Low Frequency Radio Transmission for long distance.

It's sort of the mirror image of females' tendency to say to each other thi ngs like "Oh, I _know_!" in a very sympathetic tone, when no communication has in fact occurred. ;)

Cheers

Phil Hobbs

On Tue, 3 May 2016 18:27:19 -0700 (PDT), Phil Hobbs Gave us:

Bubble Boy!

Nope, bels are always power, or else they're useless as a term for technical communication. Is the 3 dB point of a filter half power or half amplitude (1/4 power)?

See .

Cheers

Phil Hobbs

I've had this discussion with people before and some *insist* it is ok to represent voltage in bels directly, 10*log(V/Vr). I'm not interested in debating them anymore. They can live in ignorance.

As you say, ratios or logs of ratios can be of anything you wish, but bels are ratios of power.

There's that formula with a 20 in it that works okay as long as you're measuring power at the same point in the circuit, or at the same impedance level, or (as with op amp outputs) where the impedance level isn't too well defined anyway.

Cheers

Phil Hobbs

If you design electronics, you really need to be right most of the time. A good PC board might have 1000 components, 500 nodes, all sorts of tricky circuits and chips and power/thermal hazards. Every pin of every chip has to be applied right, which is a real chore on FPGAs and uPs and mixed-signal chips. If you're not right 99.9% of the time, it won't work.

Females need to be right the same amount if they design electronics.

I'm advertising for a new PCB layout person right now. If I wind up with two apparently equal applicants, a man and a woman, I'll pick the woman. Women are generally better at that job.

Or an op-amp gain in dB. It is widely understood that it is a voltage ratio with the 20 in it.

Units like dBV and dBuV are pretty common. We don't have any other handy way to express voltage on a log scale.

dBV is 20 * log (RMS volts) so power is sort of suggested, but there's no specified load impedance, no real power necessary.

Most meters measure voltage anyhow.

Yes. My experience is that women are more diligent than men.

You can also use: bels (B) 1.0 bel decabels (daB) 0.1 bels hectobels (hB) 0.01 bels kilobels (kB) 0.001 bels

decibels (dB) 10 bels centibels (cB) 100 bels millibels (mB) 1000 bels

On Wed, 4 May 2016 10:25:03 -0400, Phil Hobbs Gave us:

It is all about whether you want to refer to an absolute ground referenced value or a value referenced to a standard defined level.

RF circuits use dBm so that circuit designers can do proper maths and know how to add power amplification at points to keep things correctly leveled.

So your .connection losses (0.1 dB per) (bulkhead adapters, etc.) and splitter combiner and mixer losses and other passive elements can be compensated for properly with active elements to end up with what is needed on "the output taps" of a given module of a circuit.

On Wed, 04 May 2016 09:49:33 -0700, Jeff Liebermann Gave us: snip

Or even these...

Well, dB is 10 log(P2/P1), where P1 and P2 are both in power units. So you always have to have some reference power in mind. The most basic point here is that even if you're using the shuffle-footed 20-log formula, decibels have to go as voltage**2, not voltage. Cliff was arguing that any old order of magnitude qualified.

Cheers

Phil Hobbs

On Wed, 04 May 2016 12:03:07 -0700, John Larkin Gave us:

So you make stupid blanket statements about the entire industry. You really are stupid, and you are truly clueless about your own putzdom. It rests between your ears..

Not so. I related my personal experience.

Have you worked with male and female PCB layout people? What was your experience?

And then there's LTSpice, which prefers a rather idiosyncratic mdB quantity in its gain/attenuation plots. Yep, that's millidecibel - screw the rule about not using multiple SI prefixes together!

Dimitrij

It sort of autoranges on all plots, depending on how you zoom. It can probably be persuaded to use udB and pdB too.

pF. It took me years to get used to using pF. Then, some clever person started using nF (nanoFarad) which is responsible for a large percentage of my fumbled decimal points.

Also, I suspect that since the abrev is dB, with a capital B, the abbreviation should be deciBels, although nobody seems to do it that

On the other foot, US currency seems to be stuck on counting everything in just dollars. None of these SI prefixes are used: 1 penny = 1 centidollar = centi$ 1 dime = 1 decidollar = deci$ 1 Alex Hamilton note = 1 dekadollar = deka$ 1 Ben Franklin note = 1 hectodollar = hecto$ 1000 dollars = 1 kilodollar = kilo$ 1 billion dollars = 1 gigadollar = giga$ 1 trillion dollars = 1 teradollar = tera$ However, if the US ever truly goes metric, I would expect to see more SI Dollars mentioned.

On Wed, 04 May 2016 12:42:24 -0700, John Larkin Gave us:

As if it was a universe wide fact. You really are thick.