Jan Panteltje wrote:> On a sunny day (Wed, 3 Nov 2021 12:59:47 -0400) it happened Phil Hobbs > <pcdhSpamMeSenseless@electrooptical.net> wrote in > <9fa3d49f-9f2a-3cfd-c0e3-a904e5af284d@electrooptical.net>: > >> Jan Panteltje wrote: >>> On a sunny day (Mon, 1 Nov 2021 14:25:48 -0700 (PDT)) it happened Fred Bloggs >>> <bloggs.fredbloggs.fred@gmail.com> wrote in >>> <99d760d0-d6e3-4873-b4c6-901f408fb898n@googlegroups.com>: >>> >>>> Just the way they have that written seems funny. But its really cheap. >>>> >>>> https://digilent.com/shop/zmod-scope-1410-2-channel-14-bit-oscilloscope-module/ >>> >>> Seems expensive for what you get, for double that you can get a real scope >>> with probes etc. >>> I mean 14 bits and 3dB error at 70 MHz, what is the point? >>> >> >> All sorts of instruments can profit from that sort of performance. >> >> Cheers >> >> Phil Hobbs > > When you start thinking in decibels 3 dB is down to about 70% > 2^14 = 16384 > 70 % of 16384 = 11468.8 > difference is 16384 - 11468.8 = 4915.2 > That is close to 2^12 = 4096 > So the thing screws up 12 bits or is basically worth 2 bits at that frequency for signals that fast. > In other words > 11111111111111 > 11X? > ^ > | > 4096Straw man.> > Then you can better get a 100 MHz 8 bit flash ADC for peanuts. > For DC that 14 bit thing should work.. Although there are plenty of good 16 bit audio ADCs I think for a fraction of that money. > > So yes, probably some application exists for it but I aint buying for that money. > My math is strange I but neural net > beep >Everything has a rolloff. If you can't manage it, just use a narrower signal bandwidth. The additive quantization noise of an 8-bit ADC is 36 dB worse. For ham radio things and oscilloscopes, they're fine, but high dynamic range measurements need fast, high resolution ADCs. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
Is this right? 1125MHz 14-bit dual channel acquisition
Started by ●November 1, 2021
Reply by ●November 3, 20212021-11-03
Reply by ●November 3, 20212021-11-03
onsdag den 3. november 2021 kl. 17.59.59 UTC+1 skrev Phil Hobbs:> Jan Panteltje wrote: > > On a sunny day (Mon, 1 Nov 2021 14:25:48 -0700 (PDT)) it happened Fred Bloggs > > <bloggs.fred...@gmail.com> wrote in > > <99d760d0-d6e3-4873...@googlegroups.com>: > > > >> Just the way they have that written seems funny. But its really cheap. > >> > >> https://digilent.com/shop/zmod-scope-1410-2-channel-14-bit-oscilloscope-module/ > > > > Seems expensive for what you get, for double that you can get a real scope > > with probes etc. > > I mean 14 bits and 3dB error at 70 MHz, what is the point? > > > All sorts of instruments can profit from that sort of performance. > Cheersthe same guys have a complete instrument for about the same as the motherboard needed for that adc module https://youtu.be/ryxxYGmRCpQ
Reply by ●November 4, 20212021-11-04
On a sunny day (Wed, 3 Nov 2021 18:17:24 -0400) it happened Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote in <2604b84f-851e-d0db-fd75-6bbe47522dfb@electrooptical.net>:>Jan Panteltje wrote: >> On a sunny day (Wed, 3 Nov 2021 12:59:47 -0400) it happened Phil Hobbs >> <pcdhSpamMeSenseless@electrooptical.net> wrote in >> <9fa3d49f-9f2a-3cfd-c0e3-a904e5af284d@electrooptical.net>: >> >>> Jan Panteltje wrote: >>>> On a sunny day (Mon, 1 Nov 2021 14:25:48 -0700 (PDT)) it happened Fred Bloggs >>>> <bloggs.fredbloggs.fred@gmail.com> wrote in >>>> <99d760d0-d6e3-4873-b4c6-901f408fb898n@googlegroups.com>: >>>> >>>>> Just the way they have that written seems funny. But its really cheap. >>>>> >>>>> https://digilent.com/shop/zmod-scope-1410-2-channel-14-bit-oscilloscope-module/ >>>> >>>> Seems expensive for what you get, for double that you can get a real scope >>>> with probes etc. >>>> I mean 14 bits and 3dB error at 70 MHz, what is the point? >>>> >>> >>> All sorts of instruments can profit from that sort of performance. >>> >>> Cheers >>> >>> Phil Hobbs >> >> When you start thinking in decibels 3 dB is down to about 70% >> 2^14 = 16384 >> 70 % of 16384 = 11468.8 >> difference is 16384 - 11468.8 = 4915.2 >> That is close to 2^12 = 4096 >> So the thing screws up 12 bits or is basically worth 2 bits at that frequency for signals that fast. >> In other words >> 11111111111111 >> 11X? >> ^ >> | >> 4096 > >Straw man.Yes and no, could have put it better.