I assumed that people kept using FSK because paths to Europe can have 20-30 Hz
of Doppler spread.
73,
John
KD6OZH
- Original Message -
From: KH6TY
To: digitalradio@yahoogroups.com
Sent: Tuesday, March 09, 2010 19:08 UTC
Subject: Re: [digitalradio] Re: 1976 FCC - Delete all
The document that the author of ROS originally published, Introduction to ROS:
The Spread Spectrum, contains a good description of frequency-hopping
spread-spectrum (FHSS) techniques. Section 4 describes taking a 250 Hz wide
mode (MFSK16) and spreading it over 2 kHz by shifting the center
The HSMM working group never proposed the use of spread spectrum. It was
interested in getting the maximum data rate into limited bandwidths. SS does
the opposite of what the HSMM WG was interested in. It spreads limited amounts
of data over the maximum bandwidth.
The actual proposal was to
signal when
idling
A good portion of the FCC rules is almost cut and paste from ITU standards
which apply worldwide.
--
From: John B. Stephensen kd6...@comcast.net
Reply-To: digitalradio@yahoogroups.com
I had no doubt that it would once the document that the FCC requires was
published. Since European hams don't normally read FCC regulations, it might
be useful for the IARU or RSGB to publish an article about U.S. regulations
so this doesn't happen again.
73,
John
KD6OZH
- Original
There is a technical descrption at http://rosmodem.wordpress.com/. I doesn't
describe the start and stop tone sequences or completely describe the mapping
from the convolutional encoder to the 128 tones used for data. However, it's
more compete than some of the technical specifications on the
The problem is that the FCC regulations are overly complex and people need a
specialized engineering background to interpret some of them. 99% of the
licensees probably can't interpret every word in the regulations so they ask
for help in this forum when something is not clear.
73,
John
A new technical description was published so you should see what it describes
-- fixed start and stop sequences using 16 tones with convolutionally coded
data using 128 tones in between.
73,
John
KD6OZH
- Original Message -
From: Steinar Aanesland
To:
The FCC will say that it up to each licensee to check the legality by reading
the new technical specification. Unless someone shows that the spectrum doesn't
match the specification U.S.hams should feel safe using ROS.
73,
John
KD6OZH
- Original Message -
From: Dave Ackrill
Chapter 8 of the 2010 handbook has a short overview of spread-spectrum
techniques that could be applied to either analog or digital modulation. The
original signal cold be anything (BPSK, FSK, FM...) and is phase or frequency
modulated by a pseudorandom sequence in order to spread the signal
The FCC didn't do anything arbitrary or capricious. They read a specification
provided by the author of the software that stated that ROS is a
spread-spectrum mode. They then told the person asking for the FCC's opinion
that they should go by what the author wrote and not use ROS on HF.
The
A member of this group contacted the FCC, got a ruling, and published it here.
Just remember that you have no legal defense if the FCC decides to take action.
I keep replying to this stuff because some members of this group could led
others into losing their licenses.
73,
John
KD6OZH
-
] Consensus? Is ROS Legal in US?`
I see you have not idea waht is the meaning of Spread spectrum.
Spread spectrum reduce energy density.
--
De: John B. Stephensen kd6...@comcast.net
Para: digitalradio
to see
whether people comply.
73,
John
KD6OZH
- Original Message -
From: Dave Ackrill
To: digitalradio@yahoogroups.com
Sent: Wednesday, February 24, 2010 20:48 UTC
Subject: Re: [digitalradio] Re: Consensus? Is ROS Legal in US?`
John B. Stephensen wrote:
A member
A lawyer with an engineering degree would be the best person to interpret FCC
regulations. The ARRL has engineers and lawyers and deals with the FCC so they
are the best source of free advice in the U.S.
73,
John
KD6OZH
- Original Message -
From: Bob John
To:
CHIP64 is legal above 222 MHz -- they're assuming that the user will notice
that it's spread-spectrum and act accordingly.
73,
John
KD6OZH
- Original Message -
From: jose alberto nieto ros
To: digitalradio@yahoogroups.com
Sent: Wednesday, February 24, 2010 23:30 UTC
is legal because is not a SS modulation.
--
De: John B. Stephensen kd6...@comcast.net
Para: digitalradio@yahoogroups.com
Enviado: jue,25 febrero, 2010 00:47
Asunto: Re: [digitalradio] Is ROS Documentation
Commercial and military SS systems also use FSK so that not likely alleviate
the problem. The pseudorandom movement of the center frequency is the issue.
