Dual LNB ok Astra2/Hotbird - but not for all channels

cielobuio

cielobuio

Member
Messages
3
Likes
1
Location
Leeds
My Satellite Setup
Humax Foxsat - HDR x 2
Bware - HK520 HD receiver with Tivusat Card
Dual LNB on Wave Frontier toroidal dish
Octo LNB for Astra-2
Quad LNB for Hotbird
4 x DiSEqC switch for multi-room distribution
My Location
UK
#1
Hi,

I had a 60cm dish with dual LNB for Astra-2 and Hotbird. I have an Italian Tivusat card in one of my three receivers, which was working fine for both LNBs. We use Hotbird only for Italian TV channels. We use Astra-2 for FreeSat channels only.

A while back, some channels disappeared from the Hotbird transmission, I thought this was due to the card, but I took my receiver+card to a satellite TV supplier, who verified all was working when connected to his dish at 13deg East.

I therefore took the opportunity to change my Hotbird LNB with a spare that I had and replace my rusty old dish at the same time. I replaced it with a Wave Frontier 55cm toroidal dish. I used the SatLex site to get the dish orientation (shown at the bottom of this mail).

I managed to get Hotbird aligned and then Astra-2 at the same time (after some time).

Though I still couldn't get any of the Rai HD channels or MediaSet channels e.g.:

(see - Packages: TivùSat - KingOfSat )

Rai 1 HD - No
Rai 2 HD - No
Canale 5 - No
Rete 4 - No

Rai 1 - OK
Rai 2 - OK
Rai 3 - OK

After some manual movement of the dish, I managed to get a signal for the above failing channels, though I had to seriously change the dish skew and slightly change the vertical angle. It was a very fine setup, no error margin at all.

Naturally, after this change, I lost Astra :(

After about an hour of struggle, I concluded that I can't get the above missing channels and Astra-2 on one dish.

Can anyone tell me what I'm doing wrong ? Dish too small ? Maybe I just ought to get a separate small dish for Astra-2 and dedicate the new toroidal to Hotbird ?

Thanks in advance for any advice.

Chris








Your location:
Following values have been calculated for your location:


Latitude: 53.83° N (53° 49' 47")
Longitude: -1.58° E (1° 34' 48")
City: Leeds
Country: United Kingdom
WaveFrontier tilt angle (Skew): 103.83°
Make skew adjustment by tilting the antenna 13.83° to East which is exactly 103.83° on the scale!!!
(seen from behind the antenna)
dot.gif

WaveFrontier elevation angle: 25.33° (central satellite)
dot.gif

WaveFrontier azimuth range: 15.2° (28.2° E -> 13.0° E)
dot.gif

LNB Satellite* Azimuth angle Elevation angle LNB guide bar
1 Easternmost satellite:
Astra 2A/E/F (28.2° E) 144.67° 22.86° L -7.6
2 Badr 4/5/6 (26.0° E) 147.10° 23.64° L -5.4
3 Eutelsat 25B/Es'hail 1 (25.5° E) 147.65° 23.81° L -4.9
4 Astra 3B (23.5° E) 149.90° 24.46° L -2.9
5 Eutelsat 21B (21.5° E) 152.17° 25.07° L -0.9
Imaginary central satellite:
20.6° E
153.21° 25.33° 0.0
6 Arabsat 5C (20.0° E) 153.90° 25.50° R 0.6
7 Astra 1KR/L/M/N (19.2° E) 154.82° 25.72° R 1.3
8 Eutelsat 16A (16.0° E) 158.57° 26.52° R 4.3
9 Westernmost satellite:
Eutelsat Hot Bird 13B/C/D (13.0° E) 162.14° 27.16° R 7.3
 
M

Mickha

Super Moderator
Staff member
Messages
5,297
Likes
567
#2
Ater checking it looks like you're experiencing problems with 11766 V 29900 DVB-S2 8PSK 3/4 and 11919 V 29900 DVB-S frequencies.
Code:
https://www.lyngsat.com/Eutelsat-Hot-Bird-13B-13C-13E.html
Can you please check the link, and post back if you're missing any other channels.
Can you also post back with the signal quality readings of other channels, you are getting, from Hotbird, 13E.

