[time-nuts] Re: Z3801A GPS Rx board substitute?

[Andrew Kalman]

Hmmm ... I have four Z3805As, and one of them with 84k hours doesn't work
any more ... in its case, LH reports no az/el/signal strength for ANY
channels, i.e. it is not getting anything from the B1121P1114 Oncore
receiver. But it throws no errors. I presume there is some problem in the
front-end. +5Vdc does show up on the antenna connector ...

I tested this same unit with a later, same-form-factor R5122U1154 Oncore
8-channel NOS Oncore unit I bought off eBay, and in that case, the Z3805A
reported GPS errors (because the R5122U1154  8-channel units is not true
drop-in compatible with the B1121P1114 6-channel OnCores, apparently -- I
think the new one talks a different protocol).

TL, DR: in my particular case, it appears that the front-end of my original
6-channel B1121P1114 OnCore GPS receiver has gone bad, with all
communications between the receiver and the rest of the Z3805A still
working fine.

Sorry, I don't seem to have a LH screen cap of the problem.

Hence my interest in Synergy's drop-in upgrade for the B1121P1114 6-channel
OnCore GPS receiver in the Z3805A.

-- Andrew

On Sat, Apr 9, 2022 at 11:12 AM Dan Rae via time-nuts <
time-nuts@lists.febo.com> wrote:

> I have attached a LH screen shot which includes a two hour long holdover
> of the 3801A in question.  Needless to say none of the six other GPSDOs
> connected to the same antenna / distribution amp were affected.  It is
> certainly not an oven failure.
>
> I'll be waiting for Synergy...
>
> Dan
>
> ac6ao
>
> ___
> time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send
> an email to time-nuts-le...@lists.febo.com
> To unsubscribe, go to and follow the instructions there.
___
time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an 
email to time-nuts-le...@lists.febo.com
To unsubscribe, go to and follow the instructions there.

[time-nuts] Re: Z3801A GPS Rx board substitute?

[Andrew Kalman]

I pinged Art at oemi...@synergy-gps.com some time ago as they appear to
have announced a drop-in replacement for the Oncore modules, but I never
got a response. Dunno if they are still in business, etc.

I would like some for my HP Z3805As ...

He had previously posted to time-nuts:

" "*I apologize if the following smells overtly commercial; it's only
intended to *

*answer your questions and explain where we are in the process of producing GPS
replacement products for legacy timing instruments.*

*The 6 and 8 channel Motorola VP and 8 channel UT+ will not work as
replacements. Those products have also reached their 1024 Week-Roll Over
limits. The HP Z3801A and Z3805A products only respond to 6 channel commands
and produce 6 channel reply messages.

We have developed single-board clones for the Motorola VP and UT+ products, as
drop-in replacements, that are lower in cost than Synergy's 2-board Adaptor
Board products (Shooting for dropping to less than $190 if component prices
don't go even higher!). The SSR-VP can plug into the HP Z3801A and Z3805A
products.

A different part number SSR-VP designed to drop into HP 58503A and an SSR-UT+,
designed to drop into HP 58503B products, have also been completed but firmware
for those have yet to be tested in actual instruments. With the proper firmware
loads, the SSR Drop-In products should be candidates for upgrading many other
legacy timing instruments.

We had planned for the single board "Drop-In" products to be available near the
end of 2020 but COVID-19 changed things for us. We are now planning a small
production run to satisfy folks that have already been in touch with us but we
need to complete our boot-loader for firmware updates first. With current work
load, I'd estimate 90 - 120 days for HP Z3801A and Z3805A replacements. If you
are interested we can put you on our list."*

"

--Andrew


Andrew E. Kalman, Ph.D.


On Fri, Apr 8, 2022 at 3:01 PM Dan Rae via time-nuts <
time-nuts@lists.febo.com> wrote:

> My faithful 3801, some 207 thousand hours old, has developed an
> occasional fault that I think must be down to the Motorola Oncore 6
> channel board and I wonder if there is an available unit that could
> replace this, or what the recommended substitute is?  eBay searches
> don't show any of the original ones.   I'd like to keep it going, it was
> the first GPSDO I got, and despite getting and building many others
> since, I'm stupidly fond of it.
>
> Thanks,
>
> Dan
>
> ___
> time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send
> an email to time-nuts-le...@lists.febo.com
> To unsubscribe, go to and follow the instructions there.
___
time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an 
email to time-nuts-le...@lists.febo.com
To unsubscribe, go to and follow the instructions there.

[time-nuts] Re: 20210423: Introduction and Request for Spirent GSS4200 User Manual / Help

[Andrew Kalman]

This is a follow-up on my experience with the GSS4200 Multi-channel GPS
Simulator from Spirent.

I was able to finally get the elusive "Utilities Disk" for the GSS4200,
which includes the USB drivers and several utilities (talk over USB, talk
over GPIB, combine scenarios into a scenario library, and flash said
library over USB into the GSS4200 so that you can run the library's
scenarios).

The real limits of this particular machine (that is really locked down, to
the point where you need a particular, unique WinXP-era USB driver for this
particular model in the GSS family) are:

1) The software to load scenarios works with WinXP and maybe Win7 32-bit,
but nothing later
2) The total runtime of any loaded scenarios is around 15 minutes
3) Scenarios have to be generated via Spirent's SimSUPPORT scenario
generator, which is only available to users with a valid & current license
& subscription (and frankly, I doubt that the GSS4200 one is still online).
4) 6 channels are simulated.

I had hope to use this unit to run various simulated scenarios, but without
being able to generate new scenarios (all of the default ones on the disk
are very simple ones dating from 2003), that just doesn't cut it for me.

It's a very nicely built 2RU unit -- it may be worth more as a nice RF
signal generator than as anything else.


___
Andrew E. Kalman, Ph.D.a...@pumpkininc.com


On Sat, Apr 24, 2021 at 5:44 PM Forrest Christian (List Account) <
li...@packetflux.com> wrote:

> I have used GPS-SDR-SIM with good results.
>
> It's an open source tool that will generate the right files to be able to
> generate simulated GPS signals using many of the open source SDR platforms
> including HackRF.  It uses the publically available ephermis files along
> whith desired receiver position data to generate the "RF" output files.
>
> My experience has been that clocking the sdr with a output from a
> disciplined source results in the 1pps from a typical GPS receiver
> remaining at the same relative phase during the entire playback, for a
> definition of same which was good enough for my purposes.
>
> Two notes:
>
> This is gps only,  no other constellations.  Would love someone to write a
> similar tool for other constellations.
>
> Several platforms are supported, some are dirt cheap.  I used HackRF
> because I already had one.   Not sure about any of the others.
>
> On Sat, Apr 24, 2021, 11:56 AM Lux, Jim  wrote:
>
> > On 4/24/21 10:31 AM, Andrew Kalman wrote:
> > > Hi Paul.
> > >
> > > Yes, I've been on this same journey. After I learned (somewhat
> unrelated)
> > > that one is supposed to have an FCC license to rebroadcast GNSS signals
> > > (e.g. via a repeater inside a lab, makes eminent sense), I started
> > thinking
> > > more about GNSS simulators and how they might be added to my company's
> > > workflow. So I bid on a couple of units, got them for pennies on the
> > > dollar, and started messing with them in the hope of ending up with an
> > > ATE/rack-type setup that I can build into a nearly automatic test &
> > > validation suite.
> > >
> > > Let's say I was much more successful with the Spectracom/Orolia GSG-5
> > than
> > > with the Spirent GSS4200 ... In the case of the GSG-5, it's really
> just a
> > > question of how many options you can afford -- the rest is all there,
> you
> > > don't need a support contract, it's all easily accessible in the unit
> > > itself, and as long as the Internet exists the GSG-5 will probably keep
> > > working (it gets time, ephemeris and almanac data from servers -- it
> can
> > > simulate stuff NOW (wth the right options), not just in the past and
> > > future). The GSS4200 is about 10-15 years older, and it shows (in terms
> > of
> > > ease-of-use), along with how Spirent chose to monetize their users /
> > > subscribers. Also, the GSG-5 adds things like interference to the
> signals
> > > (all for a price, of course). IOW, the newer units (at least, from
> > > Spectracom was XL Microwave is now Orolia) are a whole lot easier to
> use
> > > ... but they come at a price. It's an interesting business.
> > >
> > > I will say that the build quality of the Spirent is very good. I have
> not
> > > opened up the GSG-5, just did a calibration and it was very close.
> > >
> > > I'm a little bit surprised that there is not an open-source, SDR-based
> > GNSS
> > > simulator (at least, one I could find).
> >
> >
> >
> > Not much demand, I suspe

[time-nuts] 20220227: Beginner problems with Lady Heather and HP Z3805A

[Andrew Kalman]

All:

I'm trying to get Lady Heather 5.00 to work with my Z3805A. I know the
Z3085A is working and talking (via direct SCPI commands over RS-232, see
below) AND Lady Heather will launch and appear to do an initial connection.

But then, Lady Heather just beeps every few seconds, and is completely
hung, necessitating killing the app. This on Windows 7.

Any ideas on what I'm doing wrong?

























*E-113> SYST:STATUS?--- Receiver Status
---SYNCHRONIZATION 
[ Outputs Valid/Reduced Accuracy ]SmartClock Mode
___   Reference Outputs ___>> Locked to
GPS: stabilizing frequency   TFOM 4 FFOM 1
 Recovery   1PPS TI -285.9 ns relative to
GPS   Holdover   HOLD THR 1.000 us
 Power-up   Holdover Uncertainty
  Predict  432.0
us/initial 24 hrsACQUISITION  [
GPS 1PPS CLK Valid ]Satellite Status __   Time
Tracking: 3Not Tracking: 5
 GPS  07:01:42 15 Jul 2002PRN  El  Az   SS   PRN  El  Az
 1PPS CLK Synchronized to GPS Time 10  56 254   85   *16  Acq .
ANT DLY  0 ns 15  33  55   29   *18  Acq . Position
 27  33 313   35   *23  Acq . MODE
Survey:6.2% complete26  14 234
Suspended: track <4 sats29  19 150
   AVG LAT  N  XX:XX:41.654
AVG LON  W XXX:XX:38.424ELEV MASK 10 deg   *attempting to track   AVG
HGT  +195.06 m  (MSL)HEALTH MONITOR
. [ OK ]Self Test:
OKInt Pwr: OK   Oven Pwr: OK   OCXO: OK   EFC: OK   GPS Rcv: OKE-113>*

--Andrew


Andrew E. Kalman, Ph.D.
___
time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an 
email to time-nuts-le...@lists.febo.com
To unsubscribe, go to and follow the instructions there.

[time-nuts] Re: electronics question or how not to fry my raspberry pi

[Andrew Kalman]

 I find that the best way to handle these translations is to use one of
TI's level translators ... each chip has two power supply rails, and
translation is done transparently across the chip, and there is good max
voltage overprotection on both sides  as well. I use them a lot to handle
5V <-> 3.3V level issues.

Try the SN74LVC8T245PWR for unidirectional level translating . They also
have some bidirectional ones ...

--Andrew


Andrew E. Kalman, Ph.D.


On Fri, Jan 28, 2022 at 11:41 AM folkert  wrote:

> Hi,
>
> I bought a GPSDO. It outputs somewhere around 3V. This is connected to a
> picdiv and then to a raspberry pi. The picdiv is happy with 3.3v, the rpi
> as well. All good.
>
> Now I bought a "Square Wave Amplifier" by BG7TBL (
> https://www.aliexpress.com/item/4000192799858.html?gatewayAdapt=glo2nld&spm=a2g0o.9042311.0.0.3d764c4dMZPAX8
> ). Documentation I could find was a bit vague about the
> output voltage but I measured 5v with a scope (see
> https://vanheusden.com/permshare/scope.png - the scope software says
> 2MHz but output is really 10MHz).
>
> I did not study electronics, am only a electronics-hobbyist so bare with
> me when this is a dumb question.
>
> The RPI doesn't like 5v on its GPIO pins.
> So I wonder:
> - can I feed the picdiv 5v on its GPIO pin while giving it a 3.3v
>   voltage so that it outputs 3.3v as well to the rpi pins?
> - or should I use a voltage divider? I was thinking of a 4.7k ohm and
>   8.2k ohm resistor giving slightly less than 3.2v - will that work? or
>   will that attenuate the signal too much? The 50 ohm bnc cable between
>   the amplifier and the rpi is 3m long. Anything else I should be aware
>   of?
>
>
> Regards,
>
> Folkert van Heusden
> PD9FVH
> ___
> time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send
> an email to time-nuts-le...@lists.febo.com
> To unsubscribe, go to and follow the instructions there.
>
___
time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an 
email to time-nuts-le...@lists.febo.com
To unsubscribe, go to and follow the instructions there.

[time-nuts] Re: High precision OCXO supplier for end costomers

[Andrew Kalman]

FYI, I contacted MTI a few years ago for some replacement 10MHz OCXO, and
their minimum buy was 5 pcs.

--Andrew


Andrew E. Kalman, Ph.D.


