97W PIT channel FEC

[meinename]

The PIT channel on 97W 11779 H 3979
It giving me a blazing hot 82%Q on my Direcway dish and Coolsat 5000

Mike's list has it listed at 3/4 but I don't usually see this Quality until the FEC drops to 2/3 or even 1/2

Could any one, with the tools, please take a moment to check what the FEC is of that TP?

 

[Smith P.]

I'm using AUTO for FEC.

 

[meinename]

I'm using AUTO for FEC.

I usually don't need to worry about FEC except to make sure it's not 5/6 or 7/8 in case I NEED to really fine tune the dish for higher quality...
If I needed the setting I would have spent the time to figure it out myself.
But all of my equipment uses AUTO for FEC, so I can't figure it out.
I'm just wondering if the uplink is really that great or did they set the FEC really low.
The last time I saw a 90%Q was when I had a Geosatpro 90cm aimed at 129W for Whitesprings
I rarely see above 72%Q most days.

I'm looking for anyone who has a moment to check.

 

[phlatwound]

I'm showing FEC 3/4 with my Visionsat.

 

[meinename]

Thanks phlatwound!

Now if RTN could get these guys to help out

 

[B.J.]

I'm showing FEC 3/4 with my Visionsat.

Broadlogic shows 3/4 also.

 

[meinename]

Thanks B.J.!

That's confirmation!

 

[AcWxRadar]

The PIT channel on 97W 11779 H 3979
It giving me a blazing hot 82%Q on my Direcway dish and Coolsat 5000

Mike's list has it listed at 3/4 but I don't usually see this Quality until the FEC drops to 2/3 or even 1/2

Could any one, with the tools, please take a moment to check what the FEC is of that TP?

Meinename,

The FEC is supposed to be 3/4 per Lyngsat and SatCoDX. If this is how they are transmitting the signal, I don't understand how you are able to alter it.

If I understand this correctly, the symbol rate for this transponder is 3979 MS/s, so then 3/4 of those symbols are sent "FORWARD" as a redundant means of correcting any errors due to losses during transmission. This would defer the errors due to rain fade or other attenuations (to some extent).

If the signal transmits one frame of video information, then 3/4 of the data being sent to represent that frame is the same information sent over again or repeated. Hence, the more redundant information sent, the less chance for your receiver to display tiling or artifacts in the video or popping and squeaking in the audio or total loss of either.

The FEC should improve your quality as the number or ratio increases. So what you are describing seems to be the opposite of what I understand. Since they transmit the signal with a specific FEC rate, there is no way that you can alter that. Please tell us how you are altering the FEC.

Need more input.

RADAR

 

[meinename]

AcWxRadar,

I'm trying out a new (to me) dish and getting a surprisingly strong signal.

I was wondering if something had changed on the uplink side that I couldn't test for.
So I asked here if some with the equipment would check for me.
I understand that FEC is something set at the uplink and not set by me.

I understand the 1/2, 2/3, 3/4 are pretty redundant, making 5/6 and 7/8 lacking in error correction.
I understand that each FEC level changes the effective bitrate in exchange for lack of tiling/dropouts

I've read that some PC DVB-S/S2 devices require the receiving FEC set along with frequency, polarity, and symbol rate.
What I was referring to was the fact that if I had one, I would have to go through each of the 5 FEC levels before the device would give me any output.
However, I don't own any devices that can have or require a manually set FEC, but others here do.

 

[AcWxRadar]

AcWxRadar,

I'm trying out a new (to me) dish and getting a surprisingly strong signal.

I was wondering if something had changed on the uplink side that I couldn't test for.
So I asked here if some with the equipment would check for me.
I understand that FEC is something set at the uplink and not set by me.

I understand the 1/2, 2/3, 3/4 are pretty redundant, making 5/6 and 7/8 lacking in error correction.
I understand that each FEC level changes the effective bitrate in exchange for lack of tiling/dropouts

I've read that some PC DVB-S/S2 devices require the receiving FEC set along with frequency, polarity, and symbol rate.
What I was referring to was the fact that if I had one, I would have to go through each of the 5 FEC levels before the device would give me any output.
However, I don't own any devices that can have or require a manually set FEC, but others here do.

Mienename,

I think I understand you. You wanted to know if you had this other equipment that offered or allowed the FEC to be set/adjusted manually, if that would help you improve your reception...?

I certainly cannot answer that with any authenticity. I could only say that my gut feeling is no. I know that I can take my channel data from my Coolsat and edit it with Channel Master. In this proggy, I notice that there is an option to alter the FEC, but I don't believe the Coolsat receiver pays attention to this when you reload the channel list back to the receiver. It is either not allowed, it is ignored or just gets dropped and the receiver defaults to "AUTO" for the FEC.

In all honesty, I have to say that I simply do not know the answer. I would certainly like to know more about this angle, however. I have some general knowledge of FEC, just enough to realize what its purpose is, but not enough to understand the finer points.

RADAR

 

[B.J.]

...

If I understand this correctly, the symbol rate for this transponder is 3979 MS/s, so then 3/4 of those symbols are sent "FORWARD" as a redundant means of correcting any errors due to losses during transmission. This would defer the errors due to rain fade or other attenuations (to some extent).

