Topics

EUMETCAST Loss of High Volume Services

Peter Chiu - UKRI STFC
 

Hello everyone,

We have an EUMETCast Linux reception station that has developed a fault on the
Ayecka SR1 DVB receiver last month.  Having replaced the SR1 receiver, we are now
able to collect all the basic services data, but only a tiny fraction of the high volume services.

Typically, we are getting the hvs-1/EPS1, EPS2, EPS5, EPS10 data during the hour
between 06:00 and 07:00 but almost nothing outside that period.

Ironically we had been getting the full hvs-1 data without issue before the breakdown on the SR1.
Currently the signal Demodulator Es/N0 is about 9db.

Before attempting the option of adjusting the dish pointing on site which being locked down,
I wonder if any one has any advice that we can try to improve the hvs1 data reception.

Many thanks.

Regards,
Peter Chiu
STFC RAL
 
 
 

Ernst Lobsiger
 

Peter,

Es/NO should at least be 13dB for good HVS reception.

Regards
Ernst

Peter Chiu - UKRI STFC
 

Thanks, Ernst,

 

Somehow we had been able to receive hvs-1 data with a lower signal strength.

I suppose there is no other way apart from adjust the dish pointing to boost signal strength.

 

Peter

 

From: MSG-1@groups.io <MSG-1@groups.io> On Behalf Of Ernst Lobsiger via groups.io
Sent: 29 April 2020 11:25
To: MSG-1@groups.io
Subject: Re: [MSG-1] EUMETCAST Loss of High Volume Services

 

Peter,

Es/NO should at least be 13dB for good HVS reception.

Regards
Ernst

Alan Sewards
 

Hi
I would suspect the new SR1 receiver first. Have you a third receiver that you could substitute to test this? Has the new receiver been set up correctly? There is a clear disconnect at the receiver substitution and it is unlikely that the dish alignment got disturbed coincidentally.
Best of luck!
Alan Sewards

On 29 Apr 2020, at 12:06, Peter Chiu - UKRI STFC <peter.chiu@...> wrote:
Hello everyone,

We have an EUMETCast Linux reception station that has developed a fault on the
Ayecka SR1 DVB receiver last month.  Having replaced the SR1 receiver, we are now
able to collect all the basic services data, but only a tiny fraction of the high volume services.

Typically, we are getting the hvs-1/EPS1, EPS2, EPS5, EPS10 data during the hour
between 06:00 and 07:00 but almost nothing outside that period.

Ironically we had been getting the full hvs-1 data without issue before the breakdown on the SR1.
Currently the signal Demodulator Es/N0 is about 9db.

Before attempting the option of adjusting the dish pointing on site which being locked down,
I wonder if any one has any advice that we can try to improve the hvs1 data reception.

Many thanks.

Regards,
Peter Chiu
STFC RAL
 
 
 

David J Taylor GM8ARV 🏴󠁧󠁢󠁳󠁣󠁴󠁿 🇪🇺
 

Thanks, Ernst,

Somehow we had been able to receive hvs-1 data with a lower signal strength.

I suppose there is no other way apart from adjust the dish pointing to boost signal strength.

Peter
======================================

Peter,

You can adjust the Link Margin thresholds in the SR1 setting when it stops receiving a signal and when it restarts. In one HVS-2 system here I have lower 0.0 dB and upper 0.1 dB. It's 4 (system), G (...Thresholds) from the main menu. I recall this as being rather lower than the default. Check and see what the values are.

However, as Ernst says, you want to be looking for a greater link margin if at all possible. You may be able to get an idea of the performance of various systems in different locations here:

Link Margin:
https://www.satsignal.eu/mrtg/performance_eumetcast-europe_link_margin.php

Es/No (SNR):
https://www.satsignal.eu/mrtg/performance_eumetcast-europe_snr.php

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

Peter Chiu - UKRI STFC
 

Thanks David,

Currently the link margins are:

G
RX Link Margin Thresholds
=========================

1. Lower threshold 0.6 dB
2. Upper threshold 0.7 dB

whereas
Demodulator Es/N0 7.2 dB

What do these link margins mean?
In your link margin chart for Loughborough
Am I right that the blue line is the HVS-1 link margin, which is between 2 and 4 dB
And the basic service green area is between 0 and 7.

What lower and upper thresholds would you suggest me to change to?

Regards,
Peter

-----Original Message-----
From: MSG-1@groups.io <MSG-1@groups.io> On Behalf Of David J Taylor via groups.io
Sent: 29 April 2020 15:43
To: MSG-1@groups.io
Subject: Re: [MSG-1] EUMETCAST Loss of High Volume Services

Thanks, Ernst,

Somehow we had been able to receive hvs-1 data with a lower signal strength.