On Mon, Jan 10, 2022 at 12:46 PM Bob kb8tq  wrote:

> Hi
>
> Ok, well, the boys at Rakon / CEPE will be happy to sell you a ~ $30,000
> OCXO
> with a lead time of about 2 years. I suspect you will have to pay at time
> of order
> unless you are a well known business …. Unlike a lot of this and that you
> see
> tossed around for specs, I’m quite sure they *do* meet their published
> numbers.
>
> The only thing I’m not 100% sure of is if the minimum order quantity is
> 1,3,5 or
> 10. If cost is no object, that should not really matter.
>
> Bob
>
> > On Jan 10, 2022, at 3:06 PM, Poul-Henning Kamp 
> wrote:
> >
> > 
> > Bob kb8tq writes:
> >
> >> My only concern here is that before one goes of and spends 5,10, or
> >> 20 thousand dollars on an OCXO, [...]
> >
> > Bob, you are kind of missing the point here...
> >
> > The entire point of Audio-Homoepathy is to spend excessive amounts
> > of money, so that you can brag about how rich you are, and how
> > super-human your refined sense of hearing is, all without wasting
> > any time or effort on it.
> >
> > How else can there be a market for $3000 CAT-6 ethernet cables ?
> >
> > It is Audio-Homoepathy, because the crucial feature is "orders of
> magnitude".
> >
> > They do not buy a slightly expensive ethernet cable, they buy one
> > which cost several orders of magnitude more than what it is worth,
> > so that nobody can doubt that money is no issue - and thereby
> > make the money the only real point.
> >
> > I know several people who are quite comfortable parting these
> > newly-rich from their money, and I cannot really fault them...
> >
> > One of those companies have a business model where they hand-build
> > quite competent amplifiers using outrageous raw materials and hawk
> > them at insane prices using industry-strength flim-flam.
> >
> > When I say "indystry-strength flim-flam" I mean it.
> >
> > At one time they had a role of teflon foil stored next to a resarch
> > nuclear reactor for some weeks, so that the "neutrons could equalize
> > the the tension in the micro-grid structure" before it got rolled
> > into capacitors with a gold foil with similar super-natural properties.
> >
> > Often the invariably "very serious buyer" will persuade them, in
> > return for a stiff compensation, to never build any more, and refuse
> > to ever talk abut it, so he can (also) brag about having the only
> > one ever made, and make up some flim-flam about why that is so
> > ("... but that reactor is closed now, and the guy who knew how to
> > reorient the rolls is dead.")
> >
> > Then they rinse & repeat, this time with capacitors wound by virgins
> > from some tropical island or whatever.
> >
> > The fact that the socalled "NFT" market has negatively impacted the
> > "high end audio" market recently tells you everything you need to
> > know about both of them.
> >
> > So the question we are really being asked here, is what which
> > OCXO can be flim-flam'ed the most, when it becomes another dose
> > of audio-homoepathy.
> >
> > Poul-Henning
> >
> > --
> > Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
> > p...@freebsd.org | TCP/IP since RFC 956
> > FreeBSD committer   | BSD since 4.3-tahoe
> > Never attribute to malice what can adequately be explained by
> incompetence.
> ___
> time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send
> an email to time-nuts-le...@lists.febo.com
> To unsubscribe, go to and follow the instructions there.
___
time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an 
email to time-nuts-le...@lists.febo.com
To unsubscribe, go to and follow the instructions there.

[time-nuts] Re: PPS latency? User vs kernel mode

[Andrew Kalman]

This issue of interrupt latency is one place where cooperative RTOSes (as
opposed to preemptive ones) have a clear advantage.

The reason is that since context switching is explicitly called out
(cooperative) instead of it happening at the interrupt level (preemptive),
in a cooperative RTOS, the only latency is the MCU's own interrupt handling
mechanism.

So if you have nested interrupts, you just "punch through" immediately to
the interrupt you want/need to service (no need to manage the context
switching register saves, etc.). If no nesting, then you do have to wait
until the currently-being-served ISR is finished. But good coding practices
and careful choices of priorities can reduce these issues to times much
smaller than 500us (that's forever!). I could see easily reaching < 1us
jitter in a PIC24EP MCU, I suspect you could get to 100ns pretty easily
when running the MCU at 60MHz.

Disclaimer: I'm the author of a proven cooperative RTOS called Salvo
(TM)  -- the User Manual
 (that I
wrote eons ago) has a lot of background material. It's been very surprising
to me (and to Salvo users) how little you end up giving up when going to a
cooperative scheduler (in constrained, but not uncommon applications). I
can guarantee that the presence of the Salvo RTOS on an MCU can (when
properly applied) have ZERO instruction cycles of impact on the operation
of the MCU's interrupt handler (and I use this to great effect in my
embedded coding).

--Andrew


Andrew E. Kalman, Ph.D.


On Mon, Dec 13, 2021 at 12:19 PM Trent Piepho  wrote:

> On Mon, Dec 13, 2021 at 6:56 AM Poul-Henning Kamp 
> wrote:
> >
> > In FreeBSD you get all that for free:
> >
> >
> https://papers.freebsd.org/2002/phk-timecounters.files/timecounter.pdf
> >
>
> "It is painfully obvious that the interrupt latency is the dominant
> noise factor in PPS timestamping in the second case."
>
> This is exactly what I found when I did this 15 years after your
> paper.  Though what I think is more interesting, is that despite using
> 15 years newer hardware, the resulting PPS precision ends up being
> nearly the same for both timestamping methods.  Your final graphs are
> very similar the one I have tried (succeeded?) at posting, other than
> you using a time series I used a histogram.
> ___
> time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send
> an email to time-nuts-le...@lists.febo.com
> To unsubscribe, go to and follow the instructions there.
>
>
___
time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an 
email to time-nuts-le...@lists.febo.com
To unsubscribe, go to and follow the instructions there.

[time-nuts] Re: 1 pps / Gerber files

[Andrew Kalman]

DaveM is absolutely right -- JLCPCB is crazy cheap (and great quality) for
small runs of PCBs, esp. in the default config (green soldermask PCBs,
simple HASL (leaded) finish, 0.062" thick, et.).

When I do PCBs I often choose alternate soldermask colors (there's a
madness to the method :-) ), and I pretty much always go with ENIG (gold
finish), to avoid any corrosion issues, etc. But that adds an easy
$20-$40/board.

If you want the absolute cheapest way to go, follow DaveM's instructions!
It's a great way for folks who are not yet experienced with PCBs to get
into handling PCBs, esp. if someone else is providing the Gerbers (the
source files for making the PCBs).

(At this point in my life I have designed around well over 500 PCBs).


--Andrew


Andrew E. Kalman, Ph.D.


