# Exploring "Audible" RF Allocation in USDOC Chart

• Good4you
Hz. This would be the frequency range where you could hear an oscillator producing an EM frequency. VLF signals occupy those frequencies already, so they are easy to translate to audio. HF bands and below tend to be pretty noisy in crowded areas.

#### Good4you

USDOC Radio Frequency allocation table (http://www.ntia.doc.gov/files/ntia/publications/2003-allochrt.pdf)
lists part of the radio spectrum as "Audible." Radio waves are electromagnetic (e.g. light), while audible waves are pressure waves in a medium (e.g. air.) They travel at very different speeds, and are very different things. We see one and hear the other (depending on the frequency.) An audible RF signal makes absolutely no sense to me. I wouldn't think a government document would get basic science so blatantly wrong, so i think i may be missing something here. If I Google "Audible VLF", there are a lot of hits on the subject. They seem to talk about something like receiving radio frequencies from lightning strikes, and playing them as audio. Or hearing buzzing in electrical lines. Neither scenario i would interpret as being an audible radio wave.

What do you suppose the allocation chart is trying to say? Is it just wrong? Or perhaps correct, but misleading? Or am i completely missing something?

It's just EM at frequencies from 10 -10kHz, plus or minus whatever definition you choose for audio frequencies. Different media obviously.

Agreed. An oscillator producing an EM frequency in that range could be heard audibly if you connected to a speaker. The speaker just does the translating from EM to waves of pressure by design. VLF signals are pretty easy to translate to audio since they occupy those frequencies already. I've heard of some folks just taking a really long wire and plugging it into the mic port on a laptop. If you crank the gain up high enough, you essentially create a basic VLF receiver. Ideally, you'd want around 150 meter-long wire for VLF though, but you could probably pick up some interesting sounds with something shorter around dawn or dusk if you're outside away from heavy EMI. HF bands and below tend to be pretty noisy in crowded areas these days.

abram said:
I've heard of some folks just taking a really long wire and plugging it into the mic port on a laptop. If you crank the gain up high enough, you essentially create a basic VLF receiver. Ideally, you'd want around 150 meter-long wire for VLF though, but you could probably pick up some interesting sounds with something shorter around dawn or dusk if you're outside away from heavy EMI. HF bands and below tend to be pretty noisy in crowded areas these days

Yup a lot of fun listening to various atmospherics ... Dawn Chorus, Whistlers etc

Dave

## 1. What is "Audible" RF allocation?

"Audible" RF allocation refers to the process of assigning specific frequencies within the radio frequency (RF) spectrum for various communication purposes, such as radio broadcasting or mobile phone usage. This ensures that different devices and services can operate without interfering with each other.

## 2. What is the USDOC chart?

The USDOC (United States Department of Commerce) chart is a visual representation of the radio frequency spectrum in the United States. It displays the frequency bands that are allocated for different uses, including broadcasting, mobile communications, and government/military operations.

## 3. Why is it important to explore "Audible" RF allocation in the USDOC chart?

Understanding and exploring "Audible" RF allocation in the USDOC chart is crucial for ensuring efficient and interference-free use of the radio frequency spectrum. It also allows for the identification of potential areas of improvement or optimization in the allocation process.

## 4. How does the USDOC determine the RF allocation in the chart?

The USDOC, specifically the National Telecommunications and Information Administration (NTIA), is responsible for managing the RF spectrum in the US. They use various factors, such as technical and operational requirements, to determine the most appropriate allocation of frequencies for different uses.

## 5. Are there any regulations or guidelines for "Audible" RF allocation in the USDOC chart?

Yes, the USDOC has established rules and regulations for the use of the radio frequency spectrum, including guidelines for "Audible" RF allocation. These regulations are regularly updated to accommodate new technologies and ensure efficient use of the spectrum.