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2ch >1GHz PCIe (or similar) ADCs on a reasonable budget. Ideas?
KaneTW:
I'm looking at old mass spectrometers on ebay and some of them just have a direct CH1/CH2 channel out. While the entire instrument is probably not worth refurbishing due to software incompatibilities and stuff, I'm wondering: how would I go about acquiring a suitable ADC to get the most ouf ot it?
Sure, I could look at the waveforms with a scope and save them, but that'll be pretty cumbersome. All google results for GSPS digitizers don't even list prices (and at that point I might just as well buy a more complete mass spec). Ideas? Maybe some alternate search terms or equipment that contains digitizers?
ogden:
--- Quote from: KaneTW on August 10, 2019, 12:23:16 am ---All google results for GSPS digitizers don't even list prices
--- End quote ---
Rest assured - it will cost a fortune. DSO with Ethernet readout seems to be much better idea.
SiliconWizard:
Yeah. Your specs are not completely clear though. What do you mean 1GHz? Do you mean 1GHz of analog bandwidth?
And what do you mean by GSPS ADC? Is it 1GSPS? 2GSPS? 5GSPS? Higher? That won't cost the same at all.
Anyway, you'll probably find something more affordable than a dedicated PCIe card with an USB oscilloscope or indeed a full-blown DSO.
PCI/PCIe acquisition cards tend to be very expensive. If you're lucky to find an affordable one second hand or something, it's likely it will be rather old, and thus have no drivers and app to use it on any recent computer... so pretty much dead beef.
And giving us a little more details about what those spectrometers output exactly may help us suggesting alternatives as well. You may not need that wide a bandwidth and/or that high a sampling rate.
KaneTW:
I don't have access to a mass spec but I presume it's an output from the detector, so it'll be detected intensity over time. Specs for the particular model I'm looking at recommend anywhere from a 2GSPS, 500MHz analog bandwidth capture card to a 4GSPS, 1.5GHz scope.
http://www.chem.cmu.edu/cma/DE-STR%20Manual.pdf
Ballparking some values, I'm thinking there'll be about 1.3ns between two adjacent peaks if two molecules are 0.1 m/z apart, and 130ps if two molecules are 0.01m/z apart.
At the same time, an acquisition would take up to around 100us.
The data is usually fairly peaky, but also has a fair bit of DC component.
SiliconWizard:
To get an idea about the price of the Acquiris boards the manual suggests: https://www.electronicproducts.com/Board_Level_Products/Digitizer_boards_cap_1-GHz_analog_bandwidth.aspx
That's around $10000-$15000. Not sure you expected to spend that much.
Something that is not quite clear to me (I still don't know exactly how those spectrometers work) is whether you really need high sampling rate acquisition (meaning do you really need single shot acquisitions?) Some kind of "sampling oscilloscope" (or a regular scope with modest max sampling rate used in equivalent time sampling mode) may be enough? (And would cost much less.)
Something like this for instance: http://www.analogarts.com/products/usb-oscilloscope/sa985-1-ghz-bandwidth-oscilloscope
It's $650, and seems to come with pretty decent software.
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