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#1
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There are various dBx measures of real signal characteristics. The most
common ones that I know of are dBm (dB over 1mW), dBV (dB over 1V, presumably ignoring impedance and therefore really just a fancy-pants amplitude measure) and dBc (dB under carrier, very important stuff to measure phase noise in an oscillator or transmitter). ====================================== RF power limitations (power into antenna) for the UK amateur radio licences are expressed in dBW 26 dBW equals 400 Watts 15 dBW equals 32 Watts etc . Frank GM0CSZ / KN6WH |
#2
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Highland Ham wrote:
There are various dBx measures of real signal characteristics. The most common ones that I know of are dBm (dB over 1mW), dBV (dB over 1V, presumably ignoring impedance and therefore really just a fancy-pants amplitude measure) and dBc (dB under carrier, very important stuff to measure phase noise in an oscillator or transmitter). ====================================== RF power limitations (power into antenna) for the UK amateur radio licences are expressed in dBW 26 dBW equals 400 Watts 15 dBW equals 32 Watts etc . Frank GM0CSZ / KN6WH Why not just say Watts or milliwatts and be done with it? Why drag dB into it? BTW dB means deci-bell, why not use a WHOLE BELL. (and the brass figligee with bronze oak-leaf palm to anybody who can guess who this unit of measure was named after!) |
#3
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Ken Scharf wrote:
RF power limitations (power into antenna) for the UK amateur radio licences are expressed in dBW 26 dBW equals 400 Watts 15 dBW equals 32 Watts etc . Why not just say Watts or milliwatts and be done with it? Why drag dB into it? Maybe because dB gives you a better idea of the limited communications benefit to be achieved by turning up the power? It also simplifies factoring in antenna gain, feadline loss, etc... Really this is same idea as using a sliderule - take the log of everything and then gain/loss becomes simple addition subtraction. One downside though is that when playing around with a signal generator calibrated in dB, you can fail to appreciate the degree to which you may be turning up the power to something under test, at least until you get used to the numbers. |
#4
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Ken Scharf wrote:
Highland Ham wrote: There are various dBx measures of real signal characteristics. The most common ones that I know of are dBm (dB over 1mW), dBV (dB over 1V, presumably ignoring impedance and therefore really just a fancy-pants amplitude measure) and dBc (dB under carrier, very important stuff to measure phase noise in an oscillator or transmitter). ====================================== RF power limitations (power into antenna) for the UK amateur radio licences are expressed in dBW 26 dBW equals 400 Watts 15 dBW equals 32 Watts etc . Frank GM0CSZ / KN6WH Why not just say Watts or milliwatts and be done with it? Why drag dB into it? ==================================== Just ask the UK licensing authority Frank GM0CSZ / KN6WH |
#5
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Ken Scharf wrote:
BTW dB means deci-bell, why not use a WHOLE BELL. (and the brass figligee with bronze oak-leaf palm to anybody who can guess who this unit of measure was named after!) Well, it wasn't named after Watson, so that only leaves one man... -- Service to my country? Been there, Done that, and I've got my DD214 to prove it. Member of DAV #85. Michael A. Terrell Central Florida |
#6
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Michael A. Terrell wrote:
Ken Scharf wrote: BTW dB means deci-bell, why not use a WHOLE BELL. (and the brass figligee with bronze oak-leaf palm to anybody who can guess who this unit of measure was named after!) Well, it wasn't named after Watson, so that only leaves one man... Art Bell? -ex |
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