You shouldn't skew the dish, but rather skew/rotate the LNB's to maximise your signal quality.
Can you please post some pictures, of your dish, and LNB's.
 
cielobuio

cielobuio

Member
Messages
3
Likes
1
Location
Leeds
My Satellite Setup
Humax Foxsat - HDR x 2
Bware - HK520 HD receiver with Tivusat Card
Dual LNB on Wave Frontier toroidal dish
Octo LNB for Astra-2
Quad LNB for Hotbird
4 x DiSEqC switch for multi-room distribution
My Location
UK
#3
Ater checking it looks like you're experiencing problems with 11766 V 29900 DVB-S2 8PSK 3/4 and 11919 V 29900 DVB-S frequencies.
Code:
https://www.lyngsat.com/Eutelsat-Hot-Bird-13B-13C-13E.html
Can you please check the link, and post back if you're missing any other channels.
Can you also post back with the signal quality readings of other channels, you are getting, from Hotbird, 13E.

You shouldn't skew the dish, but rather skew/rotate the LNB's to maximise your signal quality.
Can you please post some pictures, of your dish, and LNB's.

Thanks for the response - bear with me - It might be the weekend before I can do further testing and establish exactly which channels I'm missing.

In the meantime, here's the photo. Now you mention it, the LNBs aren't vertical and that is probably creating an issue (?) - They are both positioned on the bar at exactly the point where the bar attaches, so they had to be turned slightly (red faced).......
 

Attachments

Channel Hopper

Channel Hopper

Suffering fools, so you don't have to.
Staff member
Messages
26,038
Likes
5,892
My Satellite Setup
A little less analogue, and a lot more crap.
My Location
UK South
#4
From the image the two LNBs too close together for a 15 degree spacing on the arc.
 
cielobuio

cielobuio

Member
Messages
3
Likes
1
Location
Leeds
My Satellite Setup
Humax Foxsat - HDR x 2
Bware - HK520 HD receiver with Tivusat Card
Dual LNB on Wave Frontier toroidal dish
Octo LNB for Astra-2
Quad LNB for Hotbird
4 x DiSEqC switch for multi-room distribution
My Location
UK
#5
OK - All sorted.

So the problem with this dish is that when the LNBs are positioned as mine are, the bottom of the Hotbird LNB clashes with the arc fixing point. I therefore had to initially rotate the LNB, to get it in place.

To get things tuned properly, I had to remove one of the outer connections from the the Hotbird Quad LNB, in order to re-position the LNB vertically (see pic). It then became possible to get all channel on both Astra-2 and Hotbird. Fortunaltely, I'm not using all of the LNB outputs right now.

For the Hotbird Italian HD channels, the best signal quality I can get is about 60%, which I suppose is ok.

All working for now

Thanks
Chris
 

Attachments

Lazarus

Lazarus

Tout Rond Bon Oeuf
Staff member
Messages
25,132
Likes
7,529
My Satellite Setup
80cm Motorised.
Several small Dishes.
Much else.
My Location
North York Moors
#6
Difficult to go by numbers as they're relative, not absolute, in the main.

But if 60% gets you un-pixellated reception even in eg heavy rain, then that's all that matters.
 
A

a33

Member
Messages
380
Likes
216
My Satellite Setup
XSAT410
Clarketech HD4100+
My Location
NL
#7
Can you set optimal LNB skew now?
For 13e (with 3.535* pre-skew for Eutelsat), at your location: -6.9*
For 28e (with 7.5* preskew: is that for ALL satellittes at 28.2 and 28.5? I'm not sure), at your location: -12.5*

As the T90 and T55 have pretty stable reception strength in the range between -10 and +10, you could easily choose another 'mid'-satellite, if you want; to place your LNBs better.
(You can calculate that in satlex, by choosing another 'widest' satellite (further wide). However you can keep your dish skew the same, that you found for 13e and 28e!)

Greetz,
A33
 
Terryl

Terryl

Specialist Contributor
Messages
2,184
Likes
1,497
My Satellite Setup
OpenBox X5 on a 1 meter motorized dish.
And now a 10 foot "C" band dish.

Custom built PC
My Location
Deep in the Boonies in the central Sierra Nevada mountains of California.
#8
Did you use your old LNB's on the Wave Frontier dish? If so then this may be a problem.

You have to remember that the signals on the WF T55 and T90 dish are 180 degrees out of phase from a normal dish, the WF dish uses a front reflector, using a standard LNB will reverse the polarity on the transponders.

You may have to mount the LNB's (if they are standard LNB's) up side down to correct the signals, WF (and others) sell special LNB's setup for this.
 
