PBS Channels Signal terrible in AMC21

[robosat]

HI there.

it´s not the first time I say this. In AMC21, all PBS channels (PBS-E, PBS-W, Create, VME, World, PBS Feeds) have very bad signal again. Just a few weeks ago they seemed to be fixed, and they were OK. Now again, its signal keeps flowing between 15 and cero. It's strange that there's only 1 channel (SD07) that can be seen. There are some scrambled channels in that same AMC21 or Galaxy14(HBO, ABCFAM, etc) that have very strong signal. I suspected of the coaxial cable, then of the Openbox10. but now I tested with a MicroHD and the result is exactly the same. I'm tired of this alternancy (you see channels, now you don´t. Then you see them again, and next day you don't)

 

[jdbob]

Bad weather at PBS Networks Operations Center (Washington DC I think)? SD07 might have been uplinked from somewhere else in the country at the time.

 

[northgeorgia]

It's also worth noting that the scrambled channels are the Claro Satellite TV mux from the Caribbean, and if I'm not mistaken, have a different footprint than the PBS satellite. Where in the north of Mexico are you?

 

[DJdish]

It's also worth noting that the scrambled channels are the Claro Satellite TV mux from the Caribbean, and if I'm not mistaken, have a different footprint than the PBS satellite.

Yes you´re right, PBS is on the North American beam, while Claro is on the Caribbean one.

 

[DJdish]

HI there.

it´s not the first time I say this. In AMC21, all PBS channels (PBS-E, PBS-W, Create, VME, World, PBS Feeds) have very bad signal again. Just a few weeks ago they seemed to be fixed, and they were OK. Now again, its signal keeps flowing between 15 and cero. It's strange that there's only 1 channel (SD07) that can be seen. There are some scrambled channels in that same AMC21 or Galaxy14(HBO, ABCFAM, etc) that have very strong signal. I suspected of the coaxial cable, then of the Openbox10. but now I tested with a MicroHD and the result is exactly the same. I'm tired of this alternancy (you see channels, now you don´t. Then you see them again, and next day you don't)

What size of dish are you using, and where are you exactly ?

 

[robosat]

Almost Chihuahua City. 3 foot dish. I've been watching PBS channels for years with this dish.

 

[DJdish]

Almost Chihuahua City. 3 foot dish. I've been watching PBS channels for years with this dish.

I was wondering because in my case (sadly) I´m out of the footprint (NA beam for PBS), but I´ve learned of people in North Central Mexico who are "officially" outside footprint but still able to get it, couple of years ago I tried to lock signal with a 4 footer and couldn´t.

 

[robosat]

OK. That´s one posibility: the beam changed recently and is not as strong as before in this place.

 

[Lone Gunman]

Someone can correct me if I'm wrong here, but didn't they just go from DVB S to DVB S2 and aren't those S2 signals much harder to lock?

 

[wildbill47]

I am using a 4' offset dish and have had more problems locking now that PBS has changed to Mpeg4 h264. Lost the horz channels and pound coax at dish shield was not crimped good. now v and h tp's are working better. I use a openbox s10.

 

[pollux]

i noticed it is weak in the morning,
but at night in LA area, signal quality can reach 70%

 

[Cham]

I usually get the 12180 mux over 70% with the 33" dish, stronger than I get many Ku signals. Location here is 97W and 49N so maybe the footprint favours the north somewhat. Montana PBS at 12106 is weak with signal bouncing between 0 and 30%Q but amazingly the picture isn't broken up on the micro HD.

 

[Blindowl1234]

Since the switch Pbs is weaker here too about 60% signal. Montana is now my strongest at 67%. Okla is 35% on a clear day...clouds and rain forget it.

 

[robosat]

You´re right. Before that switch, PBS Montana had a very weak signal. Searching for reasons for not receiven well the other channels, I found out that religning the dish (just a little more Azimuth) did in fact recover some strenght in signal. I don't know if my dish moved (I doubt it. No winds and a Dish very hard to move). And certainly Montana PBS has stronger signal than before.

 

[AcWxRadar]

Hi Robosat,

I think what we need to determine is when these channels actually did change over to DVB-S2. Lets get actual dates for each specific channel if at all possible. Then, relate these dates to the approximate times that you began noticing the fallout or dropout of the signal on your equipment. If they seem to correlate, then we may have the culprit.

Next step is what to do about it. Maybe a larger dish, say a 1.2 M? Maybe just finer alignment? A little of both perhaps. Maybe RG-11 cable vs RG-6 or a shorter cable run if possible. A better LNBF?
I think the basic strategy, if this is actually the problem, would be to increase the signal quality at the receiver itself. If you are at least getting these channels to come in, albeit erratically or marginally, then nearly anything you do should improve the situation. I would expect that with a few free or inexpensive improvements (like tweaking the alignment) may get you to an acceptable signal quality and hold it there. I wouldn't jump into any high dollar improvements right off, of course.

I'd start with the alignment first. If this is a motorized dish then I wouldn't adjust the dish/motor physically. I'd try adjusting the recorded orbital position of the satellite in the receiver menus. If you are using USALS, then let's try 125.2 or 124.8 as opposed to 125.0. If you are using DiSEqC 1.2 motor controls, then just experiment around with the positioning of AMC 21. This way, you won't affect any of the other sats by physically moving the dish or motor. If it is a single fixed point dish, you can go ahead and move the dish itself. Beyond that, I would ensure that you have the shortest cable run with the best possible cable and connections that you can muster. All this should be rather cheap to do.

