Groups | Search | Server Info | Login | Register
Groups > sci.electronics.design > #740170
| From | Bill Sloman <bill.sloman@ieee.org> |
|---|---|
| Newsgroups | sci.electronics.design |
| Subject | Re: AI Will Create More Jobs Than It Eliminates By 2027 |
| Date | 2026-02-07 00:48 +1100 |
| Organization | A noiseless patient Spider |
| Message-ID | <10m4rgh$68rj$4@dont-email.me> (permalink) |
| References | (7 earlier) <o9s6oktffesgvrj9rrglqg58vamfclptb8@4ax.com> <10m187t$2ufvl$1@dont-email.me> <ufg9okd1aoaq4560cv2p0r2qu12nfa74kd@4ax.com> <10m43b8$3si94$8@dont-email.me> <g8lbokh5shoq22sc9djcmrnaa96ohpp8gf@4ax.com> |
On 6/02/2026 10:56 pm, john larkin wrote: > On Fri, 6 Feb 2026 17:56:26 +1100, Bill Sloman <bill.sloman@ieee.org> > wrote: > >> On 6/02/2026 3:29 am, john larkin wrote: >>> On Thu, 5 Feb 2026 16:01:29 +1100, Bill Sloman <bill.sloman@ieee.org> >>> wrote: >>> >>>> On 5/02/2026 3:33 am, john larkin wrote: >>>>> On Wed, 4 Feb 2026 23:50:25 +1100, Bill Sloman <bill.sloman@ieee.org> >>>>> wrote: >>>>> >>>>>> On 4/02/2026 10:37 pm, john larkin wrote: >>>>>>> On Wed, 4 Feb 2026 16:39:39 +1100, Bill Sloman <bill.sloman@ieee.org> >>>>>>> wrote: >>>>>>> >>>>>>>> On 4/02/2026 3:24 am, john larkin wrote: >>>>>>>>> On Tue, 03 Feb 2026 08:03:02 -0800, Jeff Liebermann <jeffl@cruzio.com> >>>>>>>>> wrote: >>>>>>>>> >>>>>>>>>> On Mon, 02 Feb 2026 20:47:06 -0800, john larkin <jl@glen--canyon.com> >>>>>>>>>> wrote: >>>>>>>>>> >>>>>>>>>>> On Mon, 02 Feb 2026 19:37:43 -0800, Jeff Liebermann <jeffl@cruzio.com> >>>>>>>>>>> wrote: >>>>>>>>>>> >>>>>>>>>>>> On Mon, 02 Feb 2026 17:29:26 -0800, john larkin <jl@glen--canyon.com> >>>>>>>>>>>> wrote: >>>>>>>>>>>> >>>>>>>>>>>>> On Mon, 02 Feb 2026 14:33:15 -0800, Jeff Liebermann <jeffl@cruzio.com> >>>>>>>>>>>>> wrote: >>>>>>>>>>>>> >>>>>>>>>>>>>> On Mon, 02 Feb 2026 10:05:09 -0800, john larkin <jl@glen--canyon.com> >>>>>>>>>>>>>> wrote: >>>>>> >>>>>> <snip> >>>>>> >>>>>>> We can buy cheap surface-mount XOs with ps or even fs of RMS jitter. >>>>>>> It's the DDS part that wrecks things. For 50 cents it looks like we >>>>>>> can generate any frequency up to 40 MHz with ps jitter and 36-bit >>>>>>> frequency resolution. It's cool to play with. >>>>>> >>>>>> You don't have to let the logic gates inside your FPGA wreck the jitter >>>>>> - the noise on the power rails inside the FPGA can do that - but if you >>>>>> use ECLinpS D-type clocked by your crystal oscillator to resynchronise >>>>>> the output of the FPGA to the edges of of your crystal clock you can get >>>>>> rid of a lot of that. You do have to be a bit careful to pick up FPGA >>>>>> output at a time when it is guaranteed stable - I generated a four phase >>>>>> version of the clock when I did it, and selected the phase with the best >>>>>> phase margin at final test to create the cleaned up output, but that was >>>>>> for a retrofitted clean-up. >>>>> >>>>> Our XO is 25 MHz. We use a PLL inside the FPGA to multiply that to 250 >>>>> MHz, which clocks the DDS phase accumulator and some other logic. >>>>> That's free. >>>> >>>> But nasty. Back in 1995 I could buy a 500HMHz crystal controlled >>>> oscillator with a 1 psec jitter spec. It wasn't all that