GOES 16 GRB downlink vs GVAR

[KWX]

KWX ,do you have a public email you don't mind to share,
or a temporary one I can contact you on?


No, It locked several times in the signal analyzer program without me doing anything but entering the proper info and to click the lock button.

Any way to DM you? I can only think of you going to the OSP chat room, if it can't be done here.

 

[N6BY]

KWX,

Its a bit hard to find in this forum's interface. To DM him click on his user name in the box to the left of one of his posts and then the 'Start a conversation' link.

 

[GOES 12 GVAR user]

Thanks Brett.
I contacted him waiting for a reply. The information I'm asking about KWX probably don't want on here for everyone to see.
I will strongly consider making a try for GOES 17.
I may also have some new information here that I can share about some of these signal strength issues.
I will say that all my "theory" points to the new goes satellites having quite directional (spot) L band downlink antennas.
More to come....later

 

[weather01089]

I have the DD card and you have to pull the coax a few times to get it to start sending data. My SN is 11. I have a Omicom card but it didnt seem to work. I may put it back in and test it again. Only drawback of the Omicom is that it has only one tuner. Need 2 of them for both streams.

 

[weather01089]

This is an RGB image generated from 3 GRB Channels. Some math done to fix the "green' which isnt true green in the data coming down (Band3)

 

[GOES 12 GVAR user]

I have a Omicom card but it didnt seem to work. I may put it back in and test it again.

The Ominicom card ID'd all the signal details in EBS Pro's analyzer. I don't know when you got yours but make sure that the driver is up to date. Would be my suggestion. It might just work.

Only drawback of the Omicom is that it has only one tuner.

Yes, but that's all I need AND can get here. More on that in a moment.
Nice looking Image there weather.

For what ever reason the Omnicom card had displayed the proper signal level info here when the TBS and Novra haven't.
The signal level as KWX said is 6.5 or very close to that as displayed by EBS pro in the pictures. It may be that the signal is so weak that the DVB-S2 receiver isn't capable of depicting it. It's also the reason my signal quality is so low.
It's not the feed or anything else.
So..
I (or anyone else) WILL NOT be able to get the Goes East GRB dual polarization's without a 15' dish. Yes a 15' dish or little more here in the Midwest.
It will take a 12' dish to get just the one stream here at around 8.5-9 dB C/N.
This data is confirmed by some info I got today. The info I hope to share on here to detail this reason.
So Brett I'm in the same boat with you there in Cal. with signal strength.
You guys on the East coast are lucky as the satellite's L band either spot or regional beam you fall under. The beam is pointed at Wallops Va. and the East coast.
To imagine this think of a large spot light pointed at Wallops Va.
Here is some of the hard Numbers, Weather you say that you have a 11 dB C/N there in Mass. with a 10' dish.
If you were only receiving 1 of the streams with that dish you would have somewhere near 14 dB C/N.
That's a difference of 7-7.5 dB C/N between Massachusetts and Iowa.
The next bit of info comes from KWX, he is using an 8' dish to get one stream, it will take me 12' dish to get one stream. There's a big difference.
My earlier numbers didn't even expect to see such a drop off in signal strength as you headed West. I was wayy off. It's also when I posted the very first info as the forum started that the signal was so strong at 89.5.
Hence this reason.
My information was based on the slot antenna that the N-P satellites used, even though they were single pol. their coverage was wide.
The big question is: What happens to GOES West and how will it affect Brett?
All that will come down to where they point that L band downlink beam. My theory says towards Boulder Co.
I figure that I have little chance of being able to do anything with that satellite when it's in position out West.
No this isn't frustration talking, I have been getting numbers and the info don't lie.
I really would like to see numbers of what Mike there is Fl. gets if he decides to put up a GRB station.
And this would also explain why KWX sees a signal level flux as depending on where he is in the beam in can very.

 

[KWX]

The Ominicom card ID'd all the signal details in EBS Pro's analyzer. I don't know when you got yours but make sure that the driver is up to date. Would be my suggestion. It might just work.


Yes, but that's all I need AND can get here. More on that in a moment.
Nice looking Image there weather.

