Gentlemen,

This is an exam question that trips up even some of the best students.
See what you make of it!

Q: Is this statement correct: 'The signal level at the modem input
increased by 2dBmV going from +3dBmV to +5dBmV.'

Your pal, CD.

On Wed, 10 Apr 2024 18:02:50 +0100, Cursitor Doom <cd@notformail.com>
wrote:

>Gentlemen,
>
>This is an exam question that trips up even some of the best students.
>See what you make of it!
>
>Q: Is this statement correct: 'The signal level at the modem input
>increased by 2dBmV going from +3dBmV to +5dBmV.'
>
>Your pal, CD.

I can just imagine you all furiously Googling for the answer right
now...

:-D

On Wed, 10 Apr 2024 18:02:50 +0100, Cursitor Doom <cd@notformail.com>
wrote:

>Gentlemen,
>
>This is an exam question that trips up even some of the best students.
>See what you make of it!
>
>Q: Is this statement correct: 'The signal level at the modem input
>increased by 2dBmV going from +3dBmV to +5dBmV.'
>
>Your pal, CD.

5-3=2. dBs, pineapples, whatever.

On Wed, 10 Apr 2024 11:46:02 -0700, john larkin <jl@650pot.com> wrote:

>On Wed, 10 Apr 2024 18:02:50 +0100, Cursitor Doom <cd@notformail.com>
>wrote:
>
>>Gentlemen,
>>
>>This is an exam question that trips up even some of the best students.
>>See what you make of it!
>>
>>Q: Is this statement correct: 'The signal level at the modem input
>>increased by 2dBmV going from +3dBmV to +5dBmV.'
>>
>>Your pal, CD.
>
>5-3=2. dBs, pineapples, whatever.

Very brave, John! I think the lack of response thus far indicates how
terrified the great and the good here are of getting it wrong, 'cos
those at the top have the farthest to fall in terms of reputation.
I'll provide the answer the same time tomorrow and we'll see if
there's any other brave souls out there. ;-)

"Cursitor Doom" <cd@notformail.com> wrote in message
news:c6hd1jdjimga6ifo7b0kv7bqfj9750lbk3@4ax.com...
> Gentlemen,
>
> This is an exam question that trips up even some of the best students.
> See what you make of it!
>
> Q: Is this statement correct: 'The signal level at the modem input
> increased by 2dBmV going from +3dBmV to +5dBmV.'
>
> Your pal, CD.

Changing a signal level can be thought of as multiplying the signal by a
constant.
That constant can't have units because then you'd have (dBmV)^2

So that answer is likely to be that the increase is by 2 dB not 2 dBmV

On Wed, 10 Apr 2024 20:39:19 +0100, Cursitor Doom <cd@notformail.com>
wrote:

>On Wed, 10 Apr 2024 11:46:02 -0700, john larkin <jl@650pot.com> wrote:
>
>>On Wed, 10 Apr 2024 18:02:50 +0100, Cursitor Doom <cd@notformail.com>
>>wrote:
>>
>>>Gentlemen,
>>>
>>>This is an exam question that trips up even some of the best students.
>>>See what you make of it!
>>>
>>>Q: Is this statement correct: 'The signal level at the modem input
>>>increased by 2dBmV going from +3dBmV to +5dBmV.'
>>>
>>>Your pal, CD.
>>
>>5-3=2. dBs, pineapples, whatever.
>
>Very brave, John! I think the lack of response thus far indicates how
>terrified the great and the good here are of getting it wrong, 'cos
>those at the top have the farthest to fall in terms of reputation.
>I'll provide the answer the same time tomorrow and we'll see if
>there's any other brave souls out there. ;-)

If I have a meter that shows dBmV, and it says 3 and I crank up the
input so it says 5, it went up by 2.

Do you have a counter-case? 3+2 equals something that's not 5?

