[time-nuts] Frequency counter recommendation

Bob Bownes bownes at gmail.com
Fri Dec 17 03:44:40 UTC 2010 

Very good points.

For the core counter, are you talking about an interval counter or a
more generic two input, tell the CPU what to do with the inputs kind
of model? :)

USB certainly would be the interface of choice, but serial also has
it's place. The joy is there is less software to write. That engenders
a whole discussion about a standalone counter vs a PC based counter.
Fine example is the two VNA projects out there. One of them requires a
whole bunch of ugly USB drivers to work and it isn't even recognized
by a Mac for example. You can still do spiffy GUI front ends and
USB<->serial adaptors are going to be around for a while. Or you use
an Arduino core and don't worry about drivers. Gonna be a religious
war I suspect. Standalone model circumvents all that. :)

I suspect a number of input modules could be described. Prescalers,
amplifiers, attenuators, terminations, filters, all come to mind
looking at the input options on gear on the bench. I have a nice
variant on the VE2ZAZ design already done that would get it up to
~18Ghz.

Again, several core synthesizers could be defined based on
requirments. GPSDO, 10Mhz in, txco all come to mind.

Define a power supply that doesn't exceed 12v and you are in pretty
good shape. COT technology would be a good choice.

The point about the TAPR bus and enclosure is also a great one. PC
cases are nice, but bulky. Last thing I want is another one of those
kicking around. 1U rackmount would be nice, but makes the module
design difficult. 2U much easier, but harder to come by cheap cases.

I think an overall target design would be the place to start. PICTIC
II is also a good place to start. Shoot for a 10x improvement? :)

I'm not all that fond of Wiki's but if there are people serious about
the project, I can put one up. Main mailing list certainly isn't the
place to design it. All that said, I don't know enough to design it
alone, but I have the ability to fabricate prototypes and can build to
someone else's specs. And I'm serious about wanting a better counter
than my 5328. :)