Since the object is to prevent intersymbol interference due to multipath
spread, one way around the legal issue is to transmit even symbols
Any petition should reduce regulation rather than increase its complexity by
continually adding loopholes. ROS is not the only mode that is currently
illegal -- there are single carrier PSK digital modes that U.S. amateurs can't
use because of the baud rate limit. U.S. regulations should be
The FCC only requires that a technical description be published:
Sec. 97.309 RTTY and data emission codes.
(a) Where authorized by Sec. Sec. 97.305(c) and 97.307(f) of the
part, an amateur station may transmit a RTTY or data emission using the
following specified digital codes:
(1)
Convolutional coding and Viterbi decoding may increase the occupied bandwidth
but they also decrease the amount of power required to communicate. In some
cases, like trellis-coded modulation, the bandwidth stays the same even though
the power required decreases by a factor of 2-4. Spread
These modes use interleaving and randomize data values by exclusive-ORing with
a pseudorandom binary sequence. The methods are used in most commerial products
and the FCC and NSA know how to monitor the signals.
The FCCs problem is that the military uses FHSS and DSSS to hide the existance
To: digitalradio@yahoogroups.com
Sent: Wednesday, February 24, 2010 03:37 UTC
Subject: Re: [digitalradio] Consensus? Is ROS Legal in US?`
On 02/23/2010 10:22 PM, John B. Stephensen wrote:
These modes use interleaving and randomize data values by
exclusive-ORing with a pseudorandom binary
In order for amateurs in the U.S. to use any RTTY/data mode other than Baudot,
ASCII or AMTOR over 2FSK they must be able to point to a published technical
specification for the potocol that shows that it is legal. It was condition
that we all agreed to when we were issued a license. When this
The 300 baud limit applies only to the HF RTTY/data segments. In the
phone/image segments below 29 MHz there s no baud rate limit but the bandwidth
is limited by the following parts of 97.307(f).
(1) No angle-modulated emission may have a modulation index greater
than 1 at the highest
Pactor was FSK with a 100% duty cycle (or peak to average power ratio - PAPR),
but Pactor-III is OFDM which has a PAPR similar to SSB and much less than SSB
with RF clipping so I don't see how its any worse than digital voice or SSTV.
Were the two stations in the automated segments fighting or
The attachments are a good illustration why the rules should be changed. Olivia
and ROS use a similar amount of spectrum so the FCC shouldn't be calling one
legal and the other illegal based on how they were generated.
73,
John
KD6OZH
- Original Message -
From: Tony
To:
The documentation states the data symbols modulates a carrier whose frequency
is psuedorandomly determined and ROS modulation scheme can be thought of as a
two-step process - data modulation and frequency hopping moduation.
Unfortunately, the FCC rules care about the modulation scheme rather
international treaties They are written to be quite broad in order to
permit experimentation. So long as the coding technique is public and
can be received by anyone, the real restriction is based on allowable
bandwidth and power allocated for a given frequency.
John B. Stephensen wrote
it legal in USA
--- In digitalradio@yahoogroups.com, John B. Stephensen kd6...@... wrote:
What ROS users should do is email their ARRL representative and have them
petition the FCC to change the rules. One solution is to eliminate the emission
designators and change the RTTY/data
The final ARRL petition didn't change the rules in 97.221 for automatic
stations:
APPENDIX A – AMENDED March 22, 2007
PROPOSED RULE CHANGES
Part 97 of Chapter I of Title 47 of the Code of Federal Regulation is proposed
to be amended as follows:
Section 97.3(a)(8) is amended to read as
ROS is MFSK16 with frequency hopping so it is SS per the FCC definition as the
bandwidth is expanded. However, the FCC never fined anyone during the period
when Hellscreiber was used illegally so I doubt that they would do so with ROS.
What ROS users should do is email their ARRL
I agree. Spread spectrum is illegal below 420 MHz in the U.S. and the ROS
documentation describes a spread-spectrum system. It's certainly no wider than
modes that use Walsh codes or low-rate convolutional codes but these systems
increase bandwidth by increasing redundancy and are therefore
Unfortunately, its illegal below 420 MHz in the U.S.
73
John
KD6OZH
- Original Message -
From: John Becker, WØJAB
To: digitalradio@yahoogroups.com
Sent: Friday, February 19, 2010 19:12 UTC
Subject: Re: [digitalradio] Re: ROS, legal in USA?
Ok what's the bottom
: [digitalradio] Re: ROS, legal in USA?
That's your opinion. It does not mean it's true.