On Thu, Nov 25, 2021 at 12:19 PM DM  wrote:

> To all who are interested in Gerhard's boards;
> If you just send a zip file of the Gerber files that Gerhard has provided
> to JLCPCB, you can get 5 boards, including shipping to your address (I'm in
> the USA; I can't say what shipping would be to other countries) for a grand
> total of $5.90 USD. The board manufacturing cost is $2.00 for all 5 boards,
> shipping is a measly $3.90. PCB build time is 1-2 days. Shipping is fast
> and reliable. I've used DHL for previous orders, usually arriving within a
> week.
> They accept Paypal for payment.
>
> By ordering boards yourself, you get 5 boards, for less money than having
> to go through a 3rd party, and avoiding USPO costs and delays.
>
> Cheers,
> DaveM
>
>
>
>
>
>
>
> From: "Andrew Kalman" 
> To: "Discussion of precise time and frequency measurement" <
> time-nuts@lists.febo.com>
> Sent: Thursday, November 25, 2021 12:34:41 PM
> Subject: [time-nuts] Re: 1 pps / Gerber files
>
> I have boards built regularly at JLCPCB, I could certainly order a batch
> delivered to me, but I would have to send them all to someone else, to
> deal
> with distributing them out to folks on the list (I am time-constrained).
> ___
> Andrew E. Kalman, Ph.D. a...@pumpkininc.com
>
> President
> Pumpkin, Inc.
> 750 Naples Street
> San Francisco, CA 94112 USA
> tel: (415) 584-6360
> fax: (415) 585-7948
> web: http://www.pumpkinspace.com
>
> *The information contained in this email message is intended only for the
> use of the individual or entity to which it is addressed and may contain
> information that is confidential. Furthermore, this information may be
> protected by Federal law relating to confidentiality (42 CFR Part 2)
> prohibiting any further disclosure. If the reader of this message is not
> the intended recipient or the employee or agent responsible for delivering
> this message to its intended recipient, you are hereby notified that any
> review, dissemination, distribution or copying of the communication is
> strictly prohibited. If you have received this communication in error,
> please notify Pumpkin, Inc. immediately by telephone, email or fax and
> return the original message to us via the means by which it was originally
> delivered. Thank you.*
> ___
>
>
> On Thu, Nov 25, 2021 at 10:31 AM Dan Rae via time-nuts <
> time-nuts@lists.febo.com> wrote:
>
> > On 11/24/2021 1:06 PM, Gerhard Hoffmann wrote:
> > > Hi,
> > >
> > > it took some time to make the Gerbers,
> >
> > It is much appreciated Gerhard, all the work you have done to make these
> > available to the group. Many thanks!
> >
> > Now, the inevitable query; is anyone planning on ordering some of these
> > boards, and is willing to make one available to me, in the US, for a
> > share of the cost?
> >
> > Dan
> >
> > ___
> > time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe
> send
> > an email to time-nuts-le...@lists.febo.com
> > To unsubscribe, go to and follow the instructions there.
> ___
> time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send
> an email to time-nuts-le...@lists.febo.com
> To unsubscribe, go to and follow the instructions there.
> ___
> time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send
> an email to time-nuts-le...@lists.febo.com
> To unsubscribe, go to and follow the instructions there.
>
>
___
time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an 
email to time-nuts-le...@lists.febo.com
To unsubscribe, go to and follow the instructions there.

[time-nuts] Re: 1 pps / Gerber files

[Andrew Kalman]

I have boards built regularly at JLCPCB, I could certainly order a batch
delivered to me, but I would have to send them all to someone else, to deal
with distributing them out to folks on the list (I am time-constrained).
___
Andrew E. Kalman, Ph.D.a...@pumpkininc.com

President
Pumpkin, Inc.
750 Naples Street
San Francisco, CA 94112  USA
tel: (415) 584-6360
fax: (415) 585-7948
web: http://www.pumpkinspace.com

*The information contained in this email message is intended only for the
use of the individual or entity to which it is addressed and may contain
information that is confidential. Furthermore, this information may be
protected by Federal law relating to confidentiality (42 CFR Part 2)
prohibiting any further disclosure. If the reader of this message is not
the intended recipient or the employee or agent responsible for delivering
this message to its intended recipient, you are hereby notified that any
review, dissemination, distribution or copying of the communication is
strictly prohibited. If you have received this communication in error,
please notify Pumpkin, Inc. immediately by telephone, email or fax and
return the original message to us via the means by which it was originally
delivered. Thank you.*
___


On Thu, Nov 25, 2021 at 10:31 AM Dan Rae via time-nuts <
time-nuts@lists.febo.com> wrote:

> On 11/24/2021 1:06 PM, Gerhard Hoffmann wrote:
> > Hi,
> >
> > it took some time to make the Gerbers,
>
> It is much appreciated Gerhard, all the work you have done to make these
> available to the group.  Many thanks!
>
> Now, the inevitable query; is anyone planning on ordering some of these
> boards, and is willing to make one available to me, in the US, for a
> share of the cost?
>
> Dan
>
> ___
> time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send
> an email to time-nuts-le...@lists.febo.com
> To unsubscribe, go to and follow the instructions there.
___
time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an 
email to time-nuts-le...@lists.febo.com
To unsubscribe, go to and follow the instructions there.

[time-nuts] Re: Tbolt

[Andrew Kalman]

I'm a rank amateur on the time-nuts scale ... we did some replacements of
MTI OCXOs a few years ago, and folded all that info into a manual as we
built our own drop-in replacement OCXO modules for some XL Microwave and
SRS instruments.

It has some data on trim values for IsoTemp brand OCXOs, etc. that some
might find useful.

http://www.pumpkininc.com/space/manual/UM-20_Pumpkin_OCXO.pdf

--
Andrew E. Kalman, Ph.D.


On Thu, Jul 22, 2021 at 9:37 AM Bob kb8tq  wrote:
>
>> Hi
>>
>> If you manually set the DAC with the commands LH nicely provides
>> (LH is the *best* thing about these TBolts !!!) you will find it runs from
>> -5 to +5V. The OCXO should tune linearly over that range ( all of mine
>> do).
>>
>> If you take a saw to the typical TBolt OCXO, you likely will find
>> a 10 MHz SC cut crystal in a single oven. The design changed over
>> the many years they were supplied. One date coded 1997 is not going
>> to be the same as one date coded 2005.
>>
>> On any OCXO, to see if it’s using a doubler, just hook up a spectrum
>> analyzer to the OCXO output. You *will* see the sub-harmonic. Much
>> quicker / easier than tearing the thing to pieces.
>>
>> Bob
>>
>> > On Jul 22, 2021, at 5:00 AM, Dave B via time-nuts <
>> time-nuts@lists.febo.com> wrote:
>> >
>> > On 22/07/2021 08:30, time-nuts-requ...@lists.febo.com wrote:
>> >> Message: 1
>> >> One more comment on the Vectron OCXO. My Tbolt shows a tuning voltage
>> of +0.4 Volt and has 3.6 Hz per Volt. Assuming the OCXO was sold to Trimble
>> with 0 V and my unit has at least 12 years on it (4380 days) aging is 3.29
>> E-11 per day. Not bad for an  OCXO.
>>
>>   Bert Kehren
>> >
>> > 
>> >
>> > Hi.
>> >
>> > According to Lady Heather, My T'bolt sits with it's DAC at about 0.2V
>>  I always wonder about that.
>> >
>> > From the above comment, is the DAC output (and VCXO input I guess)
>> bipolar, as in can range +- some amount from 0V?
>> >
>> > I've not seen any schematics for them, so in honesty haven't a clue
>> what it's likely range is, good bad or indifferent.
>> >
>> > I did email TVB direct about the possibility of sourcing another one or
>> two of them, but as he said (and I guessed) he was swamped with responses.
>> >
>> > I use mine mainly as a frequency reference, powered on 24/7
>> >
>> > Regards to All.
>> >
>> > Dave G8KBV (In the UK as far as I can tell.)
>> >
>> >
>> > --
>> > Created on and sent from a Unix like PC running and using free and open
>> source software:
>> >
>> > ___
>> > time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe
>> send an email to time-nuts-le...@lists.febo.com
>> > To unsubscribe, go to and follow the instructions there.
>> ___
>> time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe
>> send an email to time-nuts-le...@lists.febo.com
>> To unsubscribe, go to and follow the instructions there.
>
>
___
time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an 
email to time-nuts-le...@lists.febo.com
To unsubscribe, go to and follow the instructions there.

