Hi there,

Yes, and my point was if we just call either one a 'gain' we don't have to worry about if it is an actual gain or an actual loss.
This is done all the time so I can't figure how why this is so hard to understand for some.
Vout=Vin*K

Is K equal to 1, or is it 0.1, or is it -1, or is it -0.2, or perhaps 10 or -12? We don't have to worry about it, just multiply it by Vin and we get the right answer every single time

I brought this up so that people would perhaps become more comfortable with this idea because after all it is used in a lot of fields, and it wasn't me who started it, it was determined long ago.

It's not hard to figure out (which doesn't prevent some humans from misstating things, but that will always be the case).

I'm having a hard time figuring out just what your point is. Are you advocating that we should always and only use "gain"?

The reason why both gain and loss (attenuation) are used is because humans are not good when working with fractional values or negative numbers or extremely large and extremely small numbers. We make a lot more mistakes. So we commonly define things so that the expected values that we will need to work with are positive numbers between 1 and 1000. If you force everyone to use "gain" in contexts where losses are the norm, then you will end up with people making more mistakes.

 

And I brought up my example to show that, in common parlance, different words are often used for a positive vs negative change.

You will also never hear anyone say its -10 degrees hotter today than yesterday, or the hike went up -1000 ft, or prices are up by .75.

These examples, I would argue, are mathematically correct, but incorrect English usage.

Hi,

Well you are just repeating the same ideology when my main point was to NOT do that
I also said that if you state it differently it might sound wrong. It's for simplicity, not for human consumption as much.
We don't usually say "I am driving to fast I will change my speed by -10mph", we would probably say, "I will slow down by 10mph".
In a spread sheet though, we don't want to have to write somewhere "speed up" and "slow down", we just use signed numbers to indicate the speed.
This is where the forced ambiguity comes in. We force everything into one single signed variable, just like we do with the 'x' axis.

I am not trying to force you into anything, just suggesting that when we call something a 'gain' in electronics it is simpler to allow that to include losses or gains just by the value and the sign. I also said that this happens automatically in many cases like:
Vout=Vin*K

where K can be ANY number, and have ANY polarity. We almost have to do that in many cases or we'd have to write more equations.

 

My 2 cents:

If you work in dB instead of raw gain values, the words "gain" and "attenuation" become highly intuitive, IMHO.

-3dB gain is 3dB attenuation.

 

And I brought up my example to show that, in common parlance, different words are often used for a positive vs negative change.

You will also never hear anyone say its -10 degrees hotter today than yesterday, or the hike went up -1000 ft, or prices are up by .75.

These examples, I would argue, are mathematically correct, but incorrect English usage.

Though I can't count the number of times I have heard people -- including "meteorologists" -- say things like, "Tomorrow's highs will be twice what they were today", or, "As this cold front comes through, temperatures will be cut in half."

Other than that, I generally, though I don't know that it's so much "incorrect" English language, as just uncommon and another reflection of the that we don't like working with negative numbers if we can avoid it, so it is more common to phrase things such that we can avoid it when it can be done. When we need to have a mix of positive and negative numbers, we typically choose for the positive number to represent an increase. So we might have a list of cities alongside how much hotter they are today relative to their seasonal average. We wouldn't have any problem understanding that a city with a -10°C next to it is actually 10°C cooler than its average. Similarly, if we had a list of hike destinations and the altitude increase to each, no one would bat an eye to see a destination that had a negative altitude gain, it just means it is located at a lower altitude than the starting point.

I'm not sure what you mean by "prices are up by .75", particularly in the context of never hearing anyone say it. I would certainly consider it reasonable for someone to say that prices are up 75%, and since 75% is the same as 0.75.... A phase like, "home prices are up by half from three years ago" would not be strange,

 

It's not hard to figure out (which doesn't prevent some humans from misstating things, but that will always be the case).

I'm having a hard time figuring out just what your point is. Are you advocating that we should always and only use "gain"?

The reason why both gain and loss (attenuation) are used is because humans are not good when working with fractional values or negative numbers or extremely large and extremely small numbers. We make a lot more mistakes. So we commonly define things so that the expected values that we will need to work with are positive numbers between 1 and 1000. If you force everyone to use "gain" in contexts where losses are the norm, then you will end up with people making more mistakes.

Hi,

What I am suggesting is that people 'accept' the use of the term 'gain' when sometimes they would not. This is because we almost have to some times in technology.