A

a33

Member
Messages
380
Likes
216
My Satellite Setup
XSAT410
Clarketech HD4100+
My Location
NL
#9
You have to remember that the signals on the WF T55 and T90 dish are 180 degrees out of phase from a normal dish, the WF dish uses a front reflector, using a standard LNB will reverse the polarity on the transponders.
I thought this was only the case with (Left and Right) circular polarity; the (extra) mirror causing a reversion?
On linear polarity (Hor and Vert) I cannot see how a mirror would reverse it.
Can you explain?

greetz,
A33
 
Terryl

Terryl

Specialist Contributor
Messages
2,184
Likes
1,497
My Satellite Setup
OpenBox X5 on a 1 meter motorized dish.
And now a 10 foot "C" band dish.

Custom built PC
My Location
Deep in the Boonies in the central Sierra Nevada mountains of California.
#10
Your correct about the L/R problems, L becomes R and R becomes L, and your right. it does not really affect a H/V polarity (that much), the main problems found with a Gregorian reflector type antenna was with two or more satellites close in, (under 8 degrees of arc) there were side lobe scatter problems and what was called multi bounce, this is where the signals from two or more sources bounced around between the reflectors and cause small phase cancellations, this was due to imperfections and alignment problems in the main and sub reflectors.

This is not a problem with a single satellite/LNB setup, but found to be a problem with multi signal setups, especially with signal sources coming in from different points along the receive axes, the closer the signal's were together the bigger the multi signal problems, this is why we never went with this style of antenna for CATV head end work, (we tried) but used single dishes and LNB's for each satellite, this is also why they try and make the transponders on adjacent satellites higher or lower in frequency and polarity. Had this style of antenna worked out for us it would have saved a ton of money for the extra dishes and the land to put them on.

On a single reflector type dish the signals reflected to the LNB that miss keep going, on a dual reflector type dish the signals that miss can be redirected back into the main (it's not a perfect world) by anything, it could be the mounting hardware for the LNB's it's self, this back scatter can raise the overall background noise on some transponders quite a bit.

Remember that these dishes have a very wide field of view and can pick up signals from about 40 degrees of arc, so it may not be the satellite directly on each side but the next one over.

Again too much coffee and my brain hurts trying to remember why we didn't use this type of dish......
 
Terryl

Terryl

Specialist Contributor
Messages
2,184
Likes
1,497
My Satellite Setup
OpenBox X5 on a 1 meter motorized dish.
And now a 10 foot "C" band dish.

Custom built PC
My Location
Deep in the Boonies in the central Sierra Nevada mountains of California.
#11
I wish I still had the hardware and test lab to test this out for you all but those days are long gone.
 
Channel Hopper

Channel Hopper

Suffering fools, so you don't have to.
Staff member
Messages
26,038
Likes
5,892
My Satellite Setup
A little less analogue, and a lot more crap.
My Location
UK South
#12
Had this style of antenna worked out for us it would have saved a ton of money for the extra dishes and the land to put them on.

Again too much coffee and my brain hurts trying to remember why we didn't use this type of dish......
For a start the initial cost, and delivery schedule from most manufacturers.

Next, getting the budget approved , proving a toroidal system is better than a multi dish system to a bean counter is not easy.

Size, the performance of the antenna on a single satellite requires a toroidal system that can be three times the area. So to break even size wise you need to have continuous coverage of at least three orbital slots.

Then the site itself, an earth station will often utilise the space to the dish requirements of each slot. With a toroidal, Everything from the site foundation, the cabling and the buildings providing power, feed switching and the signal distribution is determined by the antenna superstructure.

Next, the downlink power of each satellite varies considerably. To justify the need of a 5 or 7m reflector on some 10 to 20 positions might not be viable when the majority could be picked up with no more than a 1.8 / 2.4m dish.

Not lastly, the installation. Only three companies I know of in Europe are experienced in constructing these from the ground up, and two of them are GCHQ / military compliant and cost many $$$ per day for the priviledge.

https://gdmissionsystems.com/satcom/products/antennas/multi-beam-receive-only
 
Last edited:
Terryl

Terryl

Specialist Contributor
Messages
2,184
Likes
1,497
My Satellite Setup
OpenBox X5 on a 1 meter motorized dish.
And now a 10 foot "C" band dish.

Custom built PC
My Location
Deep in the Boonies in the central Sierra Nevada mountains of California.
#13
Yah we tried those also, we went back to one dish per satellite in most cases.
 
Top