For what ever reason the Omnicom card had displayed the proper signal level info here when the TBS and Novra haven't.
The signal level as KWX said is 6.5 or very close to that as displayed by EBS pro in the pictures. It may be that the signal is so weak that the DVB-S2 receiver isn't capable of depicting it. It's also the reason my signal quality is so low.
It's not the feed or anything else.
So..
I (or anyone else) WILL NOT be able to get the Goes East GRB dual polarization's without a 15' dish. Yes a 15' dish or little more here in the Midwest.
It will take a 12' dish to get just the one stream here at around 8.5-9 dB C/N.
This data is confirmed by some info I got today. The info I hope to share on here to detail this reason.
So Brett I'm in the same boat with you there in Cal. with signal strength.
You guys on the East coast are lucky as the satellite's L band either spot or regional beam you fall under. The beam is pointed at Wallops Va. and the East coast.
To imagine this think of a large spot light pointed at Wallops Va.
Here is some of the hard Numbers, Weather you say that you have a 11 dB C/N there in Mass. with a 10' dish.
If you were only receiving 1 of the streams with that dish you would have somewhere near 14 dB C/N.
That's a difference of 7-7.5 dB C/N between Massachusetts and Iowa.
The next bit of info comes from KWX, he is using an 8' dish to get one stream, it will take me 12' dish to get one stream. There's a big difference.
My earlier numbers didn't even expect to see such a drop off in signal strength as you headed West. I was wayy off. It's also when I posted the very first info as the forum started that the signal was so strong at 89.5.
Hence this reason.
My information was based on the slot antenna that the N-P satellites used, even though they were single pol. their coverage was wide.
The big question is: What happens to GOES West and how will it affect Brett?
All that will come down to where they point that L band downlink beam. My theory says towards Boulder Co.
I figure that I have little chance of being able to do anything with that satellite when it's in position out West.
No this isn't frustration talking, I have been getting numbers and the info don't lie.
I really would like to see numbers of what Mike there is Fl. gets if he decides to put up a GRB station.
And this would also explain why KWX sees a signal level flux as depending on where he is in the beam in can very.

An 8.5 to 9dB signal still good. I've ran under those ranges under some bad weather and I might loose about half a dB. If you point your dish to GOES17, how does it look?

 

[GOES 12 GVAR user]

After the info we have collected and having an (Edison moment)
I finally have numbers for min C/N for the GRB downlink. The GRB specs. sheet has a number 15.2 dB/K G/T.

link to document.
This number has meant little to me until now. This is the spec that NOAA requires for the receiver C/N.
So who on here has numbers close to this.
Drum roll please....
Ta da, Weather01089. His downlink in Mass has a C/N of 11 on RGB. It's under the 15.2 range but it's close enough that he has a solid downlink with some margin. As I stated above if he was receiving a single stream he would have a level of near 14 dB C/N, so if looking at it from that point he would be about a dB below NOAA's spec.
So a C/N of 10.5- 11 is fine for a single (B/W) downlink.
KWX and me both fall below this number. We only have about 9 dB C/N. So this means that if the downlink changes any we may fall below the threshold for good data.
What we have learned is a 6.7 - 7 dB C/N is noise as you approach 7.5- 8 dB C/N you can get constant data with small issues (depending on location). Looking at my theatrical downlink with a 12' dish gives me a margin of 1.5 or less with a 9 dB C/N. A 9.5 dB C/N would be better.
With a 11 dB C/N would give me 3.5 dB margin.
So for newbies looking to set up a GRB downlink, you are looking for a 11 dB C/N from their system for single stream (B/W) and a 14 dB C/N or
(11 dB if signal is already split such a septum feed like weather01089) for a RGB downlink.
So Brett you are looking at an 11 dB C/N with both streams running to get color images. Or 14 dB C/N if using one (stream) to measure.
You can get as low as 10 dB C/N (on septum feed) but you will only have around 1.5 dB margin.
Less then 10 dB C/N and you will be pushing it very close.
I will not have anything close to that here with out a really big dish.
"So what dish do I need Tim?", you ask.
Well it depends on your location. This only pertains to GOES East as of now.
Most should be able to get RGB with a 10' dish on the East coast but can get away with an 8' dish (B/W). As you move West it will take a 15' or bigger dish to get RGB in the Midwest (central part of the country) 12' for the min. on B/W. South central states my be a little less due to the prox. to the satellite. North Central states maybe a little more.
The Western states and West coast may also be able to get RGB with a 15' dish but I have no data to prove that and GOES west will change this outcome.

 

[GOES 12 GVAR user]

An 8.5 to 9dB signal still good. I've ran under those ranges under some bad weather and I might loose about half a dB.

See post above.

If you point your dish to GOES17, how does it look?

Haven't repointed yet. So no info here on that. I haven't seen anything on them doing preliminary testing GRB in any info I have seen.

