[time-nuts] Form Factor
Tom Bales
tob at starhouse.org
Tue Dec 21 15:21:58 UTC 2010
Hammond boxes are great to work with and are reasonably inexpensive. You
can stack multiple boards inside, and panels are available in aluminum or
plastic. Hammond will make custom lengths, just for asking. Here's a
grandiose scheme I've been working on with help from Richard McCorkle that
uses some 1455 boxes:
http://symbiosis-foundation.org/symbiosisfoundation.html.
Tom Bales
KE4SYS
On Tue, Dec 21, 2010 at 4:32 AM, <time-nuts-request at febo.com> wrote:
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> Today's Topics:
>
> 1. Re: Form factor (Chris Albertson)
> 2. Re: Form factor (bownes)
> 3. Re: Form factor (Don Latham)
> 4. Re: Frequency counter recommendation (Bruce Griffiths)
> 5. Re: Ublox GPS board (Ulrich Bangert)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Mon, 20 Dec 2010 22:29:47 -0800
> From: Chris Albertson <albertson.chris at gmail.com>
> Subject: Re: [time-nuts] Form factor
> To: Discussion of precise time and frequency measurement
> <time-nuts at febo.com>
> Cc: Open counter <opencounter at googlegroups.com>
> Message-ID:
> <AANLkTinmF=BKjCSCj4Pc9pc837y2H8EOLOQwSGKPgd9w at mail.gmail.com>
> Content-Type: text/plain; charset=ISO-8859-1
>
> >> Eurocard has been one suggestion as a form factor. While I personally
> >> love Eurocard, the boards and connectors are expensive.
> >>
> >> Stackble connectors are a pain in assembly.
> >>
> >> Backplanes are inherently evil at high speeds.
> >>
> >> Plugging everything into one main board makes that a critical design
> >> item and that much harder to upgrade.
>
> I agree with all of the above.
>
> I think what we want is simply a mechanical standard. Something that
> will simply hold everything in place.
>
> What if every module was in it's own metal box? Each box has a
> forward or "user facing" panel that is tall and narrow and contains
> things like input jacks and status LEDs and a rear facing panel that
> is for power and module to module interconnect. Many of the
> modules, I assume would work as stand alone gadgets (a trigger is a
> usful device all by it self) To assemble a system you place all the
> boxes like books on a shelf. Maybe even some book end so they don't
> fall over. But you might build a wood cabinet, put a handle on top
> and metal bumpers on the corners. The wood cabinet would house the
> modules and also the power supply and the rats nest of interconnect
> wiresSo those who like to be neat can make nice wood cases and the
> rest of us can have a working system made of a half dozen boxea and
> cales all over the work bench
>
> Here is an example of a module box
> http://www.hammondmfg.com/pdf/1455L1601.pdf
>
> We would not have to specify a height or length, only the width needs
> to be uniform. But in our case the width becomes height when you turn
> them on edge. Some modules might need two PCBs and a wider box. We
> should make a list of connectors to be used for power and so on for
> the rear pannel
>
> I had previously suggested about the same thing but only to make the
> box the same size as a disk drive so we could use common existing
> racks. I'd still prefer that but maybe these hammond boxes are more
> popular
>
>
> --
> =====
> Chris Albertson
> Redondo Beach, California
>
>
>
> ------------------------------
>
> Message: 2
> Date: Tue, 21 Dec 2010 01:48:27 -0500
> From: bownes <bownes at gmail.com>
> Subject: Re: [time-nuts] Form factor
> To: Discussion of precise time and frequency measurement
> <time-nuts at febo.com>
> Cc: Open counter <opencounter at googlegroups.com>, Discussion of
> precise
> time and frequency measurement <time-nuts at febo.com>
> Message-ID: <E30C08A4-74FA-4CB7-9D00-D0B3A449CED4 at gmail.com>
> Content-Type: text/plain; charset=us-ascii
>
> I love those Hammond boxes until I have to pay the bill. The one for my
> n2pk VNA was about $28.
>
> But one of those as the primary enclosure with input boards and output
> boards that plug into a main board would be feasable if a tad expensive.
>
> Some modules lend themselves to plugins on a main board (output modules for
> example) while things that need to chain like input modules ( think pre amp
> followed by prescaler followed by trigger sense) don't.
