Can't detect some transponders in SatMex5 and Satmex6

[robosat]

Hi Guys.

I'm new in C Band. After several days trying to aim my new 1.8m dish to AMC18 or Satmex6 satellites without success, I finnally decided to get help from someone with experience. The antena points now to SatMex5 and SatMex6 (moving the dish with a motor). I received with good quality signal (60-70) some channels from both satellites. But there are some transponders I know they have strong signal and are working that my MicroHD receiver can´t get. Example : In SatMex5, transponder 3720 (with a lot of channels), the MicroHD can't even detect Signal level bigger than 45 (gray color), and of course, cero quality signal. I tried deleting the transponder and addin it again. Nothing happens.
Does anybody know waht is happening? What can I do in order to get this transponder?
Greetings ...

 

[FaT Air]

If you do not get a Quality reading I'd suspect adjacent satellite interference on a 1.8m dish. Satmex6 has also 3720 V 13842 active.
http://www.lyngsat.com/SatMex-5.html
http://www.lyngsat.com/SatMex-6.html
Try 'bumping' the dish a few clicks one way then the other.

 

[robosat]

True. Thanks Fat Air. But maybe that's not the problem. There are other SatMex5 Transponders wich not exist in SatMex6, and also the MicroHD can't detect. The thing is when my installer did a blind scan with his receiver, I remember seen channels in transponders that the MicroHD couldn't even scan because no signal is detected. So, the fact is that one receiver (was an old one. I don´t remember its brand, but it had the same screens that Pansat had) can detect signal in one transponder, and the MicroHD doesn't.

 

[FaT Air]

Thoughts on 'missing' transponders/channels

If one receiver gets them, and the second doesn't, I'd have to think it's the receiver. Maybe the older receiver copes with interference better.(?) Or may have a 'hotter' tuner. Have read that the mHD tuner is one of the best performers in 'pulling in' weak transponders. This may be the downfall. The receiver is too good at weaker signals increasing the chances for adjacent satellites to interfere when using a 'small' dish.

Some times there's no real reason for a channel not to come in. I, and many others here and on other forums, have run into it. Works on receiver A & B, but C, D and E don't see it.
I don't see 3920 H 29125 @ 87W on my S9 and 10 ft BUD. Others do. Some with the same receiver and a smaller dish. (Absolutely '0' Quality here, 24/7. I might get it with another brand receiver, But I don't have another, so I don't know.)

"Small Dish"
Got to remember, a 1.8m dishes main lobe beamwidth is far greater than the spacing of the satellites. Could be 5°(?). 2.5° either direction. This could result from interference from both sides. Moving the dish a few clicks, one way or the other, may put the interference in a 'null' without losing too much of the desired signal.
"Transponders"
A transponder occupies more than just the published frequency. That's basically what you could call the 'center frequency". High SR's can occupy the spectrum + 15 to 20Mhz or more. So it wouldn't necessarily have to be 'right on' the published frequency. Lower SR transponders occupy a 'narrower slice' of the band. (There's formulas to calculate it, just can't find link today) This all means transponder 4000 H 30000 could interfere with 3985 H 5600 on the adjacent satellite.

Many have 'cut their teeth' with a 6 ft dish and upgraded to a larger. Larger produces more gain so is able to 'pull in' weaker transponders. The beamwidth becomes narrower as dish size increases decreasing chances of adjacent satellite interference. 10 ft just about guarantees there's going to be no adjacent interference. If I remember right, at 10 ft, the beamwidth is around 1.5°- 2.0°, putting any adjacent at least 1.0° outside the main lobe.

That's my thoughts on it.
Have a nice day, and many more.

 

[SatelliteAV]

What LNB/feedhorn or LNBF?
Any switches in line?
Are you sure that the LNBF polarity was correctly set and not 90 degrees out? Provide an example of a channel that is coming in? Freq, Polarity and SR?
Are you blind scanning the satellite or using preprogrammed transponders?

