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- Radio Noise Problems -

AM or Shortwave Reception Problems?
We may be able to help
(without you having to spend a dime)
By Chris Justice

Old Navy Radio LabI know that this topic has been discussed and written about many times, but, I think it is important enough that we discuss it again one more time, from a technical, yet not so technical stand-point.

Good reception is very easy if you have the right tools... mostly knowledge. I have found through many years of designing products that it's always easier to fix a problem than throw a big Band-Aid on it.

If you are looking for general information on increasing your AM radio reception, please also see our article here Improving AM radio reception

Visualization: Looking at just a single station on the AM broadcast band (below). The green moving triangles are the signal that is broadcast from the station you are listening to. The blue line is, obviously the noise, the red line is the bottom noise floor that your receiver is capable of receiving under the best of circumstances. Important to note: Noise Floor is usually expressed as the receiver's maximum sensitivity and can be, and usually is misunderstood. This is because, if your home or office has too much noise, your sensitive high-dollar receiver cannot receive down to it's potential noise floor. You might as well be listening to a 5 dollar pocket radio! Don't get frustrated with your radio, it's really not it's fault. 

The radio noise problem is as old as radio itself. Unfortunately it is getting worse as technology steadily progresses and more man-made electronic products hit the shelves. This is a direct result of mainly consumer products that generate an increasingly higher noise level. The technology behind the AM broadcast signal is very out-dated as far as current technology is concerned, not to mention that the AM broadcast band is located in the very vulnerable medium wave frequency band.

For instance, looking around the room here I can spot about 80 different sources of noise. The computer I am writing this article on and the LCD monitor, those two devices generate a HUGE amount of noise and would give any regular AM receivers a very bad time. The dimmer switch for the office lights.... bad news. Even the low power flourescent lightbulbs I have overhead cause an extreme problem for any AM reception. Oh, how I wish I could experience the days before all of the digital consumer products, dimmer switches, computers, and noisy lighting products, just to experience what a noise-free AM signal sounded like. Times have really changed. One possibility to reduce the modern day, man-made noise is with a high-tech solution. The DSP (Digital Signal Processor). This is a whole different subject and a little too much to get into here. You can read a little more about DSP here.

The selection of a quality receiver is important. But the antenna and listening location is most important. A good AM or shortwave antenna, in the right location can solve your problem and make your listening much more pleasant. In addition, a good quality AM Antenna can be used to increase the reception of the signal.

Types of receivers:

Before you go out and purchase a high-dollar receiver, please take the following statement into consideration. To some extent, the type of receiver you use will help to eliminate some of your noise problem. There are many receivers with good IF filters that can help reduce the noise coming form external sources. However, in most cases, if you read this article you will already be knowledgable enough to recognize the source of your noise and can probably eliminate or reduce it. Again, this is where a directional Tuned AM Antenna, or even an Active AM Antenna will help to possibly eliminate the noise problems because the signal can be tuned directly at the station and away from the point of noise. ... Speaking of noise problems, let's get to the possible sources.

Possible sources of noise

The following are sources of noise that can generate headaches, especially on the AM and shortwave broadcast bands.

Dimmer Switches and dimming lamps. - These will make it almost impossible to receive any type of signal, regardless of the type of receiver you have or where you A BIG source of radio noise!are located. You simply will get nothing but 60 and 120 Hz noise.

Overhead power lines - Especially with dirty or worn power line insulators. The only way to tell however is to take a small portable receiver outside and walk around until you get up to the power pole and the noise is at it's maximum. Hitting the pole (yes, hitting it) can also tell you a lot. If the noise crackles or you hear it change, or even go away, this is a good tell-tale sign that the insulators are dirty. Contact your local power company if you suspect that source of the noise is coming from the insulators. They can come out and clean the insulators, thus eliminating the problem.

Visualization #2: Once you remove the source of your noise, your receiver's true potential "Sensitivity" can be recognized. It is then, and only then that you will have the quality reception that you desire. Note how the receiver's noise floor is exceptionally lower than in the previous signal on the other page. This is close to the desired effect you want to achieve. Theortically, you would like to see the blue line disappear completely, but with so many man-made noise generators, it is close to impossible. Notice how the noise floor is at the same level but the noise has been reduced.

Flourescent lights - Every fluorescent light has a ballast. A ballast is basically a transformer that is used to step the voltage up to the requirements of the fluorescent tube. This can cause a tremendous amount of noise on any nearby receiver. If you have a specific room that you listen to the radio in, get rid of all fluorescent lights! If you are really interested in the best reception possible, get rid of all of the flourescent lights in your home.

Computers - Yes, I know what you are thinking. NOT MY COMPUTER, it can't go! Well, it doesn't have to go, just turn it off when you want to listen to your radio. Computers are such a huge source of noise that it is almost impossible to list all of the components that generate noise inside of them. Now, this is not just limited to the thing in front of you with the keyboard, many things have computers inside of them. For example a clock, sprinkler timer, microwave oven (yes, most of them have computers and do generate noise), cordless phones, especially that new 900 MHz Spread Spectrum digital phone a lot of you have. I can't possibly name all of the things which contain computers... heck, even your radio. The best solution is to minimize them in your listening room. Oh, did I mention your satellite receiver?

Televisions - Turn it off or get as far away from it as possible. These things create a huge amount of noise, especially from the high-voltage transformer inside of it. If the kids or someone else in the house want to watch the television you can always take your radio outside or find some type of quality external antenna to get away from the source of noise.

Motors - Most types of motors generate or develop a large amount of electromagnetic noise. House hold motors that shouldn't be overlooked are refrigerators, fans, inside heater and air-conditioning units, dehumidifiers, bathroom fans and so on. If it makes noise, sounds like a motor and turns something, it's causing noise.

Some of these are sources of noise that even the best, highest dollar receivers and the best antenna systems in the world cannot overcome and should be momentarily turned off while listening. If you are an apartment dweller, chances are you have a neighbor right next door that has a computer or floursecent light right behind the wall next to you. If this is the unfortunate situation you are in, try speaking to your neighbor and see if you can come up with some type of solution. You can always change to another room. If that doesn't work, you can always purchase a quality FM Transmitter, place your receiver at the point of least noise and transmit the signal across your apartment to your radio..... This is always a possibility and in most cases eliminate your neighbor problem. As far as noise goes anyways.

Also, a lot of you have hear in the news, mentions of digital radio on the AM and shortwave broadcast bands. It is impossible, even for digital radio to get rid of your radio noise. Digital is a 1s and 0s thing. Basically if you have noise, you get a Big 0.... nothing at all. Your radio will simply revert back to analog mode and you will be stuck with enjoying the same high-quality buzz and hum that you have enjoyed all these years.... (smirk)

So, to summarize, get rid of your noise souce and get the full potential quality audio from your receiver.

If you have any questions or need some advise, please feel free to email me.


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