I suppose there is no other way apart from adjust the dish pointing to boost signal strength.

Peter
======================================

Peter,

You can adjust the Link Margin thresholds in the SR1 setting when it stops receiving a signal and when it restarts. In one HVS-2 system here I have lower 0.0 dB and upper 0.1 dB. It's 4 (system), G (...Thresholds) from the main menu. I recall this as being rather lower than the default. Check and see what the values are.

However, as Ernst says, you want to be looking for a greater link margin if at all possible. You may be able to get an idea of the performance of various systems in different locations here:

Link Margin:
https://www.satsignal.eu/mrtg/performance_eumetcast-europe_link_margin.php

Es/No (SNR):
https://www.satsignal.eu/mrtg/performance_eumetcast-europe_snr.php

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

Peter Chiu - UKRI STFC
 

Thanks for your reply, Alan,

 

No suitable substitute I can test it against, unfortunately.

As to the set up, I believe I have followed the Ayecka SR1 Eumetcast set up guide v3F dated 15 April 2016.

 

Essentially, I connected up the SR1 receiver over the USB port, and loaded in the configuration

file sr1cfg under SR1CFG_DVBS2_ACTIVE_CONNECTED_MNGT-MLCST-ON_HVS-ENBLD_THRHLDS06-07_v255 that I picked up from ftp.eumetsat.int.

 

The last step was to set MODCODS FILTER to x41000.

 

The basic services seem to work fine, just not the high volume services.

 

Regards,

Peter

 

From: MSG-1@groups.io <MSG-1@groups.io> On Behalf Of Alan Sewards
Sent: 29 April 2020 15:44
To: msg-1@groups.io
Subject: Re: [MSG-1] EUMETCAST Loss of High Volume Services

 

Hi

I would suspect the new SR1 receiver first. Have you a third receiver that you could substitute to test this? Has the new receiver been set up correctly? There is a clear disconnect at the receiver substitution and it is unlikely that the dish alignment got disturbed coincidentally.

Best of luck!

Alan Sewards

On 29 Apr 2020, at 12:06, Peter Chiu - UKRI STFC <peter.chiu@...> wrote:

Hello everyone,

We have an EUMETCast Linux reception station that has developed a fault on the
Ayecka SR1 DVB receiver last month.  Having replaced the SR1 receiver, we are now
able to collect all the basic services data, but only a tiny fraction of the high volume services.

Typically, we are getting the hvs-1/EPS1, EPS2, EPS5, EPS10 data during the hour
between 06:00 and 07:00 but almost nothing outside that period.

Ironically we had been getting the full hvs-1 data without issue before the breakdown on the SR1.
Currently the signal Demodulator Es/N0 is about 9db.

Before attempting the option of adjusting the dish pointing on site which being locked down,
I wonder if any one has any advice that we can try to improve the hvs1 data reception.

Many thanks.

Regards,
Peter Chiu
STFC RAL
 
 
 

Ernst Lobsiger
 

Peter,

Once again: Your Es/NO is far too low!
You gave us two figures 9db and 7.2dB.
You have *no* HVS-1 Link Margin (LM).

The following figures have been discussed and published many times.
I doubt that you ever had acceptable HVS-1 reception with Es/NO=9dB


BASIC SERVICE:    8PSK 3/5     LM = Es/NO - 5.9 dB
HVS-1 , HVS-2:  16APSK 2/3     LM = Es/NO - 9.3 dB

The two equations are AFAIK hard coded in your SR1.

For good reception you should see LM >= 4dB as recommended by EUMETSAT.
This puts you at app. Es/NO >= 10dB for BASIC and Es/NO >= 13 dB for HVS-1.

Check anntenna pointing and the whole HF side (LNB, Cables, SR1) of the reception chain.


Regards,
Ernst

David J Taylor GM8ARV 🏴󠁧󠁢󠁳󠁣󠁴󠁿 🇪🇺
 

Thanks David,

Currently the link margins are:

G
RX Link Margin Thresholds
=========================

1. Lower threshold 0.6 dB
2. Upper threshold 0.7 dB

whereas
Demodulator Es/N0 7.2 dB

What do these link margins mean?
In your link margin chart for Loughborough
Am I right that the blue line is the HVS-1 link margin, which is between 2 and 4 dB
And the basic service green area is between 0 and 7.

What lower and upper thresholds would you suggest me to change to?