 

[robosat]

SatelliteAV : I'm using a C band BSC421 LNBF, and I did de scans conecting directly to the LNBF (no switches). Some channels that are detected :
In Satmex6 : 3768H Michoacán, 3773H Yucatán, 3780H Azteca 7 Nuevo León, Coahuila y Tamaulipas, 3821H Hidalgo, 3875H Cadena Tres, etc.
I'm seeing that no one Vertical Polarity Channel has been detected in Satmex5, SatMex6 and Galaxy23 (that´s all I've scanned until now). So, maybe you're right and the LNBF Polarity is wrong (although some Vertical Channels were detected with the installer's old reveiver). I'll work on it when I have the time one of these days.
By the way, I did all types of scan (preprogrammed TTPs, Blind Normal, Blind Detailed).

Thanks a lot...

 

[robosat]

Thanks FatAir. Very useful and interesting what you wrote. I appreciate it.

 

[pro96]

I get 3720 fine on Satmex 5 using my Opensat S10 and X2 and Blind Scanned them just fine. Could be the receiver.

Sent from my SPH-L900 using Tapatalk 2

 

[SatelliteAV]

There are many vertical channels on both satellites.

I would start by checking the LNBF Skew and Focal Distance. Next, check the voltage at the LNBF when the micro is on a horizontal transponder and again when on a vertical transponder. H=18vdc / V=13vdc (+/- 10%).

Here is a SatMex 5/6 scan test that I performed last month using a microHD, 7.5ft Sami dish and a GEOSATpro C2 (C-band LNBF). This list was done using one pass on each using single polarity normal and detailed blind scans.

SatMex 5:
3720 V
3744 V
3774 V
3805 H
3815 H
3820 H
3824 H
3850 H
3854 H
3868 V
3871 V
3886 H
3889 H
3895 H
3900 H
3904 H
3904 V
3908 H
3911 H
3914 H
3949 V
3957 V
3868 V
3969 H
3984 V
3989 V
4009 V
4049 H
4032 V
4045 V
4053 V
4084 H
4095 H
4106 H
4134 H

SatMex 6
3709 V
3719 V
3724 H
3731 V
3736 V
3745 V
3752 V
3756 V
3764 V
3764 H
3768 H
3770 V
3773 V
3773 H
3779 H
3783 H
3795 H
3820 H
3825 H
3826 V
3830 H
3835 V
3846 V
3848 H
3852 H
3854 V
3857 H
3862 H
3875 H
3901 H
3944 V
3963 V
4034 H
4072 V
4080 V

Try erasing all pre-programmed transponders and blind scanning using both the normal and the detailed setting. I usually will scan the SatMex satellites several times by signal polarity to completely log all transponders.

 

[robosat]

Well... I spent about 1 hour testing skew and focal distance with the LNBF and trying to detect Vertical and Horizontal channels. I've noticed that the MicroHD marks all the channels found as Horizontal (the first time), and then as Vertical after I moved the skew a little. MicroHD (at least this MicroHD) doesn't keep the original polarity to show it after. All channels are Vertical or all channels are horizontal. I don't know why. I wrote before that the blind scan only detected Horizontal channels, but that was just what MicroHD said. Verifying with Lyngsat pages, there were Vertical and Horizontal channels, but too few. If I do the Normal or Blind Scan in Horizontal, right now the receiver doesn't find any channel. If I do it in Vertical, then it finds the same few I've been detecting (knowing that some are Vertical and some are Horizontal). I checked the voltage sent to the LBNF by the receiver when selecting a Vertical and Horizontal polarity, and it is just as you said. Voltages are correct.
So, I don't know what else to do. I've tried with another LNBF, and results were the same. I can find some transponders (that in a normal scan receiver can't) when rotating the LNBF, but I loose the others.
I've tried deleting all transponder and doing a blind scan. Channels found are exactly in the same number. The same if I delete and add later an especific Transponder (no signal level, no channels found)
Thank you for your help...

 

[SatelliteAV]

Sounds like the skew is not correctly set. Did you test the voltages out at the dish?