If the signal transmits one frame of video information, then 3/4 of the data being sent to represent that frame is the same information sent over again or repeated. Hence, the more redundant information sent, the less chance for your receiver to display tiling or artifacts in the video or popping and squeaking in the audio or total loss of either.

The FEC should improve your quality as the number or ratio increases. ...

I think you have this backward (or else I do ).

The way I understand it, 3/4 FEC means that 3/4 of the data is the actual sent data, and the remaining 1/4 is the redundant data. So the higher the FEC, (closer to 1.0), the less error checking information, and the harder it is to avoid errors.
I think the calculations are as follows:

Say you have an SR of 27800.
If you are using QPSK, then the total bitrate is twice that, or 55600.
Adjust this by 188/204= 51239 , ie some bytes are overhead, not real data.
then multiply this by the FEC to get the actual bitrate,
ie 51239 * 3/4=38429 ie this is the final bitrate of data.

Therefore, the higher the FEC, the higher the percentage of bits transmitted is actual data, and the lower percentage of error correction.
So higher FEC means more more difficult to get error free viewing.

EDIT: I guess I should have used the above 3979 as an example.
SR=3979
total bitrate 7958
after adjusting for overhead 7333
7333*3/4 = 5500 ie bitrate of real data
7333*1/4 = 1833 ie redundant error correction bits. This would be lower with higher FEC.

 

[qwert1515]

B.J. Instead of doing the calculations by hand you can play with TheList_FEC_Calculator

 

[B.J.]

B.J. Instead of doing the calculations by hand you can play with TheList_FEC_Calculator

Thanks. (Good to see it came up with the same result... )
I have my own home-made calculator too, but I was doing it by hand, because I thought that doing that illustrated the real bits vs the error correcting bits, which was what I thought was in confusion.

 

[AcWxRadar]

I think you have this backward (or else I do ).

The way I understand it, 3/4 FEC means that 3/4 of the data is the actual sent data, and the remaining 1/4 is the redundant data. So the higher the FEC, (closer to 1.0), the less error checking information, and the harder it is to avoid errors.
I think the calculations are as follows:

Say you have an SR of 27800.
If you are using QPSK, then the total bitrate is twice that, or 55600.
Adjust this by 188/204= 51239 , ie some bytes are overhead, not real data.
then multiply this by the FEC to get the actual bitrate,
ie 51239 * 3/4=38429 ie this is the final bitrate of data.

Therefore, the higher the FEC, the higher the percentage of bits transmitted is actual data, and the lower percentage of error correction.
So higher FEC means more more difficult to get error free viewing.

EDIT: I guess I should have used the above 3979 as an example.
SR=3979
total bitrate 7958
after adjusting for overhead 7333
7333*3/4 = 5500 ie bitrate of real data
7333*1/4 = 1833 ie redundant error correction bits. This would be lower with higher FEC.

Thanks B.J.

I think you are correct and I am referring to it in reverse. I was trying to search out the information but not finding the information which spelled that out for me.

As you state, the lower the ratio (like 1/2) the better the error correction as opposed to 7/8.

For a FEC of 1/2, two symbols are sent and one of the two is a redundant error correction.

For a FEC of 7/8, eight symbols are sent and one of the eight is a redundant error correction.

So the numerator is the actual original symbols sent and the denominator is the total symbols sent. Meaning that the FEC of 1/2 has one error correction for every symbol sent and a FEC of 7/8 has only one error correction for every 8 symbols sent.

Am I analyzing this appropriately?

I have a hard time today securing this in my mind. When I think of FEC I want to think of the error correction as the first number (the numerator). But, that is not how the ratio is developed.

RADAR

P.S. Hope you guys and gals will forgive me today as I have a really bad virus and I can hardly keep my eyes focused on the screen here for very long. I get a bad headache and I start sneezing and my nose is running down the back of my throat and then I gag and cough and I am basically very miserable!!!! Help! LOL

 

[B.J.]

Thanks B.J.

I think you are correct and I am referring to it in reverse. I was trying to search out the information but not finding the information which spelled that out for me.

As you state, the lower the ratio (like 1/2) the better the error correction as opposed to 7/8.

For a FEC of 1/2, two symbols are sent and one of the two is a redundant error correction.

For a FEC of 7/8, eight symbols are sent and one of the eight is a redundant error correction.

So the numerator is the actual original symbols sent and the denominator is the total symbols sent. Meaning that the FEC of 1/2 has one error correction for every symbol sent and a FEC of 7/8 has only one error correction for every 8 symbols sent.

Am I analyzing this appropriately?

RADAR

P.S. Hope you guys and gals will forgive me today as I have a really bad virus and I can hardly keep my eyes focused on the screen here for very long. I get a bad headache and I start sneezing and my nose is running down the back of my throat and then I gag and cough and I am basically very miserable!!!! Help! LOL

That's sort of the way I understand it, relative to the number of error correction bytes, however I have virtually no understanding of how they actually use the error correction. I saw a nice web page once explaining it, but never quite figured it out. It had something to do with resending the partial data with replaced bits or something, so that they somehow could tell which bytes were in error. Ie, I don't think that a 1/2 FEC means that the same info is sent twice, as it has to be sent in a way to figure out where the errors are, and sending it twice, you still wouldn't know which was right. I almost understood it once, and meant to go back and read it again, but I never found time. Hopefully someone here knows how it's done, because it was interesting.