cheap. >>>> >>>> There are parts that rely on surface acoustic waves that run even >>>> faster.They weren't off the shelf parts back then, so I wasn't interested. >>>> >>>>>>> https://www.dropbox.com/scl/fi/n12quxajp59egahv1b48i/DDS_1KHz.jpg?rlkey=8w0tlr3h1rxeif3byepzub947&raw=1 >>>>>>> >>>>>>> There's a tiny non-monoticity step at the zero crossing, caused by the >>>>>>> resistance of the FPGA outputs. That can be tuned out. >>>>>> >>>>>> Resistance alone will only generate a lag. Non-mononicity implies >>>>>> ringing - the output resistance isn't high enough to damp the inductive >>>>>> elements, but more resistance should tune that out. >>>>> >>>>> The resistance of the MSB pin output makes the step size wrong and >>>>> makes the sine wave zero cross non-monotonic. >>>>> >>>>> https://www.dropbox.com/scl/fi/exwm68xr6uwya4jyu2cbc/X116_DDS.jpg?rlkey=3b72xlxwi73uk22ni9cs80fix&raw=1 >>>> >>>> That's a remarkably cheap and nasty ADC. Buffer the FPGA outputs with >>>> proper switches and even you should be able to do a lot better. >>> >>> It's not a nasty ADC. It's a pretty good 6-bit DAC. >>> >>>> >>>>> Changing the 250r resistor to 238 makes it look nice. In frequency >>>>> domain, I guess the mismatch creates a spike at the MSB frequency >>>>> that's hard to filter and makes jitter. I think. >>>> >>>> Sometimes it pays to split the MSB over two switches so the >>>> non-linearity of the switch resistance is less salient. >>> >>> That would work. We're paralleling two pins somewhere else. But just >>> changing the MSB resisttor works too. I can't experiment with >>> paralleling because the FPGA is a BGA. >>> >>> My guys picked some FPFA pins for the MSBs that don't have >>> programmable drive strength, otherwise we could play with that. >>> >>> >>>> >>>>> We'll synth an octave of frequency and not ever run at 1 KHz, but >>>>> running slow lets us see the waveform steps. >>>> >>>> But not clearly enough to let you see how to improve them. >>> >>> I just found a small monoticity problem and fixed it. Maybe I'll FFT >>> the 1KHz sine wave and play with that too. Just for fun: the clock >>> generator looks great already. >>> >>>> >>>>> Scoping the bits gets amazing as we get anywhere near Nyquist. One >>>>> could swear they are all random noise, but they sum into a beautiful >>>>> sine. Building your own DDS is worth it for the amusement alone. >>>>> >>>>>> >>>>>> ECLinPS is designed to drive transmission lines, so it shouldn't exhibit >>>>>> that particular problem. >>>>> >>>>> One eclips gate costs about as much as our FPGA. And 15x as much as >>>>> our CPU. >>>>> >>>>> The T20 is using about 30 mA of core current, about 40 milliwatts, to >>>>> run a lot of stuff, including the 250 MHz DDS. Imagine the power and >>>>> cost of a bunch of ECL flops. And how would you make the ECLs into the >>>>> sine wave? Use an ECL-input DAC? >>>> >>>> You don't have to imagine the power and cost of a bunch of ECLinPs >>>> D-type monostables. They have part numbers and data sheets. >>> >>> My apologies for suggesting that you might ever have any imagination. >> >> Your ideas about what imagination looks like and how it works are a bit >> comical. Sensible people don't use their