>
> On Dec 21, 2010, at 1:29 AM, Chris Albertson <albertson.chris at gmail.com>
> wrote:
>
> >>> Eurocard has been one suggestion as a form factor. While I personally
> >>> love Eurocard, the boards and connectors are expensive.
> >>>
> >>> Stackble connectors are a pain in assembly.
> >>>
> >>> Backplanes are inherently evil at high speeds.
> >>>
> >>> Plugging everything into one main board makes that a critical design
> >>> item and that much harder to upgrade.
> >
> > I agree with all of the above.
> >
> > I think what we want is simply a mechanical standard. Something that
> > will simply hold everything in place.
> >
> > What if every module was in it's own metal box? Each box has a
> > forward or "user facing" panel that is tall and narrow and contains
> > things like input jacks and status LEDs and a rear facing panel that
> > is for power and module to module interconnect. Many of the
> > modules, I assume would work as stand alone gadgets (a trigger is a
> > usful device all by it self) To assemble a system you place all the
> > boxes like books on a shelf. Maybe even some book end so they don't
> > fall over. But you might build a wood cabinet, put a handle on top
> > and metal bumpers on the corners. The wood cabinet would house the
> > modules and also the power supply and the rats nest of interconnect
> > wiresSo those who like to be neat can make nice wood cases and the
> > rest of us can have a working system made of a half dozen boxea and
> > cales all over the work bench
> >
> > Here is an example of a module box
> > http://www.hammondmfg.com/pdf/1455L1601.pdf
> >
> > We would not have to specify a height or length, only the width needs
> > to be uniform. But in our case the width becomes height when you turn
> > them on edge. Some modules might need two PCBs and a wider box. We
> > should make a list of connectors to be used for power and so on for
> > the rear pannel
> >
> > I had previously suggested about the same thing but only to make the
> > box the same size as a disk drive so we could use common existing
> > racks. I'd still prefer that but maybe these hammond boxes are more
> > popular
> >
> >
> > --
> > =====
> > Chris Albertson
> > Redondo Beach, California
> >
> > _______________________________________________
> > time-nuts mailing list -- time-nuts at febo.com
> > To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> > and follow the instructions there.
>
>
>
> ------------------------------
>
> Message: 3
> Date: Tue, 21 Dec 2010 01:05:07 -0700 (MST)
> From: "Don Latham" <djl at montana.com>
> Subject: Re: [time-nuts] Form factor
> To: "Discussion of precise time and frequency measurement"
> <time-nuts at febo.com>
> Message-ID:
> <6b51078f027157e0e5afd0e09fffb3de.squirrel at webmail.montana.com>
> Content-Type: text/plain;charset=iso-8859-1
>
> I use just what you suggest for all my experimental stuff; they're old
> (cheap) NIM bin modules. They have power connectors on the back, and can
> have bnc's and the like as well, and displays etc. on the front. They fit
> into a cage that has a power supply, 24v 12v and 5 v busses (5v requires
> an external supply). I've done this for some years now. Unfortunately,
> this setup suffers from ebayitis buy it now price creep(s) and I can't
> really recommend it for everyone. If the project turns out to have
> suitable card(s) I'll surely put them in NIM modules, though.
> Don
>
> Chris Albertson
> >>> Eurocard has been one suggestion as a form factor. While I personally
> >>> love Eurocard, the boards and connectors are expensive.
> >>>
> >>> Stackble connectors are a pain in assembly.
> >>>
> >>> Backplanes are inherently evil at high speeds.
> >>>
> >>> Plugging everything into one main board makes that a critical design
> >>> item and that much harder to upgrade.
> >
> > I agree with all of the above.
> >
> > I think what we want is simply a mechanical standard. Something that
> > will simply hold everything in place.
