KU Band Transponder gets decent signal but 0 SNR, what can be done to fix it?

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enb141

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Aug 5, 2009
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Guys I was able to tune a Ku Band Transponder with my Chinese 1.2m offset dish, that transponder got pretty decent signal but SNR is 0, that means is too noisy, so I would like to know if is possible to fix?
 

pacificrim

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Oct 5, 2008
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If you are seeing a signal but not quality or showing 0 SNR, you are not locked on anything. Just connecting a LNB to a receiver will show a signal level. The problem could be anything like pointing, elevation, incorrect LO, etc.
 
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spongella

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Not sure what you mean by "tune;" do you mean using a meter or set top box (receiver)? More important than the signal level is the signal quality.
 

Cham

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What satellite and transponder is your dish looking at? Are you able to get a Q reading or better SNR from other TPs? Often higher order modulations require a higher signal to noise level to lock such as 8 and 16PSK. Also Forward Error Correction such as 9/10 on some TPs require a higher signal/noise level than 1/2 or 3/4. Sometimes you can squeeze an extra dB or so by adjusting skew and focal distance (LNB position in the bracket) to bring up a particular TP), but this might degrade others... but this is taking for granted the dish is aimed properly, which would be your first step in your dish setup procedure.
 

enb141

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Aug 5, 2009
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Hi guys, I'm trying to tune 116.8W @ 11800 H

Here is the NIT

NIT_116.8W.jpg


Here is the BlindScan

blind_scan_116.8W.jpg


As you can see from the graphic, the 11800 has a decent db (-40db) which in comparison to 11480 that has about -45db and I'm able to tune that frequency but the 11800 I can't.


Here is what I get if I try to tune 11800H

tunning_11800H.jpg


Sometimes SNR appears to be 0 and level seems to get lower / disappear as well
 

Brct203

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Dec 24, 2016
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As you can see from the graphic, the 11800 has a decent db (-40db) which in comparison to 11480 that has about -45db and I'm able to tune that frequency but the 11800 I can't.

Can you do a spectrum scan that is more focused on 11800, so that we see what's around it?

When you are comparing the signal at 11800 (Eutelsat 117WA) with the signal at 11480 (i think that Eutelsat 117 West B), I don't think that the -45 and -40 dB really matter. What matters is their level compared to the noise surrounding them (SNR). 8.4 dB might be a bit tight for an 8psk with FEC 3/4... i'm not sure

I remember seeing a table that listed the minimum SNR for each variant of modulations and FEC but now i can't find it
 

enb141

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Brct203, the weird thing is that I'm able to tune the higher frequencies of that NIT,

12040 H
12080 H
12100 V

All those frequencies I'm able to tune and pretty much those ones have about the same db (~ -45db)

Here's is the spectrum from 11790 to 11810

10800H_blindscan.jpg
 

Brct203

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i can't lock on that transponder either, neither can i lock on 11840 V. My Amiko does not even detect 11800. But now i'm wondering if those are maybe using some other modulation (16apsk? Digicipher?).

Note that those appear to be on the NAFTA beam, which covers the US, Canada and Mexico, but cuts of quite sharply around Guatemala, excluding the rest of Central America
 

N5XZS

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Let me DX this freq, since I am in New Mexico USA.:) And figure out what the signal's formats. I will get you the signal's formats if the signal I f still there.:)
 

Cham

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You likely need 10dB+ S/N in order to lock that transponder. Like Brct203 says the total signal doesn't really matter. It is the signal to noise level that is critical. According to what I see on that last graph is 2dB which is barely above the noise, however you can likely stretch out the frequency range just a bit and find a lower noise background. I have been able to lock signals in the 2-4dB range but these are DVB-S QPSK with low FEC like 1/2. 8-PSK is a different animal.
Try playing with your dish alignment and try to get it better. EBSPro uses a really nifty Android remote app that works super well for aligning your dish.
 

Cham

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11800 H 1000 DVB-S2, but modulation keeps switching between QPSK, 8PSK and 16PSK. not sure if screen cap below is readable...

upload_2018-11-2_16-1-32.png
 

Cham

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sounds like VCM.

