STG(07)16 10 STG meeting, 29-30 August 2007 Subject: Proposals regarding the Unwanted emissions dialog window Origin: Switzerland Date: 28 August 2007

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STG(07)16

10
th

STG meeting, 29
-
30 August 2007


Subject: Proposals regarding the Unwanted emissions dialog window

Origin:

Switzerland

Date:


28 August 2007




Following the problem I had with the TX power definition I propose the following
two possibilitie
s

to enter in SEAMCAT to prevent problems
:



A. Correct implementation of total power and unwanted emission mask


If you enter
the

total power and the unwanted emission mask separately it is of
the responsibility of the user that
these

2 inputs are c
orrect, e.g. the
integration over the unwanted emission mask must give the same value as entered
as total power. This is not easy if you use different reference bandwidth.

Therefore I propose the following additional calculation steps:


1.
(Editorial
)
Change the tit
l
e of the box "unwanted emissions" in
"emission mask" (becaus
e

the mask includes also the wanted emissions and fits
better what you are doing)


2.
(Editorial)
the data input could be the same as now (dF / dBc /
bandwidth ==> rename the

column: Offset / attenuation/ ref. bw)


3
.


(Calculating)
Integrate the
total
power over the entire
TX
emission mask
,
defined in 2. with the normalized reference bandwidth


4
.


(Calculate)
set this total power to 0 to get the relative power

density

(o
r dBc), e.g. if you get a total power of 17.5 dBm the relative power

density

will be
-
17.5 dBm/normalized bandwidth
. When integrating with this value over
the entire mask you get again 0.


or


B. Make a warning note


If A. seems to be too complicate
d then at least make a warning note in the
windows where you enter the unwanted emission mask stating:


The user is advised to enter normally the total emissions bandwidth of interefering transmitter (i.e.
channel width) as value for reference bandwidth

.
I
f not, the user has to check the consistency of mask
and power.




C
. Editorial: rename "unwanted emission floor" to: "emission floor"



Kind regards


Peter

Jenni

BAKOM Switzerland








History:


-----
Ursprüngliche Nachricht
-----

Von: Arturas Medei
sis [mailto:Medeisis@ERO.DK]

Gesendet: Mittwoch, 22. August 2007 17:10

An: Jenni Peter BAKOM

Betreff: RE: Seamcat



Dear Peter,


I agree with you, and we have already put a relevant warning in the current
Wiki
-
based Seamcat help database (look at the page
for Emission masks, direct
link: http://www.seamcat.org/xwiki/bin/view/Seamcat/transmission_mask_dialogbox).


Furthermore, on this particular point of unwanted mask, we even once decided to
change its presentation in a way, that the mask would contain just

the dF/dBc,
whereas interferer bandwidth would be entered separately like it is done for the
victim. But then in some cases the relationship is not so straightforward, also
the mask points could be defined with varying ref.bw, as may be seen in some
stand
ards. So all in all, we came back to where we are now.


Glad we clarified the issue,

Best regards,


Arturas


-----
Original Message
-----

From: Peter.Jenni@bakom.admin.ch [mailto:Peter.Jenni@bakom.admin.ch]

Sent: 22. august 2007 16:04

To: Arturas Medeisis

Su
bject: AW: Seamcat


Daer Arturas


Thanks for your answer.

I agree with you interpretation but it is not usual to use such large b
a
ndwidth
to define the unwanted emission mask.

It is also not elsewhere stated that you have to be careful when selecting the
t
otal TX power and defini
n
g the unwanted emission mask.

In this case there should be a warning when entering data in the unwanted
emission mask box.


Kind regards


Peter



-----
Ursprüngliche Nachricht
-----

Von: Arturas Medeisis [mailto:Medeisis@ERO.DK]

Gese
ndet: Mittwoch, 22. August 2007 14:35

An: Jenni Peter BAKOM

Cc: Jean
-
philippe Kermoal

Betreff: RE: Seamcat



Dear Peter,


Thanks for the scenario files, now I see what has been happening.


You defined the interferer's mask giving the 1 MHz reference bandwi
dth, whereas
the 0 dBc part extends over +/
-
30 MHz. So in such way you actually defined the
mask as if saying that you have "0 dBc in each 1 MHz, whereas total channel
bandwidth is 60 MHz". So then since the victim is also having even larger
bandwidth of 6
5 MHz and 0 frequency difference with interferer, you end up in
integrating (0 dBc/1 MHz)x60 MHz plus 5 MHz of slope and thus you get the
positive unwanted emissions of some 10lg(60) + plus little extra for that 5 MHz
of slope.


So if you want to say that
the full power in the entire transmitter bandwith is
0 dBm, then you should define mask with reference bandwidth of 60 MHz. So if you
just replace ref
-
bw in your mask to 60000 kHz for all points, then you will be
having integrated relative unwanted emissio
ns of ca. 0 dBc, which would
correspond to your scenario of co
-
channel interference between systems with
identical bandwidth.


Hope this clarifies the point, but do not hesitate to ask further as needed.
Best regards,


Arturas