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Interesting. But I had never before heard a description of RF ranges in octaves. I suppose it makes sense, but that completely threw me off because I thought th

Interesting. But I had never before heard a description of RF ranges in octaves. I suppose it makes sense, but that completely threw me off because I thought they were talking about sound waves for a second.

justtopost 8y ago
All waves are based in the time domain (space between waves), half or double space is an octave. Slighty unusual, but not very. I hear musical terms used a lot when it comes to analog signals. (Yes, even 'digital' signals need an analog carrier).
bcaa7f3a8bbc 8y ago
> never before heard a description of RF ranges in octaves you can read something about filter designs... > It is usual to measure roll-off as a function of logarithmic frequency, consequently, the units of roll-off are either decibels per decade (dB/decade), where a decade is a 10-times increase in frequency, or decibels per octave (dB/8ve), where an octave is 2-times increase in frequency. https://en.wikipedia.org/wiki/Roll-off https://en.wikipedia.org/wiki/Roll-off
jjoonathan 8y ago
I hear it fairly often in discussions about passives that operate in a frequency range excluding DC. If the geometry defines the frequencies, the upper and lower frequency limits will have a fixed ratio as you scale the device up/down. For instance, textbook directional couplers typically have octave range (1-2GHz, 2-4GHz, 10-20GHz) while "clever" couplers can have decade range (1-10GHz) or more. Similar stories apply to cavity or microstrip filters/resonators. Since frequency and bandwidth are banner specs the terms often leak into the names themselves -- someone might advertise a "multi-decade coupler" and compare it to "octave couplers." You can readily find examples on google. Harmonics are a key concern in RF but I usually hear the terms "fundamental, second, third, etc" used to refer to them and it would sound odd to my ear if someone used "octave" in that context.

justtopost 8y ago

All waves are based in the time domain (space between waves), half or double space is an octave. Slighty unusual, but not very. I hear musical terms used a lot when it comes to analog signals. (Yes, even 'digital' signals need an analog carrier).

bcaa7f3a8bbc 8y ago

> never before heard a description of RF ranges in octaves you can read something about filter designs... > It is usual to measure roll-off as a function of logarithmic frequency, consequently, the units of roll-off are either decibels per decade (dB/decade), where a decade is a 10-times increase in frequency, or decibels per octave (dB/8ve), where an octave is 2-times increase in frequency. https://en.wikipedia.org/wiki/Roll-off https://en.wikipedia.org/wiki/Roll-off

jjoonathan 8y ago

I hear it fairly often in discussions about passives that operate in a frequency range excluding DC. If the geometry defines the frequencies, the upper and lower frequency limits will have a fixed ratio as you scale the device up/down. For instance, textbook directional couplers typically have octave range (1-2GHz, 2-4GHz, 10-20GHz) while "clever" couplers can have decade range (1-10GHz) or more. Similar stories apply to cavity or microstrip filters/resonators. Since frequency and bandwidth are banner specs the terms often leak into the names themselves -- someone might advertise a "multi-decade coupler" and compare it to "octave couplers." You can readily find examples on google. Harmonics are a key concern in RF but I usually hear the terms "fundamental, second, third, etc" used to refer to them and it would sound odd to my ear if someone used "octave" in that context.