| Author |
Message |
Guest
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 Posted:
Wed Nov 16, 2005 1:35 am Post subject:
dBm, dBu, dBc? |
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Correct me where I am wrong, please.
dBm, decibel with reference of 1mW (at specified impedance)
dBu, decibel with reference of 1uV
What in God's name is dBc? This is in RF frequencies at 50 Ohm
impedance. I've seen it in a few service manuals, usually in relation
to harmonic levels. Please straighten me out, I would greatly
appreciate it.
Thanks,
Steve
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Pooh Bear
Guest
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| Posted:
Wed Nov 16, 2005 7:52 am Post subject:
Re: dBm, dBu, dBc? |
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sck0006 wrote:
| Quote: | Correct me where I am wrong, please.
dBm, decibel with reference of 1mW (at specified impedance)
dBu, decibel with reference of 1uV
|
No. That would be dBuV.
dBu is a voltage based measure used in ( pro ) audio where 0dBu is 0.775V.
Graham |
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Bob Monsen
Guest
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| Posted:
Wed Nov 16, 2005 8:46 am Post subject:
Re: dBm, dBu, dBc? |
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On Tue, 15 Nov 2005 19:33:20 -0600, sck0006 wrote:
| Quote: | Correct me where I am wrong, please.
dBm, decibel with reference of 1mW (at specified impedance)
dBu, decibel with reference of 1uV
What in God's name is dBc? This is in RF frequencies at 50 Ohm
impedance. I've seen it in a few service manuals, usually in relation
to harmonic levels. Please straighten me out, I would greatly
appreciate it.
|
http://www.google.com/search?hl=en&lr=&c2coff=1&oi=defmore&defl=en&q=define:dBc
---
Regards,
Bob Monsen
A great truth is a truth whose opposite is also a great truth.
- Niels Bohr
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John Larkin
Guest
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| Posted:
Wed Nov 16, 2005 9:35 am Post subject:
Re: dBm, dBu, dBc? |
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On Tue, 15 Nov 2005 19:33:20 -0600, sck0006 wrote:
| Quote: | Correct me where I am wrong, please.
dBm, decibel with reference of 1mW (at specified impedance)
dBu, decibel with reference of 1uV
What in God's name is dBc? This is in RF frequencies at 50 Ohm
impedance. I've seen it in a few service manuals, usually in relation
to harmonic levels. Please straighten me out, I would greatly
appreciate it.
Thanks,
Steve
|
Db relative to carrier power level.
John |
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Guest
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| Posted:
Wed Nov 16, 2005 5:35 pm Post subject:
Re: dBm, dBu, dBc? |
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Thank you everyone, it makes perfect sense now.
In response to dBu, dBuV.. I have a spectrum analyzer, an esa-1000,
and it uses dBu for all its measurements. Is this actually dBuV, just
abbreviated? Thanks again for the replies... Steve
On Tue, 15 Nov 2005 19:37:45 -0800, John Larkin
<jjlarkinSNIP@highTHISlandPARTtechnology.com> wrote:
| Quote: | On Tue, 15 Nov 2005 19:33:20 -0600, sck0006 wrote:
Correct me where I am wrong, please.
dBm, decibel with reference of 1mW (at specified impedance)
dBu, decibel with reference of 1uV
What in God's name is dBc? This is in RF frequencies at 50 Ohm
impedance. I've seen it in a few service manuals, usually in relation
to harmonic levels. Please straighten me out, I would greatly
appreciate it.
Thanks,
Steve
Db relative to carrier power level.
John |
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Pooh Bear
Guest
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| Posted:
Thu Nov 17, 2005 1:35 am Post subject:
Re: dBm, dBu, dBc? |
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sck0006 wrote:
| Quote: | Thank you everyone, it makes perfect sense now.
In response to dBu, dBuV.. I have a spectrum analyzer, an esa-1000,
and it uses dBu for all its measurements. Is this actually dBuV, just
abbreviated?
|
It must be.
The dBu ( for audio ) was 'invented' in the mid 70s to replace the by then
misused dBm( 600 ohms) for voltage based measurements of audio signals..
Audio circuits had long ceased to use 'matched impedance working' for a host
of practical reasons.
The IEC defines decibel units. Most consist of dB+ reference level.
E.g....
dBV ( volts )
dBW ( watts)
dBm ( milliwatts ) ( + reference impedance ) - the W is inferred -
presumably for historical reasons
Graham |
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Guest
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| Posted:
Thu Nov 17, 2005 8:58 am Post subject:
Re: dBm, dBu, dBc? |
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On Wed, 16 Nov 2005 21:09:53 +0000, Pooh Bear
<rabbitsfriendsandrelations@hotmail.com> wrote:
| Quote: |
sck0006 wrote:
Thank you everyone, it makes perfect sense now.
In response to dBu, dBuV.. I have a spectrum analyzer, an esa-1000,
and it uses dBu for all its measurements. Is this actually dBuV, just
abbreviated?
It must be.
The dBu ( for audio ) was 'invented' in the mid 70s to replace the by then
misused dBm( 600 ohms) for voltage based measurements of audio signals..
Audio circuits had long ceased to use 'matched impedance working' for a host
of practical reasons.
The IEC defines decibel units. Most consist of dB+ reference level.
E.g....
dBV ( volts )
dBW ( watts)
dBm ( milliwatts ) ( + reference impedance ) - the W is inferred -
presumably for historical reasons
Graham
|
Makes sense. Thanks for the great replies!
Steve |
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