c&p from another site,thanks goes to sci
(
a fairly long but informative post - Grynner)
Everything you always wanted to know about DiSEqC & LNB
he most troublesome area of configuring FTA's are the result of incorrect assumptions on how DiSEqC™ and LNB really work. Specially when attempting to make things work, with legacy and proprietary peripherals which are non-DiSEqC compliant.
This thread will attempt to collate in one place much needed info on these sophisticated topics:
Digital Satellite Equipment Control (DiSEqC™)
Code:
Official DiSEqC documentation:
DiSEqC Specifications
***.eutelsat.com/satellites/4 5 5.html
Bus Functional Specification
***.eutelsat.com/satellites/pdf/Diseqc/Reference%20docs/bus spec.pdf
Microcontroller in DiSEqC™ LNB and Simple Switcher Applications
***.eutelsat.com/satellite/pdf/Desqc/associated%20docs/applic info PIC microcontroller.pdf
Application Information for Tuner-Receiver/IRDS
***.eutelsat.com/satellite/pdf/Desqc/associated%20docs/applic info turner-receiver.pdf
Application Information for LNBs and Switchers
***.eutelsat.com/satellite/pdf/Desqc/associated%20docs/applic info LNB switchers.pdf
ow
Noise
Block-downconvertor (so called because it converts a whole band or "block" of frequencies to a lower band).
Code:
LNB mysteries explained:
***.satcure.co.uk/tech/lnb.htm
***.satcure.co.uk/tech/lnb2.htm
Further ebooks: (some are free)
***.satcure.co.uk/book.htm
FREE - Beginners Guide to Electronics
FREE - Understanding Sky Digital TV
Happy learning!
Additional info:
Much confusion arise from DP, DishPro, or other trademarks on legacy LNB's.
All these
proprietary LNB's are obsolete and full of idiosyncracies; they were designed to work with specific proprietary equipment, that is not general purpose or following open standards, like DiSEqC. For trouble-free FTA satellite operation, you should consider replacing them with current, standard and cost-effective devices. Standard peripherals are cheaper than proprietary stuff. Standard FTA LNB $18. Standard DiSEqC switch $5. Price has nothing to do with quality in this case. It is economies of scale that tip the balance. After all, there are only ~25 Million premium satellite subscribers in North America. The potential is an order of magnitude greater for FTA users...
Code:
***.satcure.co.uk/tech/lnb2.htm
Quote:
"Twin-output" LNB
Currently available in Standard, Enhanced and Universal form, the twin output LNB provides two outputs to feed two separate receivers. Each output can be switched by 13/17 volt input by the individual receiver to change polarisation.
"Dual-output" LNB
Was available in Standard and Enhanced form, the dual output LNB provided two outputs to feed two separate receivers. Each output had a fixed polarisation; one horizontal and one vertical.
This type of LNB was used with switching boxes such as the "Mini Magic" which could feed four separate receivers.
This type of (obsolete dual-output) LNB is no longer used in the UK and Europe, having been superseded by the "universal" type. Therefore a "mini magic" distribution system is no longer available.
Instead, you should use a "quad-output" universal LNB or, if you need more than four outputs, a "quattro LNB" plus a (expensive) head-end distribution system which will usually feed up to at least 12 (sometimes 16) receivers.
Note that a "twin-output" LNB is frequently (and incorrectly) called a "dual-output" LNB in the USA and sometimes even in the UK and Europe. Care should be taken when ordering! A "Dual LNB" usually refers to a "monobloc" or "monoblock".
"DirecTV LNB"
This is what the Americans confusingly call a "Dual Output DBS LNBF" and has a local oscillator frequency of 11.25 GHz. It is not compatible with UK systems and it's not available in the UK or Europe. I suspect that "dual output" is what we call "twin-output" but that makes me wonder what they call our "dual-output" LNB!
Input Frequency - 12.2 to 12.7 GHz
Output Frequency - 950 to 1450 MHz
Noise Figure - 1.1 dB, Max
Gain - 50 to 62 dB
LO Frequency - 11.25 GHz, ± 2 MHz
It is entirely different from LNBs used in the UK and Europe in that it has a single internal oscillator running at 11.25 GHz whereas our "universal" LNBs have two selectable oscillators running at 9.75 and 10.6 GHz respectively.
In other words, many FTA users have been cursing DiSEqC switches, when in reality, the root cause to compatibility problems with DiSEqC equipment was the use of non-DiSEqC compliant legacy and proprietary LNB's.
Legacy is an euphemism for
obsolete.
This may also shed some light as to why some people prefer "high-quality" non DiSEqC switches like the SW-xx series. For their setup, the SW-xx series works best with the obsolete LNB's, since they were designed to work together from the ground up. The corrollary to this is they were never designed with DiSEqC in mind.