> >
> > What if every module was in it's own metal box? Each box has a
> > forward or "user facing" panel that is tall and narrow and contains
> > things like input jacks and status LEDs and a rear facing panel that
> > is for power and module to module interconnect. Many of the
> > modules, I assume would work as stand alone gadgets (a trigger is a
> > usful device all by it self) To assemble a system you place all the
> > boxes like books on a shelf. Maybe even some book end so they don't
> > fall over. But you might build a wood cabinet, put a handle on top
> > and metal bumpers on the corners. The wood cabinet would house the
> > modules and also the power supply and the rats nest of interconnect
> > wiresSo those who like to be neat can make nice wood cases and the
> > rest of us can have a working system made of a half dozen boxea and
> > cales all over the work bench
> >
> > Here is an example of a module box
> > http://www.hammondmfg.com/pdf/1455L1601.pdf
> >
> > We would not have to specify a height or length, only the width needs
> > to be uniform. But in our case the width becomes height when you turn
> > them on edge. Some modules might need two PCBs and a wider box. We
> > should make a list of connectors to be used for power and so on for
> > the rear pannel
> >
> > I had previously suggested about the same thing but only to make the
> > box the same size as a disk drive so we could use common existing
> > racks. I'd still prefer that but maybe these hammond boxes are more
> > popular
> >
> >
> > --
> > =====
> > Chris Albertson
> > Redondo Beach, California
> >
> > _______________________________________________
> > time-nuts mailing list -- time-nuts at febo.com
> > To unsubscribe, go to
> > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> > and follow the instructions there.
> >
>
>
> --
> "Neither the voice of authority nor the weight of reason and argument are
> as significant as experiment, for thence comes quiet to the mind."
> R. Bacon
> "If you don't know what it is, don't poke it."
> Ghost in the Shell
>
>
> Dr. Don Latham AJ7LL
> Six Mile Systems LLP
> 17850 Six Mile Road
> POB 134
> Huson, MT, 59846
> VOX 406-626-4304
> www.lightningforensics.com
> www.sixmilesystems.com
>
>
>
>
> ------------------------------
>
> Message: 4
> Date: Tue, 21 Dec 2010 21:39:11 +1300
> From: Bruce Griffiths <bruce.griffiths at xtra.co.nz>
> Subject: Re: [time-nuts] Frequency counter recommendation
> To: Discussion of precise time and frequency measurement
> <time-nuts at febo.com>
> Message-ID: <4D1067AF.2050904 at xtra.co.nz>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> Bob Bownes wrote:
> > Comments inline.
> >
> >
> > On Mon, Dec 20, 2010 at 11:17 PM, Chris Albertson<
> albertson.chris at gmail.com
> >
> >> wrote:
> >>
> >
> >> I looked. I think we should keep the design goals modest for a first
> >> revision. Shoot for a spec that can be hand built on perf board. So
> >> I'd relax those numbers by a factor of 1000. The top frequency is in
> >> Mhz, not Ghz and the time resolution closer to ns than ps. It's good
> >> to have a cheap option. Many people are happy with an FCC1 Try for
> >> the next step after that with a goal of actually matching the state of
> >> the art in steps.
> >>
> >>
> >>
> > My initial thinking was to be better than a pictic ii, preferably on par
> > with, or better than a 5370. I'm not sure you can do that on perfboard.
> I
> > suppose if the speed is kept low it can be done that way.
> >
> >
> Around 25ps jitter is the likely lower limit with such construction
> techniques.
> > Others have pointed out (offline) 20Ghz isn't reasonabe with a decent
> noise
> > figure or prescalers. What do people think a reasonable number is? What
> > about resolution? I'd like to get better than a ns, preferably a lot
> better.
> >
> 1ps resolution is trivial just use a sufficiently high resolution ADC
> (16bit) with a short TAC interpolator range (10ns?)
> Achieving a commensurate jitter is somewhat trickier.
>
> Around 3ps or so rms short term jitter should be easy enough, the
> Wavercrest 2075 does this without using anything particularly esoteric.
>
> 10ps jitter should be very easy.
> The latest Agilent time interval counters counters achieve around 9ps or
> so.
>
> 1ps rms jitter shouldn't be beyond reach (at least with the ringing tank
> method).
> However a good layout together with at least a 4 layer board will likely
> be necessary.
>
> Adequate grounding and shielding will also be necessary.
> >
> > Why no through holes? I don't see the point of banishing them. I to
> >
> >> agree with the rest. SMT that is hand solderable by a skilled tech
> >> but now reflow ovens or solder past masks should be required . You
> >> might place a limit on component size too like 0.5mm lead pitch or
> >> whatever is reasonable.
> >>
> >>
> >>
> > I've been prototyping a lot of late and restricting the number of through
> > holes makes the job much much easier and quicker. No other real reason.