 

[KWX]

After the info we have collected and having an (Edison moment)
I finally have numbers for min C/N for the GRB downlink. The GRB specs. sheet has a number 15.2 dB/K G/T.
View attachment 132692
link to document.
This number has meant little to me until now. This is the spec that NOAA requires for the receiver C/N.
So who on here has numbers close to this.
Drum roll please....
Ta da, Weather01089. His downlink in Mass has a C/N of 11 on RGB. It's under the 15.2 range but it's close enough that he has a solid downlink with some margin. As I stated above if he was receiving a single stream he would have a level of near 14 dB C/N, so if looking at it from that point he would be about a dB below NOAA's spec.
So a C/N of 10.5- 11 is fine for a single (B/W) downlink.
KWX and me both fall below this number. We only have about 9 dB C/N. So this means that if the downlink changes any we may fall below the threshold for good data.
What we have learned is a 6.7 - 7 dB C/N is noise as you approach 7.5- 8 dB C/N you can get constant data with small issues (depending on location). Looking at my theatrical downlink with a 12' dish gives me a margin of 1.5 or less with a 9 dB C/N. A 9.5 dB C/N would be better.
With a 11 dB C/N would give me 3.5 dB margin.
So for newbies looking to set up a GRB downlink, you are looking for a 11 dB C/N from their system for single stream (B/W) and a 14 dB C/N or
(11 dB if signal is already split such a septum feed like weather01089) for a RGB downlink.
So Brett you are looking at an 11 dB C/N with both streams running to get color images. Or 14 dB C/N if using one (stream) to measure.
You can get as low as 10 dB C/N (on septum feed) but you will only have around 1.5 dB margin.
Less then 10 dB C/N and you will be pushing it very close.
I will not have anything close to that here with out a really big dish.
"So what dish do I need Tim?", you ask.
Well it depends on your location. This only pertains to GOES East as of now.
Most should be able to get RGB with a 10' dish on the East coast but can get away with an 8' dish (B/W). As you move West it will take a 15' or bigger dish to get RGB in the Midwest (central part of the country) 12' for the min. on B/W. South central states my be a little less due to the prox. to the satellite. North Central states maybe a little more.
The Western states and West coast may also be able to get RGB with a 15' dish but I have no data to prove that and GOES west will change this outcome.

Don't exclude the minimum elevation. The 15dB they have is based on a northern most ground station in which GOES16/17 is at or close to 5 degrees from the horizon. So as you can see, the further down you travel in latitude the less the dish size gets as a minimum requirement. This is validated by me being able to get close to 9.9dB at times from an 8 foot dish (given my location in the SE US). If it wasn't for a line of site obstruction, I'm quite sure I would be close to 13dB to 15dB on my 10 foot.

Also, I just recently got a septum (yeah decided to bite the bullet lol), so the readings I provided above are from it... but more specifically for RHCP. LHCP give me close to 1dB down so I gets around 8.8dB.

 

[N6BY]

Tim, I think the minimum's you listed are too conservative. I was able to get GRB with a 10' dish and an SNR of only 6.6 dB. Millions of error free frames and numerous images came through.

From my post #152 here on January 21:

...
So last night I decided to try to tweak my dish setup here. I wrapped my LNA/Saw filter with aluminum foil and grounded it. It increased the SNR to 6.6 dB.

With that simple fix, I have been streaming for quite a while with 0 errors. Over 1.2 million error free packets here and counting! So I may have written off my TBS6983 too soon....

From my post #159 here on January 24:

... It was clear last night and I got an error free signal for a few hours. I was able to use GRBStreamer and GRBDump to capture a few GRB images.

The images are far from impressive since they were captured at night. But they are some of the first that I was able to get with my 10' dish here in California....

 

[GOES 12 GVAR user]

Don't exclude the minimum elevation. The 15dB they have is based on a northern most ground station in which GOES16/17 is at or close to 5 degrees from the horizon.

Yes, I can see what you are talking about KWX.
Doing some calculations..
NOAA's figure 15.2 minus 7.5 = 7.7.
So NOAA's figure gives a 7.7 dB C/N of margin.
So again I see that.
But most of my info is based off of weather01089 results.
Which is what you state with the 10' dish comment.

If it wasn't for a line of site obstruction, I'm quite sure I would be close to 13dB to 15dB on my 10 foot.

Your setup would be as good if not slightly better then weather's in Mass. As you state.
With those results you would have a margin of 2.5 dB C/N, this would be a solid downlink as 2 dB is adequate margin.
I didn't make it clear that NOAA's min. is not the absolute min. that can be had. Numbers we are looking for should be very near weather01089 C/N.
In my opinion.
Below weather's and your margin is getting thin even though it may still work.
As I stated for Brett, depending on what happens with GOES West he may be able use an 8' dish at his location but he should be looking for a 11 dB C/N or more for RGB reception and no less then 10 on whatever he uses.
The antennas I list are safe margin chosen, as well the sizes 8',10',12',15' are common ones.
So, the South East US should be able to get by with a 10' dish for RGB. Again 8' may work but it's cutting it close.
The numbers you post 8.8 dB C/N minus 7.5 = 1.3 dB of margin above noise so that to keep the error rate to a min. even though again it still may work.

I've ran under those ranges under some bad weather and I might loose about half a dB.