--
De: John B. Stephensen kd6...@comcast. net
Para: digitalradio@ yahoogroups. com
Enviado: vie,19 febrero, 2010 20:19
.
--
De: John B. Stephensen kd6...@comcast.net
Para: digitalradio@yahoogroups.com
Enviado: vie,19 febrero, 2010 20:19
Asunto: Re: [digitalradio] Re: ROS, legal in USA?
Unfortunately, its illegal below 420 MHz in the U.S.
73
John
KD6OZH
- Original
The FCC specificly allows multiple-subcarrier transmissions on HF but bans
spead spectrum emissions using bandwidth-expansion modulation.
Multiple-subcarrier modes don't have to increase the bandwidth as the signal is
split into N parallel streams and each can occupy 1/N the bandwidth of the
Testing with a monster signal nearby will be interesting. The ADC in the SDR-IQ
digitizes several MHz at a time and then does filtering. The ADC in the sound
card digitizes only a few kHz from the TS-2000 audio. You'll see which has
better dynamic range.
73,
John
KD6OZH
- Original
The FCC could make part 97 more understandable if they adopted regulation by
bandwidth but that effort died. EZPal on 14.233-14.237 MHz is OK as there
are very few restrictions on image transmission.
73,
John
KD6OZH
- Original Message -
From: John
To: digitalradio@yahoogroups.com
I just reread it and it seems to be more restrictive than the current rules.
The current rules establish segments for automatic forwarding between
digital stations on all HF bands and these were eliminated below 28 MHz in
the ARRL proposal. The current rules allow for an automatic station that
enumerated in §97.221(b).
73,
Dave, AA6YQ
-Original Message-
From: digitalradio@yahoogroups.com [mailto:digitalra...@yahoogroups.com]on
Behalf Of John B. Stephensen
Sent: Friday, October 30, 2009 4:30 AM
To: digitalradio@yahoogroups.com
Subject: Re: [digitalradio
The baud rate limit applies but this means 300 symbol changes per second on
each subcarrier. The number of subcarriers and the number of bits per
subcarrier is not limited. The ARRL regulation by bandwidth proposal was a
better method than the current regulation by content rules but was opposed
quite
complex now
--- In digitalradio@yahoogroups.com, John B. Stephensen kd6...@... wrote:
The baud rate limit applies but this means 300 symbol changes per second on
each subcarrier. The number of subcarriers and the number of bits per
subcarrier is not limited. The ARRL
There is no bandwidth limit in the RTTY/data segments but there is a limit of
no wider than a communications-quality DSB phone signal using the same
modulation type in the phone/image segments from 160 to 1.25 meters. This is
interpreted as anything between 6 and 10 kHz by U.S. AM users but the
Hi Rud,
A DDS isn't enough. I'm still playing with an FPGA attached to an 80 Msps ADC
and DAC. I've been able to fit a soft CPU along with a quadrature DDS, filters,
I/Q modem, 256-point FFT, UART and other peripherals into a 100-pin FPGA. So
far, it works nicely for 1-30 MHz SSB and ISB
The FlexRadio products are driven from a sound card. This uses a low frequency
IF and quadrature mixing for image rejection. The HPSDR from TAPR converts
directly to and from RF using a high-speed DAC and ADC. At this point it
produces only a few milliwatts and needs an external power amlifier.
The FCC rules are antiquated. Sending anything other than voice or image is
illegal there if you use only one sideband. However, if you use both sidebands
(B7W, B8W or B9W), any content is legal.
73,
John
KD6OZH
- Original Message -
From: Rick W
To:
An FPGA is a good choice as they have advanced to the point where a 1 MHz wide
signal can be processed in a $10-20 device.
The number of points to use in the FFT is related to the multipath spread of
the received signal. HF signals with ionospheric propagation tyically have a
spread between 1
: [digitalradio] Re: Emision designators for EasyPal
--- In digitalradio@yahoogroups.com, John B. Stephensen [EMAIL PROTECTED]
wrote:
I was assuming that people use EasyPal in the phone/image portions
of the HF bands as it is marketed as an SSTV program.
73,
John
KD6OZH
EasyPal uses DRM so there are multiple subcarriers and its facsimile as it
displays an image on the screen so J2C seems appropriate. The FCC definition of
facsimile allows the image to be stored in a file before or after transmission
without affecting the emission designator. If it is used to
paperwork for them
than just responding to a request. Otherwise, you would think that they
would respond, as best they can, to avoid a petition. I would like to
see it decided one way or the other.
