How to Measure DB Level Using Digital Multimeter?

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naveen.rko1 Participant Join Date: Jul 2010 Posts: 3	How to Measure DB Level Using Digital Multimeter? 08/03/2010 3:22 AM
	how to measure the DB level of HF signal of 303.570HZ normally measured using a selective level meter impedance at hi ohmic using digital multilevelmeter?
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#3 "Re: how to measure DB level using digital multimeter?" by dvmdsc on 08/03/2010 4:14 AM (score 2)

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#2 "Re: how to measure DB level using digital multimeter?" by Del the cat on 08/03/2010 4:01 AM (score 1)

Anonymous Poster	#1 Re: how to measure DB level using digital multimeter? 08/03/2010 3:26 AM
	use a selective level meter impedance at hi ohmic using digital multilevelmeter
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Del the cat Guru Join Date: May 2007 Location: Harlow England Posts: 16497 Good Answers: 661	#2 Re: how to measure DB level using digital multimeter? 08/03/2010 4:01 AM
	I don't think you have a snowball in hell's chance of measuring powerlevels in dB using a multimeter at HF. But 303Hz is hardly HF. Measure levels on a scope and do the maths if you really must. Personally I'd much rather know a peak level at a known load than any dB figure. Del __________________ health warning: These posts may contain traces of nut.
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dvmdsc Guru Join Date: Mar 2010 Location: In the pool because it is too hot. Posts: 3055 Good Answers: 140	#4 In reply to #2 Re: how to measure DB level using digital multimeter? 08/03/2010 4:30 AM
	I interprete the frequency as 303 thousand Hz plus. The point, instead of the comma might be confusing. However dB values should be equally. Normally, specific lab voltmeters have dB. readings too or attenuators in steps. The whole show is only correct for symmetrical RMS signals. This is just my humble interpretation. Regards, D. __________________ Plenty of room here
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Del the cat Guru Join Date: May 2007 Location: Harlow England Posts: 16497 Good Answers: 661	#5 In reply to #4 Re: how to measure DB level using digital multimeter? 08/03/2010 5:11 AM
	The point, instead of the comma might be confusing. There is no 'might'. The point instead of a comma is just plain wrong. Del __________________ health warning: These posts may contain traces of nut.
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dvmdsc Guru Join Date: Mar 2010 Location: In the pool because it is too hot. Posts: 3055 Good Answers: 140	#6 In reply to #5 Re: how to measure DB level using digital multimeter? 08/03/2010 11:25 AM
	Right from your place. Isn't Europe fascinating? Or am I gone for too long? Thanks, D. __________________ Plenty of room here
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Re: how to measure DB level using digital multimeter?

08/03/2010 4:14 AM

Dear Naveen:

I suppose you will measure volts.

The US standard specifies the unit of 0 dBv as 0.775 volts, measured over an impedance of 600 Ω.

In Europe 1 Volt has been chosen and to make it somewhat complicated they call it dBV (note the big V) - and to make it more complicated, when the 600 Ω is not specific, they call it dBm, and when undetermined dBu

Here some more explanation:

• Conversion: Voltage V to Level dB, dBu, dBV

Usually we measure AC voltage V as volts_RMS.

Voltage V:	volts	( Root Mean Square RMS)
↓
Voltage level L:
L =	dBu	reference: 0.775 V
L =	dBV	reference: 1 V

The index u at decibel (dB) means

unloaded source, V (volt). Some say: The "u" in dBu
implies also that the load impedance is unspecified, or unterminated and is likely to be high.
The index m at dB (decibel) means 1 milliwatt (power) as reference value for 0 dB.

If the reverse conversion dBu, or dBV to volts is needed, go to the converter at the bottom.

• What is dBu?
A logarithmic voltage ratio with a reference voltage of V₀= 0.7746 volt ≡ 0 dBu

• What is dBV?
A logarithmic voltage ratio with a reference voltage of V₀ = 1.0000 volt ≡ 0 dBV
The max. domestic recording level of −10 dBV means 0.3162 volts, that is −7.78 dBu

I hoped to have that conversion tool working, but it doesn't.

The following link will allow you to use it.

Make sure your voltmeter is High Frequency and is able to measure the levels.

Here the link:

http://www.sengpielaudio.com/calculator-volt.htm

Good Luck, D

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Bill ML Power-User Join Date: Jul 2007 Location: Orlando Posts: 242 Good Answers: 3	#7 Re: How to Measure DB Level Using Digital Multimeter? 08/03/2010 3:44 PM
	Again I fail to understand why so many react and try to answer on questionable facts or lack of. As I see it, the OP could even be citing 303 MHz. But then it could be an audio selective measurement instrument that he has but doesn't have the manual. Some that I've seen might have a 600 ohm output. So do the math for the RMS for starters. That's as far as I would go with this.
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dvmdsc Guru Join Date: Mar 2010 Location: In the pool because it is too hot. Posts: 3055 Good Answers: 140	#9 In reply to #7 Re: How to Measure DB Level Using Digital Multimeter? 08/03/2010 7:38 PM
	Respectfully, with you as number 5, this post has not had a lot of interest. In my case, I try to be complete and as accurate as possible, otherwise I do not contribute. I could elaborate about effects of frequency on the outcome, but that is beyond this theme. 303 is a nice number and frequencies of a thousand' th of one Hertz not so relevant. I also think you are confusing input and output of your device. You and I don't know the real importance of the post and should give a workable answer. D. __________________ Plenty of room here
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portugalphilip Power-User Join Date: May 2010 Location: longo tempo dos macaco do pilas. Felizment. Posts: 251	#8 Re: How to Measure DB Level Using Digital Multimeter? 08/03/2010 5:14 PM
	Dear Nav , Measuring dB is a logarithmic scale. You need 2 reference points. By mathematics you can find the logarithmic value and you can even weight it...i.e A weighting. __________________ I am a deeply religious nonbeliever - this is a somewhat new kind of religion. Albert Einstein
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#3 "Re: how to measure DB level using digital multimeter?" by dvmdsc on 08/03/2010 4:14 AM (score 2)

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#2 "Re: how to measure DB level using digital multimeter?" by Del the cat on 08/03/2010 4:01 AM (score 1)

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Anonymous Poster (1); Bill ML (1); Del the cat (2); dvmdsc (4); portugalphilip (1)

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