CASPER
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Understanding Universal LNB's
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Start c/p
Point Of View - Universal LNBF's by ACRadio
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There is a growing number of people coming to the forums and reading
about the added value of having an FTA KU band dish in addition to
their DBS dishes. I am very happy that the FTA hobby is growing as
people discover the benefits of having the capability. Also there is a
growing number of people that, when ordering their FTA receiver, are
going ahead and getting a package deal with a thirty-something inch
dish and universal LNBF.
They are learning the virtues of motorizing their dish, and some are
picking up a Stab or SG2100. When these people get their newly acquired
equipment they are anxious to play, and frankly I don't blame them a
bit. I like to try to help people get the most out of their system with
the fewest headaches. It gets difficult at times when people want to
combine and compact their systems and be able to use one dish to
perform on several bands. I've made many posts about the fact that
sometimes DiSEqC switches just don't like to be too far away from the
receiver. On a lot of the receivers coming out today, for some reason
they sorta forget to include 0/12 volt switching as part of their
feature set, so that switching mode can't be used. That leaves 22khz
switches, but with a ton of people getting universal LNBF's, then it
gets tough to use those switches. I just wanted to look at the trend of
universal LNBF's and share my thoughts about these devices and
ask...are they really worth it?
Our North American KU band satellites primarily uses two frequency bands.
The FSS band is from 11700-12200 MHz, and uses linear polarization.
The DBS band is from 12200-12700 MHz and uses circular polarization.
Generally because of the polarization differences it's easier for most
people to use two different LNBF's to tune these services. In Europe,
Africa, and Asia, they have two lower bands of 10700-11200 and
11200-11700 MHz linear. They also share our 12200-12700 band, but it is
linear where our DBS band is circular. Universal LNBF's were developed
to be used in those locations where several different frequency bands
using the same polarization are used. By having a device that worked
like having two or three LNBF's in one, all frequencies could be tuned
with one device and one dish. The equipment that we have come to know
over the years as FTA equipment in this country is the equivalent to
DTV or DN in other countries. They aren't stuck with having to obtain,
lease, or buy equipment from their programmer, They just select the
brand of receiver they desire or can afford, obtain a CAM and card from
the programmer of their choice, and subscribe.
The FTA type receivers we know today have been in use in other
countries for many years. The universal LNBF is a mass produced item
that has made it's way into the American market in abundance. It is a
good performer, but it has it's drawbacks.
I won't get into oscillators and mixing and the sums and differences,
but in order for the universal LNBF to be able to tune such a wide
range of frequencies, it has to incorporate two local oscillators (LO).
When the lower frequency set is needed it uses the lower frequency LO,
and when the higher set is needed it uses the higher LO. There has to
be an automated way for the receiver to tell the LNBF which LO it
needs, so the uni LNBF uses a 22khz signal. If I remember correctly,
when the receiver sends the 22khz signal the LNBF uses the higher LO,
and when it doesn't it uses the lower LO.
The receiver is usually preprogrammed with a receiver "switch"
frequency, so that when setting up the particular satellite, if
"Universal" is selected as the LNB type, and a frequency above 11700
Mhz is selected, it turns on the 22khz signal so the LNBF will use the
correct LO frequency, and if it's below 11700 Mhz, it turns the 22khz
signal off. What this means is that the receiver is tying up it's 22khz
system just to deal with the universal LNBF, and in order to use both
frequency sets, you won't be able to use any kind of 22khz switch.
With 0/12 volt switching not being included in receivers much anymore,
that just leaves either DiSEqC switching or manual switching...two
choices that can have their own drawbacks.
In North America the only place we see any real use of frequencies
below 11700 are with a few satellites over the Atlantic, mainly PAS9
and a couple more. These satellites have just a few Spanish language
channels, and the two Atlantic Bird satellites have a handful of Arabic
language signals. Most people will never be able to even see the
Atlantic Bird sats, with the exception of the far right coasters. But
for most people, the advantage of having a universal LNBF is far
outweighed by being able to use 22khz as a switching method. In the
case of forum member Chance and his desire to mount a DBS LNBF beside
his uni LNBF on a motorized dish, it would be easy to stick a 22khz
switch after the motor to switch between his two LNBF's, but because
his linear LNBF is universal and wanting it to be able to receive both
bands, switching becomes more difficult. About the only alternative is
to use a DiSEqC switch after the motor, with all the problems it can
introduce.
Standard LNBF's are decently cheap, usually less than $20. The point
I'm trying to make is for all the folks coming on board the FTA ship to
think their systems through and decide if it's really worth it to give
up a fairly reliable and valuable switching method just to get a
universal LNBF that most people will never fully use anyway. Now for
those people that might be after those few channels like CubaVision on
PAS9 then by all means get them and use them. But I think the folks
that are just now getting their feet wet in FTA satellite TV would be
better served by not getting a universal LNBF, picking up a standard
LNBF with a 10750 Mhz LO frequency, and using the 22khz system in their
receiver to help them with their switching duties. For the noob it
would help to make LNBF switching a lot easier.