73,
Rick, KV9U
John B. Stephensen wrote:
EasyPal uses DRM so there are multiple
) the one you're using?
73,
- ps
John B. Stephensen wrote:
The ADC and DAC are certainly adequate for audio so it will work.
I've been interested in VHF and UHF high-speed modems so I have
a starter kit outfitted with a high-speed ADC and DAC that plug into J3.
So far I've
instruction. 3 or 4 would fit in an XC3S500E.
73,
John
KD6OZH
- Original Message -
From: Paul L Schmidt, K9PS
To: digitalradio@yahoogroups.com
Sent: Sunday, August 03, 2008 12:27 UTC
Subject: Re: [digitalradio] Has anyone looked into FPGA-based digital modes?
John B
FPGAs are useful for signal processing as you can do many operations in
parallel. FIR filter, FFT and CORDIC modules are available in the free
development software from Xilinx. They are very good for processing wideband
signals or digitizing an entire amateur band and then filtering the result.
Look for products marketed to businesses. HP loads XP on workstations like the
xw4400 but puts Vista on products for home use.
73,
John
KD6OZH
- Original Message -
From: wa0elm
To: digitalradio@yahoogroups.com
Sent: Monday, March 24, 2008 22:28 UTC
Subject: [digitalradio]
Has anyone here ever received a respose from the FCC to a legal question? They
might have a policy of not answering. There could be two problems. One would be
that it creates a body of unpublished information that makes prosecution of
offenders more difficult. The other could be that only
From what I've seen, it implements MIL-STD-188-110B appendix C which
operates at 2400 baud. It can be used in the HF phone/image segments for
digital voice and facsimile and above 50.1 MHz for any purpose.
73,
John
KD6OZH
- Original Message -
From: Andrew O'Brien [EMAIL PROTECTED]
I purchased a used 465 for about $1000 in 1992 and it worked fine for many
years until I purchased a new digtal storage 'scope. However, these were
introduced in the late 1970's so a lot depends on the condition of that
particular unit and a low price could indcate problems with the switches.
Since the filter coefficients are the impulse response, you should be able to
do a DFT of the coefficients to get the frequency response.
73,
John
KD6OZH
- Original Message -
From: Simon Brown
To: [EMAIL PROTECTED]
Cc: digitalradio@yahoogroups.com
Sent: Monday, January
party
program to prove my design, that's all :-)
Simon Brown, HB9DRV
- Original Message -
From: John B. Stephensen
Since the filter coefficients are the impulse response, you should be able
to do a DFT of the coefficients to get the frequency response.
:-)
Simon Brown, HB9DRV
- Original Message -
From: John B. Stephensen
Since the filter coefficients are the impulse response, you should be
able to do a DFT of the coefficients to get the frequency response.
The biggest problem with Pactor-3 in the U.S. is that it periodicly fuels a
desire to elimnate all digital modes with a similar bandwidth as the FCC would
never ban a specific product.
73,
John
KD6OZH
- Original Message -
From: Demetre SV1UY
To: digitalradio@yahoogroups.com
was supposed to advance the
art not mimic commercial art of decades past.
John B. Stephensen wrote:
The ARRL is publishing designs for simple phasing SSB exciters with 3-pole
filters and filter-type exciters with 4-pole crystal filters so we can't count
on DSP. Phasing transmitter kits
when open they have
enough. You will find little opposition.
Bruce
--- John B. Stephensen [EMAIL PROTECTED] wrote:
I'm not asking for 90% of the band for my own use
and I've never played a video game. Some hams don't
want to limit themselves to voice and typing text on
a keyboard
The ARRL is publishing designs for simple phasing SSB exciters with 3-pole
filters and filter-type exciters with 4-pole crystal filters so we can't count
on DSP. Phasing transmitter kits have filters with at least 5-poles so they are
somewhat better. These should be able to acheive 23 dB
An ALE network and WinLink are both useful. My comments to the FCC were:
RM-11392 attempts to address problems of interference between narrow
and wide bandwidth text and data communition modes on amateur
bands, but the proposed rule changes will create more problems than
they solve. Historicly,
a maximum of 6 kilohertz.
John B. Stephensen wrote:
An ALE network and WinLink are both useful. My comments to the FCC were:
RM-11392 attempts to address problems of interference between narrow
and wide bandwidth text and data communition modes on amateur
bands, but the proposed
a maximum of 6 kilohertz.
John B. Stephensen wrote:
An ALE network and WinLink are both useful. My comments to the FCC were:
RM-11392 attempts to address problems of interference between narrow
and wide bandwidth text and data communition modes on amateur
bands, but the proposed
taken, provided that is how the rule is actually written.
