Best Way to Receive Whole Ku Arc With Fixed Dishes?

[linuxman]

I was going to recommend tripod bucket setup but since you & Phlatwound figured out that the NPRMS would do the same thing ( and you have those on hand ) that would be more cost effective with maybe using a bucket mount as a stabilizer (third leg). if you set it up you could set it up like a bowling pin stack. 4 dishes on the front row , two on the , and one dish on the stabilizer mount. that would be seven dishes . the middle row and single dish might have to be raised a bit to shoot over the front dishes.

__________Y__________
_________/_\__________
________Y___Y_________
_______/_____\________
______Y__Y__Y_Y_______

forgive my drawing

Hey George,

That might work too!

Don't worry about the drawing. Using axcii characters to draw is by no means an easy task.

I think you are right, the nprms might do the trick and maybe a bucket mount as a stabilizer might even help out.

 

[Anole]

ramblings...

I was going to recommend tripod bucket setup ...
.... you could set it up like a bowling pin stack.
... might have to be raised a bit to shoot over the front dishes.

I like it! Very compact, too!

As for shooting over the dishes in front, I was thinking about that when the suggestion came up to have all dishes in a North-South row.
It might be possible to arrange them to sort of look between the dishes in front.

Perhaps it's possible to do the whole thing with the bowling pin layout! - :up
Maybe located in the south west or south east corner of the roof?
Give it some brainstorming - I think ya might come up with an answer.

Or, what about placing half the dishes on the east side of the building, and half on the west side.?
Naturally, the east-looking dishes would be in a low line on the east edge of the building...
All the taller dishes could be anywhere in the middle of the roof.
And the west-looking dishes could be low along the west edge of the roof.
Keeps you from accidentally walking in front of one when you are up there, too.

And it'd leave the south edge clear for your other ideas.
. . . though, the longer I talk about it, the more I wonder if one low rack of dishes across the south edge might just do the job?

Well, back to the bowling-pin triangle. Sure is compact.
Should give that some serious thought. - :up
See which dishes can peek between ones in front, and all that.
Might be a mess to wire and set up, but then it's all out of the way!


edit: oh, now I get it! (Just had to stand on my head)
Point the V to the south!
Just like you see when you face the pins!
Brilliant, and I totally missed it! Sorry Gabshpere. Great idea! Solves all the problems!

 

[linuxman]

I like it! Very compact, too!

As for shooting over the dishes in front, I was thinking about that when the suggestion came up to have all dishes in a North-South row.
It might be possible to arrange them to sort of look between the dishes in front.

Perhaps it's possible to do the whole thing with the bowling pin layout! - :up
Maybe located in the south west or south east corner of the roof?
Give it some brainstorming - I think ya might come up with an answer.

Or, what about placing half the dishes on the east side of the building, and half on the west side.?
Naturally, the east-looking dishes would be in a low line on the east edge of the building...
All the taller dishes could be anywhere in the middle of the roof.
And the west-looking dishes could be low along the west edge of the roof.
Keeps you from accidentally walking in front of one when you are up there, too.

And it'd leave the south edge clear for your other ideas.
. . . though, the longer I talk about it, the more I wonder if one low rack of dishes across the south edge might just do the job?

Well, back to the bowling-pin triangle. Sure is compact.
Should give that some serious thought. - :up
See which dishes can peek between ones in front, and all that.
Might be a mess to wire and set up, but then it's all out of the way!


edit: oh, now I get it!
Point the V to the south!
Just like you see when you face the pins!
Brilliant, and I totally missed it! Sorry Gabshpere. Great idea! Solves all the problems!

Hey Anole,

I like the idea too, but am thinking a nice slight V shape along the south edge of the roof might be better. All out of the way, and all very low profile.

I got pictures of the Prodelin and measurements, but have some work to do before I post the pictures etc.

I'll get back to you shortly.

 

[linuxman]

Here are the pictures of the 6 foot Prodelin dish and mount that I promised. I went down and talked to this guy today and took the pictures. I have been promised this dish for over a year now. I am supposed to get word later today about getting this dish tomorrow. I grovelled appropriately while begging him to let me go ahead and pick it up.

The focal length is a whopping 52 inches.

The room above the support for putting on LNBFs, brackets, etc. is 5 and 3/8 inches.

I would say you could probably put about any size LNBF, brackets you want on that dish all with 2 degree spacing.

I am sure Anole will let us know how far apart they need to be.

