To begin, I suggest you watch this YouTube video. As someone familiar with free-to-air satellite in North America, you may not quite understand it all at first, in particular why there are four cables coming from a single satellite dish. The reason is that this was originally developed for the European market. I’ll try to walk you through the differences but to get the general overview, watch the video first:
In order to understand the need for the four cables from the dish and the four inputs on a SAT>IP server we need to talk for a moment about the differences in LNB’s as used in Europe vs. those used in North America. If you are technically-minded you may want to refer to the Wikipedia page on the Low-noise block downconverter , which I’m using as a source here. I’m mostly quoting directly from the Wikipedia page for the following tables, with a few minor edits to make things a bit clearer (mostly converting GHz to MHz for consistency). To start with, these are the specifications for a North American C-band LNB:
- Local oscillator: 5,150 MHz
- Frequency: 3,400–4,200 MHz
- Noise figure: ranges from 25 to 100 kelvins (uses kelvin ratings as opposed to dB rating).
- Polarization: Linear
Block Local oscillator
Polarization Frequency band 13 V Vertical 3,400–4,200 MHz 5,150 MHz 950–1,750 MHz 18 V Horizontal 3,400–4,200 MHz 5,150 MHz 950–1,750 MHz
Note that nowadays most North American satellites use 3,700-4,200 MHz for C-band. A C-band LNB that receives the entire 3,400-4,200 MHz range is usually marketed as a “wideband” model in North America, and is generally only used to receive certain international satellites that are closer to the horizon in the eastern sky. To find the exact intermediate frequency for any given C-band frequency, subtract the C-band frequency from the local oscillator frequency of 5,150 MHz. This does mean that the higher the C-band frequency is, the lower the intermediate frequency will be. Next, these are the these are the specifications for a North American standard linear Ku-band LNB:
- Local oscillator: 10,750 MHz
- Frequency: 11,700–12,200 MHz
- Noise figure: 1 dB typical
- Polarization: Linear
Block Local oscillator
Polarization Frequency band 13 V Vertical 11,700–12,200 MHz 10,750 MHz 950–1,450 MHz 18 V Horizontal 11,700–12,200 MHz 10,750 MHz 950–1,450 MHz
What I want to point out here is that the intermediate frequency range is roughly the same for C-Band and Ku-band, the only difference being that the Ku band has a narrower frequency range. So when we in North America set up a receiver or a tuner for DVB-S or DVB-S2 signals, the only control sent to the LNB is for the voltage, in order to make it switch polarity. The LNB then sends the entire local oscillator bandwidth back to the receiver or tuner, and it is up to the receiver or tuner to pick out the correct frequency, in much the same way that a traditional TV receiver picks out one TV channel out of all those coming in over the antenna or cable.
One other difference between C-Band and Ku-Band is the way you exact intermediate frequency for any given Ku-band frequency. For Ku, you start with the Ku-band frequency and subtract the local oscillator frequency of 10,750 MHz, which is the reverse of the way it’s done for C-band. Don’t ask why, that’s just the way it is!
This brings us to the Universal LNB, or as it’s sometimes referred to in Europe, the “Astra” LNB. As Wikipedia notes:
A Universal LNB has a switchable local oscillator frequency of 9.75/10.60 GHz to provide two modes of operation: low band reception (10.70–11.70 GHz) and high band reception (11.70–12.75 GHz). The local oscillator frequency is switched in response to a 22 kHz signal superimposed on the supply voltage from the connected receiver. Along with the supply voltage level used to switch between polarizations, this enables a Universal LNB to receive both polarizations (Vertical and Horizontal) and the full range of frequencies in the satellite Ku band under the control of the receiver, in four sub-bands.
They do this because Astra uses a wider range of frequencies for Ku, starting at 10,700 MHz as in North America, but ending at 12,750 MHz. If you want the details behind this see the Wikipedia article, but the specs for the Universal LNB used in Europe are as follows:
- Noise figure: 0.2 dB typical
- Polarization: Linear
Supply Block Local oscillator
Voltage Tone Polarization Frequency band 13 V 0 kHz Vertical 10,700–11,700 MHz, low 9,750 MHz 950–1,950 MHz 18 V 0 kHz Horizontal 10,700–11,700 MHz, low 9,750 MHz 950–1,950 MHz 13 V 22 kHz Vertical 11,700–12,750 MHz, high 10,600 MHz 1,100–2,150 MHz 18 V 22 kHz Horizontal 11,700–12,750 MHz, high 10,600 MHz 1,100–2,150 MHz
Some North American satellite enthusiasts have been using 22 kHz tone switches in their setups for years, probably without knowing the original purpose for them. When we use them here, it’s typically to switch between two LNB’s, such as a C-band and a Ku-band LNB. But in Europe, they were used to switch between the upper and lower half of their expanded Ku band.
It’s not that uncommon to find Universal LNB’s with four coaxial outputs. Although in most cases the outputs can be individually switched by sending the correct voltage and by the presence of absence of the 22 kHz tone, in many cases they were used in systems where each output would be dedicated to one of the four possible states. That would make the entire European Ku band on a single Ku satellite available to a satellite distribution system.
A universal LNB can be used in North America if you have a compatible receiver or tuner, but remember that our Ku band only goes up to 12,200 so you won’t find any Ku-band signals above that.