Regards,
Peter
===================================

Peter,

Yes, you're reading the charts correctly. The Link Margin is effectively how much the signal can drop before service is lost. 7 dB is plenty. EUMETSAT recommend 4 dB. This will mean that in times of heavy rain or clouds with ice crystals the signal may be attenuated enough that the margin drops to zero, and the receiver will be unable to demodulate the signal and retrieve the data. For a given signal level (and noise level), because the HVS requires a higher data rate and a higher signal-to-noise ratio, the same signal has a lower link margin for HVS, and that service will be lost before the BS is lost.

There's an added complication in that the same signal is switched between BS and HVS, but if the signal is too low for HVS the receiver may not know when HVS is finished (this happens many times a second), so it may also fail to recover some of the BS as well. Hence if you want reliable BS, don't enable the HVS!

You can try the values I already suggested: lower 0.0 dB and upper 0.1 dB.

Do carefully check the dish alignment in azimuth, elevation and the skew of the LNB (twist). As there is another signal on the same frequency, from the same satellite, getting the skew of the LNB correct so that it rejects the signal of the unwanted polarisation is very important. Compare your dish size and location with others on my page to see what you might expect.

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

Peter Chiu - UKRI STFC
 

Thanks David,

Very useful knowledge about the use of link margins.
I shall try to give it a go and see if that helps.

Fine dish adjustment is something we shall need to look into once the site lockdown is lifted.
It is interesting to know the trade off on concurrent handling of dual services.
It has not been an issue for us for a few years somehow.
Maybe the older SR1 receivers are more tolerant in handling the two.

It is great to hear from you.

Regards,
Peter

-----Original Message-----
From: MSG-1@groups.io <MSG-1@groups.io> On Behalf Of David J Taylor via groups.io
Sent: 29 April 2020 19:25
To: MSG-1@groups.io
Subject: Re: [MSG-1] EUMETCAST Loss of High Volume Services

Thanks David,

Currently the link margins are:

G
RX Link Margin Thresholds
=========================

1. Lower threshold 0.6 dB
2. Upper threshold 0.7 dB

whereas
Demodulator Es/N0 7.2 dB

What do these link margins mean?
In your link margin chart for Loughborough Am I right that the blue line is the HVS-1 link margin, which is between 2 and 4 dB And the basic service green area is between 0 and 7.

What lower and upper thresholds would you suggest me to change to?

Regards,
Peter
===================================

Peter,

Yes, you're reading the charts correctly. The Link Margin is effectively how much the signal can drop before service is lost. 7 dB is plenty.
EUMETSAT recommend 4 dB. This will mean that in times of heavy rain or clouds with ice crystals the signal may be attenuated enough that the margin drops to zero, and the receiver will be unable to demodulate the signal and retrieve the data. For a given signal level (and noise level), because the HVS requires a higher data rate and a higher signal-to-noise ratio, the same signal has a lower link margin for HVS, and that service will be lost before the BS is lost.

There's an added complication in that the same signal is switched between BS and HVS, but if the signal is too low for HVS the receiver may not know when HVS is finished (this happens many times a second), so it may also fail to recover some of the BS as well. Hence if you want reliable BS, don't enable the HVS!

You can try the values I already suggested: lower 0.0 dB and upper 0.1 dB.

Do carefully check the dish alignment in azimuth, elevation and the skew of the LNB (twist). As there is another signal on the same frequency, from the same satellite, getting the skew of the LNB correct so that it rejects the signal of the unwanted polarisation is very important. Compare your dish size and location with others on my page to see what you might expect.

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

Peter Chiu - UKRI STFC
 

Thanks, Ernst,

 

The signal strength we get does vary at different times of the day.

Just now, the signal strength returns to 9.2 dB again, as shown below.

 

I accept that a good signal strength of 13db or above is essential.

We shall try to look into this once the site lockdown is lifted.

 

I was thinking if there is any other way to help with this situation until then.

Thanks a lot of your input, very important to know that this is hard-coded in the SR1 receiver.

So there is probably no other way.

