Many off us don't kill file you because you have a high technical knowledge of interest to those using test equipment for testing and repairs. It has zero to do with using your real name. That said, your online personality just sucks, why you need to degrade people rather than just correcting them or presenting the facts as you see them is a character flaw. Why would you kill file anyone, you need targets. Mikek
Yes, you are quite correct. My original followup is a non sequitur because it doesn't address gain. All it does is show that 6dBV level = 3dBm level = 0.5 [1]
For a 6dBV level into 50 Ohms, V = 2V and P = V^2 / R = 80mW. For a
3dBm level P = 2mW.Note.
[1] The most common attenuators have values of 3 dB, 6 dB, 10 dB and 20 dB. This corresponds to voltage ratios of 0.7, 0.5, 0.3 and 0.1 or power ratios of 0.5, 0.25, 0.1 and 0.01.Thank you,
-- Don Kuenz KB7RPU There was a young lady named Bright Whose speed was far faster than light; She set out one day In a relative way And returned on the previous night.
I'm not following you at all.
dBV is using a specific voltage as a reference, specifically 1 volt. 6 dBV gives a gain of 2 in voltage, a gain of 4 in power if into the same impedance.
dBm is using a specific power as a reference. 3 dBm is 2 mW.
How can you say
6dBV level = 3dBm level = 0.5???
6dbV will only be equal to 3 dBm if the impedances on each side are in the ratio of 1:2 to give the equal current for both voltages.What are you trying to do?
-- Rick C. --- Get 1,000 miles of free Supercharging --- Tesla referral code - https://ts.la/richard11209
------------
** You could not be more wrong abut that last claim. ** Your question has a false assumption.I correct people all the time and post the facts too.
Then, if they become defensive and act all aggressive - I have to right to shit all over them.
Fools can never learn about what they wrongly think they know already.
Fools have no right to post here at all.
And you are one of them.
.... Phil
No you don't. Your argument is frequently just... zip.
In a recent thread you claimed federal government workers universally are r equired to sign a document prohibiting them from talking about their work. When I explained I had been a government worker and never signed any such paper, your reply included the articulate and persuasive points...
** Yawnnn...*** and ***
** Your arrogant pig ignorance is your only point.Yes, that is clearly posting "the facts".
I don't know what your particular mental disease is, but it's clear you are not of sound mind. So much that you literally can't have a civil conversa tion.
-- Rick C. --+ Get 1,000 miles of free Supercharging --+ Tesla referral code - https://ts.la/richard11209
=================================
Phil Allis> >
** Yes I do - you stupid troll.** Never said "universally".
FYI f*****ad:
When complaining about a post you MUST post under it, never reword or rephrase it and never remove the context.
are required to sign a document prohibiting them from talking about their work. When I explained I had been a government worker and never signed any such paper,
** Which is a totally IDIOTIC thing to post. ** It's a damn good one too.Fools like you never know that they are fools - so I am happy to remind them.
.... Phi l
You lie universally...
"Governments rely on privacy/secrecy provisions that all public servants must sign before taking up employment."
"Govt employees are all sworn not to discuss their work"
Do you deny writing this???
Because it shows you are wrong???
Then you need to talk to the mirror. That's the biggest fool. And a wrong fool. An alwayswrong fool.
-- Rick C. -+- Get 1,000 miles of free Supercharging -+- Tesla referral code - https://ts.la/richard11209
This thread's semantical trap-doors are treacherous!
This time sloppy "signmanship," so to speak, causes confusion. Although attenuation always implies the negative case, it helps to explicitly include the negative sign.
-6dBV level = -3dBm level = 0.5 -6dBV ratio = -3dBm ratio = 0.5 -6dBV multiplier = -3dBm multiplier = 0.5 -6dBV coefficient = -3dBm coefficient = 0.5
6dBV level = 3dBm level = 2 6dBV ratio = 3dBm ratio = 2 6dBV multiplier = 3dBm multiplier = 2 6dBV coefficient = 3dBm coefficient = 2Thank you,
-- Don Kuenz KB7RPU There was a young lady named Bright Whose speed was far faster than light; She set out one day In a relative way And returned on the previous night.