This explains why most SAT>IP servers have four coaxial inputs, typically labelled V/L, V/H, H/L, and H/H. The letter before the slash is the polarity (Vertical or Horizontal) and the letter after the slash is the band (L=10,700–11,700 MHz, H=11,700–12,750 MHz). These would typically be connected to a quad output LNB that is pointed at a single satellite.
So, this fits in with the European idea of free-to-air – typically you get all your content from a single Ku-band satellite. Generally speaking, the major reason SAT>IP was developed was so that people didn’t need to run two or four coaxial cables to every receiver in their home. Instead, the SAT>IP server would stream the desired channels to the various computers and devices on the local network. If you’re familiar with a HDHomeRun device, it’s similar to that, but for satellite frequencies.
So hopefully now the video at the start of the article makes more sense, if you are one of those who’s never understood the European way of doing things.
The question you may be asking is, could we use a SAT>IP server in North America with our version of Free-To-Air? And my answer to that would be maybe, but in limited circumstances. I don’t know of anyone that’s importing SAT>IP equipment into North America, probably because at the present it would have limited usefulness here. As far as I can tell, SAT>IP servers have no way of dealing with a moveable dish – they expect the dish to be permanently pointed to a single satellite. And beyond that, I don’t know if any of them can be configured for use with a C-Band or linear Ku-band LNB. You can get dual or quad output Universal Ku-band LNB’s in North America, and by doing the math you could perhaps use a dual-output C-band LNB by configuring the server to use an equivalent Ku-band frequency (one that would be converted to the same local oscillator frequency) but you’d still be limited to pointing the dish at a single satellite.
There’s probably no reason you could not have more than one SAT>IP server on the local network, in order to receive signals from multiple satellites (assuming you have more than one satellite dish), but I have no personal experience with such devices so I cannot say that with certainty at this point in time. And another thing I don’t know is whether you can configure a SAT>IP server with four inputs to use multiple sources from different satellites. Here in North America it would make a lot more sense to use two of the inputs with a dual output linear Ku-band LNB, and the other two inputs with a dual output C-band LNB or a different dual output linear Ku-band LNB. There’s no reason either of these scenarios would not be technically possible, but if the software or firmware in the SAT>IP server doesn’t know about C-band or the North American Ku band, it would be a lot more difficult to configure.
There probably are situations a SAT>IP might be useful. If you are primarily interested in a channel or channels from a single satellite, and particularly if in order to receive that satellite you need to position the dish at some distance from your house, it might be worth using SAT>IP to backhaul the signals to your home instead of running a long run of RG-6 or RG-11 cable. You’d need to use server that’s in a waterproof, weather-resistant enclosure, and you might also want to use fiber optic cable for the run, although you’d still need some way to get power to your equipment enclosure. The same is true if you attempt to use some type of WiFi link; you still need power for the equipment at both ends.
I had originally discussed something like this in my article Minisatip: A possible way to extend the distance between a satellite dish and your TVHeadEnd (or other backend) server but at the time I wrote that, I really had no conception of what SAT>IP actually was (not that I consider myself any kind of expert on it now). The difference between what I was taking about in that article and in this one is that in the earlier article the emphasis was on software running on some kind of dedicated computer, whereas here I’m talking about a hardware device specifically built to be a SAT>IP server.
So where would you get such a hardware device? There is a list of them (and other types of SAT>IP products) at the satip.info site. The same site has links to software and hardware that can be used to view the streams. But keep in mind that if you are running a PVR backend, such as a recent version of TVHeadEnd, it may already have the capability to receive and record SAT>IP streams, and to pass on the live streams to your frontend systems. In fact, I believe the newest versions of TVHeadEnd can detect a SAT>IP server on the network and use it as a tuner, in much the same way that it would find and use a HDHomeRun device. As an aside, TVHeadEnd can also act as a SAT>IP server.
One thing I find especially interesting are the new (and possibly as yet unreleased) SAT>IP LNB units, such as this one from the Danish company TRIAX:
I’m not sure if this LNB is available for purchase yet, because I can’t find it offered for sale on any site anywhere in the world, but from the product specifications I’ve read, it appears that this is a combination LNB and SAT>IP server with eight (8) tuners! So, just by connecting this to the Internet (most likely through some type of power insertion device – the specifications state it is “Powered via 802.3@rev 2012 PoE type 1, class 2” but do not mention whether a power supply is included), you have eight Ku band tuners available from a single satellite, with no need for an additional SAT>IP server. Now, if only they would build a C-band LNB with similar capabilities! We could skip the tuner cards (with their buggy driver issues) and we’d never need to worry about RG-6 cable loss, although since underground Cat 5e or Cat 6 is limited to about 100 meters (328 feet) in length (and actually less than that as a practical matter, since packet loss can get rather significant as you approach 100 meters), you probably would want to run fiber optic cable for any extended length.
SAT>IP is an interesting technology and although it’s not yet gained wide acceptance among free-to-air users in North America, the day may come when it is more useful here, particularly for those with fixed dishes permanently parked on one location in the satellite arc. I will caution you that if you decide to order any equipment from overseas in order to experiment with the technology, it will probably not come with a North American-style power supply that plugs into a 120 VAC outlet. Unless you feel like installing a 240 volt outlet for the server, I’d check to make sure it uses a “wall wart” type power supply that can be replaced with one of similar output ratings, but that will plug into a standard USA/Canada power outlet.