Bob



On Thu, Dec 16, 2010 at 9:53 PM, Chris Albertson
<albertson.chris at gmail.com> wrote:
> You can't do anything, not even guess at a price until you have a list
> of requirements written down.  And they need to be detailed.
>
> I would break the project down into a set of sub-projects possably like this
>
> 1) The "core" counter, just counts, no pre scaler, no display or
> reference oscillator. connects to computer with USB.
> 2) A display and control panel to the instrument can be independent of
> a computer.
> 3) The "front end" pre-scaler or other kind of signal conditioning unit.
> 4) A core frequency synthesizer, no display and so on like the core counters
> 5) A A/C mains based power supply
> 6) A battery based power supply to be used in place of or in addition to #4
>
> If these parts all worked together or at least used the same size PCB
> people could get a chassis and start out simple and cheap and build up
> a larger system over time.   I was going to build a radio this way
> once, I may still do it.  My idea was to make each card or modular the
> same size as a hard disk drive.  Then I could use an old sever chassis
> intended for hold SCSI disk drives to hold the cards and each card
> would have knobs and controls on one end and electrilcal connectors of
> the other.  Id use a standard scsi 50-pin ribon cable as a backplane
> for serial control (i2c) and power.  Today I'd use a SATA backplane as
> the form factor.  They can be pushed into a rack from the front
> Something like this :
> http://www.sansdigital.com/images/stories/products/HDDRACK5/hddrack5_1.jpg
>
> The mistakes made by the HPSDR people were that each card is far to
> complex.  So much so that few people could understand and contribute
> to the design and the cards are mostly un-build-able at the hobby
> level.  and also they did not select an off the self backplane and
> enclosure.  For most people sheet metal bending is not easy, So you'd
> want to specify a common and cheap off the shelf chassis type.
>
> So,... the first step is to list out the cards and write specs for
> each and design it so it is an expandable system    A Wiki works best
> for this, not an email list.
>
> On Thu, Dec 16, 2010 at 5:15 PM, Alan Hochhalter <alanh137 at comcast.net> wrote:
>> One way to find out if people are interested enough to pledge some money up
>> front is something like this project
>>
>> http://www.kickstarter.com/projects/bushing/openvizsla-open-source-usb-protocol-analyzer
>>
>> Alan
>>
>> On 12/16/2010 12:55 PM, Bob Camp wrote:
>>>
>>> Hi
>>>
>>> If you look in detail at the ups and downs of the TAPR SDR project, it's
>>> not
>>> one I would want to emulate.
>>>
>>> If we have a few hundred people interested with cash in hand, this might
>>> indeed make sense.
>>>
>>> Bob
>>>
>>> -----Original Message-----
>>> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
>>> Behalf Of Chris Albertson
>>> Sent: Thursday, December 16, 2010 3:36 PM
>>> To: Discussion of precise time and frequency measurement
>>> Subject: Re: [time-nuts] Frequency counter recommendation
>>>
>>> Here is an example of doing something like this as a open source
>>> design by a group of HAMs
>>> http://www.tapr.org/kits_janus.html
>>> This is a software defined radio but is close to the complexity we are
>>> talking about here. It has a d/a converter and fpga and lots of
>>> surface mount parts.  TAPR is able to have these made and sell them
>>> for $180.
>>>
>>> While this is a proof by example that such a project can be done I'd
>>> not go this route.     Better I think to design a modular system where
>>> the modules  have easy and well defined interfaces and where each  can
>>> have whatever quality specs are desired.   There is a danger with
>>> these group project that you run into a requirements "race" to the top
>>> and end up with a hard to manufacture and maintain part.  I think the
>>> HPSDR project did this
>>>
>>> On Thu, Dec 16, 2010 at 11:20 AM, Bob Camp<lists at rtty.us>  wrote:
>>>>
>>>> Hi
>>>>
>>>> Yes indeed, been there done that. Not very hard at all.
>>>>
>>>> All you need is the six layer pc board (can be bought), the FPGA (Digikey
>>>> has them), a few of these and a couple of those. Spend less than $100 and
>>>> you are in business if the PC board volume is high enough.
>>>>
>>>> In this case the next step in the business is to solder the 256 ball 1 mm
>>>> spacing BGA package down on the pc board. Not so easy without the right
>>>> tools...
>>>>
>>>> Bob
>>>>
>>>> -----Original Message-----
>>>> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
>>>> Behalf Of Don Latham
>>>> Sent: Wednesday, December 15, 2010 3:48 PM
>>>> To: Discussion of precise time and frequency measurement
>>>> Subject: Re: [time-nuts] Frequency counter recommendation
>>>>
>>>> OK, time-nuts, here's the gauntlet. can't "we" generate a design for a
>>>> PC-based FPGA or chip setup that would be generally useful as a counter?
>>>> We've seen thorough discussions about trigger jitter, which IMHO is the
>>>> fundamental problem. And isn't the PIC2 Time base from 10 MHz standard,
>>>> all else should be straightforward.
>>>> I'm not a designer, just a messer-arounder, or I'd give it a shot. Robot
>>>> Basic is a nice PC software maybe.
>>>> Don
>>>>
>>>> J. L. Trantham, M. D.
>>>>>
>>>>> I suspect that this question will lead to a discussion of Dual Mixers
>>>>> but
>>>>> as
>>>>> far as the counter question goes, I would recommend you consider an HP
>>>>> 5370B.
>>>>>
>>>>> Joe
>>>>>
>>>>> -----Original Message-----
>>>>> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com]On
>>>>> Behalf Of Dave M
>>>>> Sent: Wednesday, December 15, 2010 1:55 PM
>>>>> To: TimeNuts
>>>>> Subject: [time-nuts] Frequency counter recommendation
>>>>>
>>>>> I'm a retired electronics tech and computer programmer.  I have a pretty
>>>>> decently equipped shop for almost all of my projects and experiments.
>>>>> However, my time and frequency equipment is a bit long in the tooth.  I
>>>>> have
>>>>> a couple old HP 5328A counters (commercial version; not the military
>>>>> version), one with a 10544, the other with a 10811 oscillator.
>>>>> I have an HP Z3801A that has been operating well for several years, and
>>>>> recently acquired a TBolt to keep the counters in tune.  I also have a
>>>>> good
>>>>> distribution amp and  couple of old Montronics (Fluke) frequency
>>>>> comparators.
>>>>> What I'm looking for now, is a recommendation for a good low-cost
>>>>> (<$400)
>>>>> counter that will get me on the way to performing some of the "down in
>>>
>>> the
>>>>>
>>>>> grass" noise, jitter and deviation tests that the more learned members
>>>>> of
>>>>> the group discuss.  I know that new equipment is far out of my budget,
>>>
>>> but
>>>>>
>>>>> I'm also aware that some of the older, now obsolete (also cheaper)
>>>>> equipment
>>>>> is quite capable of doing what I want to do. I prefer HP equipment since
>>>>> manuals are much easier to find than most other brands.
>>>>> I'd also like recommendation for a good low-cost GPIB controller that
>>>>> allows
>>>>> me to write software to control some of my instruments.  I have
>>>
>>> experience
>>>>>
>>>>> writing software in BASIC on a Fluke 1722A controller.  I've seen these
>>>>> controllers on the Bay and other online vendors, but I've not located
>>>>> the
>>>>> BASIC discs for them.  Any advice?
>>>>> I realize that a counter is not the only piece that I need, but it's
>>>
>>> first
>>>>>
>>>>> on my list.  Other, more applicable equipment is on my want list, but
>>>
>>> will
>>>>>
>>>>> have to wait for a bit.
>>>>>
>>>>> Thanks for advice,
>>>>> David
>>>>> dgminala at mediacombb dot net
>>>>>
>>>>> _______________________________________________
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>>>>>
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>>>>
>>>> --
>>>> "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
>>>>
>>>>
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>>>>
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>>>
>>>
>>
>>
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>
>
>
> --
> =====
> Chris Albertson
> Redondo Beach, California
>
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