On Wed, 10 Apr 2024 15:57:55 -0400, "Edward Rawde"
<invalid@invalid.invalid> wrote:

>"Cursitor Doom" <cd@notformail.com> wrote in message
>news:c6hd1jdjimga6ifo7b0kv7bqfj9750lbk3@4ax.com...
>> Gentlemen,
>>
>> This is an exam question that trips up even some of the best students.
>> See what you make of it!
>>
>> Q: Is this statement correct: 'The signal level at the modem input
>> increased by 2dBmV going from +3dBmV to +5dBmV.'
>>
>> Your pal, CD.
>
>Changing a signal level can be thought of as multiplying the signal by a
>constant.

You can change something by adding, too.

"john larkin" <jl@650pot.com> wrote in message
news:v6sd1j1sr89ntc214dku5u5e04pks5toud@4ax.com...
> On Wed, 10 Apr 2024 15:57:55 -0400, "Edward Rawde"
> <invalid@invalid.invalid> wrote:
>
>>"Cursitor Doom" <cd@notformail.com> wrote in message
>>news:c6hd1jdjimga6ifo7b0kv7bqfj9750lbk3@4ax.com...
>>> Gentlemen,
>>>
>>> This is an exam question that trips up even some of the best students.
>>> See what you make of it!
>>>
>>> Q: Is this statement correct: 'The signal level at the modem input
>>> increased by 2dBmV going from +3dBmV to +5dBmV.'
>>>
>>> Your pal, CD.
>>
>>Changing a signal level can be thought of as multiplying the signal by a
>>constant.
>
> You can change something by adding, too.
>

I haven't looked at it in detail but a bit of playing with a search engine
finds the question here:
https://broadbandlibrary.com/wise-and-mighty-decibel/

On Wed, 10 Apr 2024 16:11:39 -0400, "Edward Rawde"
<invalid@invalid.invalid> wrote:

>"john larkin" <jl@650pot.com> wrote in message
>news:v6sd1j1sr89ntc214dku5u5e04pks5toud@4ax.com...
>> On Wed, 10 Apr 2024 15:57:55 -0400, "Edward Rawde"
>> <invalid@invalid.invalid> wrote:
>>
>>>"Cursitor Doom" <cd@notformail.com> wrote in message
>>>news:c6hd1jdjimga6ifo7b0kv7bqfj9750lbk3@4ax.com...
>>>> Gentlemen,
>>>>
>>>> This is an exam question that trips up even some of the best students.
>>>> See what you make of it!
>>>>
>>>> Q: Is this statement correct: 'The signal level at the modem input
>>>> increased by 2dBmV going from +3dBmV to +5dBmV.'
>>>>
>>>> Your pal, CD.
>>>
>>>Changing a signal level can be thought of as multiplying the signal by a
>>>constant.
>>
>> You can change something by adding, too.
>>
>
>I haven't looked at it in detail but a bit of playing with a search engine
>finds the question here:
>https://broadbandlibrary.com/wise-and-mighty-decibel/
>

It says that a signal level can never go from 3 dBmV to 5 dBmV. I
think it can.

This is a silly word game.

On 4/10/24 19:02, Cursitor Doom wrote:
> Gentlemen,
>
> This is an exam question that trips up even some of the best students.
> See what you make of it!
>
> Q: Is this statement correct: 'The signal level at the modem input
> increased by 2dBmV going from +3dBmV to +5dBmV.'
>
> Your pal, CD.

Haven't we had a discussion about this already some four years ago?
Weren't you Don Kuenz then?

