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Thanks Rik,
See the post - re New Mode
, Jose has undertaken to code a 100 Hz qso mode based on
the existing ros systems , not as fast as psk , but
will comply with the 100 Hz band restrictions and
offer enhanced phase and s/n performance ... may be 125
hz could of been used , but with the on going 'flap' , it was
better to simply reduce the bw to the allowed
limit ! (but not simply for Jose .. needs quite a
lot of re-work on the code)
Hopefully it will ready to test
in a week or so
73- G ..
Sent: Thursday, May 06, 2010 6:32 PM
Subject: LF: bandwidth ?
Graham,
next question: how to define bandwidth (-3dB,
-30dB, ... edge frequencies) ?
As I couldn't find a
definition in our national ruling I had a look at "higher levels".
The only thing I found was in the
IARU-Region 1 HF managers handbook:
1.153
occupied bandwidth: The width of a frequency band such that, below the lower and above
the upper frequency limits, the mean powers
emitted are each equal to a specified percentage ı/2 of the total mean power of a given emission. Unless otherwise specified in an ITU-R
Recommendation for the appropriate class of
emission, the value of ı/2 should be taken as
0.5%.
Taking this definition it depend on the
power distribution of the signal. That makes sense, but is very hard to
measure.
73, Rik
ON7YD
Thank you , Rik,
From that , its possible that the
other permits are similar
Ok Tnx - G .
Sent: Thursday, May 06, 2010 1:19 PM
Subject: RE: LF: 500 Permit emission’s bandwidth? EU and Global
??
Graham,
the document that gives us access to 500kHz says
100Hz bandwidth, but does not say how many dB's the signal has to be attenuated
at these limits.
73, Rik ON7YD - OR7T
Ok Many thanks' for the
reply's
From that .... next is :-
From the data, I assume that
100 Hz is the common limiting factor for a narrow
band data transmission that could be used by all who
'wanted' to use it ?..(noted on the cw keying
speed ~ BW)
So if a value of 100 Hz is
specified, what is the 'presumed' roll-off of the power in the
said bands ?, assuming that the original concept was
based on CW operation , which by definition 'has to' generate
sidebands , there must be an assumed tolerance ?
Q would the deployment of a
system that could defined as 125 hz bandwidth
ie 100 Hz with +/- 12.5 Hz overspill , cause
a technical breach of the regulations or
be viewed as occupying the 'allocated' bandwidth
for a telegraphy transmission ? ,
Taking that spectral measurements in
the 10 Hz region are perhaps starting
to test even the best equipment, the area is
perhaps a little empiric ?
I use the word telegraphy, purposely to
view/observe the situation interims of the licence
conditions and not on the basis of 'mode' which
like Liverpool and Everton have there own sub cultures
but are still football teams ..
Thanks
Graham
G0NBD
Sent: Wednesday, May 05, 2010 10:39 PM
Subject: LF: 500 Permit emission’s bandwidth? EU and Global
??
500 Permit
emission’s bandwidth?
Can any one
indicated what is the permitted
‘telegraphy’ bandwidth
of the various ‘new’ 500KHz licences
or special permits issued round
the EU and now the rest of the
Globe ?
I have the
impression that 100 Hz is the maximum ‘telegraphy’ transmission bandwidth, in
some cases, eg , Belgium at 100
Hz . Others appear to be some what wider or not defined ?.
Norway is CW only ? what is the Dutch
allocation ? Southern Ireland ? ... etc
Are
Beacons defined by mode or
bandwidth ?
Tnx –
Graham
G0NBD
(I use
the word ‘telegraphy’ as defined by
the ITU R V.662-3 , please no
reference to key clicks !
)
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