Are you the sort of person who thinks you always need more power? A lot of us are like that, and I don’t blame you. But when it comes to amplifying signals, more power isn’t always best. Believe me, Solid Signal sells great amplifiers for all sorts of signals, and I’d love to sell you one. But I don’t want to sell you something you don’t need. So, let’s go over why an amplifier might not be what you think it is.
The three different kinds of amplifiers
When it comes to amplifiers for signals over a wire, there are three different kinds. Now, I’m not talking about audio amplifiers here, that’s a completely different article. I’m talking about an amplifier you might use with a TV antenna, satellite dish, commercial headend system or even a cell phone signal booster. One thing that all these systems have in common is that they use a digital signal on an analog carrier, and that means an amplifier might not act the way you expect.
Preamplifiers
The purpose of a preamplifier, or preamp for short, is to overcome the loss inherent in a long cable run. If your antenna or satellite dish is up on the roof, you probably have 50-100 feet of cable between then antenna and the TV. Typically, a signal will lose about 6-9dB as it travels over that much cable. (I say typically, because every frequency and every cable are different.) The whole point of a preamp is that it pumps up the signal enough to account for that difference, without introducing a lot of noise.
Preamplifiers are also used on antennas to try to help small antennas act like big ones. If a digital signal comes in very weakly, it’s going to be lost as it travels over a cable. Amplifying it will help with this, but it’s not going to help you get signals that can’t be received at all.
Distribution amplifiers
The purpose of a distribution amplifier is to overcome the loss inherent in splitting a signal. A typical 8-way splitter has about 14dB loss. Why? Because you’re splitting the signal 8 ways, which means each output only has 1/8 the power. Another way of saying “1/8 the power” is 12dB loss. Add another 2dB for all the wires and connectors and that’s what you get. The distribution amplifier can also act as a preamp in the sense that it can help offset the loss from longer cable runs as well. A distribution amplifier can tend to be a little “noisier” than a preamp.
Launch amplifiers
Most folks do not have any need for a launch amplifier. Launch amplifiers are used in commercial installs. The goal of a launch amplifier is to pump up the signal as high as it can possibly be without getting distorted, so it can travel through long lines and get split further down the line. You don’t find launch amplifiers in homes because the signal levels from them are so high that you couldn’t connect the line straight to a TV without damaging its tuner.
Let’s talk about noise
When you’re using digital signals, the most important measure is signal-to-noise ratio. I’ve talked about this several times before, but if you really want to dive in I’d look at this article, this article, and this article. If your signal level is too close to your noise level, then your TV or receiver won’t be able to decode the signal. As long as they’re sufficiently different levels, there’s no problem. Any amount of signal above that level isn’t going to help you at all.
If you have enough signal to overcome loss and keep the signal level higher than the noise level, more amplification won’t help you. It may actually hurt you, as I’ll explain below.
What happens when you overamplify a signal?
It’s actually fairly easy to overamplify a signal. The amount of loss over lines is relatively low, and if you’re not using a lot of large splitters, your signal level is going to be relatively strong. It could be so strong that it’s outside the “input window” that’s recommended for that sort of signal.
Signal levels are often measured in dBm, although there are other measures that are sometimes used. There’s a decent calculator here that will let you convert between standards here. So, I’m going to refer to all signals in dBm. Generally dBm is shown as a negative number, with numbers closer to zero (like -5) being stronger than numbers further from zero (like -60.) Here’s a tutorial to help you understand more.
Here’s a very simple guide to know if your signal level is too low or too high. You’ll need to have some sort of signal meter to get those numbers.
| Type of Signal | Lowest Level | Highest Level |
|---|---|---|
| Satellite TV signals (before multiswitch) | -45 | -25 |
| Satellite TV signals (at receiver) | -60 | -45 |
| Over-the-air antenna (at TV) | -50 | -5 |
| Signals for distribution in commercial setting | -50 | +20 |
If your signal level is within these parameters, you’re going to get the signal you want. If the signal is too weak, it’s going to drop out. On the other hand if it’s too high, you risk damage to the receiver or TV. At any rate the signal will be distorted. It’s sort of like when you talk too close to a microphone and your voice sounds weird and fuzzy.
Also, getting back to the idea of noise, remember that everything you add to a line (such as splitters, barrels, and connectors) increases the amount of noise on the line. With enough stuff, the amount of noise gets to be too close to the allowable signal level. At that point the whole thing stops working.
What can you do then, if you can’t get the reception you want?
If you are having problems receiving signals, you first need to ask if that signal can even be received. Here are some reasons you wouldn’t be able to receive a signal:
- It’s too far away (about 75-80 miles if you’re talking about TV antennas)
- There’s too much stuff between you and the broadcast source
- You can’t put up the antenna you need in order to get that signal
If that signal source is too far away, there’s not much you can do. Putting an antenna up high can help with this and also with obstructions. The higher the antenna is, the less stuff there is between it and the tower.
However, the biggest problem is usually that you can’t use the antenna you need. The best antenna is generally going to be the biggest one. If your HOA doesn’t allow it, or if you can’t use an outdoor antenna, that’s a problem. It’s a problem that won’t be solved by any amount of amplification.
If this all seems too hard…
Don’t worry! You have experts on your side! If you’re not sure about what you need for any sort of install you can call for help. Whether it’s home or business, satellite, TV, or cellular, we’re here to make it easy. Just call us! The number is 888-233-7563. We’re here during East Coast business hours. If it’s after hours, no problem! Fill out the form below. We’ll get right back to you!