Jeroen Belleman

On Wed, 10 Apr 2024 13:04:10 -0700, john larkin <jl@650pot.com> wrote:

>On Wed, 10 Apr 2024 20:39:19 +0100, Cursitor Doom <cd@notformail.com>
>wrote:
>
>>On Wed, 10 Apr 2024 11:46:02 -0700, john larkin <jl@650pot.com> wrote:
>>
>>>On Wed, 10 Apr 2024 18:02:50 +0100, Cursitor Doom <cd@notformail.com>
>>>wrote:
>>>
>>>>Gentlemen,
>>>>
>>>>This is an exam question that trips up even some of the best students.
>>>>See what you make of it!
>>>>
>>>>Q: Is this statement correct: 'The signal level at the modem input
>>>>increased by 2dBmV going from +3dBmV to +5dBmV.'
>>>>
>>>>Your pal, CD.
>>>
>>>5-3=2. dBs, pineapples, whatever.
>>
>>Very brave, John! I think the lack of response thus far indicates how
>>terrified the great and the good here are of getting it wrong, 'cos
>>those at the top have the farthest to fall in terms of reputation.
>>I'll provide the answer the same time tomorrow and we'll see if
>>there's any other brave souls out there. ;-)
>
>If I have a meter that shows dBmV, and it says 3 and I crank up the
>input so it says 5, it went up by 2.
>
>Do you have a counter-case? 3+2 equals something that's not 5?

I'm sure I could find someone teaching mathematics like that in our
wonderful modern school system in no time at all LOL.

On Wed, 10 Apr 2024 23:11:53 +0200, Jeroen Belleman
<jeroen@nospam.please> wrote:

>On 4/10/24 19:02, Cursitor Doom wrote:
>> Gentlemen,
>>
>> This is an exam question that trips up even some of the best students.
>> See what you make of it!
>>
>> Q: Is this statement correct: 'The signal level at the modem input
>> increased by 2dBmV going from +3dBmV to +5dBmV.'
>>
>> Your pal, CD.
>
>Haven't we had a discussion about this already some four years ago?
>Weren't you Don Kuenz then?
>
>Jeroen Belleman

I don't recall any such discussion and no, I'm not Don Kuenz either.

On Wed, 10 Apr 2024 16:11:39 -0400, "Edward Rawde"
<invalid@invalid.invalid> wrote:

>"john larkin" <jl@650pot.com> wrote in message
>news:v6sd1j1sr89ntc214dku5u5e04pks5toud@4ax.com...
>> On Wed, 10 Apr 2024 15:57:55 -0400, "Edward Rawde"
>> <invalid@invalid.invalid> wrote:
>>
>>>"Cursitor Doom" <cd@notformail.com> wrote in message
>>>news:c6hd1jdjimga6ifo7b0kv7bqfj9750lbk3@4ax.com...
>>>> Gentlemen,
>>>>
>>>> This is an exam question that trips up even some of the best students.
>>>> See what you make of it!
>>>>
>>>> Q: Is this statement correct: 'The signal level at the modem input
>>>> increased by 2dBmV going from +3dBmV to +5dBmV.'
>>>>
>>>> Your pal, CD.
>>>
>>>Changing a signal level can be thought of as multiplying the signal by a
>>>constant.
>>
>> You can change something by adding, too.
>>
>
>I haven't looked at it in detail but a bit of playing with a search engine
>finds the question here:
>https://broadbandlibrary.com/wise-and-mighty-decibel/
>

Jeez, when I said, "No Googling" I didn't seriously think anyone here
would be dumb enough to need to actually do so! :-D
From the site you pointed to:
"This kind of statement is incorrect, because signal levels cannot
increase or decrease in increments of dBmV, only dB."
Well you learn something new every day on the net, doncha? ;->

