LRPT Laboratory


Fred Albertson
 

Hi Patrick, Andrea and Josef,

I have been working on the "Laboratory" project to see what is causing the black lines
in the LRPT pictures, and I have some (a little) data. 

I set up two independent strings of equipment:

String 1: Discone antenna (poor) -> Sawbird LNA/Filter -> Rspduo -> PC 1

String 2: QFH antenna (excellent) -> LNA4all (no filter) -> RTL/SDR 2832 -> PC 2

The antennas are 28m apart, which, I think, is about 12lambda.

I got my absolute best reception on String 2 with the longest coverage and over 6000
synchros.  When String 1 came up, I got the small section with  a lot of poor periods on
the beginning and end, which I cut out of the edit. They are both the _68 pictures.

The edits are slightly different in size but as as close as I could get.

The wide bar appears identical in both pictures. The narrow bars are different in each,

What does this show?  I think it points away from the "local interference" issue, but
I have no idea what would cause it.  Josef's pictures are much cleaner than mine.
Any thoughts?

String 1 Edit:                                                                                                                                          String 2 Edit
  

All of string 2 is attached. It is a pretty good look at the east coast of the US at 0800 local time.

I am trying to figure out how to improve the String 1 antenna, but short of building another
QFH, I do not know how.  I will say I am amazed at the String 2 performance.

This is an interesting exercise...

Great day,

Fred


Patrick Lindecker
 

Hello Fred,

 

Interesting study.

 

You are right: the wide bar is a deterministic phenomena, perhaps due to the satellite itself or some other common cause (to determine). The narrow lines are clearly due to the demodulation and the decoding in front of not perfect signals (signals not fixed in frequency and with having a limited signal to noise ratio). The random character is perhaps not total  (because of possible interferences) but elevated. Narrow lines are not correlated between your 2 strings.

 

Now, the interesting question is why these wide bars among comfortable signals? Are they common to regions or not? from the satellite?

The cause is not the receiver because from your two strings, you use two different receivers. So?

 

73

Patrick

 

De : multipsk@groups.io [mailto:multipsk@groups.io] De la part de Fred Albertson
Envoyé : mercredi 2 décembre 2020 15:42
À : mu
ltipsk@groups.io
Objet : [multipsk] LRPT Laboratory

 

Hi Patrick, Andrea and Josef,

I have been working on the "Laboratory" project to see what is causing the black lines
in the LRPT pictures, and I have some (a little) data. 

I set up two independent strings of equipment:

String 1: Discone antenna (poor) -> Sawbird LNA/Filter -> Rspduo -> PC 1

String 2: QFH antenna (excellent) -> LNA4all (no filter) -> RTL/SDR 2832 -> PC 2

The antennas are 28m apart, which, I think, is about 12lambda.

I got my absolute best reception on String 2 with the longest coverage and over 6000
synchros.  When String 1 came up, I got the small section with  a lot of poor periods on
the beginning and end, which I cut out of the edit. They are both the _68 pictures.

The edits are slightly different in size but as as close as I could get.

The wide bar appears identical in both pictures. The narrow bars are different in each,

What does this show?  I think it points away from the "local interference" issue, but
I have no idea what would cause it.  Josef's pictures are much cleaner than mine.
Any thoughts?

String 1 Edit:                                                                                                                                          String 2 Edit
  

All of string 2 is attached. It is a pretty good look at the east coast of the US at 0800 local time.

I am trying to figure out how to improve the String 1 antenna, but short of building another
QFH, I do not know how.  I will say I am amazed at the String 2 performance.

This is an interesting exercise...

Great day,

Fred

Attachments:


Patrick Lindecker
 

Fred,

 

If you zoom at the east of Florida, the clouds formation is curious. It seems waves or rather draperies.