imaginations to find out >> documented facts. >> >>>> https://www.onsemi.com/download/data-sheet/pdf/mc10ep451-d.pdf >>>> >>>> Digikey seems to stock the MC100EP451. >>>> >>>> https://www.digikey.com/en/products/filter/logic/flip-flops/706?s=N4IgTCBcDaILIGECMAGFBRACgFgKxJAF0BfIA >>>> >>>> The cheapest unit price is $US 10.39 and the typical current drain is >>>> listed as 95mA. >>>> >>>> An ECL-input DAC would work, but you could use something quite as cheap >>>> and nasty as your current improvised DAC, but hanging of the ECL outputs. >>>> >>>> What your revelations have made clear is that your problems with your >>>> sinewave output aren't due to any kind of timing problem, but rather >>>> your choice of a particularly cheap and nasty improvised DAC. >>> >>> I don't have problems. I have a great DDS clock source for under 50 >>> cents. >> Sure you do. You want to describe a cheap and nasty version of a DDS >> clock source as "great". The word would be "adequate" if you haven't >> missed any other problems it may have. >> >>> It can be reprogrammed for frequency in nanoseconds, unlike >>> commercial expensive DDS chips with klunky interfaces. >> >> Most of them are intended to be used with an analog filter on the output >> and that filter will have a settling time longer than nanoseconds. > > I'm using a very simple 50 MHz lowpass filter. That settles in under > 10 ns. > > An Analog Devices DDS typically has a very pokey SPI interface and > costs around $15. > > Not many people make DDS chips these days. Maybe just ADI. It's easy to make them in FPGAs. > I ran an FFT on my sine wave at 10 KHz. The filter has no effect that > low. I'm seeing a 2nd harmonic about 20 dB down. Not terrible. Considering how crappy your improvised DAC is, 20dB is surprisingly good. A better DAC should do quite a bit better. Second harmonic distortion is entirely the top half of your sine wave being different from the bottom half. Tuning the most significant bit of your DAC output could probably reduce it dramatically. -- Bill Sloman, Sydney
Back to sci.electronics.design | Previous | Next — Previous in thread | Next in thread | Find similar
AI Will Create More Jobs Than It Eliminates By 2027 Don Y <blockedofcourse@foo.invalid> - 2026-02-02 04:38 -0700
Re: AI Will Create More Jobs Than It Eliminates By 2027 john larkin <jl@glen--canyon.com> - 2026-02-02 07:37 -0800
Re: AI Will Create More Jobs Than It Eliminates By 2027 Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2026-02-02 11:37 -0500
Re: AI Will Create More Jobs Than It Eliminates By 2027 john larkin <jl@glen--canyon.com> - 2026-02-02 08:57 -0800
Re: AI Will Create More Jobs Than It Eliminates By 2027 john larkin <jl@glen--canyon.com> - 2026-02-03 15:15 -0800
Re: AI Will Create More Jobs Than It Eliminates By 2027 Bill Sloman <bill.sloman@ieee.org> - 2026-02-05 00:59 +1100
Re: AI Will Create More Jobs Than It Eliminates By 2027 john larkin <jl@glen--canyon.com> - 2026-02-04 08:52 -0800
Re: AI Will Create More Jobs Than It Eliminates By 2027 Bill Sloman <bill.sloman@ieee.org> - 2026-02-05 16:37 +1100
Re: AI Will Create More Jobs Than It Eliminates By 2027 john larkin <jl@glen--canyon.com> - 2026-02-05 08:13 -0800
