Why FM radio station frequencies always end in an odd number

FM radio station frequencies in the United States and many other countries end in odd numbers due to the way they are allocated by regulatory authorities such as the Federal Communications Commission (FCC) in the U.S. This practice is part of an international standard established by the International Telecommunication Union (ITU), which governs the use of the radio frequency spectrum worldwide.

Here are a few reasons why FM radio station frequencies end in odd numbers:

1. Frequency Spacing and Interference:

• Avoiding Interference: Radio frequencies are spaced apart to avoid interference between stations. If frequencies were too close together, signals from neighbouring stations could overlap and cause distortion or disruptions in reception.

• Odd vs. Even Spacing: Odd-numbered frequencies are used to achieve a specific spacing between stations. This spacing is often referred to as the channel bandwidth, which is typically 200 kHz for FM radio in the U.S. and many other countries.

• Preventing Adjacent Channel Interference: By using odd-numbered frequencies, there is a consistent spacing of 200 kHz between channels. This helps prevent adjacent channel interference, where signals from one station bleed into the frequency range of another.

2. International Standards:

• ITU Guidelines: The ITU, a specialized agency of the United Nations, sets international standards for the allocation of radio frequency spectrum. These standards help ensure that radio frequencies can be used globally without causing harmful interference.

• Harmonization: By adhering to odd-numbered frequency allocations, countries around the world can harmonize their radio spectrum usage. This means that neighboring countries can use similar frequency assignments, reducing the risk of cross-border interference.

3. Bandwidth Allocation:

• Efficient Use of Spectrum: The use of odd-numbered frequencies allows for an efficient allocation of the available radio frequency spectrum. This helps maximize the number of stations that can operate without causing interference to each other.

• Frequency Planning: Radio frequency planners carefully design the allocation of frequencies to ensure that the spectrum is utilized optimally. Odd-numbered frequencies play a key role in this planning process.

4. Historical Precedence:

• Continuation of Past Practices: The use of odd-numbered frequencies for FM radio stations has been a longstanding practice. Over time, it has become an established convention that is followed by regulatory bodies and broadcasters alike.

• Consistency: Maintaining the convention of odd-numbered frequencies ensures consistency across the FM radio band. This makes it easier for broadcasters, manufacturers of radio equipment, and consumers to understand and navigate the radio dial.

In summary, FM radio station frequencies ending in odd numbers are part of an internationally established practice aimed at efficient spectrum usage, avoiding interference between stations, and ensuring global harmonization of radio spectrum allocations. This convention has been in place for decades and continues to be followed to maintain the integrity and reliability of FM radio broadcasting.

Source: Some or all of the content was generated using an AI language model