The FCC RO makes some big changes on HF. It limits the bandwidth of data
transmission to 500 Hz below 30 MHz.. It also states that data and image
transmission were never authorized in the same HF frequency segments so
data
in the phone/image segments seems to be prohibited. Considerable
The FCC RO makes some big changes on HF. It limits the bandwidth of data
transmission to 500 Hz below 30 MHz.. It also states that data and image
transmission were never authorized in the same HF frequency segments so data
in the phone/image segments seems to be prohibited. Considerable spectrum
It would be reasonable to allowswitching
between voice, data and image in the phone segment, all using the same
bandwidth. This would cause no interference to adjacent frequencies and is the
essence of regulation by bandwidth.
73,
John
KD6OZH
- Original Message -
From:
I only recently joined this list so here is some
more specific information on 6-meter wideband digital testing.
TheARRL, at therequest ofthe HSMM WG,asked for and
was granted a license to test digital modes up to 200 kHz wideon 6
meters.Agoal of 256 kbps was set as this wouldallow decent
Even though the license authorized 50.3-50.8 MHz, I stayed away from the AM
calling frequency. The only frequency used so far is 50.7 MHz, so the signal
covers 50.625-50.775 MHz and the FCC occupied bandwidth (-27 dB) is within
50.6-50.8 MHz.
73,
John
KD6OZH
- Original Message -
The ARRL told me that any data transmission mode
(defined as computer to computer file transfer)wider than 500 Hz would be
prohibited on all HF bands if the rules changes go into effect. Image
transmission bandwidth is unchanged. They also said that they are working to
convince the FCC to
I specificly asked about Pactor III and was told
thatit would be illegal. This is why the ARRL is upset with the
FCC.
73,
John
KD6OZH
- Original Message -
From:
DuBose Walt Civ AETC CONS/LGCA
To: digitalradio@yahoogroups.com
Sent: Tuesday, October 31, 2006
The current rules restrict emissionsin
various requency segents bytye of information being
transmitted(RTTY, data, phone, image) and usuallyallow either analog
or digital transmission (this is the second character in the emission
designator).
73,
John
KD6OZH
.
- Original Message
The problem with NVIS is that there are a lot of
pathsover whichthe transmittedsignalcan reach the
receiver.When DRM was tested, theymeasured a 7 ms delay spread in an
equatorial region and I've seen reports published on the Internet showing up to
13 ms. In near-polar regions, there is
The key appears to be whether the information is printed immediately or not. In
97.3, RTTY is defined as Narrow-band direct-printing telegraphy. So text is B
if it is printed or D if it is not printed.
It's interesting that emission types B7W, B8W and B9W (ISB) are still allowed,
so you can
The FCC uses the phrase quantitized or digital information in the definitions
in part 2 so anything encoded into discrete levels of amplitude, phase or
frequency is digital.
The definitions in part 97 were probably very clear when they were written. It
looks like they took amateur radio terms
To: digitalradio@yahoogroups.com
Cc: digitalradio@yahoogroups.com
Sent: Wednesday, November 22, 2006 19:49 UTC
Subject: Re: [digitalradio] Re: OFDM data is Emission Designator D1D
John B. Stephensen wrote:
its orthogonal because the state
of each subcarrier is independent
be deduced from the fact that they carry independent
streams of bits.
Rick N6RK
John B. Stephensen wrote:
I should have said that the subcarriers must be orthogonal because
Pactor-3 uses each subcarrier to send an independent stream of bits. In
someone else's email they verified
The FCC rules provide the following definitions for fax:
Image. Facsimile and television emissions having designators with
A, C, D, F, G, H, J or R as the first symbol; 1, 2 or 3 as the second
symbol; C or F as the third symbol; and emissions having B as the
first symbol; 7, 8
The FCC rules provide the following definitions for fax:
Image. Facsimile and television emissions having designators with
A, C, D, F, G, H, J or R as the first symbol; 1, 2 or 3 as the second
symbol; C or F as the third symbol; and emissions having B as the
first symbol; 7, 8
Pactor-3 is as legal as it was before the Omnibus RO, but unless you are
sending a fax it is restricted to the new RTTY/Data segments.
