Transponder is both Vertical & Horizontal??

[Mr Tony]

Here is a weird one when I was scanning this weekend

When I scan SBS6, it hits the following frequency
12008 H 13333, which registers as a 4:2:2 feed, so its scrambled

yet as it scans vertical poarity, it hits the following
12008 V I cant remember the symbol rate, and registers a couple of black screens.

I was under the assumption that a transponder was either Vertical or Horizontal, but not both...

interesting

 

[Diamond Jim]

Ice,

I have noticed that too with the 3618, on occasion when I scan horizontal a vertical will show up and vice versa. Beats me whats going on, everything time I think I have this thing figured out, something off the wall happens. :shocked

 

[drhydro]

Jim, i wasnt able to get my 3618 working with my DBS LNB using the correct LNB L.O., but when I blind scanned using default values it found all of the TP's there. I guess its one of the things that make ya go hmmmmmmmmmmmm

 

[Diamond Jim]

Yea, I have mine slaved through the 922 and was making blind scans with the 3618 on Hor & Vert. I was getting double frequencies and taking about 20 minutes per scan, then I found out that I had to scan each polarity separate and change the polarity on the 922 to match the polarity that I was scanning on the 3618. Now I get one set of signals and about a five minute scan per polarity. It's little things like that, that you have to figure out.

 

[mbarnes]

Late reply, but here's your answer. The satellite has twenty four 36 MHz transponders, yet the bandwidth is only 500 MHz. So, where does the other 364 MHz go? The transponders overlap. On a typical bird, you have transponder 14 at 11980, 15 at 12000, and 16 at 12020. Those are the center frequencies. The transponder is 36 MHz wide, so add and subtract 18 MHz to each center frequency and you get T14 at 11962-11998, T15 at 11982-12018 and T16 from 12002-12038. So you see that you have an overlap from 12002 to 12018 where there are signals on both the vertical and horizontal polarities.

That is why polarization of your LNB is so critical these days. You will have a 16 MHz overlap at each end of the transponder, except of course for T1 and T24. And, yes, the providers get premium rates for the middle four MHz and the two end transponders.