Inside the house, the main concern is that your receiver can match the choices you have made for the outside equipment, and can control it automatically so that once it is set up, you just select the channel and let the machinery take care of the rest. If you buy a new satellite installation, using the now all-prevalent Universal LNBs, most of that is already taken care of. One thing you should check is what, if any, kind of DiSEqC version the receiver is geared up for. If you want more than two LNBs, it should be able to use version 1.1. If you want a motor, greater care must be taken that the motor has the strength to pull the dish and can be controlled by the receiver (which is then called a 'positioner'). Your installer will of course normally take care of all this. Evidently, there is also a price issue here; the more versatile, the more expensive.
If you are moving from analogue to digital and want to continue using some older equipment you already have, such as pre-universal LNBs, actuator motors, combined analogue/digital receivers, greater care is needed. Most of these can be accommodated, but at a price; burning your bridges and changing everything at the same time will almost always cost you less than trying to hold on to and incorporate bits of older standards. Look carefully, and consult with specialists for each bit of equipment.
There are of course also other differences in quality and versatility between inexpensive and expensive receivers. Analogue receivers determine a channel mostly by two elements, both of which we have discussed above:
In analogue, frequency and channel was identical, each channel had its own separate frequency. That is not true of digital; any frequency can combine anything up to a dozen different channels, packed together into one signal. The receiver thus has the ability to disengage these into their separate channels. Thus, the receiver has some further settings for each channel:
- The frequency, a figure between 10,700 and 12,700 MHz
- The polarity, Horizontal or Vertical.
The reason this seems faulty is that digital receivers do not normally expect you to add channels by hand. They generally have the ability to download complete and updated lists of channels from the satellites themselves, with all info in place, and expect you to do this at regular intervals to cater for any changes. Some receivers need to know the frequencies of each satellite in advance, however, so some manual additions may be necessary. And in some receivers, downloading channel updates may replace or mess up any personal re-organization of your channel list, showing those you want to hide etc., so you may want to add any you know of manually anyway. However, this is still a fairly minor concern of convenience; the most important thing to look for is probably the span of symbol rates that the receiver can handle.
- Symbol rate, a figure between 2,000 and 50,000 (ca.). This specifies the frequency. A limited receiver may only accept symbol rates of, e.g. 20,000-30,000, and thus only channels within that spectre (the most commonly used, as it happens); a versatile one can span the full range.
- FEC, or 'forward error correction', a figure normally given as a fraction like 3/4 or 4/5. Again common to the full frequency. Not all receivers allow you to set this manually.
- Program ID, a figure from 1 to 3,000 or so. This is an identifier of each channel within the frequency package, you need to set it for the receiver to distinguish and display the channel. This is more confusing, as there are three or four different figures involved; there can be a full Program ID, a separate Video ID (VPID) and an Audio ID (APID), which may or may not be set separately. Sometimes the channel listings list one, sometimes the other; and it may not be called this in your receiver's settings. In fact, manually adding channels are often hit-and-miss, because of faulty or partial information of the ID numbers.