So then you are at .8 above min. This is what I mean.
If anything were to happen to the downlink not weather related, such as a transmitter issue/degradation you fall below that min. threshold.
I know in your case and many others you do with what you got, I understand that.
But if you could get the 10' dish to work or get one up (unobstructed) you would have that much more for give of the unexpected.

Also, I just recently got a septum (yeah decided to bite the bullet lol), so the readings I provided above are from it

Congrads, since you know it works I can see why you got one.

 

[GOES 12 GVAR user]

I was able to get GRB with a 10' dish and an SNR of only 6.6 dB. Millions of error free frames and numerous images came through.

Yes, but you couldn't hold the link which means you were right at threshold.
So at 6.6 and the signal isn't stable and even up to 7.
So I use 7.5 as a safe threshold reference for my calculations.
I figure at or below 7.5 the link may drop out at some time, even though you can still get all kinds of data .I'm looking over some of my info.
Brett, If you were able to setup a 12' dish that 6.6 should get to a 9 by my calculation.
At 9 you don't have dropouts any more but have 1.5 dB C/N of margin on RGB. Which is very usable at that level.
The next dish size 15' and by my calculation should give you a C/N 12.6. That number is above the 2 dB of margin.
Do you need a 15' dish? No, but there are not many dish sizes that are between 12 and 15' so I use what's common..
Moral of the explanation is that you could get away with a 12' dish fine, but if (as explained above) something happens that degrades the transmitter or other issue and that margin may be gone.

 

[GOES 12 GVAR user]

So a C/N of 10.5- 11 is fine for a single (B/W) downlink.

I can drop that to a 10. So a 10 dB C/N is fine for single (B/W) downlink
My correction.
Next:

So for newbies looking to set up a GRB downlink, you are looking for a 11 dB C/N from their system for single stream (B/W) and a 14 dB C/N or
(11 dB if signal is already split such a septum feed like weather01089) for a RGB downlink.

I will correct to:
So for newbies looking to set up a GRB downlink, you are looking for a 10 dB C/N from their system for single stream (B/W) and a 10 -11 dB C/N if signal is already split such a septum feed like weather01089) for a RGB downlink
The 13 dB C/N is used if you are using only a single stream feed to determine to possibility to get RGB.
How this is figured, 13 minus 3 dB = 10 dB C/N gives 2.5 dB of margin.

Next:

So Brett you are looking at an 11 dB C/N with both streams running to get color images. Or 14 dB C/N if using one (stream) to measure.
You can get as low as 10 dB C/N (on septum feed) but you will only have around 1.5 dB margin.
Less then 10 dB C/N and you will be pushing it very close.

Correction:
So Brett you are looking at an 10-11 dB C/N with both streams running to get color images. Or 13 dB C/N if using one (stream) to measure.
You can get as low as 9 dB C/N (on septum feed) but you will only have around 1.5 dB margin but still usable.

Tim, I think the minimum's you listed are too conservative.

So yes I was being a bit conservative on the numbers.

 

[GOES 12 GVAR user]

Lastly, GOES 17 is outgassing so the GRB data will not be activated until that process is done. What I read on the GOES R page.

 

[weather01089]

Thanks Brett.

I may also have some new information here that I can share about some of these signal strength issues.
I will say that all my "theory" points to the new goes satellites having quite directional (spot) L band downlink antennas.
More to come....later

that is definately not true. During the GOES16 test phase at 89.5 degrees (Mid US), I had just about the same signal level as I do now with it parked east. Also Brett had signal on an 8 ft dish in California in the 6.5 db SN range at the same time. I asked NOAA, and they say its not a spot beam, but northern hemisphere.

 

[GOES 12 GVAR user]

that is definately not true.

I asked NOAA, and they say its not a spot beam, but northern hemisphere.

I revised that in post #486 to spot or regional.

You guys on the East coast are lucky as the satellite's L band either spot or regional beam you fall under. The beam is pointed at Wallops Va. and the East coast

Anyway, I seem to be raising some eyebrows with my info so I will leave it as is.
I am wrong... I will correct the info I post.
And I have been wrong on here. (throws hands up in the air)
But I feel that these opinions are correct for the info I have now.
So with that let's see what the next step is going to be as this thing moves along.

 

[weather01089]

They will be doing some testing in the GRB link the next few weeks to start. I posted the info on the OSP chat. I am getting nice HRIT signal from GOES17 with a grid antenna but no data on that yet.

 

[GOES 12 GVAR user]

KWX, Since you are receiving HRIT I was wondering if you know that there was a (and still may be) a discussion on adding the GLM product data on HRIT.
Maybe they already added it now.
I saw that info in a bulletin that on got on email a while back.

 

[KWX]

They will be doing some testing in the GRB link the next few weeks to start. I posted the info on the OSP chat. I am getting nice HRIT signal from GOES17 with a grid antenna but no data on that yet.

Saw late yesterday a report that HRIT at GOES17 has started sending data.