Don't forget the polarity adjustment (rotation of the LNBF in the clamp). You might gain a little here, too. I wouldn't bet on it, but when every little bit helps, try everything.

Next step up would be to test a different LNBF with better Q and stability factors etc. Then next on the list is experimenting with different dish sizes. Be careful, bigger does not always mean better in all cases. You might need a DEEPER dish with a more pronounced focal point as well as a larger diameter dish.

Is there anybody near you down by Chihuahua that has a similar setup that you can compare results with? That would really help you out, too.

That's about the extent of what I can think of real quick. Maybe some of it will assist you in this dilemna, I hope it does. I wish you good luck.

RADAR

 

[Babadem]

Good explanations, RADAR. How are you doing with the move?

 

[AcWxRadar]

Good explanations, RADAR. How are you doing with the move?

Hi Babadem!

Not too bad. I am not back in my own house yet. I decided to repair and remodel the entire house while it is currently empty. Saving up the dough to pay for it all now and staying at my parents home until it is all complete. My Dad is no longer with us, but my Mom and sister are both living here. That's a plus because Mom cooks so good! I am about to ask her if I can set my motorized dish up in her back yard. I have already scoped it out and I can get 30°W Hispasat through 125.0° AMC 14 from a point way in the back yard. Got a big ole power pole and transformer that might be in the way of 83.0°W AMC 9, though. It's close, but I may skirt by it with no harm from the interference.

It was nice weather here today, so I took a walk around the back yard and surveyed the LOS possibilities. I picked out where I thought I could set the dish and get the entire arc, but I wasn't sure of Hispasat. I consulted dishpointer and compared my eyeball results with their actual LOS. I was pretty close, as a matter of fact, my proposed site for my dish was spot on where it should be according to dishpointer, but my eyeball angle to 30W was a little off from reality. I actually am better off then I expected. Now to talk Mom into allowing me to set my dish up there and run a cable into the house.

I think it will be received well once installed because I think my Mom and sis will enjoy the channels that I can bring them. My sister is currently a news nut and I think she would like Al-Jazeera and a lot of the wild feeds. Personally, I just want to get the PBS and RTV channels back on my TV. I have not watched TV since I moved out of my old place except for a little news here and there.

RADAR

 

[schlever]

I usually get the 12180 mux over 70% with the 33" dish, stronger than I get many Ku signals. Location here is 97W and 49N so maybe the footprint favours the north somewhat. Montana PBS at 12106 is weak with signal bouncing between 0 and 30%Q but amazingly the picture isn't broken up on the micro HD.

Same here in Saskatchewan, signal has gone up with the change to S2 on my 36"

 

[pendragon]

Signal quality is not a particularly meaningful statistic unless one only compares values from the SAME receiver model, and then for only the SAME modulation parameters. Thus drawing any conclusions regarding a move from DVB to DVB-S2 based only on SQ numbers will be fraught with peril. What you really want is CNR or a related value.

I don't monitor anything but the primary PBS transponders, but I have been recording HD03 nearly 24/7 for the past few years. This might be helpful to the thread as HD03 has been on 12180 V 30000 before and after the S2 upgrade. I'm pretty sure this particular transponder changed to S2 in late June/early July. The other PBS TPs changed much later. I've always used the same LNB on a 90 cm toroid, and currently see ~15 dB CNR for 12180 V in Denver. This is a gangbusters level, higher than just about anything else I see off my toroids. I don't remember the CNR for this TP when it was DVB-S, but I think it was less (12 dB?). If true PBS may have juiced 12180 V to maintain a similar link margin for their affiliates.

My gut feeling is if your setup has remained constant throughout the transition, and you are now having reception troubles, you probably have a performance problem in your reception system, and not an issue with dish size. While PBS may have increased the downlink power, this cannot overcome the additional demands S2 makes if any of the following are suboptimal:

1. LNB - many Ku LNBs have very high phase noise specs, or conveniently omit the mention of them. Phase noise is not NF.

2. Receiver - older demods tend to exhibit poor performance on S2 compared to S. I've also seen the phase noise of tuner stages degrade over time. This loss can be virtually undetectable with DVB-S, but may preclude DVB-S2 reception.

3. Poor noise margin in the distribution from the LNB to your receiver (long cables, switches, etc.) Again this might not show up for DVB-S, but preclude DVB-S2.

4. Saturated LNB or distribution system (amps or switches). I rather doubt this is a common cause, but I mention it out of completeness. If you were near the signal saturation point because of a hot LNB or a poor quality inline amplifier or switch, there is a chance that PBS boosting its power level could be saturating something in your signal chain, resulting in lower signal quality.

Since the S2 changeover, 12180 V's CNR has been very consistent for me. Once in a great while there is a momentary drop and much less frequently a short outage lasting a few seconds to a few minutes. I attribute the former to something like a beam blockage from a plane/helicopter, as I'm not that far from a community airport. I'm assuming the latter are caused by PBS messing with their transmission system or alignment. It may be wishful thinking on my part, but I'm suspicious these outages tend to cluster between feeds, shortly before the top of the hour. The only time I can recall more than a few minutes of carrier loss was when Sandy blew through. They weren't down for long, perhaps only long enough to transfer to a backup uplink somewhere else. In the last month, I have not seen any extended outages or drops in carrier level that affected my recordings.

 

[pollux]

I notice that the signal quality bar of 12180V and other PBS transponders fluctuate quite a bit, between 40% and 70%,
while other non-PBS transponders such as 11780V , 11790V are pretty stable and stay above 70% all the time.