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 legal. ROS is
another good reason for regulation by bandwidth instead of the overly
restrictive system in the current FCC regulations.
73,
John
KD6OZH
----- Original Message -----
From: KH6TY
To: digitalradio@yahoogroups.com
Sent: Friday, February 19, 2010 18:19 UTC
Subject: Re: [digitalradio] Re: ROS, legal in USA?
All,
If we accept the fact that a SSB transmitter with sufficient carrier
suppression simply generates an RF carrier equal to the suppressed carrier
frequency plus the tone frequency (USB), then frequency hopping is frequency
hopping (spread spectrum), regardless of how the carriers are generated. That
is really too bad for US hams as all morning I have been receiving alerts and
printouts from many stations on 14.080 - many times when the ROS signal can
hardly be heard above the noise.
I'm afraid that Andy's concerns are real, and unless the FCC clarifies
otherwise, ROS is currently illegal in the US in my personal opinion and
interpretation of the FCC rules.
However, it looks like a worthwhile mode to test on UHF (432 MHz) where SS
"is" allowed and we will be doing that during our daily digital experiments
every morning on 432.090 SSB. The Doppler shift, multipath distortion, and
"fast flutter", as well as QSB often as deep as 15 dB, often make even S3 phone
signals unintelligible. We have been also been testing extensively with
DominoEx 4 on FM (DominoEX does not survive Doppler shift well on SSB) and
Olivia 16-500 and 4-500 on both FM and SSB, often with better copy than with
SSB phone, and especially so when signals are near the noise threshold. The
path length is 200 miles, so signals are usually near the noise threshold
during these winter months where there is no propagation enhancement.
I'll post the results of our tests on 432 MHz here during the next two weeks
as we compare ROS to Olivia. So far, plain old CW can be copied when even
Olivia cannot, but the CW "note" is very raspy sounding, much like it is during
aroura communication. It would help a lot if it were possible to select
alternate soundcards and many of us on UHF and VHF are using a second soundcard
for digital operations.
73 - Skip KH6TY
nietorosdj wrote:
One comment: It is not the same a Spread Spectrum Transceiver (like
military radios) that to send digital data into an audio channel on standard
SSB transceiver. They are different things. So, when we read Spread Spectrum is
not legal, first we must know what we are reading.
--- In digitalradio@yahoogroups.com, Andy obrien <k3uka...@...> wrote:
>
>
<http://groups.yahoo.com/group/digitalradio/members;_ylc=X3oDMTJmbzY3MjhrBF9TAzk3MzU5NzE0BGdycElkAzE4NzExODMEZ3Jwc3BJZAMxNzA1MDYzMTA4BHNlYwN2dGwEc2xrA3ZtYnJzBHN0aW1lAzEyNjY1OTc1MzA-?o=6>Joe,
> N8FQ...
>
> http://www.arrl.org/FandES/field/regulations/news/part97/d-305.html
>
> Describes Spread Spectrum as not permitted on HF. Is there another part of
> part 97 I am missing ?
>
> Andy K3UK
>