> >
> >
> Precluding the use of RF dams (these use arrays of plated through
> holes) is probably counter productive.
> > I didn't place a limit on the lead pitch because a) I felt that limited
> the
> > component selection and b) pretty much even the finest pitch can be hand
> > assembled with care, solder wick, and 20x magnification. But if folks are
> > very against it, it can go in the 'desired qualities' list. My only fear
> is
> > the limit it might put on critical parts like a FPGA.
> >
> > Mechanical assy is going to be a killer. Let's start with overall form
> > factor.
> >
> > Rack mount or bench format?
> >
> > If rack mount, 1U or more?
> >
> > Commercial project enclosure (ala the VNA Hammond box) or do we
> take
> > an existing form factor like a disk drive as you suggest.
> >
> > Heck, if we go with a disk drive size, it could be built/slid into
> anyone's
> > lab PC case and use ribbon cable as a back plane... 1/2 :)
> >
> >
> Inadequate shielding?
> > I like 1U because it matches up with the rest of the test equipment on
> the
> > bench and it gives it a professional feel. And there are many many
> surplus
> > 1U cases out there with decent +/-12vdc,+5vdc (even some with 3.3vdc)
> power
> > supplies.
> >
> >
> Linear supplies or perhaps extremely low noise/well filtered switchmode
> supplies will likely be necessary.
> > Bob
> >
> >
> >
> Bruce
> >
> >> On Mon, Dec 20, 2010 at 6:20 PM, Bob Bownes<bownes at gmail.com> wrote:
> >>
> >>> Well said Chris. Take a look at the initial spec in the OpenCounter
> Gogle
> >>> group and tell me what you think with respect to your item #1. I think
> >>>
> >> the
> >>
> >>> core counter is going to be the really difficult part of the module
> list.
> >>>
> >>> Item #2 is going to be a tough one methinks. I love Eurocard, but, as
> you
> >>> say, it is very expensive, if only for the connectors. In cases like
> this
> >>> I'm a fan of either repurposing commercially available connectors (PCI
> >>>
> >> and
> >>
> >>> memory DIMMS are two I have used in the past) because they can be a)
> >>> purchased off the shelf, b) are manufactured in enough volume to make
> >>>
> >> cheap,
> >>
> >>> and c) are common enough that the really cheap amongst us can get them
> >>>
> >> off
> >>
> >>> of scrap boards someplace for little or nothing. The N2PK VNA is built
> to
> >>> fit into a particular HAmmond enclosure that I like but again, there
> are
> >>> many options. My feeling is that the enclosure should not dictate any
> >>> functional design decisions.
> >>>
> >>> #3 - I've created a group and appointed myself benevolent dictator. We
> >>>
> >> can
> >>
> >>> discuss things, propose designs or design criteria, call for a
> concensus,
> >>> accept, and draft volunteers to design that section to the defined
> spec.
> >>>
> >> If
> >>
> >>> there are multiple competing designs, so much the better, as long as we
> >>>
> >> all
> >>
> >>> agree on the interfaces. Sound like a process? Can you tell I've done
> >>>
> >> this
> >>
> >>> once or twice? :)
> >>>
> >>> Step one will be to agree on the overall functional spec. If we get
> >>>
> >> enough
> >>
> >>> participants, I'd like to nail that down by mid January. The next step
> is
> >>>
> >> to
> >>
> >>> agree on the interfaces between the modules. Same process, discuss,
> >>>
> >> propose,
> >>
> >>> draft, get concensus, close and move on.
> >>> Then we get folks working on the individual modules.
> >>>
> >>>
> >>> On Mon, Dec 20, 2010 at 8:43 PM, Chris Albertson
> >>> <albertson.chris at gmail.com>wrote:
> >>>
> >>>
> >>>> On Mon, Dec 20, 2010 at 2:51 PM, Dave M<dgminala at mediacombb.net>
> >>>>
> >> wrote:
> >>
> >>>>>
> >>>> .. never got off the launchpad because of their inability to come to
> >>>>
> >>>>> consensus on a set of features. I had to conclude that too many cooks
> >>>>> spoiled the broth. Everyone that had input to the project was
> >>>>>
> >> unwilling
> >>
> >>>> to
> >>>>
> >>>>> yield on anyone else's ideas. Hopefully, our project won't degrade
> >>>>>
> >> into
> >>
> >>>>> another such fiasco.