Originally Posted by
YONO
Thanks to everyone who contributed to this Thread
There are 2 different groups of KU band satellites, FSS (Fixed Satellite Service) and DBS (Direct Broadcast Satellite). DBS satellites are the type satellites used by DN, DTV, BEV, and VOOM, and the band is authorized for use in North America. They operate from 12200-12700 MHz, and their polarity is circular. FSS satellites are thought of as general purpose satellites and is the home of many different broadcast media and many different types of signals. The FSS satellites are placed worldwide around the globe. The frequency is 10700-12700 MHz and the polarity is linear. Here in NA we primarily use the portion of the band from 11700-12200 MHz. A few signals from satellites over the Atlantic can be found in the 11200-11700 MHz portion, but there are not very many.
Linear polarity satellites broadcast their signals with the waveform being sent from the antenna either in the vertical plane (oriented up-down) or the horizontal plane (oriented left-right). This allows twice the amount of channels to be transmitted by the satellite in the same amount of bandwidth, as the signals from the opposite polarity are attenuated enough so that they don't interfere with each other. Circular polarity satellites send their signal in a corkscrew pattern, and the polarity is determined by the direction of rotation of the signal, either right hand or left hand.
When the signal is reflected from the dish, it enters what is called a feedhorn. The feedhorn, or feed for short, focuses the received signal down a tuned tube, which is called a waveguide. We sometimes refer to the waveguide as the THROAT of the feedhorn. At the end of the waveguide is the entrance to the amplifier. The amp usually has 2 probes that is each oriented to correspond to the horizontal and vertical polarities, and is switched by the amplifier according to which polarity is needed. A circular feedhorn has a small device that transforms the circular signals to either horizontal or vertical signals for processing by the amp. The amplifier is generally called an LNA (low noise amplifier).
The amp does it's job and amplifies the very weak microwave signal, and then it's passed on to a device called a downconverter. A microwave signal has extremely high loss when trying to send it down a regular coax. After just a few feet there would not be much signal left because of this loss. Lower loss coax could be used, but it would be extremely expensive. The downconverter "converts" the signals to a much lower frequency so that relatively inexpensive coax can be used to get the signal from the dish to the receiver. Todays technology has allowed the combining of the LNA and downconverter into the same box. This is called an LNB, or Low Noise Block converter. And feeds are now being integrated with LNB's into a single assembly known as an LNBF.
C Band dishes work on basically the same principle above, except the feeds and dishes are MUCH bigger, and use a much lower frequency of 3400-4200 MHz. They can also be either linear or circular polarity.
You must have the proper LNBF for the type of satellite you want to receive. A DBS LNBF won't receive much of anything in the FSS band, and vice versa. 2 LNBF's are required to receive both bands. There are generally just 1 type of DBS LNBF, but there are 2 types of FSS LNBF's, standard and universal. A standard LNBF will cover a single portion of the FSS band, usually 11700-12200. It has a single local oscillator frequency, which is usually 10750 MHz. A universal LNBF is an offshoot of LNBF's that are mainly used in Europe, where they have a need to tune several sections of the KU FSS band with a single LNBF. They will tune 10700-12700 MHz. and they have 2 seperate local oscillators at 9750 and 10600 MHz, which will allow the LNBF to tune a large expanse of spectrum. The receiver uses a special signal to tell the LNBF which of the local oscillators it should use for the frequency it needs to tune. See this post for more information and my thoughts about universal LNBF's...
Some of this stuff might be a little difficult to understand, as it's a lot of information in a short space. As you learn about terms in satellite TV, maybe this will be a reference you can come back to and help you understand things a bit better.
The standard Lnb's set frequencies are:
FSS Ku-band linear LO 10750MHz
DBS circular LO 11250MHz
An euro-'universal' LNB will have two LO's and may be configured using the default values stored in the receivers
A stacked LNB uses the standard frequencies for vertical/right-circular polarisation, then move up values(depends on the oscilator) for the horizontal/left-circular transponders.
For DBS 12.2-12.7 GHz
For FSS 11.7-12.2 GHz LNBs. Oscillator runs to 24600.
For FSS 11.2-11.7 GHz LNBs Oscillator runs to 23600
Originally Posted by
YONO Point Of View - Universal LNBF's
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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 "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.
Thanks goes to ACRadio
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What is an LNB, or is it LNBF?
LNB(F) stands for Low Noise Block downconverter with integrated (Feedhorn). Either acronym may be used in the small dish world. It is the final stage of the antenna, and the first stage of the receiver. It comes in single and dual units. A dual LNB is just like two singles in the same case. Each half is independant of the other. Inside is the detector and downconverter electronics, along with circuitry designed to switch the LNB from right hand circularly polarized to its opposite. Adjacent transponders on the satellite use opposite polaritization to prevent adjacent channel interferance. The widely used Twin and Quad each have 2 dual LNBs along with an integrated switch.
For those who care to know, a "block converter" is simply a device that converts a block of radio frequencies (in this case the 12.2-12.7GHz DBS satellite signals) to a different frequency (in this case 950-1450MHz) useable by the receiver. 12GHz signals wouldn't survive through 10 feet of RG-6, never mind 100! The lower frequencies are much easier to work with.