 

Regards,

Peter

 

================================================================================

SR1c Serial No. 103776  30AAC                              Run Time:    1:03:05

SW Ver  1.05b265  V     HW Ver  2.02    FW Ver  2.02b022 V      BL Ver  1.01b15

 

RX1: Active, Locked

EUMETCast DVB-S2 1512.500 MHz, DVB-S2 8PSK 3/5, 32.995 Msps, ACM, 9.2 dB

 

RX2: Not Active, Not Locked

Profile 1 1100.000 MHz, Auto

 

RX Status 1, Configuration 2

================================================================================

1. Tuner Status                         Locked

2. Demodulator Status                   Locked

3. Transport Status                     Locked

4. Demodulator Frequency Offset         -726 KHz

5. Demodulator Es/N0                    9.4 dB

6. Signal Input Level                   -27.0 dBm

7. Demodulator BER                      0.00 e-7

8. Bad Frame Count                      2325

9. Bad Packet Count                     2631

A. Demodulator Link Margin              0.1 dB

B. Modulation Order and Code Rate       DVB-S2 16APSK 2/3

C. Link Adaptation                      ACM

D. Pilots                               On

E. Frame Type                           Normal

F. Roll Off                             25%

G. FPGA                                 Loaded

=========================================================================

 

From: MSG-1@groups.io <MSG-1@groups.io> On Behalf Of Ernst Lobsiger via groups.io
Sent: 29 April 2020 19:18
To: MSG-1@groups.io
Subject: Re: [MSG-1] EUMETCAST Loss of High Volume Services

 

Peter,

Once again: Your Es/NO is far too low!
You gave us two figures 9db and 7.2dB.
You have *no* HVS-1 Link Margin (LM).

The following figures have been discussed and published many times.
I doubt that you ever had acceptable HVS-1 reception with Es/NO=9dB


BASIC SERVICE:    8PSK 3/5     LM = Es/NO - 5.9 dB
HVS-1 , HVS-2:  16APSK 2/3     LM = Es/NO - 9.3 dB

The two equations are AFAIK hard coded in your SR1.

For good reception you should see LM >= 4dB as recommended by EUMETSAT.
This puts you at app. Es/NO >= 10dB for BASIC and Es/NO >= 13 dB for HVS-1.

Check anntenna pointing and the whole HF side (LNB, Cables, SR1) of the reception chain.


Regards,
Ernst

geojohnt@...
 

Peter,

I might have missed this information in a post from you earlier(?), I've been inundated with hundreds of post in two of my groups in the last couple of weeks.

I'm interested that you said that you used to receive HVS-1 OK, then only between 06:00 and 07:00, then not at all.

What I'm not sure about is:

The size of your dish.

The make/model of LNB used.

The length and type of cable from the dish to the receiver.

The SNR you used to get when things were running OK.

And your location. 

Oh, and does the dish have a clear line of sight to the satellite - no trees grown up recently?

Regards,
John.


_._,_._,_

David J Taylor GM8ARV 🏴󠁧󠁢󠁳󠁣󠁴󠁿 🇪🇺
 

Thanks David,

Very useful knowledge about the use of link margins.
I shall try to give it a go and see if that helps.

Fine dish adjustment is something we shall need to look into once the site lockdown is lifted.
It is interesting to know the trade off on concurrent handling of dual services.
It has not been an issue for us for a few years somehow.
Maybe the older SR1 receivers are more tolerant in handling the two.

It is great to hear from you.

Regards,
Peter
============================================

Peter,

I rather doubt there's any difference between old and new receivers.

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

Ernst Lobsiger
 

Peter,

the signal strength is never 9.2dB but what is denoted by "6. Signal Input Level" below.
More important is Es/NO which is more or less  identcal with SNR (Signal to Noise Ratio)

As you can see my Link Margin formula applies below: 0.1 = 9.4 - 9.3

Regards,
Ernst


On Thu, Apr 30, 2020 at 01:53 AM, Peter Chiu - UKRI STFC wrote:

Just now, the signal strength returns to 9.2 dB again, as shown below.

...
5. Demodulator Es/N0                    9.4 dB

6. Signal Input Level                   -27.0 dBm

Peter Chiu - UKRI STFC
 

Thanks, John, for your reply.

 

I was not directly involved in the original specification

when the dish was installed back in 2016.  So I am afraid I don’t

have all the exact details.

 

I have just checked our old records and can find that we used to have 15dB signal strength before.

The current strength has certainly dropped to 7-9dB.

 

So this rather concurs with what Ernst has said about the strong signal strength and dish adjustment.

Looks like that is what we need to do as soon as we are allowed to get on site.

 

Regards,

Peter

 

From: MSG-1@groups.io <MSG-1@groups.io> On Behalf Of geojohnt via groups.io
Sent: 30 April 2020 10:44
To: MSG-1@groups.io
Subject: Re: [MSG-1] EUMETCAST Loss of High Volume Services

 

Peter,

 

I might have missed this information in a post from you earlier(?), I've been inundated with hundreds of post in two of my groups in the last couple of weeks.

