EUMETSAT transponder tests?


David J Taylor GM8ARV 🏴󠁧󠁢󠁳󠁣󠁴󠁿 🇪🇺
 

I'm seeing the level varying on TP1 (C4) across Europe, so I guess this is EUMETSAT tests in relation to the new HVS-2 transponder C3.

If it's just a level change it confirms something I've suspected for a long time, that what we are plotting is not actually SNR, but (signal+noise)/noise, hence the limit of zero dB and the apparent non-linearity for those with weaker signals.

Interesting times!

Cheers,
David
--
SatSignal Software - Quality software for you
Web: https://www.satsignal.eu
Email: david-taylor@...
Twitter: @gm8arv


geojohnt@...
 

David,

Yes, as just posted under another 'Subject,' my HVS-2 V SNR is higher this morning than TP 1 H.
Which has not been the case since Saturday.
[Both down due to bad weather]

Regards,
John. 


-----Original Message-----
From: David J Taylor GM8ARV 🏴󠁧󠁢󠁳󠁣󠁴󠁿 🇪🇺 via groups.io <david-taylor@...>
To: MSG-1@groups.io
Sent: Tue, 15 Nov 2022 10:10
Subject: [MSG-1] EUMETSAT transponder tests?

I'm seeing the level varying on TP1 (C4) across Europe, so I guess this is
EUMETSAT tests in relation to the new HVS-2 transponder C3.

If it's just a level change it confirms something I've suspected for a long
time, that what we are plotting is not actually SNR, but (signal+noise)/noise,
hence the limit of zero dB and the apparent non-linearity for those with weaker
signals.

Interesting times!

Cheers,
David
--
SatSignal Software - Quality software for you
Twitter: @gm8arv






James Brown
 

Just to add that here in S Wales I’ve lost about 1db on the basic service (11263 H) since about 0915.

Cheers
James.


Ernst Lobsiger
 

On Tue, Nov 15, 2022 at 02:10 AM, David J Taylor GM8ARV 🏴󠁧󠁢󠁳󠁣󠁴󠁿 🇪🇺 wrote:
If it's just a level change it confirms something I've suspected for a long time, that what we are plotting is not actually SNR, but (signal+noise)/noise, hence the limit of zero dB and the apparent non-linearity for those with weaker signals.
David,

last Friday afternoon when EUMETSAT switched on HVS-2 on T1 (V) I saw
NO degradation on T1 (H). Now I see T1 (H) SNR steps down 1dB while
signal power does not change. I think SNR I plot is true SNR (ES/No):
The 0dB limit in my eLuna plots is something I have added in the graph
definition! Both my TBS SNRs and LMs can actually go negative ...

Regards,
Ernst


Charlie
 

I don't plot signal level still so can't speak for that, but the C/N out of my Digital Devices setup definitely can go negative too (seen it whilst doing dish alignment, thankfully not during service!).

Definitely had a drop on Friday matching the C3 switchon but it was very small - post skew adjustment I think that has gone away but it's small so could be other factors.



Seeing the same drop around 0920 UTC today on C1 - with rain fade on too for fun.



Charlie


On Tue, 15 Nov 2022 at 11:21, Ernst Lobsiger via groups.io <ernst.lobsiger=belponline.ch@groups.io> wrote:
On Tue, Nov 15, 2022 at 02:10 AM, David J Taylor GM8ARV 🏴󠁧󠁢󠁳󠁣󠁴󠁿 🇪🇺 wrote:
If it's just a level change it confirms something I've suspected for a long time, that what we are plotting is not actually SNR, but (signal+noise)/noise, hence the limit of zero dB and the apparent non-linearity for those with weaker signals.
David,

last Friday afternoon when EUMETSAT switched on HVS-2 on T1 (V) I saw
NO degradation on T1 (H). Now I see T1 (H) SNR steps down 1dB while
signal power does not change. I think SNR I plot is true SNR (ES/No):
The 0dB limit in my eLuna plots is something I have added in the graph
definition! Both my TBS SNRs and LMs can actually go negative ...

Regards,
Ernst


Charlie
 

Dang and blast it - guess images don't work properly replying through Gmail?!


Hopefully this works now, the two relevant charts out of eLuna.

Charlie


David J Taylor GM8ARV 🏴󠁧󠁢󠁳󠁣󠁴󠁿 🇪🇺
 

On 15/11/2022 11:33, Charlie wrote:
I don't plot signal level still so can't speak for that, but the C/N out of my Digital Devices setup definitely can go negative too (seen it whilst doing dish alignment, thankfully not during service!).
Definitely had a drop on Friday matching the C3 switchon but it was very small - post skew adjustment I think that has gone away but it's small so could be other factors.
Delighted that your meter can measure S/N rather than S+N/N which can never be less than 1, of course.