 

73

Patrick

 

De : multipsk@groups.io [mailto:multipsk@groups.io] De la part de Fred Albertson
Envoyé : mercredi 2 décembre 2020 15:42
À : multipsk@groups.io
Objet : [multipsk] LRPT Laboratory

 

Hi Patrick, Andrea and Josef,

I have been working on the "Laboratory" project to see what is causing the black lines
in the LRPT pictures, and I have some (a little) data. 

I set up two independent strings of equipment:

String 1: Discone antenna (poor) -> Sawbird LNA/Filter -> Rspduo -> PC 1

String 2: QFH antenna (excellent) -> LNA4all (no filter) -> RTL/SDR 2832 -> PC 2

The antennas are 28m apart, which, I think, is about 12lambda.

I got my absolute best reception on String 2 with the longest coverage and over 6000
synchros.  When String 1 came up, I got the small section with  a lot of poor periods on
the beginning and end, which I cut out of the edit. They are both the _68 pictures.

The edits are slightly different in size but as as close as I could get.

The wide bar appears identical in both pictures. The narrow bars are different in each,

What does this show?  I think it points away from the "local interference" issue, but
I have no idea what would cause it.  Josef's pictures are much cleaner than mine.
Any thoughts?

String 1 Edit:                                                                                                                                          String 2 Edit
  

All of string 2 is attached. It is a pretty good look at the east coast of the US at 0800 local time.

I am trying to figure out how to improve the String 1 antenna, but short of building another
QFH, I do not know how.  I will say I am amazed at the String 2 performance.

This is an interesting exercise...

Great day,

Fred

Attachments:


Fred Albertson
 

HI,

I used to live in Miami and the cloud patterns were magnificent.  I they
are highly influenced by the Jet stream and the Gulf stream. 

This morning the winds were flowing strongly down the Florida peninsula,
driven by a cold front.  Caused the moisture to "stack up" off the coast.

Great day,

Fred


Andrea Dalbagno
 

Hello Fred

Very interesting experience!
As I read somewhere, the large black dash arises from synchro stuff of the sat scan system, so we can't do much about it.
I'm convinced that the other lines are the effect of ACARS, VSL-2 an VHF Signals, at least as I correlated them at my position, observing the waterfall on a "parallel" string.
This dosen't mean tha thare couldn't be other causes :-)

73
Andrea



Il giorno mer 2 dic 2020 alle ore 15:42 Fred Albertson <albertso@...> ha scritto:
Hi Patrick, Andrea and Josef,

I have been working on the "Laboratory" project to see what is causing the black lines
in the LRPT pictures, and I have some (a little) data. 

I set up two independent strings of equipment:

String 1: Discone antenna (poor) -> Sawbird LNA/Filter -> Rspduo -> PC 1

String 2: QFH antenna (excellent) -> LNA4all (no filter) -> RTL/SDR 2832 -> PC 2

The antennas are 28m apart, which, I think, is about 12lambda.

I got my absolute best reception on String 2 with the longest coverage and over 6000
synchros.  When String 1 came up, I got the small section with  a lot of poor periods on
the beginning and end, which I cut out of the edit. They are both the _68 pictures.

The edits are slightly different in size but as as close as I could get.

The wide bar appears identical in both pictures. The narrow bars are different in each,

What does this show?  I think it points away from the "local interference" issue, but
I have no idea what would cause it.  Josef's pictures are much cleaner than mine.
Any thoughts?

String 1 Edit:                                                                                                                                          String 2 Edit
  

All of string 2 is attached. It is a pretty good look at the east coast of the US at 0800 local time.

I am trying to figure out how to improve the String 1 antenna, but short of building another
QFH, I do not know how.  I will say I am amazed at the String 2 performance.

This is an interesting exercise...

Great day,

Fred

Attachments:





Fred Albertson
 

Hi Andrea,

I wonder, though, why the smaller lines are not in both of
the pictures.  If a VDL2 signal came up, I would expect it
on both images at roughly the same position. 

