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AM modulation index

--- No, it won't.

There are always people drifting through here who wouldn't be aware that a shun was in place (If one could even get put place, since trying to get everyone here to agree to it would be like trying to herd cats) and Phil would go after them.

--- Grow thicker skin.

-- John Fields Professional Circuit Designer

Reply to
John Fields
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Don't know actually, but it makes sense.

Meindert

Reply to
Meindert Sprang

aren't

Oh? And in what way does it differ?

Meindert

Reply to
Meindert Sprang

"Passive" tags simply rectify to double the frequency.

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
     It\'s what you learn, after you know it all, that counts.
Reply to
Jim Thompson

I didn't see any response besides Larkin responding to Phil Allison's crap.

So I didn't think there was any interest beyond perpetuating flame.

But I'll dig it up and post "it" or "them". "Them" use passive 90° phase shifters and thus have "bandwidth".

"It" used quadrature dividers (for synthesizer use).

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
     It\'s what you learn, after you know it all, that counts.
Reply to
Jim Thompson

On Thu, 23 Mar 2006 20:12:56 +0100, "Meindert Sprang" wrote:

--- An earlier post of mine to Rich Grise explains the difference, at least in the way I understood the OP's meaning.

Because I thought a notch filter centered on 100kHz might be the way to go, I simulated one being driven by a 250VPP source modulated by a 10mV square wave in order to see whether the modulation could be easily recovered. Even with a 120dB notch at 100kHz and perfect components the results weren't too encouragaging, and if you've got Linear's simulator you can run this circuit file to see why:

Version 4 SHEET 1 880 852 WIRE -512 336 -512 112 WIRE -512 512 -512 416 WIRE -512 576 -512 512 WIRE -336 112 -512 112 WIRE -272 416 -272 304 WIRE -272 512 -512 512 WIRE -272 512 -272 496 WIRE -160 304 -272 304 WIRE -160 512 -272 512 WIRE -160 512 -160 352 WIRE -112 112 -256 112 WIRE -112 176 -112 112 WIRE -112 288 -112 256 WIRE -112 512 -160 512 WIRE -112 512 -112 368 WIRE 16 112 -112 112 WIRE 16 656 16 112 WIRE 48 112 16 112 WIRE 48 656 16 656 WIRE 160 112 128 112 WIRE 160 144 160 112 WIRE 160 368 160 208 WIRE 160 512 -112 512 WIRE 160 512 160 368 WIRE 160 560 160 512 WIRE 160 656 112 656 WIRE 160 656 160 640 WIRE 192 112 160 112 WIRE 192 368 160 368 WIRE 208 656 160 656 WIRE 304 112 272 112 WIRE 304 368 272 368 WIRE 304 368 304 112 WIRE 304 656 272 656 WIRE 304 656 304 368 FLAG -512 576 0 SYMBOL res 144 96 R90 WINDOW 0 -52 59 VBottom 0 WINDOW 3 -38 58 VTop 0 SYMATTR InstName R1 SYMATTR Value 1591.55 SYMBOL res 288 96 R90 WINDOW 0 -48 62 VBottom 0 WINDOW 3 -43 61 VTop 0 SYMATTR InstName R2 SYMATTR Value 1591.55 SYMBOL res 176 656 R180 WINDOW 0 36 76 Left 0 WINDOW 3 36 40 Left 0 SYMATTR InstName R3 SYMATTR Value 795.77 SYMBOL cap 144 144 R0 WINDOW 0 -61 31 Left 0 WINDOW 3 -67 61 Left 0 SYMATTR InstName C3 SYMATTR Value 2e-9 SYMBOL cap 112 640 R90 WINDOW 0 70 33 VBottom 0 WINDOW 3 70 34 VTop 0 SYMATTR InstName C1 SYMATTR Value 1e-9 SYMBOL cap 272 640 R90 WINDOW 0 72 33 VBottom 0 WINDOW 3 74 34 VTop 0 SYMATTR InstName C2 SYMATTR Value 1e-9 SYMBOL voltage -512 320 R0 WINDOW 3 24 44 Invisible 0 SYMATTR Value SINE(0 250 100000) SYMATTR Value2 AC 1 SYMATTR InstName V1 SYMBOL res -240 96 R90 WINDOW 0 -39 54 VBottom 0 WINDOW 3 -35 57 VTop 0 SYMATTR InstName R5 SYMATTR Value 10 SYMBOL sw -112 384 M180 WINDOW 0 32 15 Left 0 WINDOW 3 32 44 Left 0 SYMATTR InstName S1 SYMBOL voltage -272 400 R0 WINDOW 39 0 0 Left 0 WINDOW 3 -227 105 Invisible 0 WINDOW 0 -50 6 Left 0 SYMATTR Value PULSE(0 1 0 1e-6 1e-6 .0005 .001) SYMATTR InstName V2 SYMATTR Value2 AC 1 SYMBOL res -128 160 R0 SYMATTR InstName R6 SYMATTR Value 2.4999e5 SYMBOL res 288 352 R90 WINDOW 0 0 56 VBottom 0 WINDOW 3 32 56 VTop 0 SYMATTR InstName R7 SYMATTR Value 1e6 TEXT -474 538 Left 0 !.ac dec 64 10 1e6 TEXT -144 0 Left 0 ;fc = 1/2 pi r1 c1 TEXT -144 32 Left 0 ;R1 = R2 = 2R3 TEXT -144 64 Left 0 ;C1 = C2 = C3/2 TEXT -474 570 Left 0 !;tran 0 .03 .01 TEXT -520 624 Left 0 !.model SW SW(Ron=1 Roff=10Meg Vt=0.5Vh=0)

