Radio History: FM (No Static At All) Mystery Cache

This cache is not at the posted coordinates. In fact, you'll be on private property if you look for it at the virtual location. Please do not attempt to look for it there. You need to solve a puzzle to find the final coordinates, which are under half a mile away.

So you've arrived at the finale of the Radio History series. You've read about radio's beginnings by finding GC6FQMH – The Code. You've also read about the oldest transmission method in the world, AM radio, by finding the night cache: GC6HFPT . Now we'll wrap things up by bringing you into the present day with this cache.

FM, or Frequency Modulation, is one of the most widely used forms of transmitting music, data, and otherwise. Edwin Howard Armstrong is widely known as the inventor of FM, describing its use as far back as 1933. The first station started broadcasting in 1937. Around this time, television had its beginnings as well. Mobile phones started appearing in 1949 in limited markets. Believe it or not, that cell phone in your hand or in your pocket uses radio waves too. It is essentially a walkie-talkie. There are many good sources on the history of cell phones a quick search will reveal. Now even cellphones contain FM radios (carrier dependent).

FM has many advantages over its older AM cousin. For one, wider audio bandwidth means that we can listen to music with clarity very close to the original product. FM is also more robust against noise. During a thunderstorm with AM radio, you'll hear the lightning crackles. FM, much less so or not at all. FM is also more well known for being in stereo (both left and right channels) although AM has a similar concept that is frankly underused (CQUAM). It is these differences that make FM very popular.

The first FM band was assigned to 42 to 50 MHz. A number of factors necessitated a shift to higher frequencies we know today (88.1 FM to 107.9 FM), including interference (atmospheric and otherwise) and reducing crowding. It was this move that also set FM radio back from taking off, keeping AM the dominant mode of transmission well into the 1960s and 70s. By the end the 70s, most listeners had gone to FM however, reaching 70% of a global audience by 1982.

FM stations in the United States are spaced .2 MHz apart, so a station can be on 88.1, 88.3, 88.5 etc. Some radio stations broadcast a digital technology alongside the analog signal known as RDS. Many stations in St. Cloud carry RDS. In the first decade of the 2000s, a new technology that claimed to bring CD quality audio to FM stations began to show up on stations across the country. Many people began to confuse this with over the air television, though the two are completely different. In fact the name of this technology has been said to mean absolutely nothing (other than being a clever marketing ploy that seems to have not helped the company).

What does the future of FM broadcasting hold? Many countries abroad are abandoning traditional AM/FM radio as we know it, and going for digital audio broadcasting. The United States isn't likely to do so any time soon, but we can only see. A lot of devices depend on FM radio, so chances are it isn't going anywhere for a long time.

To solve this puzzle, you'll need to look at the image of the table below and find the numbers in the frequencies you see. You may need to view this on geocaching.com if your device doesn't render images.

Your coordinates will look like AB CD.EFG North HI JK.LMN West. Simple enough right?

You can check how well you know the radio dial by verifying this puzzle on GeoChecker.com.