[time-nuts] Re: XL microwave

[Andrew Kalman]

Yes it is ... Thank you!

On Thu, Jun 17, 2021, 09:32 Lisa Perdue  wrote:

> This is what I have. Sorry, I don't know if it is relevant to the
> counter(s) you have or are interested in.
>
> On Tue, Jun 15, 2021 at 4:43 AM Andrew Kalman  wrote:
>
>> I'm also interested in a service manual (w/schematics) for these counters
>> ...
>>
>> --Andrew
>>
>> 
>> Andrew E. Kalman, Ph.D.
>>
>>
>> On Tue, Jun 15, 2021 at 1:28 AM Jan Boutsen 
>> wrote:
>>
>> > Hello all,
>> >
>> > I am looking for the SERVICE manual of a XL MICROWAVE counter .
>> > The counter is like this one:
>> >
>> >
>> >
>> http://www.ebay.com/itm/XL-Microwave-3400-40-GHz-Frequency-Counter-/20181920
>> > 0442
>> >
>> > Any help??
>> >
>> > Jan ON4MMW
>> > Jan dot BOUTSEN at telenet dot be
>> >
>> >
>> >
>> > ___
>> > time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe
>> send
>> > an email to time-nuts-le...@lists.febo.com
>> > To unsubscribe, go to and follow the instructions there.
>> >
>> >
>> ___
>> time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe
>> send an email to time-nuts-le...@lists.febo.com
>> To unsubscribe, go to and follow the instructions there.
>>
>
>
> --
> Lisa Perdue
>
___
time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an 
email to time-nuts-le...@lists.febo.com
To unsubscribe, go to and follow the instructions there.

[time-nuts] Re: XL microwave

[Andrew Kalman]

I'm also interested in a service manual (w/schematics) for these counters
...

--Andrew


Andrew E. Kalman, Ph.D.


On Tue, Jun 15, 2021 at 1:28 AM Jan Boutsen  wrote:

> Hello all,
>
> I am looking for the SERVICE manual of a XL MICROWAVE counter .
> The counter is like this one:
>
>
> http://www.ebay.com/itm/XL-Microwave-3400-40-GHz-Frequency-Counter-/20181920
> 0442
>
> Any help??
>
> Jan ON4MMW
> Jan dot BOUTSEN at telenet dot be
>
>
>
> ___
> time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send
> an email to time-nuts-le...@lists.febo.com
> To unsubscribe, go to and follow the instructions there.
>
>
___
time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an 
email to time-nuts-le...@lists.febo.com
To unsubscribe, go to and follow the instructions there.

[time-nuts] Re: 20210423: Introduction and Request for Spirent GSS4200 User Manual / Help

[Andrew Kalman]

An update:

I was able to obtain the complete Spirent GSS4200 Utilities disk/installer
... it seems to have everything required (scenarios, USB drivers, etc.).

I haven't had a chance to play with them yet.

If anyone is in a similar position to me and in need of this disk, let me
know ...

--Andrew




On Sat, Apr 24, 2021 at 1:19 AM Andrew Kalman  wrote:

> So, an update. I was graciously provided with the User Manual for the
> GSS4200 (thank you!). Having read through it and having played with my
> GSS4200, I conclude the following:
>
>- My unit is functionally working (well) -- 10MHz clock was not far
>off, output levels are correct, etc., it is generating a signal where one
>should be.
>- Most of the "commanded" behavior I had been observing (using the
>GSS6100 user manual as a guide, issuing commands over GPIB) was the
>behavior of the unit when operating in GSS6100 emulation mode (single
>channel, ability to change the SVID, maybe the ability to change the week,
>etc.).
>- This GSS4200 has (sadly) only one scenario loaded in its NVM memory
>-- "4200calibration" that is 10 minutes long. It basically outputs a
>single-channel signal on PRN 1, makes sense for calibration.
>- Based on my reading of the manual, at a minimum, if you have access
>to the utilities CD ROM, you can load scenario "libraries" (#sats, signal
>strengths, ground trajectories, etc.) and then run them (in a looping mode,
>if you want) on this unit. A combination of utilities (that work only over
>USB) load scenarios into the GSS4200.
>- Each scenario also includes the appropriate ephemeris and almanac
>info (provided by Spirent).
>- Scenarios must be under 5 minutes long.Dunno how the 4200calibration
>scenario is 600s long ...
>- The scenario and other file formats are not / not well documented.
>Spirent had a server that you would provide scenario requests to, and I'm
>guessing that it would generate the scenario file along with the
>accompanying ephemeris and almanac info, and crunch that all into a .scb
>scenario file. You can then use a provided utility to combine multiple
>scenarios into a scenario library that you can then load into the GSS4200.
>Note that there is no obvious way for a user to ** generate **  their own
>scenarios (or ephemeris or almanac).
>- GSS6100 emulation is "independent" of GSS4200 scenario operation.
>For example, the GSS4200 manual does not mention an explicit level command
>(that is part of the GSS6100's command set), yet the example scenarios
>alter the output level, so clearly the unit can do that.
>- So, the intended way to use this unit appears to be:
>   - Obtain supplied/default scenarios (*.scb) or ones built for you
>   via the Spirent web interface
>   - Optionally combine them into libraries (*.scl) via the Scenario
>   Selection Tool
>   - Download them into the GSS4200 (max 512KB worth) using the Flash
>   Loader Utility
>   - Run the scenario via RUNS  for one run, or LOOP  for
>   looping, where  is the scenario number.
>
>
>- So, I'm kinda stuck here. I want the GSS4200 available for a quick
>and consistent validation of the proper operation of GPS receivers. For
>that, at a minimum, I need some complete scenarios (the default ones
>supplied with the unit would be alright) that I can load into the unit to
>run in looping mode. There are 18 default scenarios, 3 each (different
>power levels, stationary vs. moving, etc.) for six cities: Boston, LA,
>Tokyo, Hanover, Seoul and Shanghai.They all run at various dates in 2003,
>suggesting that the GSS4200 was released around that time.
>- My unit only has the one calibration scenario (PRN 1 only, standard
>output level) loaded ... I'm not really clear on the usefulness of a single
>channel of GPS signal.
>- This unit differs from more modern units like Spectracom/Orolia GSG
>series units in that the newer units allow you to generate your own
>scenarios, and they pull ephemeris and almanac data directly from the
>internet. Plus more channels and constellations, more interference and
>other simulations, etc.
>
> So, I conclude that without the full GSS4200 utilities disk, I'm kinda
> stuck. :-(
>
> --Andrew
>
> 
> Andrew E. Kalman, Ph.D.
>
>
> On Fri, Apr 23, 2021 at 1:15 PM Andrew Kalman  wrote:
>
>> Hello.
>>
>> [SNIP]
>>
>> I am ** desperate ** for a User Manual for the Spirent GSS4200 GNSS
>> simulator (e.g.,
>> https://www.testequipmentconnection.com/548

[time-nuts] Re: Measuring the Thermodynamic Cost of Timekeeping

[Andrew Kalman]

Wow .. I'm trying to visualize a non-thermodynamic clock :-)


Andrew E. Kalman, Ph.D.