"john larkin" <jl@650pot.com> wrote in message
news:tgud1jh3e4s3u0nupgusk01tj0rebb4iov@4ax.com...
> On Wed, 10 Apr 2024 16:11:39 -0400, "Edward Rawde"
> <invalid@invalid.invalid> wrote:
>
>>"john larkin" <jl@650pot.com> wrote in message
>>news:v6sd1j1sr89ntc214dku5u5e04pks5toud@4ax.com...
>>> On Wed, 10 Apr 2024 15:57:55 -0400, "Edward Rawde"
>>> <invalid@invalid.invalid> wrote:
>>>
>>>>"Cursitor Doom" <cd@notformail.com> wrote in message
>>>>news:c6hd1jdjimga6ifo7b0kv7bqfj9750lbk3@4ax.com...
>>>>> Gentlemen,
>>>>>
>>>>> This is an exam question that trips up even some of the best students.
>>>>> See what you make of it!
>>>>>
>>>>> Q: Is this statement correct: 'The signal level at the modem input
>>>>> increased by 2dBmV going from +3dBmV to +5dBmV.'
>>>>>
>>>>> Your pal, CD.
>>>>
>>>>Changing a signal level can be thought of as multiplying the signal by a
>>>>constant.
>>>
>>> You can change something by adding, too.
>>>
>>
>>I haven't looked at it in detail but a bit of playing with a search engine
>>finds the question here:
>>https://broadbandlibrary.com/wise-and-mighty-decibel/
>>
>
> It says that a signal level can never go from 3 dBmV to 5 dBmV. I
> think it can.
>
> This is a silly word game.
>

How about this for an exam question.

Give an example of the construction of a 6dB power splitter, for use in a 50
ohm system, using only resistors.
Assume that the resistors do not have any frequency dependent characteristcs
at any frequency of use.
There is no need to calculate any resistor values.

What happens to the other half of the power going into the 6 dB splitter
when it is delivering one quarter of the input power through each output?

Why is it not possible to make a 3 dB power splitter using only resistors?

Or this.

Draw an op amp with the + input grounded using two 1K ohm resistors in an
inverting conviguration.
The op amp is shown with +12V and -12V power rails.
Connect the input of this circuit to the centre of two 2K ohm resistors as a
potential divider between +12V and 0V (ground)
Ask what will be on the op amp's output when measured with a high impedance
voltmeter.

..

"Cursitor Doom" <cd@notformail.com> wrote in message
news:kl1e1jl6g3f708a7csfumkccbhmh3greha@4ax.com...
> On Wed, 10 Apr 2024 13:04:10 -0700, john larkin <jl@650pot.com> wrote:
>
>>On Wed, 10 Apr 2024 20:39:19 +0100, Cursitor Doom <cd@notformail.com>
>>wrote:
>>
>>>On Wed, 10 Apr 2024 11:46:02 -0700, john larkin <jl@650pot.com> wrote:
>>>
>>>>On Wed, 10 Apr 2024 18:02:50 +0100, Cursitor Doom <cd@notformail.com>
>>>>wrote:
>>>>
>>>>>Gentlemen,
>>>>>
>>>>>This is an exam question that trips up even some of the best students.
>>>>>See what you make of it!
>>>>>
>>>>>Q: Is this statement correct: 'The signal level at the modem input
>>>>>increased by 2dBmV going from +3dBmV to +5dBmV.'
>>>>>
>>>>>Your pal, CD.
>>>>
>>>>5-3=2. dBs, pineapples, whatever.
>>>
>>>Very brave, John! I think the lack of response thus far indicates how
>>>terrified the great and the good here are of getting it wrong, 'cos
>>>those at the top have the farthest to fall in terms of reputation.
>>>I'll provide the answer the same time tomorrow and we'll see if
>>>there's any other brave souls out there. ;-)
>>
>>If I have a meter that shows dBmV, and it says 3 and I crank up the
>>input so it says 5, it went up by 2.
>>
>>Do you have a counter-case? 3+2 equals something that's not 5?
>
> I'm sure I could find someone teaching mathematics like that in our
> wonderful modern school system in no time at all LOL.