That's the best result I've heard so far. One question is whether the optimum skew to reject C3 is the same as that to reject C4 - given satellite and LNB tolerances. Which do you adjust for - on a weak system adjust for best BAS/HVS-1 and drop HVS-2, perhaps? And it all changes when the new satellite is launched and working - November 20 - fine tweaks could need re-doing.

Cheers,
David
--
SatSignal Software - Quality software for you
Web: https://www.satsignal.eu
Email: david-taylor@...
Twitter: @gm8arv


Charlie
 

Perpendicularity of the pins in the individual LNB will definitely be the strongest determining factor on that - on mine it seems to be very good (Inverto C120 White Tech quad) as the C/N appeared to peak in the same place on skew on both H and V... and the adjustment was *very* sharp compared to how much leeway there was with it with just H on. Often a lot of variance between units of the same model on that! Also the cross-polarisation isolation performance of both dish and feed/LNB will be in play here - definitely some better than others again, the Inverto BU 40mm LNBF models that people seem to like in this group are usually a good performer on that metric from what I gather.

Unfortunately (as mentioned in another post) I'm actually quite a long way down on max C/N I could achieve on 11263 V compared to 11263 H, when it stops raining I will twist the whole thing 90 degrees and see if the lower strength follows. If it does like I expect that means the V circuit is faulty... more expenditure!

My opinion on which to adjust for? I'd see what the compromise gives but if it is a big drop on BAS/HVS-1 I'd take that as the priority as I find it more volatile with packet loss on my DD receiver. YMMV etc.

 

Charlie


James Brown
 

Looking at your EUMETCast Europe pages. My web browsers show your page David stuck on Nov 12 for link margin and some of the others don’t seem to be updating.

Tried on two devices so not sure what might be happening?

Cheers,

James.

On 15 Nov 2022, at 10:37, James Brown <satellite@...> wrote:

Just to add that here in S Wales I’ve lost about 1db on the basic service (11263 H) since about 0915.

Cheers
James.





Ernst Lobsiger
 

David,

regarding negative SNR values IMHO this is an mrtg limitation (probably unless you use it in RRDtool mode):

https://groups.google.com/g/comp.dcom.net-management/c/_wGrZVOVaO8

Ernst


James Brown
 

Seems correct now.
Cheers

James.

On 15 Nov 2022, at 12:29, James Brown <satellite@...> wrote:

Looking at your EUMETCast Europe pages. My web browsers show your page David stuck on Nov 12 for link margin and some of the others don’t seem to be updating.

Tried on two devices so not sure what might be happening?

Cheers,

James.

On 15 Nov 2022, at 10:37, James Brown <satellite@...> wrote:

Just to add that here in S Wales I’ve lost about 1db on the basic service (11263 H) since about 0915.

Cheers
James.









geojohnt@...
 

David and All,

The front has just cleared my location and I'm back to clear sky reception.

BS/HVS-1 SNR 12.6 dB Power -18.0 dBm.
HVS-2 SNR 13.1 dB Power -21.0 dBm.

Something is very wrong!
TP 1 SNR is 1 dB down on normal.

My E 9-B reception on the same dish (aligned on E 10-A) is at the usual 'signal values' so I do not believe my dish has become mis-aligned during the gales here.

Regards,
John.

+++++++++++++++++++++++++


-----Original Message-----
From: geojohnt via groups.io <geojohnt@...>
To: MSG-1@groups.io <MSG-1@groups.io>
Sent: Tue, 15 Nov 2022 10:32
Subject: Re: [MSG-1] EUMETSAT transponder tests?

David,

Yes, as just posted under another 'Subject,' my HVS-2 V SNR is higher this morning than TP 1 H.
Which has not been the case since Saturday.
[Both down due to bad weather]

Regards,
John. 


-----Original Message-----
From: David J Taylor GM8ARV 🏴󠁧󠁢󠁳󠁣󠁴󠁿 🇪🇺 via groups.io <david-taylor@...>
To: MSG-1@groups.io
Sent: Tue, 15 Nov 2022 10:10
Subject: [MSG-1] EUMETSAT transponder tests?

I'm seeing the level varying on TP1 (C4) across Europe, so I guess this is
EUMETSAT tests in relation to the new HVS-2 transponder C3.