Erase all transponders and Blind Scan the satellite only once using only the vertical polarity. Do not adjust the polarity.

Please report the satellite, frequencies and symbol rates that are found.

 

[robosat]

I spent more time trying with different skews, and... voila! I got the channels. Nevertheless, I observed this : I went to a friend's house an did a Blind Scan with mi MicroHD and his 3m dish, obviously detecting more channels that with my 1.8m dish. But... When a get home and connected my receiver to my dish, almost all channels are seen. If I do a new Blind Scan with my dish, there are some channels that can't detect the MicroHD and were detected in the 3m dish. Curious thing is that those same channels that Blind Scan won't detect, they can be seen in the 1.8m dish just as they were detected with a Blind Scan in the 3m dish. In other words : Do a Blind Scan with your receiver using a big antenna (3m or more), go home and connect your receiver to your small antena (1.8m in my case) and you will see channels that won't see with a Blind Scan with your own antenna. I didn't know that.
I'll write in another post my whole experience mounting this 1.8m antenna in a HH Diseq motor and will include some photos. Thanks guys for your help

 

[FaT Air]

When a get home and connected my receiver to my dish, almost all channels are seen

Quite possible. During a blind scan, only so much time is allocated to 'get the channels' before moving on. May miss some because of the reasons previously outlined. You may get them by manually programming them and doing a TP scan. May require also programming the PIDs. You did say "almost all" which makes sense, as these are probably either too weak, or too interfered with, on the small dish.

1.8m antenna in a HH Diseq motor

Think that would have to be one heavy duty motor.

 

[SatelliteAV]

A larger reflector or a better tuned dish will attenuate undesirable signals that cause errors and increase the carrier to noise ratio for the signals that you are trying to tune. Makes perfect sense that the 3m dish is logging transponders and channels that are marginal on the 1.8m.

 

[Anole]

That's why I won't recommend 6' dishes for C-band.
Take what you get and hope you live in a hot zone for your favorite birds.

Otherwise, a top of the line 8'er, well tuned & well equipped would be wise.
Or an average 10' dish should get the job done.

 

[pro96]

That's why I won't recommend 6' dishes for C-band.
Take what you get and hope you live in a hot zone for your favorite birds.

Otherwise, a top of the line 8'er, well tuned & well equipped would be wise.
Or an average 10' dish should get the job done.

Gotta love my 6

Sent from my SPH-L900 using Tapatalk 2

 

[Tron]

I've always wanted to take my microHDs in their travel rack case over to an engineer friend at a local network affiliate and hook up to their monster dishes. Someday I will do this and snap some cool pictures. I want to see how high that ALI meter can go ...

 

[hags]

For giggles I tried Sat'AV's suggestion and erased all channels and TPs on one satellite on my microHD. I then did a blind scan.

Wow, the number of TPs increased, the number of channels increased and signal strength increased. Since doing this I've done a couple more, the suggestion was so effective that I will soon go through and do the rest.

I have a Turbo HD dish set up with a SL1PLL pointed at 125w getting the PBS feeds for the kids. Prior to this all but two channels were marginal and I could only scan in maybe 8 channels depending on conditions. Now, even with snow coming down, I have a solid lock and there are 25 channels scanned in, including some subscription channels that I haven't seen before.

I'm new to this hobby and I have no idea why this would be the case but it is. I'm kinda PO'd I didn't do this to begin with.

I would recommend this to anyone with a microHD that hasn't done this already.

 

[carlospr43]

Look for a new channel just when up yesterday

 

[Anole]

I have a Turbo HD dish set up with a SL1PLL pointed at 125w getting the PBS feeds for the kids.
. . .
Now, even with snow coming down, I have a solid lock and there are 25 channels scanned in, including some subscription channels that I haven't seen before.

I'm still amazed every time I read this.
Thats not much of a dish! 19 x 24" ?
http://sadoun.com/Sat/Products/Dishnetwork/Dishes/Dish-1000point2.htm
So, all credit to the SatAV PLL LNBF, microHD, and your careful aiming!