If + is a boolean Or operator then perhaps 3 + 2 = 3

"Cursitor Doom" <cd@notformail.com> wrote in message
news:i52e1j9ctjqi1k1m9ej1aid2493foetnsq@4ax.com...
> On Wed, 10 Apr 2024 16:11:39 -0400, "Edward Rawde"
> <invalid@invalid.invalid> wrote:
>
>>"john larkin" <jl@650pot.com> wrote in message
>>news:v6sd1j1sr89ntc214dku5u5e04pks5toud@4ax.com...
>>> On Wed, 10 Apr 2024 15:57:55 -0400, "Edward Rawde"
>>> <invalid@invalid.invalid> wrote:
>>>
>>>>"Cursitor Doom" <cd@notformail.com> wrote in message
>>>>news:c6hd1jdjimga6ifo7b0kv7bqfj9750lbk3@4ax.com...
>>>>> Gentlemen,
>>>>>
>>>>> This is an exam question that trips up even some of the best students.
>>>>> See what you make of it!
>>>>>
>>>>> Q: Is this statement correct: 'The signal level at the modem input
>>>>> increased by 2dBmV going from +3dBmV to +5dBmV.'
>>>>>
>>>>> Your pal, CD.
>>>>
>>>>Changing a signal level can be thought of as multiplying the signal by a
>>>>constant.
>>>
>>> You can change something by adding, too.
>>>
>>
>>I haven't looked at it in detail but a bit of playing with a search engine
>>finds the question here:
>>https://broadbandlibrary.com/wise-and-mighty-decibel/
>>
>
> Jeez, when I said, "No Googling" I didn't seriously think anyone here
> would be dumb enough to need to actually do so! :-D

I don't see any mention of any search engine in your first post.

I tend to agree with John Larkin on this.

If a student can use a meter to see that a signal which was 3 somethings is
now 5 somethings (depending on what is being measured) then I give them a
pass.

On Wed, 10 Apr 2024 18:18:21 -0400, "Edward Rawde"
<invalid@invalid.invalid> wrote:

>"Cursitor Doom" <cd@notformail.com> wrote in message
>news:i52e1j9ctjqi1k1m9ej1aid2493foetnsq@4ax.com...
>> On Wed, 10 Apr 2024 16:11:39 -0400, "Edward Rawde"
>> <invalid@invalid.invalid> wrote:
>>
>>>"john larkin" <jl@650pot.com> wrote in message
>>>news:v6sd1j1sr89ntc214dku5u5e04pks5toud@4ax.com...
>>>> On Wed, 10 Apr 2024 15:57:55 -0400, "Edward Rawde"
>>>> <invalid@invalid.invalid> wrote:
>>>>
>>>>>"Cursitor Doom" <cd@notformail.com> wrote in message
>>>>>news:c6hd1jdjimga6ifo7b0kv7bqfj9750lbk3@4ax.com...
>>>>>> Gentlemen,
>>>>>>
>>>>>> This is an exam question that trips up even some of the best students.
>>>>>> See what you make of it!
>>>>>>
>>>>>> Q: Is this statement correct: 'The signal level at the modem input
>>>>>> increased by 2dBmV going from +3dBmV to +5dBmV.'
>>>>>>
>>>>>> Your pal, CD.
>>>>>
>>>>>Changing a signal level can be thought of as multiplying the signal by a
>>>>>constant.
>>>>
>>>> You can change something by adding, too.
>>>>
>>>
>>>I haven't looked at it in detail but a bit of playing with a search engine
>>>finds the question here:
>>>https://broadbandlibrary.com/wise-and-mighty-decibel/
>>>
>>
>> Jeez, when I said, "No Googling" I didn't seriously think anyone here
>> would be dumb enough to need to actually do so! :-D
>
>I don't see any mention of any search engine in your first post.
>
>I tend to agree with John Larkin on this.
>
>If a student can use a meter to see that a signal which was 3 somethings is
>now 5 somethings (depending on what is being measured) then I give them a
>pass.

So going back to the orginal question as stated, you're saying the
statement in quotes is *correct* then. Nice to have a straight answer.

