It's a shame about the kickstarter, I think the problem is that in the US (and Israel and to a lesser extent Asia) you can just too cheaply pick up old Tek sampling scopes.
Many DSO on the market do exactly the same, even my cheapo Siglent 1000CML does the same at '5GHz'.
Their bandwidth is limited by their probes, front end and ADC, they can use equivalent time sampling but it's futile ... the information is gone. At best they can use repeated sampling to increase the vertical resolution.
At these frequencies you need to use SMA connected directly to the DUT, you need to have nothing on the front end except maybe an attenuator (unless you're Tek or Agilent and can afford integrated MEMS relays) and you need a 10s of ps range sampling gate (or in this case latched comparator). Many DSOs do not have this.
The DS800 doesn't really sample at 8GHz, it needs a repetitive waveform to allow it to gather enough samples to simulate an 8GHz sample rate.
Many DSO on the market do exactly the same, even my cheapo Siglent 1000CML does the same at '50GHz'.
Wow, your cheap Siglent DSO is capable to display a 1 GHz signal without attenuation?
Maybe you train yourself about the difference of a sampler and a DSO
Yeah, it's a pity this one didn't go through. The plan was to chip in at about 80% complete (don't have that much random cash lying around to get in at the start
). It looked pretty damn interesting for the money, even if it meant having to do the software side of it yourself.
I hope he tries it again in the not-too-distant future after working a bit on his kickstarter marketing skills. I think he may have gotten more backers if he showed some example uses + screenshots of working software + direct links to noob-proof datasheets.
Or maybe not, but one can always hope.
What did amuse me though was his other succesfully backed project. So on the one hand we have a pretty awesome (affordable!) sampler that doesn't even make it to 10% backed. And on the other hand we have Yet Another Whatever With Silver Ink, reaching $674k. What is this world coming to?
I hope he tries it again in the not-too-distant future after working a bit on his kickstarter marketing skills. I think he may have gotten more backers if he showed some example uses + screenshots of working software + direct links to noob-proof datasheets.
Or maybe not, but one can always hope.
What did amuse me though was his other succesfully backed project. So on the one hand we have a pretty awesome (affordable!) sampler that doesn't even make it to 10% backed. And on the other hand we have Yet Another Whatever With Silver Ink, reaching $674k. What is this world coming to?
He didn't mention words like Arduino, iPhone, Raspberry Pi, Android, smart phone and/or tablet.
Hey ... an android interface would be handy :p
I think we just worked out his next angle.
"Android / IPhone 10 GHz OMGWTFBBQ Sampler. Sample your arduino blinky leds like you never sampled them before! Also works with an RPi!". Should get him started at $674k easily.
It's a shame about the kickstarter, I think the problem is that in the US (and Israel and to a lesser extent Asia) you can just too cheaply pick up old Tek sampling scopes.
Why the US, Israel, and Asia?
Military Industrial Complex and Equipment scrapping.
I'm currently working on a rather similar sampling oscilloscope. The frontend is practically identical (ADCMP582 as 'sampler', ADCMP567 as trigger comparator). The trigger-to-sample-delay is generated by a ring oscillator (the majority of the delay comes from a long pcb trace) and a LVPECL delay line. The bandwidth is about 5GHz, the step response looks acceptable.
It'll be finished in a year or two and released as open source hardware/software, since another hardware revision is to come (the frontend will be detachable) and the software on the PC side has grown in complexity because this shouldn't be another USB oscilloscope with crappy software. Seriously, I haven't come across a reasonably-priced oscilloscope with great software, that doesn't look like it has been slapped together using Visual Basic or even Labview. The best oscilloscope software I know is the FlexDCA (aside from the ability to choose from ~10 ugly themes and ~5 mode transition animations...) software from Agilent. Unfortunately, it's only compatible with oscilloscopes that cost >10.000$.
And what is the bloody point of a sampling oscilloscope ? They are only useful on repetitive signals and you can look at eye diagrams ...
They are useless for day to day work , debugging work , signal analysis (analog or digital).
Walk in a bog circle around those things. If you are really in need of a sampling machine look for a used one on ebay.
None of the scope makers build em anymore.
