It is inadequate, Al.
There are lots of transceivers that create a very broadband noise.
The noise is adequately suppressed to meet the legal specs, but if you hang
an amp on them, a neighbor a mile away might have problems.
A next door neighbor will have problems every time that radio transmits,
regardless of what band it is on.
Yet it passes the specs.
I am not aware of the details of 97.307; does it specify just 3rd order IMD
or does it specify more?
Does it just specify 2-tone testing?
In the meantime Rob is testing using white noise in addition to the 2-tone
tests.
This more closely resembles speech.
Part of the problem is, some of the modern radios have really bad 5th, 7th,
9th (etc.) order IMD and even farther out.
One of Rob's presentations was quite long. I was unable to upload the Audio
file (too large) so I split the presentation into 3 parts, with
"Transmitters" being one of the 3.
Anyone interested in more info on this theme should look at his presentation
and listen to Rob in the audio file.
The presentation was his 2011 BARC presentation, entitled "Transceiver
Performance; What's new in 2011?"
Here is a link to the presentation and 3 audio files which accompany it:
http://www.dj0ip.de/transceivers/sherwood/barc-new-in-2011/
The middle presentation, slides 24-43 address the transmitter issues.
73
Rick, DJ0IP
-----Original Message-----
From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of Al Gulseth
Sent: Sunday, June 16, 2013 8:52 PM
To: tentec@contesting.com
Cc: Richards
Subject: Re: [TenTec] RF Speech Processor "TX IMD"
Actually, there is already a government mandated "clean transmitter
standard."
It's called "Sec. 97.307" (as in FCC Part 97) and is titled "Emission
standards." Might an update of this section of Part 97 to address the issues
raised in this discussion perhaps be in order?
Although, the "spirit" of 97.307 already addresses several of the items you
mention: concerning "a limit on bandwidth," note, for example, that it says
(a) No amateur station transmission shall occupy more bandwidth than
necessary for the information rate and emission type being transmitted,
in
accordance with good amateur practice.
My reading of this section would seem to indicate a mandate for "clean,
narrow banded signals with minimal splatter" is there already. While
needless to say improper equipment design is responsible for some of the
"garbage" on the bands, many more of the poor on-air signals we hear are due
to misadjustment by the operator and/or simple failure to follow "good
amateur practice."
73, Al
On Sun June 16 2013 1:02:39 pm Richards wrote:
> OK. You need a page about this on your web site, with one of your
> world famous spread sheets (ala your tuner spec report) and that will
> be a start. I forget how many Arlo Guthrie says makes a "movement"
> ... ;-)
>
> In retrospect,... maybe Bob has a better idea than we first thought.
>
> Although I favor laissez faire economics, and less gov-mt intrusion
> overall, perhaps it would not exactly hurt if the FCC promulgated a
> clean transmitter standard, something like the amplifier purity
> standards ... you know... like the German (Reinheitsgebot) beer purity
> law... that mandates transceivers must meet a minimum, but
> sufficiently strict, standard for spectral purity and accuracy - like
> they do with linear amplifiers - and maybe provide a limit on
> bandwidth (yep, that should start a fist fight...) and mandate clean,
narrow banded signals
> with minimal splatter. (I am speaking generally here - I am not an
> expert on this... sure got kicked on the processor issue...) :-)
>
> So, perhaps, a new regulation on the matter might be helpful - it
> would elicit a more prompt response from manufacturers than our market
> pressure plan.
>
> Again, while I don't favor gov-mt action, perhaps it couldn't hurt in
> this case. Let me know when you get your new clean transmitter page
> on the web site.
>
> -------------------- K8JHR ------------------
>
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