John B. Stephensen wrote:
I used 8 kHz because the FCC will specify the maximum bandwidth at
-23 dB. Users want 6 kHz minimum bandwidth with minimal attenuation.
Maufacturers of ham radio equipment usually specify
ham radio
license would ever come out and say this
FROM .
--- John B. Stephensen [EMAIL PROTECTED] wrote:
If the rule changes are to extend beyond 29 MHz,
narrow-band segments on the VHF and UHF bands should
allow a maximum bandwidth of 8 kHz. This provides
protection
to
Kill Digital Radio?)
I cannot believe the holder of a valid ham radio
license would ever come out and say this
FROM .
--- John B. Stephensen [EMAIL PROTECTED] wrote:
If the rule changes are to extend beyond 29 MHz,
narrow-band segments on the VHF and UHF bands should
allow
Band segments for narrow modes at the low end up to segments suitable for AM at
the high end of each band seems a reasonable way to minimize intererence.
However, the restriction on content needs to be eliminated so that stations in
a QSO can send text, image or voice in analog or digital form
The best solution is then regulation by bandwdth so that text and data can be
sent in the current phone/image segment. The rtty/data segments could become
the 500 Hz bandwidth segments, the phone/image segments the 3 kHz bandwidth
segments, and there could be 6 kHz and 50 Hz bandwidth segments
You should be able to use Ethernet video cameras and Wifi on the 13 and 5 cm
bands.
73,
John
KD6OZH
- Original Message -
From: Andrew O'Brien
To: DIGITALRADIO
Sent: Saturday, December 15, 2007 18:45 UTC
Subject: [digitalradio] Digital high frame rate video via amateur
In the U.S. the FCC has approved a system called IBOC (In-Band On Channel) to
add digitial audio to existing AM and FM stations. In broadcast radio, there
isn't the luxury of unused channels that allow every station to have one analog
and one digital transmitter. I haven't seen any terrestrial
Hi Rud,
I just sent you the Pascal source code for generating and receiving OFDM via
wav files. There is also a simple program that will modify a file to simulate
multipath by converting it into multiple rays.
I agree with Vojtech that it's not very useful to flip bits for testing as any
If you have an inner and outer code that would be the situation, but I'm not
sure that flipping one bit would always be accurate. A Viterbi decoder might
generate small bursts of errors. HDTV uses TCM with an outer Reed-Solomon code.
Even though there are 12 interleaved convolutional encoders,
codes.
Rud Merriam K5RUD
ARES AEC Montgomery County, TX
http://TheHamNetwork.net
-Original Message-
From: digitalradio@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of
John B. Stephensen
Sent: Tuesday, November 06, 2007 2:30 PM
To: digitalradio@yahoogroups.com
RTTY is binary FSK so the bandwidth is approximately the deviation (170 Hz)
plus the baud rate or 215 Hz.
73,
John
KD6OZH
- Original Message -
From: John Becker, WØJAB
To: digitalradio@yahoogroups.com
Sent: Saturday, October 27, 2007 01:04 UTC
Subject: Re: [digitalradio]
The best mode to use depends on how much data you want to transmit in a given
bandwidth. Moving lots of data in a small bandwidth requires sending one or
more bits per subcarrier. Otherwise, you can spread one bit out over multiple
subcarriers. For any given user data rate, increasing the
Differential PSK should be more reliable in the presence of frequency drift and
Doppler spread. There are two ways to do this: 1) compare the phase with the
previous phase of the same subcarrier or 2) compare the phase with the phase of
the next higher or lower subcarrier. In the first case,
, is this why it is the base waveform used
in the MIL-STD/FED-STD/STANAG modems?
What is your view on single tone modems as used in those standards vs.
the OFDM that is proposed by Rud and is used in Pactor 3?
73,
Rick, KV9U
John B. Stephensen wrote:
Differential PSK should
Rud:
What language are you developing in? I have some software that generates and
receives OFDM with 8PSK subcarriers using .wav files containing I and Q
samples. The source code is about 1500 lines of Delphi (Pascal). It's fairly
slow as it uses a DFT and IDFT and floating point arithmentic,
B. Stephensen
Sent: Wednesday, October 24, 2007 8:37 PM
To: digitalradio@yahoogroups.com
Subject: Re: [digitalradio] OFDM Proposal: Details
Differential PSK should be more reliable in the presence of frequency drift
and Doppler spread. There are two ways to do this: 1) compare
Look at KA9Q's web site, especially http://www.ka9q.net/code/fec/, for FEC
software.