"Cursitor Doom" <cd@notformail.com> wrote in message
news:cs4e1j5ohhb7fpcmnft14ad6pv66jtvi34@4ax.com...
> On Wed, 10 Apr 2024 18:18:21 -0400, "Edward Rawde"
> <invalid@invalid.invalid> wrote:
>
>>"Cursitor Doom" <cd@notformail.com> wrote in message
>>news:i52e1j9ctjqi1k1m9ej1aid2493foetnsq@4ax.com...
>>> On Wed, 10 Apr 2024 16:11:39 -0400, "Edward Rawde"
>>> <invalid@invalid.invalid> wrote:
>>>
>>>>"john larkin" <jl@650pot.com> wrote in message
>>>>news:v6sd1j1sr89ntc214dku5u5e04pks5toud@4ax.com...
>>>>> On Wed, 10 Apr 2024 15:57:55 -0400, "Edward Rawde"
>>>>> <invalid@invalid.invalid> wrote:
>>>>>
>>>>>>"Cursitor Doom" <cd@notformail.com> wrote in message
>>>>>>news:c6hd1jdjimga6ifo7b0kv7bqfj9750lbk3@4ax.com...
>>>>>>> Gentlemen,
>>>>>>>
>>>>>>> This is an exam question that trips up even some of the best
>>>>>>> students.
>>>>>>> See what you make of it!
>>>>>>>
>>>>>>> Q: Is this statement correct: 'The signal level at the modem input
>>>>>>> increased by 2dBmV going from +3dBmV to +5dBmV.'
>>>>>>>
>>>>>>> Your pal, CD.
>>>>>>
>>>>>>Changing a signal level can be thought of as multiplying the signal by
>>>>>>a
>>>>>>constant.
>>>>>
>>>>> You can change something by adding, too.
>>>>>
>>>>
>>>>I haven't looked at it in detail but a bit of playing with a search
>>>>engine
>>>>finds the question here:
>>>>https://broadbandlibrary.com/wise-and-mighty-decibel/
>>>>
>>>
>>> Jeez, when I said, "No Googling" I didn't seriously think anyone here
>>> would be dumb enough to need to actually do so! :-D
>>
>>I don't see any mention of any search engine in your first post.
>>
>>I tend to agree with John Larkin on this.
>>
>>If a student can use a meter to see that a signal which was 3 somethings
>>is
>>now 5 somethings (depending on what is being measured) then I give them a
>>pass.
>
> So going back to the orginal question as stated, you're saying the
> statement in quotes is *correct* then. Nice to have a straight answer.

If you mean that do I think that something increases by 2 when it goes from
3 to 5 then yes that seems reasonable to me.

You can also multiply it by 5/3 to get the same effect if you want. I don't
mind.

On 2024-04-10, Cursitor Doom <cd@notformail.com> wrote:
> Gentlemen,
>
> This is an exam question that trips up even some of the best students.
> See what you make of it!
>
> Q: Is this statement correct: 'The signal level at the modem input
> increased by 2dBmV going from +3dBmV to +5dBmV.'
>
> Your pal, CD.

db is a logarythmic ratio. an increase from +3dBmV to +5dBmV is an increase by 2dB
(not 2dBmV)

Adding 2dBmV to +3dBmV will not get you +5dBmV because it's a
logarythmic scale.

--
Jasen.
🇺🇦 Слава Україні

On 4/10/24 23:42, Cursitor Doom wrote:
> On Wed, 10 Apr 2024 23:11:53 +0200, Jeroen Belleman
> <jeroen@nospam.please> wrote:
>
>> On 4/10/24 19:02, Cursitor Doom wrote:
>>> Gentlemen,
>>>
>>> This is an exam question that trips up even some of the best students.
>>> See what you make of it!
>>>
>>> Q: Is this statement correct: 'The signal level at the modem input
>>> increased by 2dBmV going from +3dBmV to +5dBmV.'
>>>
>>> Your pal, CD.
>>
>> Haven't we had a discussion about this already some four years ago?
>> Weren't you Don Kuenz then?
>>
>> Jeroen Belleman
>
> I don't recall any such discussion and no, I'm not Don Kuenz either.