I can see the VDL2 activity on the edge of the spectrum.
Perhaps, because my antennas are so different, I pick up
the planes on one antenna and not the other, depending
on their position in the sky.  I can not see any VDL2 ground
stations from my location. If I could, it would be easier to
figure out, because movement would not be a factor.

BTW: I can't see any ground VDL2 stations because I have
mountains (my size, not yours!) between me and large
airports.

I'm going to keep playing.

Great day,

Fred


Josef Garcia
 

Hello everybody,
 
For your understanding: Meteor always sends a carrier signal at the beginning and end of a flyover.
Figure 1: Carrier signal in the waterfall.
Figure 2: At the top of the picture, the black wide bar, that is the carrier signal. 

73 Josef
DE3JGA


Patrick Lindecker
 

So wide bars are carrier signals sent regularly by Meteor, as synchronization signals. Thanks Josef for the information!

 

73

Patrick

 

De : multipsk@groups.io [mailto:multipsk@groups.io] De la part de Josef Garcia
Envoyé : jeudi 3 décembre 2020 10:02
À : multipsk@groups.io
Objet : Re: [multipsk] LRPT Laboratory

 

Hello everybody,

 

For your understanding: Meteor always sends a carrier signal at the beginning and end of a flyover.

Figure 1: Carrier signal in the waterfall.

Figure 2: At the top of the picture, the black wide bar, that is the carrier signal. 

73 Josef
DE3JGA

Attachments:


Fred Albertson
 

Hi Josef,

That is really good information,

Thank you.

Fred


Fred Albertson
 

Hi Patrick, Andrea and Josef,

More mysteries:

Yesterday, I took the QFH antenna and split the receive.  The resulting layout:

String 1: QFH antenna (split) -> Sawbird LNA/Filter -> Rspduo -> PC 1

String 2: QFH antenna (split) -> LNA4all (no filter) -> RTL/SDR 2832 -> PC 2

The attached picture shows the results from the two strings side by side:


I honestly do not know what I am seeing. I understand why I might
see more lines in the String 2 picture, since there is no filter in that
chain, but why are the lines different in thickness?

Any thoughts?

Great day,

Fred


Patrick Lindecker
 

Hello Fred,

 

It proves that the first configuration is better than the second one, for sure. Now about the thickness, it will deserve a big study… So it will remain a mystery.

 

73

Patrick

 

 

De : multipsk@groups.io [mailto:multipsk@groups.io] De la part de Fred Albertson
Envoyé : vendredi 4 décembre 2020 23:28
À : multipsk@groups.io
Objet : Re: [multipsk] LRPT Laboratory

 

Hi Patrick, Andrea and Josef,

More mysteries:

Yesterday, I took the QFH antenna and split the receive.  The resulting layout:

String 1: QFH antenna (split) -> Sawbird LNA/Filter -> Rspduo -> PC 1

String 2: QFH antenna (split) -> LNA4all (no filter) -> RTL/SDR 2832 -> PC 2

The attached picture shows the results from the two strings side by side:


I honestly do not know what I am seeing. I understand why I might
see more lines in the String 2 picture, since there is no filter in that
chain, but why are the lines different in thickness?

Any thoughts?

Great day,

Fred


Phil Walls
 

HI, i found this explanation from jeff K2SDR via reddit if it helps :

"It is the processing of the LRPT image on-board the satellite. There is no fix on the ground.

It generally happens around every 6:30 minutes (If I recall) but is less predictable in the evening.

Jeff K2SDR".

Phil.


On Sat, Dec 5, 2020 at 9:48 AM Patrick Lindecker <f6cte@...> wrote:

Hello Fred,

 

It proves that the first configuration is better than the second one, for sure. Now about the thickness, it will deserve a big study… So it will remain a mystery.