73,
John
KD6OZH
- Original Message -
From: Roger J. Buffington
To: digitalradio@yahoogroups.com
Sent: Wednesday, November 29, 2006 02:03 UTC
If radiated power is not limited, data rate is directly proportional to
bandwidth, but the maximum data rate per kHz depends on the amount of time
(multipath) spreading and amount of frequency (Doppler) spreading. NVIS has
a multipath spread of 6-12 ms and there needs to be a gap between symbols
Dopper shift increases with ionospheric disturbance and the solar geophysical
reports always show that the effect is more pronounced in northern latitudes. I
don't know a lot about the physics of the ionosphere but I assume that it's for
the same reason the aurora always occurs near the poles.
Look at http://www.fcc.gov/sptf/reports.html to see what the FCC thinks.
Their
spectrum policy report states:
As a general proposition, flexibility in spectrum regulation is critical to
improving
access to spectrum. In this context, flexibility means granting both
licensed users
and
The 3kHz bandwidth is dissappointing.
73,
John
KD6OZH
- Original Message -
From: DuBose Walt Civ AETC CONS/LGCA
To: digitalradio@yahoogroups.com
Sent: Friday, February 23, 2007 19:17 UTC
Subject: [digitalradio] ARRL Seeks Comments on New HF Digital Protocol
The bandwidth limit applies only to the phone segments.
73,
John
KD6OZH
- Original Message -
From: expeditionradio
To: digitalradio@yahoogroups.com
Sent: Friday, March 16, 2007 01:35 UTC
Subject: [digitalradio] Re: no bandwidth limit
There is no finite bandwidth limit
The ARRL deleted other changes below 30 MHz, but wants to change the
voice/image segment bandwidth from the existing communications quality voice
to 3 kHz.
73,
John
KD6OZH
- Original Message -
From: kv9u
To: digitalradio@yahoogroups.com
Sent: Saturday, March 24, 2007 19:50
to pass, it would not be possible to get that changed for a very long time.
73,
Rick, KV9U
John B. Stephensen wrote:
The ARRL deleted other changes below 30 MHz, but wants to change the
voice/image segment bandwidth from the existing communications
quality voice to 3 kHz
What you're proposing is regulation by bandwidth. Once you're in a QSO with
another station it shouldn't matter what you send. The only issue is where the
different band segments for the different bandwidths are located.
73,
John
KD6OZH
- Original Message -
From: n6vl
To:
The original ARRL regulation by bandwidth proposal put wide data in the same
band segments with image and voice transission. Their members seem to have
convinced them otherwise. Perhaps they need to hear from supporters of
regulation by bandwidth.
73,
John
KD6OZH
- Original Message
The international broadcaster's signals are wider (5-10 kHz vs. 2.5 kHz) so an
AM or NBFM IF filter and a wider audio bandwidth is required to feed the sound
card. See drm.sourceforge.net and www.drmrx.org for software. Many radios won't
allow the BFO to be offset far enough to receive SSB this
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
The VHF and UHF bands have explicit bandwidth limits on data emissions and
image has a bandwidth limit on HF. Unfortunately, image transmission benefits
the most from increased bandwidth. This maybe a group concerned mainly with
RTTY and data but there are other modes that woud benefit from
(was Re: ARRL wake up
..)
--- In digitalradio@yahoogroups.com, John B. Stephensen [EMAIL PROTECTED]
wrote:
47cfr97.307(f)(2) limits the bandwidth of all transmissions in the
phone/image segments to that of AM or SSB communications quality audio
which is usually interpreted as 3 kHz
@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
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
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
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
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
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
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
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]
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
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
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
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
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
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
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
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
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.
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.
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]
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
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]
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.
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
) 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
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
: [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
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
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:
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.
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
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
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
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
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
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
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
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
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