Hello, and thank you for posting this. I am responsible for Anechoic chamber Characterization at work and found this information very useful in generating ideas for setting up tests and getting more range out of the equipment here. TG in Silicon Valley
@ak47only
10 жыл бұрын
Useful video as always. thanks for sharing
@KD0CAC
10 жыл бұрын
Thanks Alan , I was set [ except the funds ] to saving for the Rigol 815TG , now I think it will take longer to get a spectrum analyzer . 2nd time I've seen this from Tektronix , 1st on SignalPathBlog . You guys get to play with all the good toys ;)
@w2aew
10 жыл бұрын
The one that you saw on SignalPathBlog was the MDO4000, the one in this video is the MDO3000. The 3000 does not have the time-correlated feature with its spectrum analyzer that the 4000 has. Note that neither of these has a tracking generator available. In many cases, you can use other techniques, but just wanted to let you know.
@jonahansen
3 жыл бұрын
Alan - you're such a smartie-pants! Seriously, thanks...
@w2aew
3 жыл бұрын
LOL!
@zenonsouzajr1735
10 жыл бұрын
Very good.
@JimGriffOne
10 жыл бұрын
Ah, so the perfect comb generator is just a series of Dirac spikes continuing to infinity in the time domain. I wouldn't have guessed!
@88merc300e
10 жыл бұрын
Very helpful. I always look forward to your videos. Thanks!
@THEWATERENERGY1
10 жыл бұрын
Thanks for sharing,It's make sense..!!
@oriole8789
10 жыл бұрын
Another very helpful video, thanks Alan!! Wish I had known about this before I had purchased a 4GHz microwave signal gen just to test a few things. I have a request haha! I'm very interested to know how phase noise analyzers work, namely how they manage to test down to dynamic ranges of below -200dBc... my current guess is that they employ some elaborate gain circuitry and filters to split one sideband of the impulse into multiple gain stages? (hence taking a fairly long time per measurement?) I couldn't really find anything online in terms of actual implementation. Just curious! :)
@w2aew
10 жыл бұрын
From what I've seen, making measurements which are than far down from the carrier, is done by notching the fundamental so that the analyzer can be set with less attenuation and even a preamp.
@oriole8789
10 жыл бұрын
***** That makes a lot of sense :0 I guess it's just a matter of making sure that the notch filter is applied perfectly and doesn't interfere with the measured sidebands. Thanks for the reply! :)
@vtrandal
8 жыл бұрын
excellent
@svandal1
7 жыл бұрын
Excellent video, as always from you, thank you for doing that.
@garyluis7418
3 жыл бұрын
pro tip : you can watch movies at flixzone. Been using it for watching loads of movies these days.
@brodieeli5653
3 жыл бұрын
@Gary Luis Definitely, been watching on flixzone for since november myself :)
@akremihassen5701
4 жыл бұрын
can you show us how it is made from inside ?
@AccessControlForum
10 жыл бұрын
Thumbs up! thanks!
@stevecreasey3737
10 жыл бұрын
Thanks so much for your videos! They are so interesting, informative and very well done. You have a real gift for teaching :). Thank you for sharing it.
@Pwaak
10 жыл бұрын
You bring to us fascinating information / technology...Thank You! Does a harmonic, or tooth of the comb, get its power/energy from a fundamental? If so, then as it takes power to expand a fundamental (increase frequency), the result is a diminished harmonic (tooth)?
@w2aew
10 жыл бұрын
If only a SRD (step recovery diode) is used, then the fundamental energy is effectively divided amongst the harmonics (with some loss of course). Often time, a packaged comb generator module will include some amplifiers which help to increase the power in the harmonics. You can see in the video that as the input frequency is lowered, more teeth are created in the frequency domain, and the power level of each tone is decreased.
@Pwaak
10 жыл бұрын
***** Thank you for the reply!
@PapasDino
10 жыл бұрын
Thanks, as usual a great informative video! 73 - Dino KL0S
@Mr.Laidukas
10 жыл бұрын
Now whose voice do I hear here :) www.tek.com/product-demo/getting-started-rsa306-and-signalvu-pc
@w2aew
10 жыл бұрын
Yep - that would be me... ;-)
@Mr.Laidukas
10 жыл бұрын
***** Incredible pricing from Tektronix, I have some savings so already inquired prices from my local dealer. I believe this tool will significantly improve my hobbyist lab. Just a little bit sad regarding those spurious below -55dBm. I wounder how much it will cost here in Europe.
@mejoe444
Жыл бұрын
Hello, how short are the pulse width of each impulse?
@w2aew
Жыл бұрын
They're on the order of 500ps as shown in the video at 2:37.
@DAVET38
10 жыл бұрын
Another very interesting video Alan. Thank you.