>> Then you can better get a 100 MHz 8 bit flash ADC for peanuts. >> For DC that 14 bit thing should work.. Although there are plenty of good 16 bit audio ADCs I think for a fraction of that >> money. >> >> So yes, probably some application exists for it but I aint buying for that money. >> My math is strange I but neural net >> beep >> > >Everything has a rolloff. If you can't manage it, just use a narrower >signal bandwidth. > >The additive quantization noise of an 8-bit ADC is 36 dB worse. For ham >radio things and oscilloscopes, they're fine, but high dynamic range >measurements need fast, high resolution ADCs.Many if not most analog video digitizing circuits used 8 bit flash ADCs The bandwidth needed was than < 10 MHz, maybe < 5 MHz, I was using a TDA8708A (video input processor with 8 bit ADC and 32 MHz sampling rate) in that FPGA project from around year 2009. http://panteltje.com/pub/2h/alles2.jpg it is one the top board, sorry for bad picture, had hard time finding any picture from it. connectors right board are: video in, video out... Must still have that stuff somewhere... After digital video came here in 2006 things moved to 100% sofware...
Reply by ●November 4, 20212021-11-04
On Thursday, November 4, 2021 at 3:29:23 AM UTC-4, Jan Panteltje wrote:> On a sunny day (Wed, 3 Nov 2021 18:17:24 -0400) it happened Phil Hobbs > <pcdhSpamM...@electrooptical.net> wrote in > <2604b84f-851e-d0db...@electrooptical.net>: > >Jan Panteltje wrote: > >> On a sunny day (Wed, 3 Nov 2021 12:59:47 -0400) it happened Phil Hobbs > >> <pcdhSpamM...@electrooptical.net> wrote in > >> <9fa3d49f-9f2a-3cfd...@electrooptical.net>: > >> > >>> Jan Panteltje wrote: > >>>> On a sunny day (Mon, 1 Nov 2021 14:25:48 -0700 (PDT)) it happened Fred Bloggs > >>>> <bloggs.fred...@gmail.com> wrote in > >>>> <99d760d0-d6e3-4873...@googlegroups.com>: > >>>> > >>>>> Just the way they have that written seems funny. But its really cheap. > >>>>> > >>>>> https://digilent.com/shop/zmod-scope-1410-2-channel-14-bit-oscilloscope-module/ > >>>> > >>>> Seems expensive for what you get, for double that you can get a real scope > >>>> with probes etc. > >>>> I mean 14 bits and 3dB error at 70 MHz, what is the point? > >>>> > >>> > >>> All sorts of instruments can profit from that sort of performance. > >>> > >>> Cheers > >>> > >>> Phil Hobbs > >> > >> When you start thinking in decibels 3 dB is down to about 70% > >> 2^14 = 16384 > >> 70 % of 16384 = 11468.8 > >> difference is 16384 - 11468.8 = 4915.2 > >> That is close to 2^12 = 4096 > >> So the thing screws up 12 bits or is basically worth 2 bits at that frequency for signals that fast. > >> In other words > >> 11111111111111 > >> 11X? > >> ^ > >> | > >> 4096 > > > >Straw man. > Yes and no, could have put it better. > >> Then you can better get a 100 MHz 8 bit flash ADC for peanuts. > >> For DC that 14 bit thing should work.. Although there are plenty of good 16 bit audio ADCs I think for a fraction of that > >> money. > >> > >> So yes, probably some application exists for it but I aint buying for that money. > >> My math is strange I but neural net > >> beep > >> > > > >Everything has a rolloff. If you can't manage it, just use a narrower > >signal bandwidth. > > > >The additive quantization noise of an 8-bit ADC is 36 dB worse. For ham > >radio things and oscilloscopes, they're fine, but high dynamic range > >measurements need fast, high resolution ADCs. > Many if not most analog video digitizing circuits used 8 bit flash ADCs > The bandwidth needed was than < 10 MHz, maybe < 5 MHz, > I was using a TDA8708A (video input processor with 8 bit ADC and 32 MHz sampling rate) in that FPGA project from around year 2009. > http://panteltje.com/pub/2h/alles2.jpg > it is one the top board, sorry for bad picture, had hard time finding any picture from it. > connectors right board are: video in, video out... Must still have that stuff somewhere... > After digital video came here in 2006 things moved to 100% sofware...The Vital Industries NTSC special effects system (SqueezeZoom) used a 12 bit ADC, in the mid '80s. It was a custom hybrid, that still sold for over $1400 in 1988. It wasn't a cheap system. Studios were waiting up to a year to sped $250,000 on each of them, as fast as they could be built. When used with our 1" Sony decks and RCA TK46A cameras we had the cleanest video in the Orlando market. The low video quality of a couple network stations was embarrassing. Digital TV was still a decade away, but they wouldn't spend money for anything that was beyond just staying on the air.