So its merely a trap for those who are not aware what a sampling scope is, and that shouting ... "LOOK !!! GHz scope under for just few hundreds dollar !! I'm buying one !!" ... is that it ?
And what is the bloody point of a sampling oscilloscope ? They are only useful on repetitive signals and you can look at eye diagrams ...
They are useless for day to day work , debugging work , signal analysis (analog or digital).
Walk in a bog circle around those things. If you are really in need of a sampling machine look for a used one on ebay.
None of the scope makers build em anymore.
Just because you happen to have access to an awesome scope with 10 GHz analog bandwidth, doesn't mean everyone has.
This sort of sampler for $300 would enable several classes of measurement which otherwise are a wee bit out of reach. And yes, as you point out, all of them on repetitive boring repetitive signals that are repetitive.
And what is the bloody point of a sampling oscilloscope ? They are only useful on repetitive signals and you can look at eye diagrams ...
They are useless for day to day work , debugging work , signal analysis (analog or digital).
Walk in a bog circle around those things. If you are really in need of a sampling machine look for a used one on ebay.
None of the scope makers build em anymore.
That you are not working in RF/VHF/UHF-projects doesn't mean that noone does
None of the scope makers build em anymore.
Not in this low frequency range, but they still do make em.
They are useless for day to day work , debugging work , signal analysis (analog or digital).
Absolute nonsense. Anyone working on picosecond electronics will need a sampling scope to verify their designs. Just because it's a design area you have no knowledge of doesn't mean it doesn't exist.
They are useless for day to day work , debugging work , signal analysis (analog or digital).
Absolute nonsense. Anyone working on picosecond electronics will need a sampling scope to verify their designs. Just because it's a design area you have no knowledge of doesn't mean it doesn't exist.
I strongly agree. A cheap sampling scope is very usefull if you work on HF circuits. Because the sampling rate of the ADCs is quite low (10k to 500k) you can easely use 10 to 16 bit ADCs which make is very accurate. I've been doing some experiments myself with a diode sampler front-end. These are not very hard. The biggest problem when desigining these kind of scopes is a trigger system with ultra low jitter .
Interesting, which sampling diodes did you use, how did you drive them?
I've been doing some experiments myself with a diode sampler front-end. These are not very hard. The biggest problem when desigining these kind of scopes is a trigger system with ultra low jitter .
Interesting indeed. Wondering pretty much the same thing as Lukas. Which diodes did you use, and how did you hook things up?
I've been doing some experiments myself with a diode sampler front-end. These are not very hard. The biggest problem when desigining these kind of scopes is a trigger system with ultra low jitter .
Interesting indeed. Wondering pretty much the same thing as Lukas. Which diodes did you use, and how did you hook things up?
So far mostly only simulation with BAS70 dual diodes. The trick is to feed a pulse into a shorted piece of stripline which makes the diodes conduct for a short period charging or discharging 2 capacitors (the voltage across is the sampled valued minus the previous sample). The rise time of the pulse is driving the sampling window. I did some tests with a 2N2904 transistor in an avelanche pulse generator. The only time I needed 10V/div in 50 Ohm mode on my scope
Still I didn't like the risetime. So far it all looked good mostly on paper but I never experimented further due to lack of time and ideas about the triggering.
Anyway, yhis appnote from Linear covers some of the basics of a diode sampler:
http://cds.linear.com/docs/en/application-note/an79.pdf
Bummer, I wanted one to check my serdes channels
[...] ideas about the triggering.
What about random sampling? Continoulsy run the sampling clock and determine the time of the trigger event using a TDC.
[...] ideas about the triggering.
What about random sampling? Continoulsy run the sampling clock and determine the time of the trigger event using a TDC.
Heh, you beat me to it. Either use a TDC from Acam or roll your own with an fpga.
@Lukas: what would you use for the dithered clock? A regular clock that you "dirtied up" with added noise to get your dithering? Or a noise generator + gated clock? I have used the latter for testing my fpga based TDC, but never played with the former.
Then again, if the resolution of those delay lines is good AND they can be adjusted fast enough then that could be better. It would really depend on the linearity of the delay line and the settling time (and resolution
).
Mmmh, I see Acam
added a new one since last I looked.