@over00lordunknown12
6 жыл бұрын
+w2aew (or anyone else who knows) Would it be possible to use this in an example like this: The previous version of a device required frequency 93.2, and the new version of the device uses 99.3, and you need both to receive a signal from the same transmitter?
@w2aew
6 жыл бұрын
No, probably not. The comb generator produces harmonics of the input signal, not specifically selected frequencies.
@shadowfax54
10 жыл бұрын
Very well made and informative, I wonder if the Comb gen. would have applications for testing spread spectrum microwave receivers and amplifiers ? mike W2LLI
@w2aew
10 жыл бұрын
Sure, I can see that.
@budleyca1
10 жыл бұрын
Excellent explanation, tnx Alan... Bud...
@YellowsourceOrg
6 жыл бұрын
Could you fast edge TDR circuit based on 74AC (
@w2aew
6 жыл бұрын
Sure it could, but you're mainly going to get just the odd harmonics of the fundamental oscillating frequency, and the amplitude of each tone will decrease over frequency.
@TheHexorg
10 жыл бұрын
I just got my callsign recently, but wasn't able to do anything, since most of ham equipment if expencive (I'm a college student). Do you find yourself building your own circuits for transmitting / receiving or just buying premade equipment?
@w2aew
10 жыл бұрын
I've done both. You certainly can build your own transmitter and receiver, or pick up something used - both can be done very in expensively. Check into your local amateur radio clubs, many will have equipment to lend to new hams or there may be members that are willing to do the same.
@Roy_Tellason
3 жыл бұрын
And then there's always the Baofeng stuff, typically can be had for under $30...
@jlfqam
9 жыл бұрын
Thanks for this and many other interesting videos, when the DSA or computer after FFT analysis displays the spectrum of a square pulse or pulse like the one you show in the video, If I properly understand the phenomenon, no actual oscillation of current exists in the circuit, in these two examples of pulses I mention. It's an arctifact or math output of the FFT algorithm to reconstruct the pulse shape, right? Physically it's just a semiconductor "gate" opening and closing, conducting or not conducting, right? The comb pattern is useful, maybe as an analog computer, for comparison with other signals in the frequency domain, signals, that may or may not be real oscillations of charge in circuits, but share a common frequency. I am sorry, but I do not know the technical name of the short, quickly fading, ringing pulse, but, is it true that if this pulse is fed into a coil or inductor it will actually produce an oscillation, but the output frequency from the coil or inductor, wil mainly depend on the resonating frequency of the coil or inductor, or it will also depend on the amplitude and frequency of ringing of the inital burst or pulse. Does this process also work for square pulses, not going into negative Voltages? Do you know where I can find information on that process? Greetings, JL
@w2aew
9 жыл бұрын
jlfqam The frequency content of a square pulse does indeed consist of the summation of sinusoids at the fundamental frequency and its odd harmonics (scaled by 1/N). See this video on the topic: kzitem.info/news/bejne/xnlpnHWnhWeeqm0 So, it's not just an artifact of the FFT, it is real. Regarding the "ringing" of a coil, you might want to check out the second half of this video: kzitem.info/news/bejne/mGqc4G2fsIyQpoI Whether you are considering square waves or narrow impulses, the steepness of the edge (rise/fall time) governs the frequency content. Faster edges = higher frequency content.
@jlfqam
9 жыл бұрын
***** Thanks for the response. In your video #59, the AWG soft sends a wave composed only of the odd harmonics, but the DSA still shows the even harmonics. The DSA uses FFT right, do you know which algorithm? I would like to measure if there are oscillations in the circuit, other than the regular pulse. Do you know how can this be done? should I use filters to select only one harmonic at a time, is it possible in a simple way? Greetings
@w2aew
9 жыл бұрын
jlfqam Yes, but those even harmonic components are simply distortion products, and are typically more than 50dB down from the fundamental - very small. The spectrum analyzer shown uses a Chirp-Z transform to compute the spectrum (this is similar to an FFT, but without the n^2 record size limitation). Ideally, filters can be used to select only one harmonic component. The practicality of this depends a lot on the harmonic frequency spacing and filter design.
@SeAfasia
10 жыл бұрын
Thanks, are you develop a test circuit e.g a pll to apply the device to see how it works?
@engineereuler1762
3 жыл бұрын
Amazing video. Here's an idea, why not modify/tweak the 74AC14 Schmitt trigger fast oscillator that you showed once to get only one pulse (or ones that are separated far enough) that has no top (an impulse, or theoretically, a realizable Dirac Delta Function en.wikipedia.org/wiki/File:Dirac_function_approximation.gif, or mathworld.wolfram.com/DeltaFunction.html) that give a close to a horizontal line frequency spectrum to check filters and components. Another video idea that only you with your equipment that's worth about 51% of the eastern coastal states can do
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