Allright then. The statement is wrong. An increase is in dB, not
in dBmV.

Jeroen Belleman

On Wed, 10 Apr 2024 21:10:59 -0400, "Edward Rawde"
<invalid@invalid.invalid> wrote:

>
>"Cursitor Doom" <cd@notformail.com> wrote in message
>news:cs4e1j5ohhb7fpcmnft14ad6pv66jtvi34@4ax.com...
>> On Wed, 10 Apr 2024 18:18:21 -0400, "Edward Rawde"
>> <invalid@invalid.invalid> wrote:
>>
>>>"Cursitor Doom" <cd@notformail.com> wrote in message
>>>news:i52e1j9ctjqi1k1m9ej1aid2493foetnsq@4ax.com...
>>>> On Wed, 10 Apr 2024 16:11:39 -0400, "Edward Rawde"
>>>> <invalid@invalid.invalid> wrote:
>>>>
>>>>>"john larkin" <jl@650pot.com> wrote in message
>>>>>news:v6sd1j1sr89ntc214dku5u5e04pks5toud@4ax.com...
>>>>>> On Wed, 10 Apr 2024 15:57:55 -0400, "Edward Rawde"
>>>>>> <invalid@invalid.invalid> wrote:
>>>>>>
>>>>>>>"Cursitor Doom" <cd@notformail.com> wrote in message
>>>>>>>news:c6hd1jdjimga6ifo7b0kv7bqfj9750lbk3@4ax.com...
>>>>>>>> Gentlemen,
>>>>>>>>
>>>>>>>> This is an exam question that trips up even some of the best
>>>>>>>> students.
>>>>>>>> See what you make of it!
>>>>>>>>
>>>>>>>> Q: Is this statement correct: 'The signal level at the modem input
>>>>>>>> increased by 2dBmV going from +3dBmV to +5dBmV.'
>>>>>>>>
>>>>>>>> Your pal, CD.
>>>>>>>
>>>>>>>Changing a signal level can be thought of as multiplying the signal by
>>>>>>>a
>>>>>>>constant.
>>>>>>
>>>>>> You can change something by adding, too.
>>>>>>
>>>>>
>>>>>I haven't looked at it in detail but a bit of playing with a search
>>>>>engine
>>>>>finds the question here:
>>>>>https://broadbandlibrary.com/wise-and-mighty-decibel/
>>>>>
>>>>
>>>> Jeez, when I said, "No Googling" I didn't seriously think anyone here
>>>> would be dumb enough to need to actually do so! :-D
>>>
>>>I don't see any mention of any search engine in your first post.
>>>
>>>I tend to agree with John Larkin on this.
>>>
>>>If a student can use a meter to see that a signal which was 3 somethings
>>>is
>>>now 5 somethings (depending on what is being measured) then I give them a
>>>pass.
>>
>> So going back to the orginal question as stated, you're saying the
>> statement in quotes is *correct* then. Nice to have a straight answer.
>
>If you mean that do I think that something increases by 2 when it goes from
>3 to 5 then yes that seems reasonable to me.

I'm afraid that's not exactly the question, though.
Here's what was asked again:

Q: Is this statement correct: 'The signal level at the modem input
increased by 2dBmV going from +3dBmV to +5dBmV.'

You've already nailed your colours to the mast with your opinion that
the statement is correct. Are you happy with that or would you like to
change your mind?

