At least in my opinion it is certainly somewhat odd to test HF equipment
according to specifications for
25 kHz channel spacing, which normally is used for VHF/UHF FM equipment.
However, it is quite likely that your HF equipment will pass the tests with
"flying colours"...
The "occupied bandwidth" specifications that I am most familiar with come from
the "ICAO Annex 10" HF system specifications from which the performance
standards in "ARINC Characteristic 719" are derived. The ICAO and ARINC
"spectrum masks" are in the form of "stair step shaped" masks or templates,
with the emission center frequency in the middle. 99% of the emission power
should be contained within this center portion, which is referred as 0 dB.
Further out, spaced a multiple of the "occupied bandwidth" from the center
frequency, there are "steps" that are a suitable amount of dB down from the
center to accommodate 3rd and higher order IM products.
The emissions used in these specifications are the J2D (datalink traffic using
audio subcarriers into an SSB transmitter), J3E (SSB voice) and H2A ( SELCAL
emission; SSB with full carrier and tone modulation).
As far as I know, amateur equipment in most parts of the world are currently
exempt from explicit "occupied bandwidth" specifications, but there have
recently been discussions about an ETSI spectral purity specification for
transmitters in general.
This regulation, if adopted, would impose an "occupied bandwidth" requirement
and measurement for all transmitting equipment offered for sale in the EU
countries.
73/
Karl-Arne
SM0AOM
----- Original Message -----
From: "Martin Sole" <msole@loxinfo.co.th>
To: <amps@contesting.com>
Sent: Monday, September 11, 2006 2:43 PM
Subject: [Amps] Technical specification question, possibly OT !
> Please excuse if this is off topic but if you think it through I think
> it could be argued as amplifier related, sort of..
>
> I'm in the process of importing a radio, doesn't matter what but suffice
> to say that any radio that enters the country has to be tested at the
> government facility by the government 'experts'. Testing consists of
> fairly basic checks, power output and frequency coverage are the two
> most significant for a transmitter. I have been present when most of my
> stuff has been through this process as a lot is tube type of which the
> 'experts' have little knowledge. In the course of testing the other day
> my eyebrow raised when the 'expert' started to measure occupied
> bandwidth. I really do understand how this is important in a commercial,
> or even, amateur, channelized service but cannot quite get a handle on
> why it is would be necessary to determine this for our typical HF type
> of operation. Well maybe since it indicates how narrow the signal is and
> I suppose could be considered a measure of transmitter cleanliness but
> as they were measuring with settings based on 25KHz channel spacing it
> seemed a little odd.
>
> I'm interested to hear what 'competent' professionals and others might
> have to say about this. I have never seen a specification for this in
> any amateur literature.
>
> Regards
>
> Martin, HS0ZED
>
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