Here are the pics:

 

[gremlin411]

hey Linuxman here is something you might can use when you get that dish. maybe make you a polar mount for it. Maybe !!!

 

[Anole]

calc for first three eastern dishes

Using post #22:

Dish 1
30W (Hispasat) using oem primestar lnbf with h/v outputs
43W (IS-3R) using oem primestar lnbf with h/v outputs
I think it might be possible to get both these on one dish at 13 degrees apart by not having an LNBF in the center, and they will be far enough apart to use these bigger LNBFs. Dish center would be aimed approximately at 36W.

I used a center bird from the GeoSatFinder table, so not what you called out.
All measurements are relative to the virtual LNB and bird.

[FONT=Fixedsys]LNB offset [/FONT][FONT=Fixedsys]degrees   for 84e  for 6'Prodelin centered @ 37.5°
30° Horiz:  +5.8°    +2.197"     +5.25"
    Vert:   +5.7°    +2.16"      +5.16"

43° Horiz:  -4.6°    -1.75"      -4.17"
    Vert:   -4°      -1.5"       -3.62"
[/FONT]

Dish 2
72W (AMC6)
74W (H2 AKA SBS6)
79W (AMC5)
83W (AMC9)
Would need the dual output tiny LNBFs. Use no LNBF in the center and aim center of dish at 76.5W, might get all 4 of these on one dish. 72W will be a tight squeeze.

For these birds, we used a virtual bird at 76.8 to do the calculations:

[FONT=Fixedsys]LNB [/FONT][FONT=Fixedsys]offset degrees   for 84e  for 6'Prodelin centered @ 76.8°
72° Horiz:  +6.0°    +2.61"      +6.247"
    Vert:   +1.7°    +0.645"     +1.54"

74° Horiz:  +4.1°    +1.55"      +3.71"
    Vert:   +0.9°    +0.34"      +0.81"

79° Horiz:  -3.3°    -1.25"      -2.99"
    Vert:   -0.7°    -0.265"     -0.635"

83° Horiz:  -9.4°    -3.55"      -8.49"
    Vert:   -1.5°    -0.569"     -1.36"
[/FONT]

Dish 3 . . . . . 87°, 91°, 95°, 99°, using 93° as the center bird.

[FONT=Fixedsys]LNB offset [/FONT][FONT=Fixedsys]degrees   for 84e  for 6'Prodelin centered @ 93°
87° Horiz:  +9.5°    +3.589"     +8.58"
    Vert:   +0.1°    +0.0379"    +0.090"

91° Horiz:  +3.2°    +1.21"      +2.90"
    Vert:     0°       0"          0"
[/FONT][FONT=Fixedsys]
95° Horiz:  -3.2°    -1.214"     -2.90"
    Vert:   +0.2°    +0.0759"    +0.18"

[/FONT][FONT=Fixedsys]99° Horiz:  -9.5°    -3.589"     -8.58"
    Vert:   +0.9°    +0.34"      +0.81"
[/FONT]

 

[Anole]

how to use the calculations

All calculations are based on the math suggested by MJflash in his thread.
It was all pretty well documented two years ago.

Here's an easy way to put the results to use:

- get a pad of 1/4 inch graph paper.
- turn it sideways
- place a dot in the middle of the page, where two lines cross
- measure left/right and up/down from the middle, and draw dots for each LNB
- prominently mark the page with the satellite orbital locations!
- use a compass and draw circles around each LNB representing all common sizes:
--- 1½ inches for SatelliteAV's MINI LNBs
--- 2¼ inches for common LNBs like Sky Mexico
--- TBD (to be determined) for original LNB horns from Primestar dishes
- if two LNBs overlap, choose smaller ones or relocate the LNB to another dish
- poke a ¼ inch hole in the center of each LNB location on your paper
- when LNBs are mounted onto your brackets, use a marker and place an ink dot in the center of each feedhorn
- use the paper template, and verify all LNB dots line up with the holes in the paper
- this is the starting poing for aligning the LNBs.
- don't forget to set each LNBs skew, as required!
- connect the two outside LNBs to two receivers, and aim the dish for simultaneous best quality.
- then connect the remaining LNBs to receivers and fine-tune their locations

Oh, and please verify my calculations.
It's easy to make a goof, and then carry that through the entire set of numbers.
Also note, the above numbers are only valid for the general neighborhood of St Louis, Mo.
For anyone a substantial distance from that location, you must recalculate!
I haven't done a study, but I'd think 100 miles would be okay, and 500 would not be.

