What is the difference between bandwidth and wavebands?

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Discussion Overview

The discussion centers around the distinction between the terms "bandwidth" and "waveband," particularly in the context of AM radio broadcasts. Participants explore the definitions and implications of these terms, comparing them to other contexts such as internet bandwidth.

Discussion Character

  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants note that "waveband" refers to a large section of the radio spectrum used for similar purposes, while "bandwidth" pertains to the frequency interval that contains most of the energy in a signal.
  • One participant explains that the bandwidth of AM broadcasts on the LW and MW wavebands is 9 kHz, indicating the spectrum space occupied by the upper and lower sidebands of the AM signal.
  • Another participant emphasizes that the term "bandwidth" in digital contexts does not have a straightforward relationship with spectral occupancy, as coding and modulation methods can significantly affect the bit rate.
  • Some contributions seek clarification on the definitions of "bandwidth" and "waveband," with requests for differentiation between the two terms.
  • A participant mentions that when tuning into a radio station, the signal is 9 kHz wide, and adjacent stations must be spaced beyond that bandwidth to avoid interference.
  • It is noted that a waveband encompasses all the bandwidths contained within that particular range.

Areas of Agreement / Disagreement

Participants express varying interpretations of the terms "bandwidth" and "waveband," and while some definitions are proposed, no consensus is reached on a singular understanding of the terms.

Contextual Notes

Some definitions depend on specific contexts, such as radio broadcasting versus digital communications, and participants highlight the complexity of these terms without resolving the distinctions.

Who May Find This Useful

This discussion may be of interest to individuals studying radio communications, signal processing, or those curious about the technical language used in physics and engineering contexts.

Pranav Jha
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My physics book repeatedly refers to the term "waveband" while explaining the bandwidth of AM broadcasts

It states that : The bandwidth of AM broadcasts on the LW and MW wavebands is 9kHz.

However, I haven't been able to deduce the meanings of the term "bandwidth" and "wavebands" in the sentence.
How is the term "bandwidth" in this sentence difference from the bandwidth of an internet connects (say 128 Kbps)??
 
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Wave band such as LW or MW refers to a large section of the radio spectrum used for a similar purpose. Bandwidth refers to the highest audio frequency that a given signal can transmit.

According to Wikipedia, LW (long wave) is defined as a carrier frequency of 148.5 kHz–283.5 kHz, while MW (medium wave) is 520 kHz–1,610 kHz. Broadcasting rights are assigned at particular carrier frequencies, 10 kHz apart in the US and 9 kHz apart elsewhere.
 
Pranav Jha said:
My physics book repeatedly refers to the term "waveband" while explaining the bandwidth of AM broadcasts

It states that : The bandwidth of AM broadcasts on the LW and MW wavebands is 9kHz.

However, I haven't been able to deduce the meanings of the term "bandwidth" and "wavebands" in the sentence.
How is the term "bandwidth" in this sentence difference from the bandwidth of an internet connects (say 128 Kbps)??

"bandwidth", in the strict sense, refers to the frequency interval which contains (most of) the energy in a signal. In the case of an RF carrier, Amplitude Modulated by a sound signal the bandwidth would be defined as space between the upper and lower frequencies which have, on average, spectral components which are half the power level of those near the carrier frequency. (You could relate this to the upper and lower -3dB points on the frequency response.) Your figure of 9Khz is the spectrum space occupied by both upper and lower sidebands of the AM signal. This means that the maximum audio frequency will be no more than 4.5kHz in this ancient and rather wasteful system.

When used to describe digital capacity, the term 'bandwidth' is not really correct - although usage has made it acceptable. The bit rate doesn't have a simple relationship with actual spectral occupancy because the coding and modulation method can make a huge difference to the Hz per baud. It depends on to the immunity to noise and interference that you want. Modern systems can squeeze an enormous number of bits per second into each Hz of frequency spectrum. Also, the way that the source signals (pictures or sound) are coded will affect the amount of 'perceived' information greatly - hence the hierarchy of coding levels which you can choose, according to the quality of sound /picture you want.
 
Please differentiate between "bandwidth" and "waveband"
 
Pranav Jha said:
"The bandwidth of AM broadcasts on the LW and MW wavebands is 9kHz."
Pranav Jha said:
Please differentiate between "bandwidth" and "waveband"
Each radio station broadcasts a signal that is 9 kHz wide (a bandwidth of 9 kHz), for example from 193.5 kHz to 202.5 kHz.

The LW waveband contains all long wave radio signals, from 148.5 kHz to 283.5 kHz in Europe.

The MW waveband contains all medium wave radio signals, from 526.5 kHz to 1606.5 kHz in Europe.
 
To jump on what Dr. Greg was saying, when you tune into a "station" on the radio, that signal is 9khz wide. The next station that you can tune into must be beyond that bandwidth or the signals get mixed.

A waveband is the range of all of the bandwidths which that particular waveband contains.
 

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