outside the
Rick,
I wasn't around back then but from what I have read, the standard for
RTTY was set that the Mark was the high RF frequency and the Space
the low RF frequency. To avoid problems with audio harmonics and the
fact that some rigs could not handle 2975, LSB had to be used. Most
Here are a couple of interesting RTTY History articles.
http://www.rtty.com/history/w6owp.htm
http://www.hertzmail.com/rtty/ttyinfo1.pdf
73,
Mark N5RFX
Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org
Other areas of interest:
The MixW Reflector :
Yep, it is probably one of those things that was set in concrete and
never changed. But it really doesn't matter how you want to do it as
long as Mark is the higher RF frequency, since that is the frequency
you give as your operating frequency for RTTY. Now programs like
MixW allow you to
The reason that LSB historically has been used for RTTY was that the
equipment in the early days had difficulty dealing with FSK. On the
demodulator side you had to choose frequencies that would not
produce harmonics to fool the demodulator. Back then the frequency
shift was 850Hz, and it
Jim,
I agree, but we are talking about a test. The test signal would have to
have a signal that either sweeps or is shifted in frequency. This would be
a test like a two tone test. A two tone test is not a real world test, but
it is made with very specific signals and the results are well
I agree and this concern has been considered in this thread. The modem
used in the MIL STD 188-110 MARS ALE implementation was modified to
accommodate amateur rigs. With the exception of SDR radios, COTS radios
will typically have a 2.4 to 2.7 KHz transmit bandwidth. I agree that if
these
WinDRM - HF Digital Radio Mondiale
http://n1su.com/windrm/ WinDRM is a digital mode on HF that lets you do
digital voice, image and data. You can transfer data at almost 1KB/s
without using proprietary hardware!
SDR1000 http://www.flex-radio.com/ is a product of FlexRadio Systems and is
Jose,
I think you are correct. SDR allows you to make the radio for whatever
type of modulation/protocol you want to send. As you say, if that
modulation/protocol changes, just change the firmware. I think that this
will be the next homebrew revolution. FPGA's are getting very cheap and
Rick,
Yes group delay is an issue, but with adaptive training this too can be
overcome. Sound cards, or external modems using DSP or preferably FPGA's
would be a fine compliment to most amateur gear. The SDR (software defined
radio) that Jose mentioned will be the best solution going forward
I guess my point is, do you know what your passband is in your
radio. Are the 3 db points really at 300 and 2700 Hz? Are there
any fluctuations at other frequencies in the passband? What about
phase variances throughout the passband?
I have made measurements on my IC-746. I set the RX filter to
Can you or anyone explain why they need this high speed on HF when even
300 baud is pushing the limit on the higher HF bands?
I think this limit only applies to protocols that do not make use of FEC,
redundancy and
adaptive training. Adaptive training may be the most important element.
73,
MIL-STD 188-141 http://tracebase.nmsu.edu/hf/standards/MIL/141Bn1.pdf .
MIL-STD 188-110 http://tracebase.nmsu.edu/hf/standards/MIL/188-110B.pdf
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The MixW Reflector :
I am looking for a Baycom Modem. If anyone has one they would like to part
with please email me.
[EMAIL PROTECTED]
73,
Mark N5RFX
Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org
Other areas of interest:
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My measurements on 10 Mhz show that MT63 has 20% less errors than PSK63 on
the same channel.
The is not enough to offset the negative points.
Very interesting. It would seem that MT63 would better remain a broadcast
mode like Amtor Mode B or PACTOR FEC.
73,
Mark N5RFX
Need a Digital
Steve,
Is there adaptive equalization used in the PCALE or
MARSALE implementation of 188-110A or B?
73,
Mark N5RFX
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DigiPol:
This is needed,
absolutely mandatory, to mitigate the fading multipath HF channel.
Bob,
Thanks. I have not had a opportunity to send images with 188-110, but
after reading the specification, I thought adaptive equalization would be
necessary. I look forward to sending images. I have
After reading the spec at
http://tracebase.nmsu.edu/hf/standards/MIL/188-110B.pdf I see from a high
level how the fixed frequency modem works. Table XIX in the document gives
a great summary. I have taken a snapshot of that table an posted it at
This standard may be found at
http://tracebase.nmsu.edu/hf/standards/MIL/141Bn1.pdf .
The single frequency modem is 8FSK running at 125 baud, 3 bits per symbol,
375 bits per second.
A word is 24 bits. 3 bits are preamble, 21 bits are 7 bit characters.
Each 24 bit word is encoded into a Golay
I went searching in my archives for some testing that was done in May of
2002 with Packet on HF using different Baud Rates and shifts. MixW has the
capability of setting custom Baud Rates and Frequency shifts. Looking
through my notes I noticed that we started with 100 Baud and a 60 Hz
shift.
In the limited testing I've tried with image files, it works very
well, indeed. Perhaps we can try exchanging some images next time we
link.
Bonnie,
Great. Yes I have had some QRN here and the QSB has been a problem too.,
and none of the 8FKS signals I have seen have been super strong.
To be honest, using a high speed baud rate modem on HF and then encoding
it to
slow down the effective bps, seems the exact opposite of what is
normally done
with slower baud rate and higher order modulation to get the higher
throughput.
Rick,
The actual BPS rate for 188-110B is 7200,
There is no equipment for the emission
to be FSK or PSK.
This should read there is no requirement for the emission to be FSK or PSK.