 

[phlatwound]

Thanks phlatwound!

Now if RTN could get these guys to help out

You're welcome! I hear ya on the RTN, it's been marginal for me the last couple of weeks.

 

[AcWxRadar]

That's sort of the way I understand it, relative to the number of error correction bytes, however I have virtually no understanding of how they actually use the error correction. I saw a nice web page once explaining it, but never quite figured it out. It had something to do with resending the partial data with replaced bits or something, so that they somehow could tell which bytes were in error. Ie, I don't think that a 1/2 FEC means that the same info is sent twice, as it has to be sent in a way to figure out where the errors are, and sending it twice, you still wouldn't know which was right. I almost understood it once, and meant to go back and read it again, but I never found time. Hopefully someone here knows how it's done, because it was interesting.

I understand you there, B.J.

I ran across all sorts of explanations and detailed information regarding FEC, but with my head feeling as bad as it is today, I couldn't really digest the information. I saved one of the pages to revisit later. It was quite in depth.

I don't think that this is information that we really need to be concerned with as most of our receivers handle this in an automatic sense. It will be fun to research this (when I get feeling better) however.

RADAR

 

[Smith P.]

Just short technical conclusion: you can't use improper FEC, if you sat-tuner cannot automatically change it to find correct one.

 

[meinename]

Mienename,

I think I understand you. You wanted to know if you had this other equipment that offered or allowed the FEC to be set/adjusted manually, if that would help you improve your reception...?

Close, I have nothing that tells me what the FEC level is that I'm receiving.
The different FEC levels have a direct effect on what the threshold Quality level is and how quickly the meter goes up the scale on my Coolsat.

Bad example:
1/2 FEC :up
Whitesprings takes almost no effort to get 72-90% on boresight. Offset 69%Q
If I work at it I can get 72%Q
Quality can drop to 58-60% before breakup/loss-of-signal
Estimated Time to Completion: 5 mins

3/4 FEC
Equity transponders fluctuate, so they are some of the best to learn how important it is to get it right the first time. When I go to aim at the Equity channels, I have to balance both Equity an my weather to figure out if it's just the Wx or if the Dish is off.
11720 V can be 66%-69%
11800 V usually is 69-72%
With bad weather in both places can drop down to 63%/66% (11720/11800, respectivly)
ETC:20 mins, up to an hour

7/8 FEC
3CTV on 123W requires some TLC and attention to bring up to 72%
However threshold is only at 70%. A good storm and 3CTV has no signal for
the duration of the storm.
ETC: 2 hours, probably more during a GOOD rainshower/rainstorm or two

NASA is also good for aiming D500's since it's a 7/8 FEC TP. Too bad I can almost never get above 72% but meh *shrugs*

I hear y'all screaming at me "preaching to the choir", and "I can do faster!"
It's my experience. I'm using it as an example.

I certainly cannot answer that with any authenticity. I could only say that my gut feeling is no. I know that I can take my channel data from my Coolsat and edit it with Channel Master. In this proggy, I notice that there is an option to alter the FEC, but I don't believe the Coolsat receiver pays attention to this when you reload the channel list back to the receiver. It is either not allowed, it is ignored or just gets dropped and the receiver defaults to "AUTO" for the FEC.

I've had the same experience with Channelmaster's FEC setting and loading various set FEC levels into my Coolsat.
I believe the FEC setting just gets ignored since I've loaded a fixed FEC setting list into the Coolsat, re-downloaded it as a completely different file, opened it in Channelmaster, and the setting was still there. But in watching channels, it seems to make no difference.

In all honesty, I have to say that I simply do not know the answer. I would certainly like to know more about this angle, however. I have some general knowledge of FEC, just enough to realize what its purpose is, but not enough to understand the finer points.

RADAR

So I saw an unusually strong transponder yesterday and today. :up
Unusually high quality even for a 3/4 FEC
I checked my equipment and couldn't find any changes, so I asked here for a datapoint that I can't find out on my own with what I have.
I wanted to know if the uplinkers had changed something or did just get good/lucky

And yes, P. Smith I realize that setting FEC wrong gives you nothing.
But I would be able to try them one at a time, 1/2 nothing; 2/3, nothing; 3/4; nothing; 5/6, nothing; 7/8, yep locked but weak. :
Good ol' process of elimination.

 

[Smith P.]

Unfortunately HW/FW and the error correction protocol cannot be changed that way what you using . I would say you're lucky to have the receiver what could lock with the wrong FEC command.
But inside of it it will do that job if it use correct value.
Short, you cannot cut variable number of bits from one packet when the count predetermined as per FEC value [created] before uplink.

Let me say other way - you can't start engine after you fueled 78 octane gas by changing tires or just telling the engine - "Start it !".