> >>>>>
> >>>>
> >>>> THAT is the number one problem to solve. Technical issues are easy
> >>>>
> >>>> I think the solution is to
> >>>> (1) chop the project up into small enough parts, each on it's own PCB
> >>>> so that each part is "easy" and has some wider user outside the
> >>>> project.
> >>>> (2) Find a mechanical standard so all the PCBs can be mounted in some
> >>>> kind of chassis. I'm thinking now that maybe a 160-3U Eurocard would
> >>>> be about right size. But the parts are expensive.
> >>>> (3) Need some sort of design process that allows everyone to
> >>>> contribute. And everyone can. Projects always are lacking technical
> >>>> writers and quality control people
> >>>>
> >>>> Of those a "process" and "mechanical standard", I think are the
> >>>> hardest. We always give managers a hard time but that is what is
> >>>> needed. The person who will make this happen will be a manager and
> >>>> organizer maybe not a designer.
> >>>>
> >>>>
> >>>> --
> >>>> =====
> >>>> Chris Albertson
> >>>> Redondo Beach, California
> >>>>
> >>>> _______________________________________________
> >>>> time-nuts mailing list -- time-nuts at febo.com
> >>>> To unsubscribe, go to
> >>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> >>>> and follow the instructions there.
> >>>>
> >>>>
> >>> _______________________________________________
> >>> time-nuts mailing list -- time-nuts at febo.com
> >>> To unsubscribe, go to
> >>>
> >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> >>
> >>> and follow the instructions there.
> >>>
> >>>
> >>
> >>
> >> --
> >> =====
> >> Chris Albertson
> >> Redondo Beach, California
> >>
> >> _______________________________________________
> >> time-nuts mailing list -- time-nuts at febo.com
> >> To unsubscribe, go to
> >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> >> and follow the instructions there.
> >>
> >>
> > _______________________________________________
> > time-nuts mailing list -- time-nuts at febo.com
> > To unsubscribe, go to
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> >
> >
>
>
>
>
>
> ------------------------------
>
> Message: 5
> Date: Tue, 21 Dec 2010 10:30:51 +0100
> From: "Ulrich Bangert" <df6jb at ulrich-bangert.de>
> Subject: Re: [time-nuts] Ublox GPS board
> To: "'Discussion of precise time and frequency measurement'"
> <time-nuts at febo.com>
> Message-ID: <E501B6433AAC4B7BAB42C94DDF61FEEF at athlon>
> Content-Type: text/plain; charset="us-ascii"
>
> John,
>
> in a lot of cases such "accuracy" specs are specified (without being
> explicitely mentioned) for ONE sigma of the statistical distribution of the
> pulses. In your case this would mean that 66% of the pulses are within +/-
> 50 ns and 99% of the pulses are within +/- 150 ns. These numbers apply
> exactly only to normal distributed values but in any case give you an idea
> of what you may expect.
>
> Best regards
> Ulrich Bangert
>
> > -----Ursprungliche Nachricht-----
> > Von: time-nuts-bounces at febo.com
> > [mailto:time-nuts-bounces at febo.com] Im Auftrag von John Green
> > Gesendet: Montag, 20. Dezember 2010 17:03
> > An: time-nuts at febo.com
> > Betreff: [time-nuts] Ublox GPS board
> >
> >
> > I recently bought 4 older UBLOX GPS boards on eBay for $15
> > with free shipping. I hooked one up to my 1992 and comparing
> > it with the Z3801, I am seeing it jump all over the place. I
> > am using the 10 MHz output from the 3801 to start and the 1
> > PPS from the UBLOX to stop. I will have to bring in a TBolt
> > just to verify the test set up. Has anyone here ever made any
> > measurements on the UBLOX TIM-LF-0-000? These are not timing
> > grade, by the way. The spec. sheet says the accuracy of the
> > time pulse is 50 nSec. If that is +/- 50, then what I am
> > seeing might be OK.
> >
> > _______________________________________________
> > time-nuts mailing list -- time-nuts at febo.com
> > To unsubscribe, go to
> > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> > and follow the instructions there.
>
>
>
>
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>
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