-6dBV is a power level but you need to know the resistance that the system is relating dBV to. -3dBm is an absolute power level...0.5 mW
These are not ratios. dB's are ratios.
dBs can be thought of as multiplies, not dBv's and dBm's
dB system relates one thing to another. It helps to know one of those two things. dBms and dBV's are the known items. dBs is how you express a relationship of something to a known something.
6dBV is not 2. It's 2V. Likewise, 3dBm is not 2. It's 2mW. You have to keep your units straight.
Signal gains or losses are ratios, expressed in dB without suffix. It would be OK to say that 3dB=2, but only if we were talking about power gain. It'd be OK to say that 6dB=2, but only when referring to voltage gain.
Just 6dBV = 3dBm is true only when the load impedance happens to be 2kOhm.
Jeroen Belleman
Let's try it this way:
A loss of 6 dB corresponds to a voltage ratio of 0.5. A loss of 3 dB corresponds to a power ratio of 0.5.
A gain of 6 dB corresponds to a voltage ratio of 2. A gain of 3 dB corresponds to a power ratio of 2.
Thank you,
-- Don Kuenz KB7RPU There was a young lady named Bright Whose speed was far faster than light; She set out one day In a relative way And returned on the previous night.
The hardest part of decibels for me isn't the math nor the mechanics of grinding out answers. It's the precise nomenclature.
A loss of 6 dB corresponds to a voltage ratio of 0.5. A loss of 3 dB corresponds to a power ratio of 0.5.
A gain of 6 dB corresponds to a voltage ratio of 2. A gain of 3 dB corresponds to a power ratio of 2.
Thank you,
-- Don Kuenz KB7RPU There was a young lady named Bright Whose speed was far faster than light; She set out one day In a relative way And returned on the previous night.
You nailed it.
Cheers, Jeroen Belleman
r a
The problem is unless the impedances are specified these quantities are not equivalent. By using 1 volt or 1 mW as a reference, the scales are not pu re ratios anymore but absolute measurements. So the equations above are no t valid without clarification of the impedance.
Let me explain it this way. 6 dBV is not 2. It is 2 volts. 3 dBm is not
2 it is 2 mW. 2 volts is only 2 mW when driving a 2 kohm load. Is that mo re clear?My previous post on this talked about impedance ratios as if the dBV and dB m were comparing two measurements. I had myself confused.
-- Rick C. +-- Get 1,000 miles of free Supercharging +-- Tesla referral code - https://ts.la/richard11209
Yes, exactly!
-- Rick C. +-+ Get 1,000 miles of free Supercharging +-+ Tesla referral code - https://ts.la/richard11209
Yes 6dBV is 2V Across some resistance that you need to know before it is (generally)relevant.
0dBV is 1V6dBV = 0dBV + 6dB = 6dBV = 2V across some resistance (which is power)
d
after
=0.08
in.
This thread seems to have rumbled on for some time generating much heat but little light. May I refer you to an application note 1MA98 from Rohde and Schwarz
Scott.
On 2020-04-21 12:45, Prof78 wrote: [Snip!]
There's a bit missing from that R&S link. Here is it completed; .
It's 44 pages long, amazingly. I have an issue with section 5.2 too, but that's a bit off topic.
Jeroen Belleman
It's more on topic than the threads about politics. This short link was posted by me a few days ago. It fits usenet better.
Besides _Hamlet_, there's a second nod to Dr. David Reuben's sex book.
About that issue in section 5.2, here's the things that catch my attention.
Thank you,
-- Don Kuenz KB7RPU There was a young lady named Bright Whose speed was far faster than light; She set out one day In a relative way And returned on the previous night.
entitled: dB or not dB? [with a nod to Shakespeare and Hamlet Prince
It's 44 pages long, amazingly. I have an issue with section 5.2
Those weren't my issues. The maximum available noise power from a resistor is indeed P=kTB, and that is in fact where the commonly used formula Vn=sqrt(4kTRB) comes from. Not the other way around.
My issue was the statement that the noise power at the input of a receiver is -174dBm/Hz, which just isn't true. Nor is it true that only cooled receiver input stages can do better. I've done much better, even with ordinary room-temperature circuitry.
But neither have anything to do with decibels per se. The note is about decibels, not about noise.
Jeroen Belleman
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.