If it's just a level change it confirms something I've suspected for a long
time, that what we are plotting is not actually SNR, but (signal+noise)/noise,
hence the limit of zero dB and the apparent non-linearity for those with weaker
signals.

Interesting times!

Cheers,
David
--
SatSignal Software - Quality software for you
Twitter: @gm8arv






James Brown
 

My loss is increasing and not weather related. Now down about 1.4db on this time yesterday.

James.

On 15 Nov 2022, at 12:41, James Brown <satellite@...> wrote:

Seems correct now.
Cheers

James.

On 15 Nov 2022, at 12:29, James Brown <satellite@...> wrote:

Looking at your EUMETCast Europe pages. My web browsers show your page David stuck on Nov 12 for link margin and some of the others don’t seem to be updating.

Tried on two devices so not sure what might be happening?

Cheers,

James.

On 15 Nov 2022, at 10:37, James Brown <satellite@...> wrote:
Just to add that here in S Wales I’ve lost about 1db on the basic service (11263 H) since about 0915.

Cheers
James.













geojohnt@...
 

All,

I've just reported these findings to Ops.

John


-----Original Message-----
From: geojohnt via groups.io <geojohnt@...>
To: MSG-1@groups.io <MSG-1@groups.io>
Sent: Tue, 15 Nov 2022 13:09
Subject: Re: [MSG-1] EUMETSAT transponder tests?

David and All,

The front has just cleared my location and I'm back to clear sky reception.

BS/HVS-1 SNR 12.6 dB Power -18.0 dBm.
HVS-2 SNR 13.1 dB Power -21.0 dBm.

Something is very wrong!
TP 1 SNR is 1 dB down on normal.

My E 9-B reception on the same dish (aligned on E 10-A) is at the usual 'signal values' so I do not believe my dish has become mis-aligned during the gales here.

Regards,
John.

+++++++++++++++++++++++++


-----Original Message-----
From: geojohnt via groups.io <geojohnt@...>
To: MSG-1@groups.io <MSG-1@groups.io>
Sent: Tue, 15 Nov 2022 10:32
Subject: Re: [MSG-1] EUMETSAT transponder tests?

David,

Yes, as just posted under another 'Subject,' my HVS-2 V SNR is higher this morning than TP 1 H.
Which has not been the case since Saturday.
[Both down due to bad weather]

Regards,
John. 


-----Original Message-----
From: David J Taylor GM8ARV 🏴󠁧󠁢󠁳󠁣󠁴󠁿 🇪🇺 via groups.io <david-taylor@...>
To: MSG-1@groups.io
Sent: Tue, 15 Nov 2022 10:10
Subject: [MSG-1] EUMETSAT transponder tests?

I'm seeing the level varying on TP1 (C4) across Europe, so I guess this is
EUMETSAT tests in relation to the new HVS-2 transponder C3.

If it's just a level change it confirms something I've suspected for a long
time, that what we are plotting is not actually SNR, but (signal+noise)/noise,
hence the limit of zero dB and the apparent non-linearity for those with weaker
signals.

Interesting times!

Cheers,
David
--
SatSignal Software - Quality software for you
Twitter: @gm8arv






Charlie
 

Clear here in SE London now and getting approx 11.2 dB (varying a *lot* between 10.9 and 11.5, usually very consistent on this dish) on 11263 H and 11.2 dB on 11388 H. About normal for C10 but a solid 0.8 dB down right now on C4.

Definitely got an LNB fault with the V pol after the 90 degree test... so can't speak fully for performance on C3 11263 V beyond the x-pol noise it is(n't) causing me!

 

Is your reported SNR there for HVS-2 on the old or new transponder, John?

 

Charlie


geojohnt@...
 

Charlie,

Yes, sorry, I have never received HVS-2 so all my reports are on the 'new' HVS-2 channel 11.623 GHz V.

All I have to do is change the SR1 H/V switch.
Mind you, I'm not licensed for HVS-2 so I - 

Oh my goodness!
My BS/HVS-1 SNR has just 14:43 gone up to where it should be 13.7 dB.

Regards,
John.


-----Original Message-----
From: Charlie <charlie.johnson119@...>
To: MSG-1@groups.io
Sent: Tue, 15 Nov 2022 14:24
Subject: Re: [MSG-1] EUMETSAT transponder tests?