I'll be posting 'the answer' in about 5 hours' time for those who have
yet to stick their heads above the parapet and might be tempted to
participate. It's been a bit deafeningly quiet so far. ;-)

>
>You can also multiply it by 5/3 to get the same effect if you want. I don't
>mind.
>

On Thu, 11 Apr 2024 09:50:14 +0200, Jeroen Belleman
<jeroen@nospam.please> wrote:

>On 4/10/24 23:42, Cursitor Doom wrote:
>> On Wed, 10 Apr 2024 23:11:53 +0200, Jeroen Belleman
>> <jeroen@nospam.please> wrote:
>>
>>> On 4/10/24 19:02, Cursitor Doom wrote:
>>>> Gentlemen,
>>>>
>>>> This is an exam question that trips up even some of the best students.
>>>> See what you make of it!
>>>>
>>>> Q: Is this statement correct: 'The signal level at the modem input
>>>> increased by 2dBmV going from +3dBmV to +5dBmV.'
>>>>
>>>> Your pal, CD.
>>>
>>> Haven't we had a discussion about this already some four years ago?
>>> Weren't you Don Kuenz then?
>>>
>>> Jeroen Belleman
>>
>> I don't recall any such discussion and no, I'm not Don Kuenz either.
>
>Allright then. The statement is wrong. An increase is in dB, not
>in dBmV.
>

Nice, unequivocal answer there, Jeroen; many thanks.

On Thu, 11 Apr 2024 06:38:30 -0000 (UTC), Jasen Betts
<usenet@revmaps.no-ip.org> wrote:

>On 2024-04-10, Cursitor Doom <cd@notformail.com> wrote:
>> Gentlemen,
>>
>> This is an exam question that trips up even some of the best students.
>> See what you make of it!
>>
>> Q: Is this statement correct: 'The signal level at the modem input
>> increased by 2dBmV going from +3dBmV to +5dBmV.'
>>
>> Your pal, CD.
>
>db is a logarythmic ratio. an increase from +3dBmV to +5dBmV is an increase by 2dB
>(not 2dBmV)
>
>Adding 2dBmV to +3dBmV will not get you +5dBmV because it's a
>logarythmic scale.

The question does require a "correct/incorrect" answer. It's a binary
choice. Your answer is....?

On 4/11/24 14:58, Cursitor Doom wrote:
> On Thu, 11 Apr 2024 09:50:14 +0200, Jeroen Belleman
> <jeroen@nospam.please> wrote:
>
>> On 4/10/24 23:42, Cursitor Doom wrote:
>>> On Wed, 10 Apr 2024 23:11:53 +0200, Jeroen Belleman
>>> <jeroen@nospam.please> wrote:
>>>
>>>> On 4/10/24 19:02, Cursitor Doom wrote:
>>>>> Gentlemen,
>>>>>
>>>>> This is an exam question that trips up even some of the best students.
>>>>> See what you make of it!
>>>>>
>>>>> Q: Is this statement correct: 'The signal level at the modem input
>>>>> increased by 2dBmV going from +3dBmV to +5dBmV.'
>>>>>
>>>>> Your pal, CD.
>>>>
>>>> Haven't we had a discussion about this already some four years ago?
>>>> Weren't you Don Kuenz then?
>>>>
>>>> Jeroen Belleman
>>>
>>> I don't recall any such discussion and no, I'm not Don Kuenz either.
>>
>> Allright then. The statement is wrong. An increase is in dB, not
>> in dBmV.
>>
>
> Nice, unequivocal answer there, Jeroen; many thanks.

If you really want to open a can of worms, consider what might
happen when you *add* a 2dBmV and a 3dBmV signal together.
Granted, dBs weren't invented for making that easy.

Jeroen Belleman

On 11/04/2024 3:02 am, Cursitor Doom wrote:
> Gentlemen,
>
> This is an exam question that trips up even some of the best students.
> See what you make of it!
>
> Q: Is this statement correct: 'The signal level at the modem input
> increased by 2dBmV going from +3dBmV to +5dBmV.'
>
> Your pal, CD.

It's not a complex metaphysical conundrum - it is the kind of pedantic
exam question set by the sort of lecturer who has a bee in his bonnet
about getting the units right. If you sat through his course you'd know
what his idea of what the right answer would be.

The rest of us don't have to worry because it doesn't actually matter.

--
Bil Sloman, Sydney