 

73

Patrick

 

 

De : multipsk@groups.io [mailto:multipsk@groups.io] De la part de Fred Albertson
Envoyé : vendredi 4 décembre 2020 23:28
À : multipsk@groups.io
Objet : Re: [multipsk] LRPT Laboratory

 

Hi Patrick, Andrea and Josef,

More mysteries:

Yesterday, I took the QFH antenna and split the receive.  The resulting layout:

String 1: QFH antenna (split) -> Sawbird LNA/Filter -> Rspduo -> PC 1

String 2: QFH antenna (split) -> LNA4all (no filter) -> RTL/SDR 2832 -> PC 2

The attached picture shows the results from the two strings side by side:


I honestly do not know what I am seeing. I understand why I might
see more lines in the String 2 picture, since there is no filter in that
chain, but why are the lines different in thickness?

Any thoughts?

Great day,

Fred






--
We swear by the southern cross, to stand truly by each other and to fight to defend our rights and liberties- 1854


Phil Walls
 

And more from jeff: " Attention!!! There is error in BIS-MW (adopter MSU-MR to LRPT). 2-bits Sequence Flag in the CCSDS primary header is faulty. Device BIS-MW instead of the flag last segment («10») erroneously generates the flag continuation segment («00»). Image compression algorithm for JPEG for equipment BIS-MW (adopter MSU-MR to LRPT) Jeff".


On Sat, Dec 5, 2020 at 9:58 AM Phil Walls via groups.io <dxtech01=gmail.com@groups.io> wrote:
HI, i found this explanation from jeff K2SDR via reddit if it helps :

"It is the processing of the LRPT image on-board the satellite. There is no fix on the ground.

It generally happens around every 6:30 minutes (If I recall) but is less predictable in the evening.

Jeff K2SDR".

Phil.


On Sat, Dec 5, 2020 at 9:48 AM Patrick Lindecker <f6cte@...> wrote:

Hello Fred,

 

It proves that the first configuration is better than the second one, for sure. Now about the thickness, it will deserve a big study… So it will remain a mystery.

 

73

Patrick

 

 

De : multipsk@groups.io [mailto:multipsk@groups.io] De la part de Fred Albertson
Envoyé : vendredi 4 décembre 2020 23:28
À : multipsk@groups.io
Objet : Re: [multipsk] LRPT Laboratory

 

Hi Patrick, Andrea and Josef,

More mysteries:

Yesterday, I took the QFH antenna and split the receive.  The resulting layout:

String 1: QFH antenna (split) -> Sawbird LNA/Filter -> Rspduo -> PC 1

String 2: QFH antenna (split) -> LNA4all (no filter) -> RTL/SDR 2832 -> PC 2

The attached picture shows the results from the two strings side by side:


I honestly do not know what I am seeing. I understand why I might
see more lines in the String 2 picture, since there is no filter in that
chain, but why are the lines different in thickness?

Any thoughts?

Great day,

Fred






--
We swear by the southern cross, to stand truly by each other and to fight to defend our rights and liberties- 1854





--
We swear by the southern cross, to stand truly by each other and to fight to defend our rights and liberties- 1854


Fred Albertson
 

Hi Phil,

Thank you for this information, and of course, thanks to Jeff.

That is really interesting and may explain our "lines problem."
It  also indicates that there is nothing we can do reduce the errors.

Appreciate your jumping in to the discussion to help.

Great day,

Fred



Andrea Dalbagno
 

Hello Fred
You made a very interesting test!
It seems to me that the string 1 image has a cut away part on the right margin compared to the string 2: in that part there are most of the lines that make the difference. Am I wrong?
Anyway I see some strong correlation in position (and consequently in time) between the rest of the lines.
So, we could summarize at least 3 type of lines:
- internal process syncro lines, the thickest ones.
- interference lines from VDL2, ACARS, VHF Coms, NOAA, that are on the same position (time) in 2 pictures taken in "parallel".
- random lines arising from the quality of the "string".
We can't do much against the first two phenomena, but we could improve our strings

Thanks Phil, for that piece of info.