On Tue, May 18, 2021 at 12:04 AM Azelio Boriani 
wrote:

> 
> the full article is available
>
> related:
> 
> 
> ___
> time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send
> an email to time-nuts-le...@lists.febo.com
> To unsubscribe, go to and follow the instructions there.
>
>
___
time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an 
email to time-nuts-le...@lists.febo.com
To unsubscribe, go to and follow the instructions there.

[time-nuts] Re: 2nd Run of TimeHats

[Andrew Kalman]

I'm interested in 1-2 units.

--Andrew


Andrew E. Kalman, Ph.D.


On Mon, Apr 26, 2021 at 9:58 AM John Miller via time-nuts <
time-nuts@lists.febo.com> wrote:

> Hello everyone,
>
> I’ve seen a number of messages lately that reference the TimeHat boards I
> put together a couple of months ago, with lots of positive feedback, which
> I really appreciate. The first run of boards I did sold fairly quickly, and
> based on a number of emails I have gotten lately there seems to be some
> renewed interest.
>
> As such, I’m going to order up another batch of PCBs and parts, but I’d
> like to get an idea of how many I need to order to satisfy current demand.
> The GPS modules come from China, so there is about a two or three week wait
> them, so I want to make sure I have enough.
>
> For those not familiar, you can learn more about the TimeHat here:
> https://millerjs.org/timehat
>
> Regards,
> John
> ___
> time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send
> an email to time-nuts-le...@lists.febo.com
> To unsubscribe, go to and follow the instructions there.
___
time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an 
email to time-nuts-le...@lists.febo.com
To unsubscribe, go to and follow the instructions there.

[time-nuts] Re: 20210423: Introduction and Request for Spirent GSS4200 User Manual / Help

[Andrew Kalman]

(Egg on face -- I meant to say exaHz-class processor, not attoHz :-)  )

--Andrew


Andrew E. Kalman, Ph.D.


On Sun, Apr 25, 2021 at 12:02 PM Andrew Kalman  wrote:

> Just a comment on real-time programming.
>
> Obviously the accuracy of the real-time performance is a function of the
> hardware/software system's clock speed -- if you have an attoHz-class
> microprocessor (MCU), most things are going to look real-time to most
> people (except time nuts, of course :-) ) no matter how they are coded ...
>
> In the real world, where clocks are usually in the MHz range, you can
> achieve the real-time performances of your hardware (say, of a 32-bit
> output compare timer peripheral or a 12-bit DAC) as long as the overlaid
> software does not interfere with the peripheral's proper functioning. With
> a "set-and-forget" peripheral that is easy. With one that e.g. needs to be
> "fed" by the overlaid software (say, a DAC that is fed by DMA from data
> coming from outside), that is a bit more difficult. And if some of that
> real-time performance needs to happen in a task, then you really need a
> couple of software architectural features to get you there.
>
> As an example, an MCU-based system that uses queues to manage priority is
> not going to achieve real-time task performance, because e.g. the time to
> enqueue a task will not be constant-time, and it will thereby introduce
> timing jitter into the execution of all tasks. If, OTOH, in this example
> the queuing mechanism were implemented via a hardware timer and ISR that
> handles queueing via a an array (so that the queuing algorithm is
> constant-time), AND that ISR is elevated to the highest priority, then the
> task jitter in that system will be rather minimal, subject only to time
> deltas due to the system serving any other interrupts (regardless of
> interrupt preemption, etc). I.e. if the MCU is serving say a UART interrupt
> when the "main" timing interrupt occurs, either the system has to (HW)
> context-switch out of the UART interrupt to go service the timer ISR (and
> (SW) context-switch), OR it has to wait for the UART ISR to end, before
> servicing the timer interrupt. In the former, jitter will be a function of
> the MCU's interrupt handling; in the latter, it'll be a function of your
> code.
>
> While hardware preemption is always your friend, software preemption (in
> the general case) is not a panacea. For example, in a preemptive RTOS,
> every context switch is going to involve an interrupt. That "extra"
> interrupt will affect the responsiveness and jitter of your other
> interrupts. A cooperative RTOS does not involve any interrupts when
> context-switching, and so (from one of several perspectives), a cooperative
> RTOS (that in theory is not as responsive as a preemptive one) may in fact
> yield certain better real-time performances than a preemptive RTOS.
>
> So, bottom-line rule of thumb: if you want to get minimal timing jitter
> out of an MCU application, it is possible to run an RTOS (of any sort, most
> are soft real-time, very very few are hard real-time) on that MCU, and with
> careful attention to how you architect the system split between hardware
> peripherals and firmware on the MCU, you can get to the exact hardware
> timing specifications of the MCU itself. IMO the use of an RTOS makes a ton
> of sense here, because you can e.g. implement a complete GUI, comms system,
> terminal or other as part of the MCU application, safe in the knowledge
> that all this "RTOS overhead" has _zero_ impact on the real-time
> performance you hoped to get out of the MCU. This does require careful
> coding in certain areas ...
>
> I am a huge proponent of loosely-coupled, priority-based, event-driven MCU
> programming. Assuming it's coded well, it is not incompatible with
> nearly-real-time programming. For high-performance MCU programming, I
> generally follow these rules:
>
>- For 1-to-100-instruction-cycle timing accuracy, use straight-line
>(uninterrupted) instructions (Assembly, or C if your compiler is good)
>while interrupts are disabled. Here, your jitter is your fundamental clock
>jitter as it passes through the MCU.
>- For 100-to-1000-instruction-cycle timing accuracy, code it using an
>interrupt. Here, your jitter is dependent on the interrupt handling of the
>MCU.
>- For greater than 1000-instruction-cycle timing accuracy, hand it
>over to the (properly configured) RTOS. Here, your jitter is dependent on
>how the foreground (interrupt-level) vs. background (task-level) code
>operates in your application.
>
>
> --Andrew
>
> 

[time-nuts] Re: 20210423: Introduction and Request for Spirent GSS4200 User Manual / Help

[Andrew Kalman]

Just a comment on real-time programming.

