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DIY PC Oscilloscope

Started by Unknown March 9, 2013
Hi all,
I've started designing a 200 MSPS Oscilloscope with a 25 MHz analog bandwidth, 3Ksample/channel buffer.
The oscilloscope can be connected to a PC via USB, and eventually via Ethernet and WiFi.
The  trigger is ( at moment) rising, falling... auto, normal.

I would appreciate suggestions and or  comment for possible improvement and functionality that could make this oscilloscope interesting.

Thanks,
Francesco
On Sat, 9 Mar 2013 10:22:38 -0800 (PST), francescopoderico@googlemail.com wrote:

>Hi all, >I've started designing a 200 MSPS Oscilloscope with a 25 MHz analog bandwidth, 3Ksample/channel buffer. >The oscilloscope can be connected to a PC via USB, and eventually via Ethernet and WiFi. >The trigger is ( at moment) rising, falling... auto, normal. > >I would appreciate suggestions and or comment for possible improvement and functionality that could make this oscilloscope interesting. > >Thanks, >Francesco
It will have 5 ns p-p trigger jitter, unless you do tricks, which would be interesting. Are you using an FPGA? Even low-end parts usually have more memory than that. The hard part is the front-end, attenuators and such. You can build a scope with nasty transient response, untweaked attenuators and such, and fix the response in the PC software. What's the cheapest comparable thing on the market now? Your parts cost might be in the $40 ballpark, maybe even at 50 MHz. -- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators
On a sunny day (Sat, 9 Mar 2013 10:22:38 -0800 (PST)) it happened
francescopoderico@googlemail.com wrote in
<c1ad2481-696a-4257-8242-a8c92169124b@googlegroups.com>:

>Hi all, >I've started designing a 200 MSPS Oscilloscope with a 25 MHz analog bandwidth, 3Ksample/channel buffer. >The oscilloscope can be connected to a PC via USB, and eventually via Ethernet and WiFi. >The trigger is ( at moment) rising, falling... auto, normal. > >I would appreciate suggestions and or comment for possible improvement and functionality that could make this oscilloscope >interesting.
Add TV: http://panteltje.com/panteltje/scope_tv/index.html
>Thanks, >Francesco
this is the blog of the oscilloscope:

http://thefpproject01.blogspot.co.uk/

this is the blog of the oscilloscope:
http://thefpproject01.blogspot.co.uk/
On Saturday, 9 March 2013 18:37:34 UTC, John Larkin  wrote:
> On Sat, 9 Mar 2013 10:22:38 -0800 (PST), francescopoderico@googlemail.com=
wrote:
>=20 >=20 >=20 > >Hi all, >=20 > >I've started designing a 200 MSPS Oscilloscope with a 25 MHz analog band=
width, 3Ksample/channel buffer.
>=20 > >The oscilloscope can be connected to a PC via USB, and eventually via Et=
hernet and WiFi.
>=20 > >The trigger is ( at moment) rising, falling... auto, normal. >=20 > > >=20 > >I would appreciate suggestions and or comment for possible improvement =
and functionality that could make this oscilloscope interesting.
>=20 > > >=20 > >Thanks, >=20 > >Francesco >=20 >=20 >=20 > It will have 5 ns p-p trigger jitter, unless you do tricks, which would b=
e
>=20 > interesting. >=20
In theory is possible to have a 5 ns p-p trigger jitter, but only when the = noise floor is less then 0.5 LSB, otherwise you need to add some form of hi= steresys that will increase the jitter opening. but in theory is possible
>=20 >=20 > Are you using an FPGA? Even low-end parts usually have more memory than t=
hat.
>=20
I'm using an FPGA for triggering and buffer. at moment a small device, as = I'm quite impressed with the results (tomorrow I will post a video on my bl= og) next revision I'm planning a SPartan 6 with external memory IF.=20
>=20 > The hard part is the front-end, attenuators and such. >=20 >=20
Correct, I have spend 2 months or maybe 3 just to design the analog parts, = I must admit I believe I have over designed, but i'm very happy with the re= sults so far. My plan is to measure and publish the analog bandwidth.
>=20 > You can build a scope with nasty transient response, untweaked attenuator=
s and
>=20 > such, and fix the response in the PC software.
The scope has a compensated attenuation in the front end that seems doing a= good job. Therefore there is not needed for SW tricks. I personally don't = like=20
>=20 >=20 >=20 > What's the cheapest comparable thing on the market now? Your parts cost m=
ight be
>=20 > in the $40 ballpark, maybe even at 50 MHz.
I think the Picoscope 200 series is the main competitor, which is around 20= 0=A3 + VAT
>=20 >=20 >=20 >=20 >=20 >=20 >=20 > --=20 >=20 >=20 >=20 > John Larkin Highland Technology Inc >=20 > www.highlandtechnology.com jlarkin at highlandtechnology dot com =20 >=20 >=20 >=20 > Precision electronic instrumentation >=20 > Picosecond-resolution Digital Delay and Pulse generators >=20 > Custom timing and laser controllers >=20 > Photonics and fiberoptic TTL data links >=20 > VME analog, thermocouple, LVDT, synchro, tachometer >=20 > Multichannel arbitrary waveform generators
"Francesco Poderico" <francescopoderico@googlemail.com> wrote in message 
news:214d6abd-3678-4159-8d1f-05184763d036@googlegroups.com...
>I'm using an FPGA for triggering and buffer. at moment a small device, > as I'm quite impressed with the results (tomorrow I will post a video > on my blog) next revision I'm planning a SPartan 6 with external memory > IF.
Why only 25MHz? Yes it's easier, but the ADC probably has an analog bandwidth in the GHz. Why waste it? My TDS460 has 100MSa/s and 350MHz bandwidth. For periodic signals, it's as good as an off-the-shelf MSO or DPO series (arguably better since it doesn't have that retarded DPO crap you can't turn off), which usually claim something ignorant like 5GSa/s and a mere 100MHz. As John says, the attenuator is the hard part. Perhaps you could pilfer them from old analog or digital scopes, and feed the output to your ADC and trigger generator. Tim -- Deep Friar: a very philosophical monk. Website: http://seventransistorlabs.com
On Sat, 9 Mar 2013 10:22:38 -0800 (PST),
francescopoderico@googlemail.com wrote:

>I've started designing a 200 MSPS Oscilloscope with a 25 MHz analog bandwidth, 3Ksample/channel buffer. >The oscilloscope can be connected to a PC via USB, and eventually via Ethernet and WiFi. >The trigger is ( at moment) rising, falling... auto, normal. >I would appreciate suggestions and or comment for possible improvement and functionality that could make this oscilloscope interesting. >Francesco
There are plenty of similar USB scopes on the market with similar specs. Use their feature list as a checklist to see if you're missing something. I presume that you're asking for advice on how to make the hardware unique in order to obtain a marketing advantage. Most of the product differentiation is in the software, so I'll comment only on the hardware. What *I* might want in a USB scope is (whether I'm willing to pay for these is another question): 1. USB microscope camera on the probe tip so that I can see where I'm sticking the probe. 2. IR thermometer with LED targeting on the probe so that I can simultaneously measure and record any localized heating. 3. Replacable front end so that when I inevitably blow it out, it can be easily replaced. 4. Built in function generator, pattern generator, arbitrary waveform generator, two tone generator, DDS generator, white/pink noise, sweep generator generator. Extra points for adding AM/FM/PM/pulse modulation. 5. DC power output for powering active probes and assorted sensors. 6. Presumably, it's dual channel. If so, make it stackable via a common bus or preferably via ethernet, so that multiple units can be conglomerated into a 4,6,8, etc channel scope. 7. Switchable low pass filter on input for high RF level environments. 8. Self test and calibration check. 9. An accurate and readable schematic so I can fix it. 10. Security cable to keep it from getting um.... borrowed. 11. Built in smoke detector. -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
On Saturday, 9 March 2013 20:08:22 UTC, Tim Williams  wrote:
> "Francesco Poderico" <francescopoderico@googlemail.com> wrote in message > > news:214d6abd-3678-4159-8d1f-05184763d036@googlegroups.com... > > >I'm using an FPGA for triggering and buffer. at moment a small device, > > > as I'm quite impressed with the results (tomorrow I will post a video > > > on my blog) next revision I'm planning a SPartan 6 with external memory > > > IF. > > > > Why only 25MHz? Yes it's easier, but the ADC probably has an analog > > bandwidth in the GHz. Why waste it? > > > > My TDS460 has 100MSa/s and 350MHz bandwidth. For periodic signals, it's > > as good as an off-the-shelf MSO or DPO series (arguably better since it > > doesn't have that retarded DPO crap you can't turn off), which usually > > claim something ignorant like 5GSa/s and a mere 100MHz. > > > > As John says, the attenuator is the hard part. Perhaps you could pilfer > > them from old analog or digital scopes, and feed the output to your ADC > > and trigger generator. > > > > Tim > > > > -- > > Deep Friar: a very philosophical monk. > > Website: http://seventransistorlabs.com
Thanks Tim, good point, Actually in theory I could use the DLL inside the FPGA and changing the clock phase with a resolution of 25 ps... so in theory I have a 1 GSPS FPGA for repetitive signals! Do you think it would make more attractive to buy? Actually the maximum bandwidth is 70 MHz, I'm low filtering for aliasing.
On Saturday, 9 March 2013 21:30:36 UTC, Jeff Liebermann  wrote:
> On Sat, 9 Mar 2013 10:22:38 -0800 (PST), > > francescopoderico@googlemail.com wrote: > > > > >I've started designing a 200 MSPS Oscilloscope with a 25 MHz analog bandwidth, 3Ksample/channel buffer. > > >The oscilloscope can be connected to a PC via USB, and eventually via Ethernet and WiFi. > > >The trigger is ( at moment) rising, falling... auto, normal. > > >I would appreciate suggestions and or comment for possible improvement and functionality that could make this oscilloscope interesting. > > >Francesco > > > > There are plenty of similar USB scopes on the market with similar > > specs. Use their feature list as a checklist to see if you're missing > > something. I presume that you're asking for advice on how to make the > > hardware unique in order to obtain a marketing advantage. Most of the > > product differentiation is in the software, so I'll comment only on > > the hardware. What *I* might want in a USB scope is (whether I'm > > willing to pay for these is another question): > > > > 1. USB microscope camera on the probe tip so that I can see where I'm > > sticking the probe. > > 2. IR thermometer with LED targeting on the probe so that I can > > simultaneously measure and record any localized heating. > > 3. Replacable front end so that when I inevitably blow it out, it can > > be easily replaced. > > 4. Built in function generator, pattern generator, arbitrary waveform > > generator, two tone generator, DDS generator, white/pink noise, sweep > > generator generator. Extra points for adding AM/FM/PM/pulse > > modulation. > > 5. DC power output for powering active probes and assorted sensors. > > 6. Presumably, it's dual channel. If so, make it stackable via a > > common bus or preferably via ethernet, so that multiple units can be > > conglomerated into a 4,6,8, etc channel scope. > > 7. Switchable low pass filter on input for high RF level > > environments. > > 8. Self test and calibration check. > > 9. An accurate and readable schematic so I can fix it. > > 10. Security cable to keep it from getting um.... borrowed. > > 11. Built in smoke detector. > > > > -- > > Jeff Liebermann jeffl@cruzio.com > > 150 Felker St #D http://www.LearnByDestroying.com > > Santa Cruz CA 95060 http://802.11junk.com > > Skype: JeffLiebermann AE6KS 831-336-2558
Thnanks Jeff, I like the idea of the Cable that stop "unwanted borrowed" I will actually do this... not sure about the camera on probe :-)... I may add a block diagram ( notthe full schematic) to show people how to calibrate the scope and some test points and hits to help people to self repair the scope. also the function generator, could be a good sales point Thanks