 

[linuxman]

Wow Anole!!!

Those are fabulous numbers!!!

You must have worked very hard getting all that information into a couple of posts.

I have the accurate information from Mike Kohl that I just got in an email from him about how many degrees from center you can get with a 6 foot Prodelin dish for Ku.

Here's Mike's response:

A six foot Prodelin has a fairly narrow beamwidth when compared to a 3 foot offset antenna.
It focuses on a smaller area of sky, but in its sweet spot or window---has tons of signal.

20 degrees either side of center is a bit of a stretch for Ku-band. That would be a good number for DBS, which has more power to throw away, given its higher receive EIRP levels.

Strong Ku-band would probably be limited to within 10-12 degrees of center, and past 15 degrees it would be a crapshoot requiring a bit of luck and skill in precise alignment. But within this center area one can expect C/N readings in the 10 to 14 dB range.

Well I got the 6 foot Prodelin that I have waited so long for along with it's commercial NPRM. I have it outside and the mount partially setup on the ground. I think I will completely set it up on the ground and then move everything to the roof for it's permanent resting place.

Let's go with Mike's numbers and say we have 24 degrees of the arc to play with on this Prodelin. We might try and stretch it to 30 degrees.

Those of you who know the Ku arc like the back of your hand, where would you center it, trying to receive the greatest number of satellites possible on this nice big dish?

Keep in mind that we also want to maximise the number of satellites left on the 84Es to get the entire arc on the least amount of dishes including this one.

I'll post pics in the dish hunting thread.

 

[voomvoom]

I think I would center it on G11/G17 @ 91 and see if it will get to 105 on the west side and 79 on the other side. If not, then I would center on 93 and try for the same sats. Then I might would try to center around 92 and see if it would do any better, but that would depend on the first 2 results...?

 

[Anole]

I agree with VoomVoom on the 93° bird.
Bore sight the dish on that; we already have numbers above for the 87° and 99° birds.
The signal levels of those first satellites will be interesting.
If they look good, we can calculate some more distant birds such as 79° and 105° as VoomVoom suggested.
The good news is, the LNBs will be far apart!

 

[linuxman]

I agree with VoomVoom on the 93° bird.
Bore sight the dish on that; we already have numbers above for the 87° and 99° birds.
The signal levels of those first satellites will be interesting.
If they look good, we can calculate some more distant birds such as 79° and 105° as VoomVoom suggested.
The good news is, the LNBs will be far apart!

I think both you and Al are correct. I was thinking somewhere between 87 and 93 for the center.

From wherever the center is, will just be trial and error to see how far you can go out and still get nice fat signals.

I think some of it will depend on what satellites we think the most S2 signals might fall which might help determine where to put the center, both now and future possibilities.

Will wait to hear from other fixed dish users.

EDIT:

The good news is, the LNBs will be far apart!

That's the best part about using this dish.

 

[Keith Brannen]

Will wait to hear from other fixed dish users.

91 or 93, as close to your true south as possible, to lessen the height of the arc for the LNBs you'll need on the brackets (with enough LNBs, it's going to look like a smile!).

 

[linuxman]

91 or 93, as close to your true south as possible, to lessen the height of the arc for the LNBs you'll need on the brackets (with enough LNBs, it's going to look like a smile!).

Hey Keith.

My TS is 91W.

Should I be thinking about a straight bar, or a slightly curved bar to mount the LNBFs on?

 

[Anole]

I only chose 93° as the center bird because I had conveniently already done the calculations for it.
If there is a pressing reason, we can redo 'em for anywhere.
I just wanted to suggest you try those birds to see what performance you'd get, and how far out.

You'll notice the elevation of all the LNBs is pretty close to a flat line.
And don't forget all the in-between birds that'll fit right along with those listed. :up

What worries me is that you might get 4 birds on an 84e, and no more than 8 birds on the 6' Prodelin.
Questions include: is it worth it?
Would it have better rain fade?
That's a big heavy piece of equipment to lug up to the roof, so its capability and performance should be justified.

Of course, if putting an S2 Ku bird in its cross hairs gives you a good sweep of other nearby birds, maybe that's justification enough.
It's probably overkill to separate 123° from 125°, though. -

 

[linuxman]

I only chose 93° as the center bird because I had conveniently already done the calculations for it.
If there is a pressing reason, we can redo 'em for anywhere.
I just wanted to suggest you try those birds to see what performance you'd get, and how far out.

