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From: john larkin <jlarkin_highland_tech>
Newsgroups: sci.electronics.design
Subject: Re: "Sampler??"
Date: Tue, 30 Jul 2024 17:34:51 -0700
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On Tue, 30 Jul 2024 21:58:44 -0000 (UTC), Cursitor Doom
<cd999666@notformail.com> wrote:

>On Tue, 30 Jul 2024 21:08:34 -0000 (UTC), Cursitor Doom wrote:
>
>> On Tue, 30 Jul 2024 13:15:59 -0700, john larkin wrote:
>> 
>>> On Tue, 30 Jul 2024 19:21:28 -0000 (UTC), Cursitor Doom
>>> <cd999666@notformail.com> wrote:
>>> 
>>>>On Tue, 30 Jul 2024 10:39:37 -0700, john larkin wrote:
>>>>
>>>>> On Tue, 30 Jul 2024 08:58:35 -0000 (UTC), Cursitor Doom
>>>>> <cd999666@notformail.com> wrote:
>>>>> 
>>>>>>On Tue, 30 Jul 2024 05:16:24 GMT, Jan Panteltje wrote:
>>>>>>
>>>>>>> On a sunny day (Mon, 29 Jul 2024 09:29:04 -0700) it happened john
>>>>>>> larkin <jlarkin_highland_tech> wrote in
>>>>>>> <72gfajl8ke966lsu54bpajpang9dvgmt63@4ax.com>:
>>>>>>> 
>>>>>>>>On Mon, 29 Jul 2024 05:19:06 GMT, Jan Panteltje
>>>>>>>><alien@comet.invalid> wrote:
>>>>>>>>
>>>>>>>>>On a sunny day (Sun, 28 Jul 2024 21:40:41 -0000 (UTC)) it happened
>>>>>>>>>Cursitor Doom <cd999666@notformail.com> wrote in
>>>>>>>>><v86dsp$3n74$1@dont-email.me>:
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>>I still can't see where the 'sampling' bit comes into it. AFAICT,
>>>>>>>>>>there's are two signals into this thing and one signal out. The
>>>>>>>>>>signal from the LHS is passed through a very fast diode which
>>>>>>>>>>generates harmonics from that fundamental. The signal from the
>>>>>>>>>>RHS is unmodified and mixed with the desired harmonic to give the
>>>>>>>>>>necessary output signal which is then filtered to get rid of the
>>>>>>>>>>unwanted mixing products. If that's all correct, as I believe it
>>>>>>>>>>is,
>>>>>>>>>>where does any *sampling* come into it?
>>>>>>>>>
>>>>>>>>>A 'sampler' is fact a non-linear mixer.
>>>>>>>>
>>>>>>>>In the audio world, a "mixer" is a linear summer.
>>>>>>>>
>>>>>>>>In RF, a mixer is usually a multiplier, typically a 4-quadrant
>>>>>>>>diode thing or a Gilbert cell type circuit. Or a 2-quadrant thing
>>>>>>>>like a pentode. Or even a single diode. All do some flavor of
>>>>>>>>multiplying.
>>>>>>>>
>>>>>>>>Some mixers inherently multiply a signal by a square wave, which
>>>>>>>>resembles other multiplier-type things once you lowpass filter the
>>>>>>>>output. That's a "synchronous detector", which we usually do in an
>>>>>>>>FPGA.
>>>>>>>>
>>>>>>>>A sampler is a signal multiplier too.
>>>>>>>>
>>>>>>>>These are all variations on the basic idea of multiplying two
>>>>>>>>signals.
>>>>>>> 
>>>>>>> A the word 'mixer' in RF is not the same as a multiplier,,
>>>>>>> Multipliers are like harmonic generating stages say you have a 1
>>>>>>> MHz distorted sine wave and then a second stage tuned at 3 MHz,..
>>>>>>> turned to third harmonic.
>>>>>>> 
>>>>>>> mamamatical speaking RF mixing is indeed multiplication.
>>>>>>> 
>>>>>>> Like Shakepierce once said:
>>>>>>>  "What's in a name..." CocaCola wihout coke
>>>>>>
>>>>>>I think in this context, HP is using the term "sampler" to mean
>>>>>>something which 'sniffs' a small amount of a signal for testing
>>>>>>purposes. Like a few turns of wire around a transmission line will
>>>>>>'sniff' a small sample of what's going on in the line.
>>>>>>Where I went wrong was rigidly thinking HP meant 'sampling' in the
>>>>>>manner a sampling oscilloscope works. That's what threw me. I tend to
>>>>>>interpret things very literally. :(
>>>>> 
>>>>> The sampler in the SA schematic is precisely the sort of sampler used
>>>>> in a sampling scope. It contains a step-recovery diode impulse
>>>>> generator and no doubt some sampling diodes.
>>>>
>>>>How can you say that when you haven't seen the schematic? If you've
>>>>been able to find it online somewhere then kindly post a link to it
>>>>here.
>>> 
>>> You posted an excerpt from the HP manual where the sampler is
>>> described.
>> 
>> But you said:
>> "The sampler in the SA schematic is precisely the sort of sampler used
>> in a sampling scope."
>> 
>> So you must have had sight of the schematic. I'd really appreciate it if
>> you could post a link to it.

No, all I saw was the description.

>
>Also, you said the SRD was acting as an "impulse generator" when I assumed 
>it was simply generating harmonics to boost the M/N loop output up in 
>order to mix with the output of the YTO.

They are really the same thing. An impulse train is a harmonic comb.