Reply by ●November 4, 20212021-11-04
On a sunny day (Thu, 4 Nov 2021 04:51:57 -0700 (PDT)) it happened Michael Terrell <terrell.michael.a@gmail.com> wrote in <ac1b2b41-706c-4b1e-9cf5-ee1977be8b2dn@googlegroups.com>:>The Vital Industries NTSC special effects system (SqueezeZoom) used a 12 bit >ADC, in the mid '80s. It was a custom hybrid, that still sold for over $1400 >in 1988. It wasn't a cheap system. Studios were waiting up to a year to >sped $250,000 on each of them, as fast as they could be built. When used with >our 1" Sony decks and RCA TK46A cameras we had the cleanest video in the >Orlando market. The low video quality of a couple network stations was embarrassing. >Digital >TV was still a decade away, but they wouldn't spend money for anything >that was beyond just staying on the air.I left broadcasting in 1976 it was I think, so have not worked with any of that stuff, we had Ampex VR2000 and AVR1 quadruplex, many of those. AVR1 had a sort of digital time base compensator but do not remember any ADC DAC details.. or did it not just switch analog delay lines? Ah, google knows: AMPEX AVR-1 2" Quad VTR, Accessorie & Part - BroadcastStore.com model_detail The servos would also allow playback of a tape without a control track. The timebase corrector used a series of glass delay lines for dropout compensation and ... Thing was called 'the buffer' IIRC. Nice old tech! I once modified a Philips LDL1000 BW video tape recorder by adding 64 uS PAL glass delay lines so it could record and play color by sequentially recording lines in red, green and blue. And also did that by recording the down converted chroma as 'bias' on the FM video modulation, same system as Sony Umatic after they showed one in the studio ? 1973? Analog days! Not an ADC in sight!
Reply by ●November 4, 20212021-11-04
Jan Panteltje wrote:> On a sunny day (Wed, 3 Nov 2021 18:17:24 -0400) it happened Phil > Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote in > <2604b84f-851e-d0db-fd75-6bbe47522dfb@electrooptical.net>: > >> Jan Panteltje wrote: >>> On a sunny day (Wed, 3 Nov 2021 12:59:47 -0400) it happened Phil >>> Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote in >>> <9fa3d49f-9f2a-3cfd-c0e3-a904e5af284d@electrooptical.net>: >>> >>>> Jan Panteltje wrote: >>>>> On a sunny day (Mon, 1 Nov 2021 14:25:48 -0700 (PDT)) it >>>>> happened Fred Bloggs <bloggs.fredbloggs.fred@gmail.com> wrote >>>>> in <99d760d0-d6e3-4873-b4c6-901f408fb898n@googlegroups.com>: >>>>> >>>>>> Just the way they have that written seems funny. But its >>>>>> really cheap. >>>>>> >>>>>> https://digilent.com/shop/zmod-scope-1410-2-channel-14-bit-oscilloscope-module/ >>>>> >>>>> >>>>>>Seems expensive for what you get, for double that you can get a real scope>>>>> with probes etc. I mean 14 bits and 3dB error at 70 MHz, what >>>>> is the point? >>>>> >>>> >>>> All sorts of instruments can profit from that sort of >>>> performance. >>>> >>>> Cheers >>>> >>>> Phil Hobbs >>> >>> When you start thinking in decibels 3 dB is down to about 70% >>> 2^14 = 16384 70 % of 16384 = 11468.8 difference is 16384 - >>> 11468.8 = 4915.2 That is close to 2^12 = 4096 So the thing screws >>> up 12 bits or is basically worth 2 bits at that frequency for >>> signals that fast. In other words 11111111111111 11X? ^ | 4096 >> >> Straw man. > > Yes and no, could have put it better. > > >>> Then you can better get a 100 MHz 8 bit flash ADC for peanuts. >>> For DC that 14 bit thing should work.. Although there are plenty >>> of good 16 bit audio ADCs I think for a fraction of that money. >>> >>> So yes, probably some application exists for it but I aint buying >>> for that money. My math is strange I but neural net beep >>> >> >> Everything has a rolloff. If you can't manage it, just use a >> narrower signal bandwidth. >> >> The additive quantization noise of an 8-bit ADC is 36 dB worse. >> For ham radio things and oscilloscopes, they're fine, but high >> dynamic range measurements need fast, high