 

I'm interested that you said that you used to receive HVS-1 OK, then only between 06:00 and 07:00, then not at all.

 

What I'm not sure about is:

 

The size of your dish.

 

The make/model of LNB used.

 

The length and type of cable from the dish to the receiver.

 

The SNR you used to get when things were running OK.

 

And your location. 

 

Oh, and does the dish have a clear line of sight to the satellite - no trees grown up recently?

 

Regards,

John.

 

 

David J Taylor GM8ARV 🏴󠁧󠁢󠁳󠁣󠁴󠁿 🇪🇺
 

Thanks, Ernst,

The signal strength we get does vary at different times of the day. Just now, the signal strength returns to 9.2 dB again, as shown below.

I accept that a good signal strength of 13db or above is essential. We shall try to look into this once the site lockdown is lifted.

I was thinking if there is any other way to help with this situation until then. Thanks a lot of your input, very important to know that this is hard-coded in the SR1 receiver. So there is probably no other way.

Regards,
Peter
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

SR1c Serial No. 103776 30AAC Run Time: 1:03:05
SW Ver 1.05b265 V HW Ver 2.02 FW Ver 2.02b022 V BL Ver 1.01b15

RX1: Active, Locked
EUMETCast DVB-S2 1512.500 MHz, DVB-S2 8PSK 3/5, 32.995 Msps, ACM, 9.2 dB

RX2: Not Active, Not Locked
Profile 1 1100.000 MHz, Auto

RX Status 1, Configuration 2
================================================================================
1. Tuner Status Locked
2. Demodulator Status Locked
3. Transport Status Locked
4. Demodulator Frequency Offset -726 KHz
5. Demodulator Es/N0 9.4 dB
6. Signal Input Level -27.0 dBm
7. Demodulator BER 0.00 e-7
8. Bad Frame Count 2325
9. Bad Packet Count 2631
A. Demodulator Link Margin 0.1 dB
B. Modulation Order and Code Rate DVB-S2 16APSK 2/3
C. Link Adaptation ACM
D. Pilots On
E. Frame Type Normal
F. Roll Off 25%
G. FPGA Loaded
=========================================================================

For comparison, my HVS-2 SR-1 shows:

================================================================================
SR1c Serial No. 111682 30AAC Run Time: 456:32:50
SW Ver 1.05b264 V HW Ver 2.10 FW Ver 2.02b922 O BL Ver 1.01b14

RX1: Active, Locked
EUMETCast.T2 1637.500 MHz, DVB-S2 16APSK 2/3, 32.995 Msps, ACM, 11.3 dB
================================================================================

RX Status 1, Configuration 1
============================
1. Tuner Status Locked
2. Demodulator Status Locked
3. Transport Status Locked
4. Demodulator Frequency Offset 152 KHz
5. Demodulator Es/N0 11.4 dB
6. Signal Input Level -41.0 dBm
7. Demodulator BER 0.00 e-7
8. Bad Frame Count 11869
9. Bad Packet Count 61456
A. Demodulator Link Margin 2.1 dB
B. Modulation Order and Code Rate DVB-S2 16APSK 2/3
C. Link Adaptation ACM
D. Pilots On
E. Frame Type Normal
F. Roll Off 20%
G. FPGA
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

So it seems that my software is slightly behind yours, and the hardware is slightly different (newer?).

Roll-off is interesting. You ahve 25%, I have 20%, and yet the EUMETCast specification is 5%!

https://www.eumetsat.int/website/home/Data/DataDelivery/EUMETCast/ReceptionStationSetup/index.html

I can imagine that some margin in the receiver is sensible, but are we both making the receiver bandwidth somewhat larger than is strictly required, and hence letting in slightly more noise than is strictly necessary? In the configuration guide it shows roll-off configuration as "Auto" and the status as 20%, so the transponder must be telling the receiver to set 20%.

I wonder.... If it wasn't for the lockdown I'd ask EUMETSAT to clarify this.

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

David J Taylor GM8ARV 🏴󠁧󠁢󠁳󠁣󠁴󠁿 🇪🇺
 

Hello everyone,
[]
Typically, we are getting the hvs-1/EPS1, EPS2, EPS5, EPS10 data during the hour
between 06:00 and 07:00 but almost nothing outside that period.
[]
Regards,
Peter Chiu
========================================

With everything else discussed, it suggests the disk is misaligned and only near enough to correct pointing during that period. plotting Link Margin versus time of day would be interesting:

https://www.satsignal.eu/wxsat/dvb-s2/sr1-mrtg.html

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