Re: AI Will Create More Jobs Than It Eliminates By 2027 Bill Sloman <bill.sloman@ieee.org> - 2026-02-06 17:43 +1100
Re: AI Will Create More Jobs Than It Eliminates By 2027 john larkin <jl@glen--canyon.com> - 2026-02-02 10:05 -0800
Re: AI Will Create More Jobs Than It Eliminates By 2027 bitrex <user@example.net> - 2026-02-02 13:47 -0500
Re: AI Will Create More Jobs Than It Eliminates By 2027 Don Y <blockedofcourse@foo.invalid> - 2026-02-02 12:07 -0700
Re: AI Will Create More Jobs Than It Eliminates By 2027 Jeff Liebermann <jeffl@cruzio.com> - 2026-02-02 14:33 -0800
Re: AI Will Create More Jobs Than It Eliminates By 2027 john larkin <jl@glen--canyon.com> - 2026-02-02 17:29 -0800
Re: AI Will Create More Jobs Than It Eliminates By 2027 Jeff Liebermann <jeffl@cruzio.com> - 2026-02-02 19:37 -0800
Re: AI Will Create More Jobs Than It Eliminates By 2027 john larkin <jl@glen--canyon.com> - 2026-02-02 20:47 -0800
Re: AI Will Create More Jobs Than It Eliminates By 2027 Bill Sloman <bill.sloman@ieee.org> - 2026-02-03 16:08 +1100
Re: AI Will Create More Jobs Than It Eliminates By 2027 Jeff Liebermann <jeffl@cruzio.com> - 2026-02-03 08:03 -0800
Re: AI Will Create More Jobs Than It Eliminates By 2027 john larkin <jl@glen--canyon.com> - 2026-02-03 08:24 -0800
Re: AI Will Create More Jobs Than It Eliminates By 2027 Bill Sloman <bill.sloman@ieee.org> - 2026-02-04 16:39 +1100
Re: AI Will Create More Jobs Than It Eliminates By 2027 john larkin <jl@glen--canyon.com> - 2026-02-04 03:37 -0800
Re: AI Will Create More Jobs Than It Eliminates By 2027 Bill Sloman <bill.sloman@ieee.org> - 2026-02-04 23:50 +1100
Re: AI Will Create More Jobs Than It Eliminates By 2027 john larkin <jl@glen--canyon.com> - 2026-02-04 08:33 -0800
Re: AI Will Create More Jobs Than It Eliminates By 2027 Bill Sloman <bill.sloman@ieee.org> - 2026-02-05 16:01 +1100
Re: AI Will Create More Jobs Than It Eliminates By 2027 Gerhard Hoffmann <dk4xp@arcor.de> - 2026-02-05 12:38 +0100
Re: AI Will Create More Jobs Than It Eliminates By 2027 john larkin <jl@glen--canyon.com> - 2026-02-05 08:36 -0800
Re: AI Will Create More Jobs Than It Eliminates By 2027 Bill Sloman <bill.sloman@ieee.org> - 2026-02-06 17:47 +1100
Re: AI Will Create More Jobs Than It Eliminates By 2027 john larkin <jl@glen--canyon.com> - 2026-02-06 11:06 -0800
Re: AI Will Create More Jobs Than It Eliminates By 2027 Bill Sloman <bill.sloman@ieee.org> - 2026-02-07 15:32 +1100
Re: AI Will Create More Jobs Than It Eliminates By 2027 john larkin <jl@glen--canyon.com> - 2026-02-07 08:24 -0800
Re: AI Will Create More Jobs Than It Eliminates By 2027 Bill Sloman <bill.sloman@ieee.org> - 2026-02-08 15:26 +1100
Re: AI Will Create More Jobs Than It Eliminates By 2027 Gerhard Hoffmann <dk4xp@arcor.de> - 2026-02-07 11:37 +0100
Re: AI Will Create More Jobs Than It Eliminates By 2027 Bill Sloman <bill.sloman@ieee.org> - 2026-02-08 00:16 +1100
Re: AI Will Create More Jobs Than It Eliminates By 2027 Jeroen Belleman <jeroen@nospam.please> - 2026-02-07 15:45 +0100
Re: AI Will Create More Jobs Than It Eliminates By 2027 Bill Sloman <bill.sloman@ieee.org> - 2026-02-08 02:35 +1100
Re: AI Will Create More Jobs Than It Eliminates By 2027 liz@poppyrecords.invalid.invalid (Liz Tuddenham) - 2026-02-07 16:37 +0000