resolution ADCs. > > > Many if not most analog video digitizing circuits used 8 bit flash > ADCs The bandwidth needed was than < 10 MHz, maybe < 5 MHz,So what? Video is a very low-SNR application with no serious interfering signals (once you get to the video signal, that is). Things like NMR are quite different--you're looking for a small signal in a lot of noise. Lots of optical measurements just have a huge dynamic range. Using dither to get N more bits is exponentially slow--even granting a sufficiently clean clocking and dithering system, extending your 100 MHz 8-bit ADC to get six extra bits would slow it down to 400 kHz or thereabouts. (Using a high-resolution DAC to apply deterministic dither would help, but you still have to fight the 8-bit quantization noise.)> I was using a TDA8708A (video input processor with 8 bit ADC and 32 > MHz sampling rate) in that FPGA project from around year 2009. > http://panteltje.com/pub/2h/alles2.jpg it is one the top board, sorry > for bad picture, had hard time finding any picture from it. > connectors right board are: video in, video out... Must still have > that stuff somewhere... After digital video came here in 2006 things > moved to 100% sofware...Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
Reply by ●November 4, 20212021-11-04
On a sunny day (Thu, 4 Nov 2021 10:36:04 -0400) it happened Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote in <c30fe97a-319c-5e9d-6ac0-57bc231883d7@electrooptical.net>:>Using dither to get N more bits is exponentially slow--even granting a >sufficiently clean clocking and dithering system, extending your 100 MHz >8-bit ADC to get six extra bits would slow it down to 400 kHz or >thereabouts. (Using a high-resolution DAC to apply deterministic dither >would help, but you still have to fight the 8-bit quantization noise.)Yes, but why not use 14 fast comparators? I think you have lots of experience with low offset stuff?
Reply by ●November 4, 20212021-11-04
Jan Panteltje wrote:> On a sunny day (Thu, 4 Nov 2021 10:36:04 -0400) it happened Phil Hobbs > <pcdhSpamMeSenseless@electrooptical.net> wrote in > <c30fe97a-319c-5e9d-6ac0-57bc231883d7@electrooptical.net>: > >> Using dither to get N more bits is exponentially slow--even granting a >> sufficiently clean clocking and dithering system, extending your 100 MHz >> 8-bit ADC to get six extra bits would slow it down to 400 kHz or >> thereabouts. (Using a high-resolution DAC to apply deterministic dither >> would help, but you still have to fight the 8-bit quantization noise.) > > Yes, but why not use 14 fast comparators? > I think you have lots of experience with low offset stuff? >What would you use them for? To make it a true flash converter, you need 2**14-1 comparators, not 14. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
Reply by ●November 4, 20212021-11-04
I wrote>Yes, but why not use 14 fast comparators?mean 2^14 of course :-) I mean with milions of things on a chip these days..
Reply by ●November 4, 20212021-11-04
Am 04.11.21 um 15:54 schrieb Phil Hobbs:> Jan Panteltje wrote:>> Yes, but why not use 14 fast comparators? >> I think you have lots of experience with low offset stuff? >> > > What would you use them for?� To make it a true flash converter, you > need 2**14-1 comparators, not 14.Back in time when 8 Bit/20 MSPS was bleeding egde we used one of these for ultrasonic reactor wall testing. We got an additional ADC from TRW in a plexiglas cube. One could see the reference ladder and the comparator string with the bare eye. < https://www.flickr.com/photos/137684711@N07/50270501968/in/album-72157662535945536/lightbox/ > It is the large black chip on the blurred board on the bottom right. The white blob reads "TRW". The rest of the boards is a real-time averager. Some years later I condensed the entire board set to one board with some Xilinx FPGAs. It had a pipeline 20 stages deep. There was an interim solution with Fairchild F100K, but that ran too hot. Cheers, Gerhard