--------------------------------------------------------------------------------
Start c/p
Point Of View - Universal LNBF's by ACRadio
--------------------------------------------------------------------------------
There is a growing number of people coming to the forums and reading
about the added value of having an FTA KU band dish in addition to
their DBS dishes. I am very happy that the FTA hobby is growing as
people discover the benefits of having the capability. Also there is a
growing number of people that, when ordering their FTA receiver, are
going ahead and getting a package deal with a thirty-something inch
dish and universal LNBF.
They are learning the virtues of motorizing their dish, and some are
picking up a Stab or SG2100. When these people get their newly acquired
equipment they are anxious to play, and frankly I don't blame them a
bit. I like to try to help people get the most out of their system with
the fewest headaches. It gets difficult at times when people want to
combine and compact their systems and be able to use one dish to
perform on several bands. I've made many posts about the fact that
sometimes DiSEqC switches just don't like to be too far away from the
receiver. On a lot of the receivers coming out today, for some reason
they sorta forget to include 0/12 volt switching as part of their
feature set, so that switching mode can't be used. That leaves 22khz
switches, but with a ton of people getting universal LNBF's, then it
gets tough to use those switches. I just wanted to look at the trend of
universal LNBF's and share my thoughts about these devices and
ask...are they really worth it?
Our North American KU band satellites primarily uses two frequency bands.
The FSS band is from 11700-12200 MHz, and uses linear polarization.
The DBS band is from 12200-12700 MHz and uses circular polarization.
Generally because of the polarization differences it's easier for most
people to use two different LNBF's to tune these services. In Europe,
Africa, and Asia, they have two lower bands of 10700-11200 and
11200-11700 MHz linear. They also share our 12200-12700 band, but it is
linear where our DBS band is circular. Universal LNBF's were developed
to be used in those locations where several different frequency bands
using the same polarization are used. By having a device that worked
like having two or three LNBF's in one, all frequencies could be tuned
with one device and one dish. The equipment that we have come to know
over the years as FTA equipment in this country is the equivalent to
DTV or DN in other countries. They aren't stuck with having to obtain,
lease, or buy equipment from their programmer, They just select the
brand of receiver they desire or can afford, obtain a CAM and card from
the programmer of their choice, and subscribe.
The FTA type receivers we know today have been in use in other
countries for many years. The universal LNBF is a mass produced item
that has made it's way into the American market in abundance. It is a
good performer, but it has it's drawbacks.
I won't get into oscillators and mixing and the sums and differences,
but in order for the universal LNBF to be able to tune such a wide
range of frequencies, it has to incorporate two local oscillators (LO).
When the lower frequency set is needed it uses the lower frequency LO,
and when the higher set is needed it uses the higher LO. There has to
be an automated way for the receiver to tell the LNBF which LO it
needs, so the uni LNBF uses a 22khz signal. If I remember correctly,
when the receiver sends the 22khz signal the LNBF uses the higher LO,
and when it doesn't it uses the lower LO.
The receiver is usually preprogrammed with a receiver "switch"
frequency, so that when setting up the particular satellite, if
"Universal" is selected as the LNB type, and a frequency above 11700
Mhz is selected, it turns on the 22khz signal so the LNBF will use the
correct LO frequency, and if it's below 11700 Mhz, it turns the 22khz
signal off. What this means is that the receiver is tying up it's 22khz
system just to deal with the universal LNBF, and in order to use both
frequency sets, you won't be able to use any kind of 22khz switch.
With 0/12 volt switching not being included in receivers much anymore,
that just leaves either DiSEqC switching or manual switching...two
choices that can have their own drawbacks.
In North America the only place we see any real use of frequencies
below 11700 are with a few satellites over the Atlantic, mainly PAS9
and a couple more. These satellites have just a few Spanish language
channels, and the two Atlantic Bird satellites have a handful of Arabic
language signals. Most people will never be able to even see the
Atlantic Bird sats, with the exception of the far right coasters. But
for most people, the advantage of having a universal LNBF is far
outweighed by being able to use 22khz as a switching method. In the
case of forum member Chance and his desire to mount a DBS LNBF beside
his uni LNBF on a motorized dish, it would be easy to stick a 22khz
switch after the motor to switch between his two LNBF's, but because
his linear LNBF is universal and wanting it to be able to receive both
bands, switching becomes more difficult. About the only alternative is
to use a DiSEqC switch after the motor, with all the problems it can
introduce.
Standard LNBF's are decently cheap, usually less than $20. The point
I'm trying to make is for all the folks coming on board the FTA ship to
think their systems through and decide if it's really worth it to give
up a fairly reliable and valuable switching method just to get a
universal LNBF that most people will never fully use anyway. Now for
those people that might be after those few channels like CubaVision on
PAS9 then by all means get them and use them. But I think the folks
that are just now getting their feet wet in FTA satellite TV would be
better served by not getting a universal LNBF, picking up a standard
LNBF with a 10750 Mhz LO frequency, and using the 22khz system in their
receiver to help them with their switching duties. For the noob it
would help to make LNBF switching a lot easier.