Obviously the accuracy of the real-time performance is a function of the
hardware/software system's clock speed -- if you have an attoHz-class
microprocessor (MCU), most things are going to look real-time to most
people (except time nuts, of course :-) ) no matter how they are coded ...

In the real world, where clocks are usually in the MHz range, you can
achieve the real-time performances of your hardware (say, of a 32-bit
output compare timer peripheral or a 12-bit DAC) as long as the overlaid
software does not interfere with the peripheral's proper functioning. With
a "set-and-forget" peripheral that is easy. With one that e.g. needs to be
"fed" by the overlaid software (say, a DAC that is fed by DMA from data
coming from outside), that is a bit more difficult. And if some of that
real-time performance needs to happen in a task, then you really need a
couple of software architectural features to get you there.

As an example, an MCU-based system that uses queues to manage priority is
not going to achieve real-time task performance, because e.g. the time to
enqueue a task will not be constant-time, and it will thereby introduce
timing jitter into the execution of all tasks. If, OTOH, in this example
the queuing mechanism were implemented via a hardware timer and ISR that
handles queueing via a an array (so that the queuing algorithm is
constant-time), AND that ISR is elevated to the highest priority, then the
task jitter in that system will be rather minimal, subject only to time
deltas due to the system serving any other interrupts (regardless of
interrupt preemption, etc). I.e. if the MCU is serving say a UART interrupt
when the "main" timing interrupt occurs, either the system has to (HW)
context-switch out of the UART interrupt to go service the timer ISR (and
(SW) context-switch), OR it has to wait for the UART ISR to end, before
servicing the timer interrupt. In the former, jitter will be a function of
the MCU's interrupt handling; in the latter, it'll be a function of your
code.

While hardware preemption is always your friend, software preemption (in
the general case) is not a panacea. For example, in a preemptive RTOS,
every context switch is going to involve an interrupt. That "extra"
interrupt will affect the responsiveness and jitter of your other
interrupts. A cooperative RTOS does not involve any interrupts when
context-switching, and so (from one of several perspectives), a cooperative
RTOS (that in theory is not as responsive as a preemptive one) may in fact
yield certain better real-time performances than a preemptive RTOS.

So, bottom-line rule of thumb: if you want to get minimal timing jitter out
of an MCU application, it is possible to run an RTOS (of any sort, most are
soft real-time, very very few are hard real-time) on that MCU, and with
careful attention to how you architect the system split between hardware
peripherals and firmware on the MCU, you can get to the exact hardware
timing specifications of the MCU itself. IMO the use of an RTOS makes a ton
of sense here, because you can e.g. implement a complete GUI, comms system,
terminal or other as part of the MCU application, safe in the knowledge
that all this "RTOS overhead" has _zero_ impact on the real-time
performance you hoped to get out of the MCU. This does require careful
coding in certain areas ...

I am a huge proponent of loosely-coupled, priority-based, event-driven MCU
programming. Assuming it's coded well, it is not incompatible with
nearly-real-time programming. For high-performance MCU programming, I
generally follow these rules:

   - For 1-to-100-instruction-cycle timing accuracy, use straight-line
   (uninterrupted) instructions (Assembly, or C if your compiler is good)
   while interrupts are disabled. Here, your jitter is your fundamental clock
   jitter as it passes through the MCU.
   - For 100-to-1000-instruction-cycle timing accuracy, code it using an
   interrupt. Here, your jitter is dependent on the interrupt handling of the
   MCU.
   - For greater than 1000-instruction-cycle timing accuracy, hand it over
   to the (properly configured) RTOS. Here, your jitter is dependent on how
   the foreground (interrupt-level) vs. background (task-level) code operates
   in your application.


--Andrew


Andrew E. Kalman, Ph.D.


On Sun, Apr 25, 2021 at 7:14 AM Lux, Jim  wrote:

> On 4/25/21 6:40 AM, Bob kb8tq wrote:
> > Hi
> >
> >
> >> On Apr 25, 2021, at 9:31 AM, Lux, Jim  wrote:
> >>
> >> On 4/25/21 6:02 AM, Bob kb8tq wrote:
> >>> Hi
> >>>
> >>> The thing that I find useful about a GPS simulator is it’s ability to
> calibrate the
> >>> time delay through a GPS based system. In the case of a GPSDO, there
> may be
> >>> things beyond the simple receiver delay that get into the mix. Getting
> the entire
> >>> offset “picture” all at once is nice thing. Yes, that’s a Time Nutty
> way to look at it…..
> >>>
> >>> So far, I have not seen any

[time-nuts] Re: 20210423: Introduction and Request for Spirent GSS4200 User Manual / Help

[Andrew Kalman]

Hi Paul.

Yes, I've been on this same journey. After I learned (somewhat unrelated)
that one is supposed to have an FCC license to rebroadcast GNSS signals
(e.g. via a repeater inside a lab, makes eminent sense), I started thinking
more about GNSS simulators and how they might be added to my company's
workflow. So I bid on a couple of units, got them for pennies on the
dollar, and started messing with them in the hope of ending up with an
ATE/rack-type setup that I can build into a nearly automatic test &
validation suite.

Let's say I was much more successful with the Spectracom/Orolia GSG-5 than
with the Spirent GSS4200 ... In the case of the GSG-5, it's really just a
question of how many options you can afford -- the rest is all there, you
don't need a support contract, it's all easily accessible in the unit
itself, and as long as the Internet exists the GSG-5 will probably keep
working (it gets time, ephemeris and almanac data from servers -- it can
simulate stuff NOW (wth the right options), not just in the past and
future). The GSS4200 is about 10-15 years older, and it shows (in terms of
ease-of-use), along with how Spirent chose to monetize their users /
subscribers. Also, the GSG-5 adds things like interference to the signals
(all for a price, of course). IOW, the newer units (at least, from
Spectracom was XL Microwave is now Orolia) are a whole lot easier to use
... but they come at a price. It's an interesting business.

I will say that the build quality of the Spirent is very good. I have not
opened up the GSG-5, just did a calibration and it was very close.

I'm a little bit surprised that there is not an open-source, SDR-based GNSS
simulator (at least, one I could find).

--Andrew


Andrew E. Kalman, Ph.D.


