[time-nuts] HP-3586B SSB L.O. Mods...

Tue Mar 22 16:24:46 UTC 2011

Hi

The other approach would be to simply take the samples, do a mix down, and
get the phase from an ATAN calculation on the I/Q results. That would give
you pure phase and thus frequency. 

You do indeed still need things like filtering, but it's likely a better way
to get the job done than an FFT. 

Bob

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of paul swed
Sent: Tuesday, March 22, 2011 9:02 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] HP-3586B SSB L.O. Mods...

Thanks Bob indeed I have figured it out in spec lab. Thats why I say I am
not sure that application can ever work. Its really intended for a different
application. Soooo time to ask Mr. Google.

Another approach I thought up last night.
If every thing is locked to the same ref and it can be.
Inject say a 1 MC sig into the 3586. That will generate a 16KC IF don't
recall the exact freq.

Generate the same freq using a HP 3335 sig gen trig a scope take the IF out
to another channel on the scope. In theory they should be stable and locked
in phase relationship.
Any jitter will be that of the 3586 PLL system and I am sure there will be.
Believe that I can check the 3335 by taking its 1mc and comparing. Have done
this in the past and its very solid. So really eliminating that from the
question.

If the IF is stable or there is jitter then I know thats not the BFO
system....
Regards
Paul.

On Tue, Mar 22, 2011 at 7:44 AM, Bob Camp <lists at rtty.us> wrote:

> Hi
>
> It's all a matter of "how many bins". There are packages out there that
> will work with 64K bins. At an 8 KHz sample rate, that would give you  1/8
> Hz resolution. It would also take you a while to get the data. There is no
> practical limit to the number of bins, other than "how big is your
> computer". I suspect somebody out there has broken the million bin
barrier.
>
> Weather any of the fancy stuff has a usable interface (rather than C
code),
> or will hook up to a sound card - who knows...
>
> Bob
>
>
> On Mar 21, 2011, at 11:09 PM, paul swed wrote:
>
> > Interesting because its going to be very hard for spec lab to do it. I
> > experimented tonight and the results were not good.
> > What I can say is the 3586 is stable to spec labs resolution.
> >
> > On Mon, Mar 21, 2011 at 7:43 PM, Bob Camp <lists at rtty.us> wrote:
> >
> >> Hi
> >>
> >> I forget exactly which programs do which, but there are some free
> spectrum
> >> analysis programs that will get you way into the sub-Hz resolution with
> an
> >> <=8 KHz sample rate.
> >>
> >> Bob
> >>
> >>
> >> On Mar 21, 2011, at 5:44 PM, paul swed wrote:
> >>
> >>> It can actually be calculated and it is in Berts tables.
> >>> But last night I used spectrum lab and and could see the difference
> >> between
> >>> usb worse case.5 Hz and LSB .3Hz. It was very stable no drifting at
all
> >>> while tuned to wwvb. But spectrum lab was not really optimized to give
> me
> >>> better detail. Sub Hz res. Need to figure out how you would do that
> >> actually
> >>> and maybe you simply can't.
> >>> Regards
> >>> Paul
> >>> WB8TSL
> >>>
> >>> On Mon, Mar 21, 2011 at 5:29 PM, Burt I. Weiner <biwa at att.net> wrote:
> >>>
> >>>> Bert,
> >>>>
> >>>> This looks very interesting.  Have you been able to determine the
> actual
> >>>> error between the receiver's "tuned to" frequency and the 1850.000.00
> Hz
> >>>> audio tone error out of the receivers audio for upper and lower SSB?
> >> This
> >>>> could make a good group project kit.
> >>>>
> >>>> Burt, K6OQK
> >>>>
> >>>>
> >>>> Date: Mon, 21 Mar 2011 10:11:04 -0700 (PDT)
> >>>>> From: "Bert, VE2ZAZ" <ve2zaz at yahoo.ca>
> >>>>> To: time-nuts at febo.com
> >>>>> Subject: Re: [time-nuts] HP 3586A/B/C entirely referenced to 10MHz:
A
> >>>>>      solution
> >>>>> Message-ID: <258386.19056.qm at web112008.mail.gq1.yahoo.com>
> >>>>> Content-Type: text/plain; charset=us-ascii
> >>>>>
> >>>>> Hello Everyone,
> >>>>>
> >>>>> I have spent the last few weeks modifying the HP 3586 Selective
Level
> >>>>> Meter. The
> >>>>> intent was to modify the unit and reference the SSB product detector
> >> stage
> >>>>> to
> >>>>> the internal reference. This would make the entire SLM locked to the
> >> 10MHz
> >>>>> reference, whether internal or externally fed.
> >>>>>
> >>>>> I have completed the modification with satisfactory results. I use a
> >>>>> DDS-Based
> >>>>> Function Generator 16-pin IC and a small 8-pin PIC micro.  For more
> >>>>> detail,
> >>>>> visit my website at
> http://ve2zaz.net/HP3586_AD5962/HP3586_AD5962.htm.
> >>>>>
> >>>>> This has been a very good exercise from a DDS perspective and I have
> >>>>> learned a
> >>>>> lot on the topic. I would be interested in hearing from those who
> >> proceed
> >>>>> with
> >>>>> the mod.
> >>>>>
> >>>>> Thanks,
> >>>>>
> >>>>> Bert, VE2ZAZ
> >>>>>
> >>>>
> >>>> Burt I. Weiner Associates
> >>>> Broadcast Technical Services
> >>>> Glendale, California  U.S.A.
> >>>> biwa at att.net
> >>>> www.biwa.cc
> >>>> K6OQK
> >>>>
> >>>> _______________________________________________
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> >>>>
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> >>
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