Clear here in SE London now and getting approx 11.2 dB (varying a *lot* between 10.9 and 11.5, usually very consistent on this dish) on 11263 H and 11.2 dB on 11388 H. About normal for C10 but a solid 0.8 dB down right now on C4.
Definitely got an LNB fault with the V pol after the 90 degree test... so can't speak fully for performance on C3 11263 V beyond the x-pol noise it is(n't) causing me!
 
Is your reported SNR there for HVS-2 on the old or new transponder, John?
 
Charlie


geojohnt@...
 

All,

My BS/HVS-1 SNR has just, 14:43, gone back to where it should be - 13.7 dB.

Regards,
John


-----Original Message-----
From: geojohnt via groups.io <geojohnt@...>
To: MSG-1@groups.io <MSG-1@groups.io>
Sent: Tue, 15 Nov 2022 13:39
Subject: Re: [MSG-1] EUMETSAT transponder tests?

All,

I've just reported these findings to Ops.

John


-----Original Message-----
From: geojohnt via groups.io <geojohnt@...>
To: MSG-1@groups.io <MSG-1@groups.io>
Sent: Tue, 15 Nov 2022 13:09
Subject: Re: [MSG-1] EUMETSAT transponder tests?

David and All,

The front has just cleared my location and I'm back to clear sky reception.

BS/HVS-1 SNR 12.6 dB Power -18.0 dBm.
HVS-2 SNR 13.1 dB Power -21.0 dBm.

Something is very wrong!
TP 1 SNR is 1 dB down on normal.

My E 9-B reception on the same dish (aligned on E 10-A) is at the usual 'signal values' so I do not believe my dish has become mis-aligned during the gales here.

Regards,
John.

+++++++++++++++++++++++++

_._,_._,_


David J Taylor GM8ARV 🏴󠁧󠁢󠁳󠁣󠁴󠁿 🇪🇺
 

On 15/11/2022 12:29, James Brown wrote:
Looking at your EUMETCast Europe pages. My web browsers show your page David stuck on Nov 12 for link margin and some of the others don’t seem to be updating.
Tried on two devices so not sure what might be happening?
Cheers,
James.
Yes, I've seen this happening as well, not only on my own data but others too. Usually a Ctrl-F5 will fix the problem. It could be something in the browser caching - I see that when you click on the graph to get the four-graph page the date and time is correct, but the image is not.

I also recall from ages ago that Windows would not alter the modification date of a file if it was rewritten within a few seconds. That may not be relevant, and may no longer be Windows behaviour. If anyone knows a fix, I'd love to hear it!

Cheers,
David
--
SatSignal Software - Quality software for you
Web: https://www.satsignal.eu
Email: david-taylor@...
Twitter: @gm8arv


David J Taylor GM8ARV 🏴󠁧󠁢󠁳󠁣󠁴󠁿 🇪🇺
 

On 15/11/2022 12:36, Ernst Lobsiger via groups.io wrote:
David,
regarding negative SNR values IMHO this is an mrtg limitation (probably unless you use it in RRDtool mode):
https://groups.google.com/g/comp.dcom.net-management/c/_wGrZVOVaO8 <https://groups.google.com/g/comp.dcom.net-management/c/_wGrZVOVaO8>
Ernst
Agreed.

In a similar context, Wi-Fi signal strengths can be given in a 0..100 "quality" measure, which I understand to be dBm+110, so it's never negative! "70" is "good".

https://www.satsignal.eu/mrtg/raspi23-wifi-dbm.html

Cheers,
David
--
SatSignal Software - Quality software for you
Web: https://www.satsignal.eu
Email: david-taylor@...
Twitter: @gm8arv


David J Taylor GM8ARV 🏴󠁧󠁢󠁳󠁣󠁴󠁿 🇪🇺
 

On 15/11/2022 13:09, geojohnt via groups.io wrote:
David and All,
The front has just cleared my location and I'm back to clear sky reception.
BS/HVS-1 SNR 12.6 dB Power -18.0 dBm.
HVS-2 SNR 13.1 dB Power -21.0 dBm.
Something is very wrong!
TP 1 SNR is 1 dB down on normal.
My E 9-B reception on the same dish (aligned on E 10-A) is at the usual 'signal values' so I do not believe my dish has become mis-aligned during the gales here.
Regards,
John.
John,

I don't think anything is "wrong" but I do understand that tests may be carried out to understand how the new on=frequency transponder may be affecting the existing BAS/HVS-1 reception.

Your reports, and others, to EUMETSAT will be very welcome.

Cheers,
David
--
SatSignal Software - Quality software for you
Web: https://www.satsignal.eu
Email: david-taylor@...
Twitter: @gm8arv