You'll notice the elevation of all the LNBs is pretty close to a flat line.
And don't forget all the in-between birds that'll fit right along with those listed. :up

Yes, I am planning on all those in-between birds.

What worries me is that you might get 4 birds on an 84e, and no more than 8 birds on the 6' Prodelin.
Questions include: is it worth it?
Would it have better rain fade?
That's a big heavy piece of equipment to lug up to the roof, so its capability and performance should be justified.

Of course, if putting an S2 Ku bird in its cross hairs gives you a good sweep of other nearby birds, maybe that's justification enough.
It's probably overkill to separate 123° from 125°, though. -

I quoted Mike above as getting 12 degrees out from center on each side. At 2 degree spacing, that is 12 satellites minimum. I am pretty sure he is being conservative in his information, so 15 degrees out from center from each side might be do-able. We'll just have to wait and see.

Is it worth it? I would say definitely.
When it is broke down, it isn't all that heavy. My 14 year old son and I dis-mantled it and loaded everything on the trailer by ourselves.

I am sure rain fade will affect it some, but probably not as bad as smaller dishes.

I am looking forward to the project. Weather is supposed to change here overnight.

Cold and snowy next week, so who know how much time I will get to work on it, but whenever I can, I will.

 

[turbosat]

the big spread

I vote for pointing it at 95, and see what kind of slice of the arc you get. For some reason I have a hard time seeing a 6' getting more than 6birds 2degrees apart, but then I never tried it either. Anole's math was impressive (I can barely understand a tire pressure guage lol) . Really curious to learn what the prodelin can do though, its a fine looking dish.

 

[phlatwound]

That dish is a beauty, nice mount too. Can't wait to see what you dream up for this one.

 

[Keith Brannen]

Hey Keith.

My TS is 91W.

Yes I know, I looked it up! 91 would be good in that it would be the lowest LNB on the bracket, all others would be above it in height.

Should I be thinking about a straight bar, or a slightly curved bar to mount the LNBFs on?

Depends on what you mean. If you mean a slightly curved bar to adjust for the arc, then no, a straight bar would be best, because what you really want is a slightly curved bar that mimics the dish to keep the focal point the same for the outer LNBs as is it for the centre LNB. If you look at the photos I posted earlier in the thread, you can see the type of curve I mean (though on the dish it is on it really wasn't required, just happen to have one to use).

You'll notice the elevation of all the LNBs is pretty close to a flat line.

Top of the arc is good for lessen elevation variations, but when mounting LNBs (especially if the LNBs go 12 to 15 degrees either side of true south) it can add up to quite a difference from the centre LNB. Just as an example, my true south is 82, the dish in the photo has LNBs at 91 (39.4 degrees elevation), 97 (37.8 degrees), 103 (35.6 degrees), 110 (27.5 degrees).

 

[Tron]

Fred, I'll be watching this thread with great interest to see your Prodelin results, as there are tons of those dishes around here (seems to be the most common VSAT dish in use...)

If I find one with a broken dish, I can still use that enormous NPRM for my 7.5' Perfect 10

 

[linuxman]

Thanks Phlatwound and Turbosat!

For some reason I have a hard time seeing a 6' getting more than 6birds 2degrees apart, but then I never tried it either.

That's why I am going to try it out on the ground. I'll find out what it can do before moving it to the roof. If it doesn't work out, as Tron says I still will have a nice C-Band sized NPRM to put a fixed C-Band dish on.

Yes I know, I looked it up! 91 would be good in that it would be the lowest LNB on the bracket, all others would be above it in height.

Agreed.

Depends on what you mean. If you mean a slightly curved bar to adjust for the arc, then no, a straight bar would be best, because what you really want is a slightly curved bar that mimics the dish to keep the focal point the same for the outer LNBs as is it for the centre LNB. If you look at the photos I posted earlier in the thread, you can see the type of curve I mean (though on the dish it is on it really wasn't required, just happen to have one to use).

See drawing below.

Imagine standing above the dish and looking down.

Of the curves I have drawn, black being straight, dark blue, or light blue?

Top of the arc is good for lessen elevation variations, but when mounting LNBs (especially if the LNBs go 12 to 15 degrees either side of true south) it can add up to quite a difference from the centre LNB. Just as an example, my true south is 82, the dish in the photo has LNBs at 91 (39.4 degrees elevation), 97 (37.8 degrees), 103 (35.6 degrees), 110 (27.5 degrees).

Yes, I understand!