To bore everyone further, LNB is not technically "short" for LNBF, since LNBs CAN come without feedhorns, like on most C-band (big) dishes, where the C-band (or Ku band or both) LNB bolts to the feedhorn on the dish. All DBS LNBs I've ever seen have the feedhorn built-in, so the "F" is essentially unnecessary, just like the "A" (all LNBs have amplifiers, yet we don't call them "LNABs"!)
In the "old days" the low-noise amplifier and downconverters were separate units, so the amplifier was called an "LNA", which then plugged into the downconverter with a really thick chunk of short RG-11 cable, before feeding into the house on RG-59 (typically.)
Eventually the LNA and converter merged into one unit, which back then was either called an LNB or LNC depending on whether you thought "Block converter" or "Converter" deserved an initial. LNB finally stuck. Satellite "old-timers" still often call LNBs LNAs, the same way our grandfathers still refer to refrigerators as "ice boxes."
UNDERSTAND DISH PRO STACKED TECHNOLOGY
DishPro LNBFs are a new technology that is only supported in the newest receivers from Dish Network (Models 301, 501, 508, and 721). DishPro LNBFs and switches allow for longer runs up to 200 feet from receivers to the dish. DishPro installations are easier as there are fewer cables to run from the dish to the switch(es) for more than 2 receivers as well as simpler installations if more than 4 satellite feeds are needed (especially important now that 721s and 921s need 2 satellite feeds per receiver).
Quick lesson: all DBS providers have up to 32 frequencies to use per orbital slot. The Frequencies are opposite polarities either even or odd. Legacy LNBFs and switches can only transmit one polarity at a time down the feed cable to your receiver. Legacy switches and LNBFs use a voltage signal from your receiver to change the polarity of the LNBF it is connected to, 13 volts is odd, 18 volts is even. Since voltage will drop as the length of the cable gets longer, at some point the attenuation of the cable will drop the voltage from the receiver below 18 volts so that the LNBF can't switch to the even polarity even though the signal from the receiver is 18 volts the LNBF is only able to use the 13 volt or odd polarity.
DishPro is different as it will stack or transmit both even and odd signals down the same wire, by shifting the frequencies up so both polarities can travel the same feed to the receiver or switch. Since this is the case the LNBF doesn't need the receiver voltage to switch back and forth. A switch is necessary to be able to connect one stacked 119° feed and one stacked 110° feed to each receiver. The only way a legacy receiver will work with this arrangement of LNBFs and Dish Pro switches is with a DishPro adapter that can down convert the stacked frequencies to the standard odd or even only frequencies. Each legacy receiver has to use this adapter which must be installed within 10 feet of the receiver.
FTA testing requires to change all Horizontal polarity to Vertical due to the fact that Dish Pro uses stacked technology(bandstacking scheme the IF frequency of the horizontal block is shifted upwards to vertical) They will need to be edited for example( just go to Menu-Installaytion-Tp/edit and set all to V) then subtract all horiz. transps. frecuencies from 25600. enter result as your new transp freq. (IE. on sat 119 transp 6 is 12297h. doing the subtraction, you get 13303. So change transp 6 to 13303). This is needed because dishpro lnbs use an oscilator that runs at 25600mhz. this is mixed with the horizontal transp freqs and new freqs are generated.
Interesting tidbits of information concerning proprietary satellite peripherals.
Quote:
Switch Info
2 Way Switch- Used to combine 2 Dish Network signals together on one Dish This is a must for The High definition and Twin Dish 500 System.
4 Way Switch- Designed for four DSS satellite receiver system
- Used to provide satellite signals from one satellite dish to up to eight
receivers - Allow for each receiver to be independently switched from horizontal or vertical channels giving full channel reception to each receiver.
- Matrix routs between any input to any output
- Combines TV inputs with the satellite outputs
- Heavy duty zinc die-cast housing
8 Way Switch- Designed for four or eight DSS satellite receiver system
- Used to provide satellite signals from one satellite dish to multiple receivers
- Allow for each receiver to be independently switched from horizontal or vertical channels giving full channel reception to each receiver.
- Matrix routs between any input to any output
- Combines TV inputs with the satellite outputs
- Heavy duty zinc die-cast housing
Dual LNB (Low Noise Block down-converter)- Amplifies received signals and converts them from microwaves to lower frequency signals which are then sent along a cable to the satellite receiver.
- An LNB can be either single or double.
- A double LNB is required when more than one receiver is used allowing the viewing of different channels on other televisions.
Single LNB (Low Noise Block down-converter)- Amplifies received signals and converts them from microwaves to lower frequency signals which are then sent along a cable to the satellite receiver.
- An LNB can be either single or double.
- A double LNB is required when more than one receiver is used allowing the viewing of different channels on other televisions.
Sat Finder- A Perfect satellite meter designed specifically for the self-installer
- Complete with an audible tone and a needle display
Linear Mode
