Voltage and dbm formula
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(sorry - something went wrong while pasting) Y = 15.9 x X - 91.6 <- this is the equation you've asked for. You can check it: double check: So, with a RSSI voltage on port of 3.5 Volt, the RSL is around -36 dBm Your question: "if we have on multimeter during alignment 3V ,what's corresponding in dbm ?" X = 3 => Best Regards ahXing |
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Hello, dear. Are you looking for this formula?
For more information, you can refer to the following materials. Thanks！ |
user_4034933
Created Nov 24, 2020 07:49:45
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Thanks for sharing that, But any equation there between voltage and dbm? 
ahXing
Reply user_4034933 Created Nov 24, 2020 11:52:11
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Dear user_4034933, You could derive the equation like this: Y = 15.9 x X - 91.6 Suppose: X = RSSI port voltage Y = RSL (in dBm) then: Y = aX +b -90 = a(0.1) + b -20 = a(4.5) + b b = -20 - a(4.5) -90 = a(0.1) + [-20 - a(4.5)] -90 = a(0.1) -20 - a(4.5) -a(4.4) = -90 + 20 -a(4.4) = -70 a = 70/4.4 = 15.9 b = -20 - a(4.5) -> b = -20 - 15.9*(4.5) b = -20 - 71. |
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user_4034933
Created Nov 24, 2020 06:53:27
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Need formula between voltage received in multimeter and received RSL in dbm. for example:- if we have on multimeter during alignment 3V ,what's corresponding in dbm ? |
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Hello, dear. Are you looking for this formula?
For more information, you can refer to the following materials. Thanks！ |
user_4034933
Created Nov 24, 2020 07:49:45
(0)
(0)
Thanks for sharing that, But any equation there between voltage and dbm?
ahXing
Reply user_4034933 Created Nov 24, 2020 11:52:11
(0)
(0)
Dear user_4034933, You could derive the equation like this: Y = 15.9 x X - 91.6 Suppose: X = RSSI port voltage Y = RSL (in dBm) then: Y = aX +b -90 = a(0.1) + b -20 = a(4.5) + b b = -20 - a(4.5) -90 = a(0.1) + [-20 - a(4.5)] -90 = a(0.1) -20 - a(4.5) -a(4.4) = -90 + 20 -a(4.4) = -70 a = 70/4.4 = 15.9 b = -20 - a(4.5) -> b = -20 - 15.9*(4.5) b = -20 - 71. |
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(sorry - something went wrong while pasting) Y = 15.9 x X - 91.6 <- this is the equation you've asked for. You can check it: double check: So, with a RSSI voltage on port of 3.5 Volt, the RSL is around -36 dBm Your question: "if we have on multimeter during alignment 3V ,what's corresponding in dbm ?" X = 3 => Best Regards ahXing |
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user_4034933 wrote: Yes, there is... which is:
and R, is the impedance (in radio systems = 50 Ω ; television and video systems = 75 Ω ). For calibrations however not suitable, because of the way how RSSI is being derived. Especially nowadays, with modern fast changing complex digital signals... the averaging of the signal power can cause for dramatic misjudgements. Therefore, this value is rectified, filtered and processed (implementation dependent, mostly at IF stage). So, for calibration - stick to the tables and diagrams provided for that device. Another reason why this equation is unsuitable for Rx calibration: please realize, you are not measuring the voltage at antenna port, but way back (at IF probably) - after the filters and amplifiers. Hope this helps. ahXing |
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