73,
John
KD6OZH
- Original Message -
From: Rud Merriam
To: digitalradio@yahoogroups.com
Sent: Monday, October 22, 2007 05:13 UTC
Subject: RE: [digitalradio] Re: OFDM Proposal
Ed,
I
ARES AEC Montgomery County, TX
http://TheHamNetwork.net
-Original Message-
From: digitalradio@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of
John B. Stephensen
Sent: Monday, October 22, 2007 7:40 AM
To: digitalradio@yahoogroups.com
Subject: Re: [digitalradio
It depends on the characteristics of the path. If it's NVIS, the guard interval
should be at least 8 ms as the communicating stations are operating far below
the MUF. If you have a copy of Ionospheric Radio (ISBN 0-86341-186-X) there
is a graph of multipath spread versus path length on page
The FFT averages the signal over the entire sample period so any ISI during
that interval will increase the error rate. I haven't implemented anything on
HF yet, but there will be another affect that is important on ionospheric
paths. Doppler spread is 1-10 Hz and can be up to 100 Hz on auroral
If you're going for maximum reliability, it might be useful to use the widest
possible subcarrier spacing to minimize sensitivity to Doppler combined with a
guard interval long enough to compensate for NVIS multipath. This should give
the widest possible coverage area. A carrier spacing of
You may be thinking of mixing the real signal with cosine and sine signals at
1/4 the sampling rate. The sequence can be +1, 0, -1, 0 and 0, +1, 0, -1 for
cosine and sine or +1, +1, -1, -1 and +1, -1, -1, +1. In the first case,
computation can be minimized if the next stage is a FIR filter as
The testing that was done on DRM showed that the worst multipath spread is on
NVIS paths and is about 8 ms. They originally could accomodate only about 5 ms
of multipath but had to create a new mode with a longer guard interval to
support South American stations using the 41, 49, 60, 75, 90 and
Perhaps there are those that think that there are more limitations than
actually exist in the FCC rules, but there are differences that should be
remedied. PDFs can be defended as being images, but many other types of files
are clearly prohibited as they aren't formatted to print on a page. Any
: [digitalradio] Digi Voice: No Bandwidth Limit
John,
While I agree with you that we should be allowed to mix voice and ASCII
text (primarily for emergency communications use), what makes you think
we can use voice in the 7075 to 7100 here in the U.S.?
73,
Rick, KV9U
John B
bandwidth and what mode? What design criteria would be needed
to use this, especially in J3D?
Jim
WA0LYK
--- In digitalradio@yahoogroups.com, John B. Stephensen [EMAIL PROTECTED]
wrote:
If I'm at the low end of an HF band, I can now send send text
(RTTY), data or images using PSK31
I know of that could possibly do so out of the box.
Basically, there aren't any well known commercial rigs available to do
this bandwidth using sound card modems.
Jim
WA0LYK
--- In digitalradio@yahoogroups.com, John B. Stephensen [EMAIL PROTECTED]
wrote:
In J3D you just need
I agree, and there are modfications shown on web sites for DRM software.
In my case, I have home-brew radios so I can easily support wide bandwidths.
Since I've got code to transmt and receive OFDM using FPGAs I should modify it
for narrower subcarrier spacings and do wideband HF OFDM some
@yahoogroups.com, John B. Stephensen [EMAIL PROTECTED]
wrote:
The basic problem is that the current regulations restrict the
content of amateur transmissions. It shouldn't matter whether you are
transmitting text, voice or images. On HF, you can transmit voice or
images in a 3 kHz or 6 kHz
WinDRM and HamDRM are good examples of modes where all functions shoud be legal
in the image/phone segments in the U.S. but sending a text file in most HF
image/phone segments is dissallowed by current rules. The crazy thing is that
you can render the text as glyphs and send it as an image but
One problem is that very wide modems are allowed only outside the phone/image
segments, which is the opposite of what is reasoable for users. Another example
is that data modes are only allowed a 100 kHz bandwidth on 70 cm which is 30
MHz wide.
73,
John
KD6OZH
- Original Message -
B. Stephensen [EMAIL PROTECTED]
To: digitalradio@yahoogroups.com
Sent: Tuesday, May 1, 2007 10:30:10 AM
Subject: Re: [digitalradio] Re: ARRL wake up ..
One problem is that very wide modems are allowed only outside the phone/image
segments, which is the opposite of what is reasoable
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