Re: AI Will Create More Jobs Than It Eliminates By 2027 Bill Sloman <bill.sloman@ieee.org> - 2026-02-08 15:13 +1100
Re: AI Will Create More Jobs Than It Eliminates By 2027 liz@poppyrecords.invalid.invalid (Liz Tuddenham) - 2026-02-08 12:38 +0000
Re: AI Will Create More Jobs Than It Eliminates By 2027 Bill Sloman <bill.sloman@ieee.org> - 2026-02-09 00:59 +1100
Re: AI Will Create More Jobs Than It Eliminates By 2027 john larkin <jl@glen--canyon.com> - 2026-02-07 08:54 -0800
Re: AI Will Create More Jobs Than It Eliminates By 2027 Bill Sloman <bill.sloman@ieee.org> - 2026-02-08 15:43 +1100
Re: AI Will Create More Jobs Than It Eliminates By 2027 Jeroen Belleman <jeroen@nospam.please> - 2026-02-07 19:13 +0100
Re: AI Will Create More Jobs Than It Eliminates By 2027 john larkin <jl@glen--canyon.com> - 2026-02-07 10:51 -0800
Re: AI Will Create More Jobs Than It Eliminates By 2027 wmartin <wwm@wwmartin.net> - 2026-02-07 15:06 -0800
Re: AI Will Create More Jobs Than It Eliminates By 2027 Bill Sloman <bill.sloman@ieee.org> - 2026-02-08 15:56 +1100
Re: AI Will Create More Jobs Than It Eliminates By 2027 Bill Sloman <bill.sloman@ieee.org> - 2026-02-08 15:53 +1100
Re: AI Will Create More Jobs Than It Eliminates By 2027 john larkin <jl@glen--canyon.com> - 2026-02-07 08:38 -0800
Re: AI Will Create More Jobs Than It Eliminates By 2027 Bill Sloman <bill.sloman@ieee.org> - 2026-02-08 15:58 +1100
Re: AI Will Create More Jobs Than It Eliminates By 2027 john larkin <jl@glen--canyon.com> - 2026-02-07 08:34 -0800
Re: AI Will Create More Jobs Than It Eliminates By 2027 Bill Sloman <bill.sloman@ieee.org> - 2026-02-08 16:00 +1100
Re: AI Will Create More Jobs Than It Eliminates By 2027 john larkin <jl@glen--canyon.com> - 2026-02-05 08:29 -0800
Re: AI Will Create More Jobs Than It Eliminates By 2027 Bill Sloman <bill.sloman@ieee.org> - 2026-02-06 17:56 +1100
Re: AI Will Create More Jobs Than It Eliminates By 2027 john larkin <jl@glen--canyon.com> - 2026-02-06 03:56 -0800
Re: AI Will Create More Jobs Than It Eliminates By 2027 Bill Sloman <bill.sloman@ieee.org> - 2026-02-07 00:48 +1100
Re: AI Will Create More Jobs Than It Eliminates By 2027 john larkin <jl@glen--canyon.com> - 2026-02-06 09:06 -0800
Re: AI Will Create More Jobs Than It Eliminates By 2027 Bill Sloman <bill.sloman@ieee.org> - 2026-02-07 15:44 +1100
Re: AI Will Create More Jobs Than It Eliminates By 2027 Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2026-02-04 10:52 -0500
Re: AI Will Create More Jobs Than It Eliminates By 2027 john larkin <jl@glen--canyon.com> - 2026-02-04 08:47 -0800
Re: AI Will Create More Jobs Than It Eliminates By 2027 bitrex <user@example.net> - 2026-02-02 14:11 -0500
Re: AI Will Create More Jobs Than It Eliminates By 2027 Don Y <blockedofcourse@foo.invalid> - 2026-02-02 12:24 -0700
Re: AI Will Create More Jobs Than It Eliminates By 2027 Don Y <blockedofcourse@foo.invalid> - 2026-02-07 06:51 -0700
Re: AI Will Create More Jobs Than It Eliminates By 2027 "Edward Rawde" <invalid@invalid.invalid> - 2026-02-02 19:31 -0500
Re: AI Will Create More Jobs Than It Eliminates By 2027 john larkin <jl@glen--canyon.com> - 2026-02-02 19:33 -0800
csiph-web