73,
Mark N5RFX
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The MixW Reflector :
So what would be the difference if I transmitted 64 tones/carriers each
modulated at 300 baud but transmitted them through one transmitter or 64
tones/carriers through 64 transmitters into one antenna?
Walt,
From a regulatory standpoint I don't think there is a problem. I think
that Pawel
I wasn't picking on Pawel at all...I just used MT63 as an example.
Walt,
I understand. My diatribe was to make the point that the occupied bandwidth
has a bearing on the general acceptance of a mode.
73,
Mark N5RFX
Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org
The 2400 and 4800 baud is a composite baud rate for the mode/protocol NOT
the discrete baud rate of any individual component of the waveform.
Can you explain further? I saw that:
MIL-STD-188-110A serial tone modem is just that, a single PSK carrier
frequency that by the standard is locked
If I gave you some parameters of a waveform, what would you use to base
your measurement of baud rate?
I would look at the data, and see how it is modulated into an analog
waveform. For FSK we know that a 1 produces one symbol, and a 0 another
symbol. MFSK16 the symbols represent
0001
Bonnie,
I will give it a shot if we can get a link between us. I can start
scanning the 20 meter channels.
73,
Mark N5RFX
At 07:25 PM 9/1/2006, you wrote:
On HF, I have used the fast PSK modem built into PCALE for sending JPG
and GIF image files in the 20 meter phone band. FS-1052 / MIL STD
I'm not a lawyer either, Walt, but the 300 baud symbol rate
limitation from ยง97.305(c)(3) below applies to a RTTY or data
emission, not the individual components of that emission IMHO.
I am not a lawyer either, but since the Walsh FEC code is 64 bits, the
character rate is the same as the
A-63 is legal on the ham bands, since each tone runs at 10 or 20
baud depending upon the commonly used versions of this mode, but has 64
tones, it would seem that it is running well over 300 baud when you
consider the entire waveform.
The entire waveform is one symbol. There are 10 symbols per
Bonnie,
Thanks. I found the definions for the
AMD automatic message display
DBM data block message
DTM data text message
It is interesting that you say that we were using 8FSK, I have observed the
eight orthogonal tones on my waterfall before, and didn't know exactly what
was producing them.
At this time I am not sure what G4GUO is
planning for PC-ALE in this regard. However under current FCC Part 97
Rules, ALE can be used in the digital sub bands for two-way digital
data comm and in the Voice sub bands for SELCAL (and more but not
digital data comm) and of course Digital Voice
for not using a 386 computer for the card. But at
that time the 386 was barely even invented and 286 machines were state
of the art.
73,
Rick, KV9U
Mark Miller wrote:
At 10:33 PM 8/23/2006, you wrote:
I am not very knowledgeable on CRF (Crest Factors). Can you give us an
idea of converting
If I were a company technology officer, of a company who's purpose was
developing communications technology...or the technology officer for
amateur radio, I would be very dis-heartened at the data
protocols/modes/modems produces as well as the HF E-Mail applications
developed. None are really
At 04:29 PM 8/23/2006, you wrote:
It in deed would. That is the reason Pactor and Amtor
work so well. It's the AQR - even with the hi S/N needed.
There is some value to ARQ, I wonder how we would quantify the
advantage? In a point to point link I think it would be easy, but in a
point to
Note also in Figure 6, the real world test by using distance on 80
meters daytime. The worst performance was by Amtor, followed by Pactor 1
and closely by PSK31. The best performer was RTTY at these slow speeds
and he gives his explanation as why he believes this occurs. It sounds
reasonable to
At 10:33 PM 8/23/2006, you wrote:
I am not very knowledgeable on CRF (Crest Factors). Can you give us an
idea of converting peak power/average power into CRF?
Using powers, crest factor = Peak Instantaneous Power / Average Power. A
more piratical way of measuring crest factor is (PEP/Average
I am looking for sound card digital mode software that will allow data to
be entered via the serial port for transmitting, and for receive data to be
brought out of a serial port. I would imagine these would be Linux
applications. My purpose in doing this is to do some BER measurements
.
At 09:55 PM 7/28/2006, KV9U wrote:
A low cost scanner
could be used to scan the image and then convert to bmp file format.
Any suggestions on whether this is feasible?
Scanning the image sounds like a good idea. The image could be converted
from .bmp to .jp2 and sent using HamPal or DigTRX.
Apparently the basic fax mode is only half duplex. The circuit I saw was a
basic
hybrid to separate the two wire telephone line into send/receive and to
sense when the local fax was sending to trigger the radio (VOX)
There is a good discussion of facsimile theory at
Are you able to put your hands on the info by chance?
HAL has a system that allows fax over radio:
http://www.halcomm.com/docs/fax4100.pdf
73,
Mark N5RFX
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The MixW Reflector :
The individual wanting to do this, is primarily interested in running two
bands (e.g., 2 meters/440) with full duplex.
Well if it was absolutely necessary to use telephone fax machines, then at
the originating end you would need a device that supplies -48 volts to the
fax machine telephone
At 06:05 PM 6/8/2006, you wrote:
It would be of no use to the US hams as we are limited to 5KHz on 2 meters.
Joe Ivey
W4JSI
Not true. For 2 meters 97.307 (f) (5) applies:
A RTTY, data or multiplexed emission using a specified digital code listed
in
Keep in mind there is no regulatory baud rate limit for digital voice or
digital SSTV. Any emission designators with a second symbol of 1 or 2, and
a third symbol of E or C are considered Phone/Image respectively. There
are no baud limits for these emissions. The baud limits are for emission
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