73
Andrea

Il sab 5 dic 2020, 01:01 Fred Albertson <albertso@...> ha scritto:
Hi Phil,

Thank you for this information, and of course, thanks to Jeff.

That is really interesting and may explain our "lines problem."
It  also indicates that there is nothing we can do reduce the errors.

Appreciate your jumping in to the discussion to help.

Great day,

Fred






Fred Albertson
 

Hi Andrea, et al,

I think the right margin issue was my fault.  I had a terrible time getting the
pictures side by side in MS Paint. I apologize. I do not think that is anything
but operator error, but I will check to see if most of the lines are on the
right side in the future.

I agree with your continuing analysis.  I know that the strings are not equal.
The RSP is a far better radio than the other dongle. With both radios on the
QFH antenna, the reception start/finish times  (measured by solid Synchro)
are much better with the RSP. The Sawbird is also a factor.

I think I will go back to the maximum quality string and see if I can correlate
VHF interference somehow.

Thanks and great day,

Fred







Patrick Lindecker
 

Hello Fred and all,

 

Among all the options, it seems that a QFH antenna and a SDRplay is the best choice. But what about the 137 MHz Sawbird  amplifier + filter? Do you have better receptions with or without this device?

 

73

Patrick

 

De : multipsk@groups.io [mailto:multipsk@groups.io] De la part de Fred Albertson
Envoyé : samedi 5 décembre 2020 14:53
À : multipsk@groups.io
Objet : Re: [multipsk] LRPT Laboratory

 

Hi Andrea, et al,

I think the right margin issue was my fault.  I had a terrible time getting the
pictures side by side in MS Paint. I apologize. I do not think that is anything
but operator error, but I will check to see if most of the lines are on the
right side in the future.

I agree with your continuing analysis.  I know that the strings are not equal.
The RSP is a far better radio than the other dongle. With both radios on the
QFH antenna, the reception start/finish times  (measured by solid Synchro)
are much better with the RSP. The Sawbird is also a factor.

I think I will go back to the maximum quality string and see if I can correlate
VHF interference somehow.

Thanks and great day,

Fred






Tiziano Gmail
 

This is my picture that I get from Noaa, with SDR receiver, QFH antenna, without pre-amplifier and 25 meters of wire RG58..😬




Tiziano Pattaro - Ik3cob 


Il giorno 5 dic 2020, alle ore 20:19, Patrick Lindecker <f6cte@...> ha scritto:



Hello Fred and all,

 

Among all the options, it seems that a QFH antenna and a SDRplay is the best choice. But what about the 137 MHz Sawbird  amplifier + filter? Do you have better receptions with or without this device?

 

73

Patrick

 

De : multipsk@groups.io [mailto:multipsk@groups.io] De la part de Fred Albertson
Envoyé : samedi 5 décembre 2020 14:53
À : multipsk@groups.io
Objet : Re: [multipsk] LRPT Laboratory

 

Hi Andrea, et al,

I think the right margin issue was my fault.  I had a terrible time getting the
pictures side by side in MS Paint. I apologize. I do not think that is anything
but operator error, but I will check to see if most of the lines are on the
right side in the future.

I agree with your continuing analysis.  I know that the strings are not equal.
The RSP is a far better radio than the other dongle. With both radios on the
QFH antenna, the reception start/finish times  (measured by solid Synchro)
are much better with the RSP. The Sawbird is also a factor.

I think I will go back to the maximum quality string and see if I can correlate
VHF interference somehow.

Thanks and great day,

Fred









Fred Albertson
 

Hi Patrick,

That is my next test process: Sawbird in and out.

Great weekend,

Fred


Fred Albertson
 

Hi Tiziano,

That is truly a beautiful picture. 

Was that from one of the NOAA Satellites on 137.1 or 137.62 or 137.9125?
What program did you use to receive and to colorize it?

Fred