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High-speed, Multi-channel 8 or 16 Bit sampling system

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Tim B

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Hi,

I have been thinking for some time now that a high-speed sampling system could be extremely useful. However, proprietry solutions are just a fraction expensive.

I think I have nearly sourced enough components to start building a system myself. It will primarily consist of an 8 channel, 8 bit ADC, and a memory IC (16-Bit IC later if I feel like it). Obviously there will be a few driver chips and things in it as well. Additionally, it will have a parallel port interface, so that the data in memory can be copied to computer. The interface will also allow driving of the ADC directly.

So two questions... Does anyone think it has commercial potential? and has anyone done anything similar?

Incidentally, the unit will not have a PIC or anything else in it. It will be "hard wired" in logic circuitry, though there could be an option to select the number of channels. Naturally, there will be a memory usage readout included.

Any ideas, comments or requests?

Tim B.
 
Tim B said:
So two questions... Does anyone think it has commercial potential? and has anyone done anything similar?

There already plenty of similar commercial units, both as data-loggers and as PC Based Scopes. The main difference is the speed and number of channels.
 
My ordinary cell phone records, stores and transmits audio, pics, videos and data. My ordinary MP3 player records, stores and transmits audio or data. They have a lot more "channels" than only 8.
 
audioguru said:
My ordinary cell phone records, stores and transmits audio, pics, videos and data. My ordinary MP3 player records, stores and transmits audio or data. They have a lot more "channels" than only 8.

How so? Audio is only two channels. Adding video brings it to three.

Mike
 
Nigel Goodwin said:
Tim B said:
So two questions... Does anyone think it has commercial potential? and has anyone done anything similar?

There already plenty of similar commercial units, both as data-loggers and as PC Based Scopes. The main difference is the speed and number of channels.

and cost differences.. ranging from the dirt cheap sub 100USD to the multi-thousand dollar systems.

Tim, the market is saturated with this kind of thing in a variety of incantations.
 
My cell phone records the audio in videos in mono, not stereo.
I haven't tried it but I suppose it is busy as a phone when it is recording or playing a video, so maybe it is also recording my missed calls.

So it has only 3 simultaneous channels. Besides stereo and surround sound, what else would you need more channels for?
 
I would be most suspicious of scientific measurements made with a mobile phone.

when I said "has anyone done anything similar" I meant non-professionally.

I Just thought it might be an interesting project. And one should always consider the marketability,

Tim B.
 
Tim B said:
I would be most suspicious of scientific measurements made with a mobile phone.

when I said "has anyone done anything similar" I meant non-professionally.

I Just thought it might be an interesting project. And one should always consider the marketability,

How fast are you planning sampling?.
 
You seem to be thinking of something called a digitizer. Its basically a multi channel ADC/DAC board that is configured by the computer and samples data stores it internal memory and then is dumped to the computer VIA some common programs such as MATLAB or LabView. They are sometimes called data acquisition boards. Typically digitizers have much higher sampling rates. I looked into one for my Master's thesis, turned out I never needed it though.
 
You need to have an intended purpose in mind. We already have any number of ADC chips around that all do slightly different things.

Putting together one without a PIC or other controller onboard is nearly impossible, and foolish. PICs will solve all your problems and multiply possible features dirt cheap.

Parallel port is old stuff. Go with the serial port. The wiring alone saves you a lot of time. Or, to be really impressive, make it USB. Some newer PICs already have hardware USB controllers built into them so this is easy.
 
Sampling rate of upto about 4 MHz at 8 bits, half that for 16 bits I suspect (that's what the sums say) realistically, probably upto 1MHz.

I agree that the parallel port is "old fashioned" it is also slow. It's redeeming feature is that most machines have them and there are USB converters for them. They are also extremely easy to read from and write to in the computer code itself. Using a serial port would be a waste of time, because the ADC is parralell, as is the memory, so there is no need to introduce a serial port.

I was trying not to use a PIC for two reasons... a) to show it could be done. b) to cut down the programming complexity. Since I'm considering straight data-bus mapping from ADC to memory there is little point, except to control the ADC and memory, which can be done much faster by just using a few linked BCD counters.

Tim B.
 
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