-- John Fields Professional Circuit Designer

Reply to
John Fields 

--
So, the next time I direct a question at you, It\'ll be OK if Phil
answers it for you?
Reply to
John Fields

formatting link

Best regards, Spehro Pefhany

--
"it\'s the network..."                          "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com
Reply to
Spehro Pefhany 

--
Nice...!
Reply to
John Fields 

--
Not true.

You see Phil\'s insults whenever you download a post which contains a
reply from him to _any_ post(er) which you haven\'t filtered.
Reply to
John Fields

Something here doesn't make any sense. How can you receive with the same antenna while you are transmitting? Exactly what do you think you are really measuring?

If you are measuring voltage at the antenna input with respect to ground and you are seeing millivolt changes when the transponder shorts its own coil, then all you are seeing is a change in the antenna impedance caused by the shorted coil. The change in the antenna impedance causes a small change in the voltage on your transmitter final. Your antenna impedance is the load impedance seen by your transmitter final. That's why everything else also causes a change in what you are seeing.

This is not really amplitude modulation since 100% modulation would imply a zero load resistance (i.e. output voltage equal to zero) and therefore no power transfer at all on negative peaks.

As John points out for metal detectors, you really need a separate receiving apparatus. It should be tuned to the oscillator frequency you are using on your transmitter. I assume your transponder puts out its digital stream at a certain frequency. You could monitor for a bitstream at that frequency. I suspect all you would need is a simple product detector to recover the bitstream.

tim ab0wr

Reply to
tim gorman

[snip]

I never see Phil's replies (since I killfile on Phil Allison "as author").

I only see his crap when someone, like Larkin, continues the flame.

Fields, You sure you understand Usenet filtering ?:-)

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
     It\'s what you learn, after you know it all, that counts.
Reply to
Jim Thompson

Posted at.......

Newsgroups: alt.binaries.schematics.electronic Subject: Re: AM modulation index - SSB-Mixer-ExampleForSED.zip Message-ID:

...Jim Thompson

-- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | |

formatting link
| 1962 | It's what you learn, after you know it all, that counts.

Reply to
Jim Thompson

Simple solution: killfile me too.

John

Reply to
John Larkin

I thought of that, but OCCASIONALLY you have something useful to offer ;-)

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
     It\'s what you learn, after you know it all, that counts.
Reply to
Jim Thompson

--- Yeah, sure, but most of the time I don't give a shit.

That is, if an asshole like you (or any other asshole) posts something inflammatory, why should I care? What I'm usually interested in is the nuts and bolts of the problems that are posted here and how to help get those problems solved.

Hobbs seems to be interested in proving that he's the detector of the smallest mistake, therefore (in his own mind) making him capable of making judgements about the largest mistakes, ergo, he should be king of the universe, while you seem to be intent on proving to everyone that you're smarter than they are, ergo you're also jockeying for that "King of the universe" spot.

Tomorrow, (Well, in a couple of months) my onions will bloom whether either of you want them to or not, so f*ck you both.

-- John Fields Professional Circuit Designer

Reply to
John Fields

Sweet?

Only thing I've tried to grow around here was tomatoes... they do quite well in the shade in the entry patio ;-)

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
     It\'s what you learn, after you know it all, that counts.
Reply to
Jim Thompson

I'll try to be more careful.

The problem with your killfiling people like Phil is that you can't see his posts, so you can't ignore sub-threads that he starts. You see responses, and you have to read them before you realize that he's involved.

I think it's easier to just see and ignore posts from people you don't like or aren't interested in, and ignore the entire rest of that branch.

Or you could do like Guy Macon, and killfile everybody.

John

Reply to
John Larkin

I hope you mean Phil Allison, not Phil Hobbs. Not that I mean to, err, be detecting your mistakes.

Oh, never mind.

John

ps - Phil Hobbs' book is a good read, practically worth the insane price. If Allison ever wrote a book, it would be composed entirely of four-letter words.

Reply to
John Larkin
[snip]
[snip]

John! Great idea! You solved the problem in a way that Agent could implement!

I've been after the Forte guys for years to filter on content, but you can't do that without downloading bodies.

But headers contain all the thread/sub-thread information.

Marvelous... just kill ANY "descendent" threads!

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
     It\'s what you learn, after you know it all, that counts.
Reply to
Jim Thompson

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