Sure is.. actually ACM. It's vertical polarity too unless there is supposed to be one on horizontal as well. I'm up in Canada so the list might look different farther south.:

Eutelsat 117 West A 116.8W 2432 TBS 6903 DVBS/S2 Tuner 1 11802 Vertical 999.83 QPSK 3/4 DVB-S2 ON 0.20 Inverted ACM 1.487 1.199 10.9 -43 MIS: 1, BER: 0.0000000, Time to lock: 613 ms 2018-11-02 5:51:19 PM
 

Brct203

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Sure is.. actually ACM. It's vertical polarity too unless there is supposed to be one on horizontal as well. I'm up in Canada so the list might look different farther south.:

Eutelsat 117 West A 116.8W 2432 TBS 6903 DVBS/S2 Tuner 1 11802 Vertical 999.83 QPSK 3/4 DVB-S2 ON 0.20 Inverted ACM 1.487 1.199 10.9 -43 MIS: 1, BER: 0.0000000, Time to lock: 613 ms 2018-11-02 5:51:19 PM

it's strange that you're getting that on vertical and so narrow... what does the spectrum look like? On satsignature it's not showing anything that narrow around 11800, and 117W and 116.8 don't seem to have any beam that would bring different content to Canada (unlike 115W)
 

enb141

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Guys, This is the information taken from another transponder that belongs to the same NIT

DVB-S Orbital Position: 116.8W
Frequency: 11.800 GHz
Modulation: 8PSK (DVB-DSNG/Turbo/DVB-S2)
Polarity: Horizontal
Symbol Rate: 32720 MSps
FEC: 3/4

Some of you claim (Cham) that the SR is about 1000 so maybe is that why I cannot lock that transponder.

AFAIK that transponder is intended for south america but some of you are showing another one so maybe at the center of the continent (Guatemala in my case) those two transponders unite making it impossible to lock up.

Can somebody from the north can really tune 11.800 (I think is SR = 1000) and tell us that it is?
 

Brct203

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Dec 24, 2016
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That satellite (Eutelsat 117WA) has 3 Ku beams:
- Hemi - covers most of the Americas
- NAFTA - US, Mexico, Southern Canada, a bit of Guatemala
- South America - does not include Central America (cuts off in Panama)

(there's also Eutelsat 117WB but all of its transponders are in lower Ku band)

According to http://frequencyplansatellites.altervista.org/SatMex/Satmex_8.pdf, the Hemi beam is only above 12020 MHz

The NAFTA and South America beams use the same frequency plan from 11700 to 12020 but don't overlap at all in coverage

so from Guatemala, 11800H has to be the NAFTA beam, so should be the same all across North America. So the spectrum at SatSignature should be applicable to Guatemala as well as my location, and probably Cham's location, maybe with reduced power.

PortalEDS lists a mux at 11800H32727, but since the site is more about South America than central America, I have to guess that that mux is on the South American beam.

I don't see any other listing that shows anything at 11800H on that satellite, so maybe it's just a data transponder
 

enb141

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Aug 5, 2009
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According to that pdf file, there's two 11800 (Horizontal) frequencies, one for NAFTA and the other one is for South America, so that means why I'm getting high power (about -40db) because I'm getting some signal from both.

Once ago I did a blind scan and as far as I remember was able to get sr = 32727, instead of the sr = 1000 that many guys in this thread were getting, so that means I'm getting more power the South America beam (that I initially tough), but I'm also getting power from the NAFTA frequency, that's why I got lots of noise.
 

Brct203

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Dec 24, 2016
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According to that pdf file, there's two 11800 (Horizontal) frequencies, one for NAFTA and the other one is for South America, so that means why I'm getting high power (about -40db) because I'm getting some signal from both.

Once ago I did a blind scan and as far as I remember was able to get sr = 32727, instead of the sr = 1000 that many guys in this thread were getting, so that means I'm getting more power the South America beam (that I initially tough), but I'm also getting power from the NAFTA frequency, that's why I got lots of noise.

I doubt you're getting the South America beam because it's supposed to end more or less near the Panama/Colombia border according to the coverage maps
Satbeams - World Of Satellites at your fingertips
so quite far from your location.

Also SatSignature.com shows a wide signal on 11800H (something that looks like it could be a SR of 30000 or more). That is from the US Southwest. So my guess is that it's using some modulation that even the TBS cards can't properly detect
 

Titanium

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I doubt you're getting the South America beam because it's supposed to end more or less near the Panama/Colombia border according to the coverage maps
Satbeams - World Of Satellites at your fingertips
so quite far from your location.

Also SatSignature.com shows a wide signal on 11800H (something that looks like it could be a SR of 30000 or more). That is from the US Southwest. So my guess is that it's using some modulation that even the TBS cards can't properly detect
The 6922 doesn't decode ACM or VCM. I also understand that it doesn't do 16 or 32 psk. Need a different TBS card to support these formats.
 
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