Consider the reverse current gain of a bipolar transistor, it's always going to be less than 1. Should we call it the reverse current loss or attenuation?
I guess we could, but we'd still have to provide a number like 0.1 or even 0.01 which is much less than 1.
The current gain is usually greater than 1, but the reverse current gain is always less than 1. We call them both the respective 'gain'.

This actually started with the considerations for bipolar and FET type transistors also. Maybe we should confine the discussion to those areas of technology even though we see this in other interesting areas too. I didn't want to state that too soon because I did not want to upset anyone that thought we can't do this, ever.

 

My 2 cents:

If you work in dB instead of raw gain values, the words "gain" and "attenuation" become highly intuitive, IMHO.

-3dB gain is 3db attenuation.

Hi,

Yeah that's interesting too. When we state the 'gain' in dB, we usually don't have to specify if it is an actual gain or actual loss.
A gain of 3dB, a gain of -3dB, we don't have to specify 'attenuation' or 'loss' unless we want to.

 

Hi,

What I am suggesting is that people 'accept' the use of the term 'gain' when sometimes they would not. This is because we almost have to some times in technology.

Consider the reverse current gain of a bipolar transistor, it's always going to be less than 1. Should we call it the reverse current loss or attenuation?
I guess we could, but we'd still have to provide a number like 0.1 or even 0.01 which is much less than 1.
The current gain is usually greater than 1, but the reverse current gain is always less than 1. We call them both the respective 'gain'.

This actually started with the considerations for bipolar and FET type transistors also. Maybe we should confine the discussion to those areas of technology even though we see this in other interesting areas too. I didn't want to state that too soon because I did not want to upset anyone that thought we can't do this, ever.

What "people"? It seems like you are manufacturing a problem that doesn't exist. Can you cite any examples where it is maintained that a gain of less than unity cannot be described as a gain of less than unity, but instead must be described as an attenuation?

 

What "people"? It seems like you are manufacturing a problem that doesn't exist. Can you cite any examples where it is maintained that a gain of less than unity cannot be described as a gain of less than unity, but instead must be described as an attenuation?

Hi,

Not sure where you read that. I certainly did not mean that at all and am saying just the opposite.

 

Hi,

Yeah that's interesting too. When we state the 'gain' in dB, we usually don't have to specify if it is an actual gain or actual loss.
A gain of 3dB, a gain of -3dB, we don't have to specify 'attenuation' or 'loss' unless we want to.

Yes, and if you're building an "attenuator", would it make sense to specify "gain" or "attenuation"?

 

Hi,

Yeah that's interesting too. When we state the 'gain' in dB, we usually don't have to specify if it is an actual gain or actual loss.
A gain of 3dB, a gain of -3dB, we don't have to specify 'attenuation' or 'loss' unless we want to.

Since dB is DEFINED as the ratio of output power over input power, it is DEFINED as being a GAIN.

If you want to describe the result in terms of attenuation (which is commonly done to avoid a bunch of negative numbers), then you need to specify that explicitly somehow.

 

Hi,

Not sure where you read that. I certainly did not mean that at all and am saying just the opposite.

It's hard to figure out just what you are saying, because you just said, " What I am suggesting is that people 'accept' the use of the term 'gain' when sometimes they would not. ", but when I ask you to cite an example of where it is maintained that a gain of less than unity cannot be described as a gain of less than unity, you insist that you are not saying that and am somehow saying just the opposite.

So. What, exactly, are you saying?

 

If you want to describe the result in terms of attenuation (which is commonly done to avoid a bunch of negative numbers), then you need to specify that explicitly somehow.

And yet, if someone said “an attenuation of -3bB” I would never assume that meant a gain, would you?

 

Hi there,

Yes, and my point was if we just call either one a 'gain' we don't have to worry about if it is an actual gain or an actual loss.
This is done all the time so I can't figure how why this is so hard to understand for some.
Vout=Vin*K

Is K equal to 1, or is it 0.1, or is it -1, or is it -0.2, or perhaps 10 or -12? We don't have to worry about it, just multiply it by Vin and we get the right answer every single time

I brought this up so that people would perhaps become more comfortable with this idea because after all it is used in a lot of fields, and it wasn't me who started it, it was determined long ago.

I fear you are conflating domains. If you want to do math on signal paths that alter the amplitude of the input compared to the output you can call it "gain" and have the one variable. If you want to talk about amplification and attenuation, or gain and loss then using the complementary pair of words suitable to the circumstances is much more useful.

In fact, in domains where gain (K>1) is the expectation then calling the referent of K should be called "gain" while in domains were loss is the expected outcome (K<1) then the referent of K should be called "loss"—for purposes of clarity.

Perhaps it is even good to use something like relative amplitude for cases where K has expected values with bounds on both sides of 1.

In the math it doesn't matter, but people create ghosts by trying to turn names into analogies and reducing the chance of doing that is worthwhile.

 

It's hard to figure out just what you are saying, because you just said, " What I am suggesting is that people 'accept' the use of the term 'gain' when sometimes they would not. ", but when I ask you to cite an example of where it is maintained that a gain of less than unity cannot be described as a gain of less than unity, you insist that you are not saying that and am somehow saying just the opposite.

So. What, exactly, are you saying?

Hi again,

In short, I am saying that if we call all of this a 'gain' and forget for a minute about 'attenuation' or 'loss', we can use just one variable and don't need a wordy description about what it is all about.

 

And yet, if someone said “an attenuation of -3bB” I would never assume that meant a gain, would you?

Only if the input signal was -5dB or the like.

 

And yet, if someone said “an attenuation of -3bB” I would never assume that meant a gain, would you?

Depends on context. If it were in a situation in which a chain of processing elements was strung together and most of them were expected to cause attenuation, then seeing one described as having a negative attenuation (in dB) would catch my attention, causing me to consider whether it was reasonable for that element to have an actual gain. But if it were just a case of someone saying that, without an establishing context, I would certainly want to verify it with them, if possible, because my suspicion would be that they are being sloppy/careless.

 

Hi again,

In short, I am saying that if we call all of this a 'gain' and forget for a minute about 'attenuation' or 'loss', we can use just one variable and don't need a wordy description about what it is all about.

Of course!

We routinely do this!

And we have been routinely doing this for far longer than I've been alive.

So, again, you seem to be trying to solve a problem that doesn't exist.

 

Only if the input signal was -5dB or the like.

The size of the input signal should have nothing to do with the amount of attenuation, since that is a characteristic of the system, not the signal.

I also wouldn't know how to interpret what an input signal of -5 dB even is. There's no reference. I would expect it to be expressed relative to some reference power, such as milliwatts (dBm) or watts (dBW).

 

I fear you are conflating domains. If you want to do math on signal paths that alter the amplitude of the input compared to the output you can call it "gain" and have the one variable. If you want to talk about amplification and attenuation, or gain and loss then using the complementary pair of words suitable to the circumstances is much more useful.

In fact, in domains where gain (K>1) is the expectation then calling the referent of K should be called "gain" while in domains were loss is the expected outcome (K<1) then the referent of K should be called "loss"—for purposes of clarity.

Perhaps it is even good to use something like relative amplitude for cases where K has expected values with bounds on both sides of 1.

In the math it doesn't matter, but people create ghosts by trying to turn names into analogies and reducing the chance of doing that is worthwhile.

Hi,

I agree with most of that. In some contexts though, we would just call it all a 'gain' even if it is a loss. That's because it's actually easier to think about it being a gain in so many cases. The reverse current gain of a bipolar transistor for example.

In texts about converters for example, the resistive divider that divides the output by some factor like K, we would not say it's an attenuation we would say it's a gain. In this case it would be G=1/K, but we never point that out. If K=10 then we would just say G=0.1 and that's all. That is easy to understand too and works well with any following gains that may be encountered because we just ALWAYS multiply, we never have to divide.
If we had three gains G1, G2, G3, the total gain would be G=G1*G2*G3, and any of these three gains can be positive, negative, less that 1, more than 1, equal to 1, etc.. We don't want to keep up with thinking about which ones are gains and which ones are really losses or we'd have to do:
G=G1*G2/K1*G3/K2, etc., and then what if G=0.1 we have to be aware of that and change it to K=G1*G2/K1*G3/K2.
It actually avoids confusion in these cases.

The main point though is that we can call a lot of things a 'gain' and the understanding comes from the value if need be. In cases where we don't yet know the 'gain' or 'loss' if you will, we have no way of knowing YET anyway:
Vout=Vin*A

Is A a gain factor or a loss factor? We don't know yet and we don't have to know yet, symbolically.

 

The size of the input signal should have nothing to do with the amount of attenuation, since that is a characteristic of the system, not the signal.

I also wouldn't know how to interpret what an input signal of -5 dB even is. There's no reference. I would expect it to be expressed relative to some reference power, such as milliwatts (dBm) or watts (dBW).

Except -3dB is a higher amplitude then -5dB so it's gain, not loss. It is an amplification, not an attenuation. (People often leave off the baseline indication when using dB in a non relative way.)