On Sat, Apr 24, 2021 at 9:14 AM paul swed  wrote:

> Andrew
> Welcome to time-nuts. I really appreciate your detailed write up. I have
> seriously considered a used gps emulator a few times. Really don't need
> complex solutions. Its more for recovering and working on quite old GPS
> receivers and down converters like Austron 2201s. 1990s stuff.
> Whats great about the writeup is at least for this unit I can see the
> requirements for operation that are far more complex then I would have
> expected. I seem to recall there was a series of GPS emulators on ebay that
> were priced about right for a hobbyist to consider.
> Now at least if some unit shows up I will know what to look out for. Other
> wise its a expensive box.
> Thanks
> Paul
> WB8TSL
>
> On Sat, Apr 24, 2021 at 7:02 AM Andrew Kalman  wrote:
>
>> So, an update. I was graciously provided with the User Manual for the
>> GSS4200 (thank you!). Having read through it and having played with my
>> GSS4200, I conclude the following:
>>
>>- My unit is functionally working (well) -- 10MHz clock was not far
>> off,
>>output levels are correct, etc., it is generating a signal where one
>> should
>>be.
>>- Most of the "commanded" behavior I had been observing (using the
>>GSS6100 user manual as a guide, issuing commands over GPIB) was the
>>behavior of the unit when operating in GSS6100 emulation mode (single
>>channel, ability to change the SVID, maybe the ability to change the
>> week,
>>etc.).
>>- This GSS4200 has (sadly) only one scenario loaded in its NVM memory
>> --
>>"4200calibration" that is 10 minutes long. It basically outputs a
>>single-channel signal on PRN 1, makes sense for calibration.
>>- Based on my reading of the manual, at a minimum, if you have access
>> to
>>the utilities CD ROM, you can load scenario "libraries" (#sats, signal
>>strengths, ground trajectories, etc.) and then run them (in a looping
>> mode,
>>if you want) on this unit. A combination of utilities (that work only
>> over
>>USB) load scenarios into the GSS4200.
>>- Each scenario also includes the appropriate ephemeris and almanac
>> info
>>(provided by Spirent).
>>- Scenarios must be under 5 minutes long.Dunno how the 4200calibration
>>scenario is 600s long ...
>>- The scenario and other file formats are not / not well documented.
>>Spirent had a server that you would provide scenario requests to, and
>> I'm
>>guessing that it would generate the scenario file along with the
>>accompanying ephemeris and almanac info, and crunch that all into a
>> .scb
>>scenario file. You can then use a provided utility to combine multiple
>>scenarios into a scenario library that you can then load into the
>> GSS4200.
>>Note that there is no obvi

[time-nuts] Re: Request for Spirent GSS4200 User Manual

[Andrew Kalman]

Nigel:

Yes, my conclusions, too. But even the 18 scenarios would be useful to me
as-is from the standpoint of a quick validation of a GPS receiver.

--Andrew


Andrew E. Kalman, Ph.D.


On Sat, Apr 24, 2021 at 3:36 AM  wrote:

> Having taken a more detailed look at the 4200 manual I see that it boots
> up in 4100 simulation mode, so this is probably where the direct control
> comes in and why you can only get one channel.
>
> I'm also getting the impression, could be wrong of course, not unknown:-),
> that even if you find the utilities disk the only obvious way to
> personalise the mutli chanel performance is indeed via the configuration
> "scenarios" for the 4200 that need to be set up via online access to the
> Spirent registered customers only support page.
>
> They really do seem to have this locked down tight:-(
>
> Nigel GM8PZR
>
>
> -Original Message-
> From: Andrew Kalman 
> To: gandal...@aol.com; Discussion of precise time and frequency
> measurement 
> Sent: Sat, 24 Apr 2021 10:28
> Subject: Re: [time-nuts] Re: Request for Spirent GSS4200 User Manual
>
> Nigel.
>
> Thanks -- the file download worked, and now I have the USB drivers I'll
> have to test.Once I have the utilities disk, that is :-)
>
> One thing that I find odd is that the 4200 is a 6-channel machine, and it
> does 4100/6100 emulation, but there is no obvious way to "engage" the
> various channels via a command. I have noticed that a "CHAN" command does
> not generate an error, but it also doesn't appear to enable more channels
> than 1 -- it's as if only the scenarios can get the other channels working.
> This may also be an ambiguity / result of how the GPIB commands work -- if
> "CHAN" is an argument to some command, that might also be why treating it
> as a command does not result in an error.
>
> The GSS4200 manual you posted is a bit younger than the first one I got,
> but materially they're pretty much identical.
>
> --Andrew
>
> 
> Andrew E. Kalman, Ph.D.
>
>
> On Sat, Apr 24, 2021 at 2:13 AM Nigel gm8pzr via time-nuts <
> time-nuts@lists.febo.com> wrote:
>
> Spirent have indeed done a very good job of removing just about everything
> from the public domain.Having spent many hours a few years ago trying to
> find a copy of SimChan for the GSS4100 I also had to give up, despite
> finding references not that much older which indicated it had previously
> been readily available.I think the crunch came when a lot of Spirent gear
> hit the surplus market and perhaps affected sales of new equipment, so
> can't really blame them.
>
> I do have the user manual for the GSS4200, it doesn't seem to have a vast
> amount of detail but does cross reference in places to the GSS4100, which
> can also be directly controlled via GPIB, so I have now updated my previous
> GSS4100 file on Mediafire to include both.The file also includes some USB
> drivers, although I always used GPIB, plus a few Spirent App notes etc
> https://www.mediafire.com/file/di0jiayxlz0demg/Spirent_4100_4200.zip/file
> I've checked that the file downloads ok but any problems please let me
> know and I can try again.
> I never did come across a copy of SimChan so if you ever find that I know
> I won't be the only who'd be grateful for a copy:-)
> Nigel GM8PZR
>
>
> I am ** desperate ** for a User Manual for the Spirent GSS4200 GNSS
> simulator (e.g.,
> https://www.testequipmentconnection.com/54837/Spirent_GSS4200.php). That
> model is somewhat unique, in that it's one of only a very few that Spirent
> released that can/will run without an external "control" program. Using the
> manual from the GSS6100, I'm able to do a couple of things with the GSS4200
> over GPIB, but for the life of me I cannot figure out how to get the
> GSS4200 into a mode other than single-channel (it supports 6 channels, and
> has a single-channel mode). I suspect there is a command to do this, but I
> have not been able to figure it out.
>
> I have spent 8+ hours searching sites and archives, to no avail. Spirent
> has done a rather impressive job of locking down their support software and
> docs behind a paywall (and I wonder if they even have the docs for the
> GSS4200 any more). Any help is appreciated, I'm happy to give back if
> someone wants to snag another GSS4200 (around $700 used) and use it as a
> simulator.
>
> Thanks,
> ___
> Andrew E. Kalman, Ph.D.a...@pumpkininc.com
>
>
>
> *
> 

[time-nuts] Re: Request for Spirent GSS4200 User Manual

[Andrew Kalman]

Nigel.

Thanks -- the file download worked, and now I have the USB drivers I'll
have to test.Once I have the utilities disk, that is :-)

One thing that I find odd is that the 4200 is a 6-channel machine, and it
does 4100/6100 emulation, but there is no obvious way to "engage" the
various channels via a command. I have noticed that a "CHAN" command does
not generate an error, but it also doesn't appear to enable more channels
than 1 -- it's as if only the scenarios can get the other channels working.
This may also be an ambiguity / result of how the GPIB commands work -- if
"CHAN" is an argument to some command, that might also be why treating it
as a command does not result in an error.

The GSS4200 manual you posted is a bit younger than the first one I got,
but materially they're pretty much identical.

--Andrew


Andrew E. Kalman, Ph.D.


On Sat, Apr 24, 2021 at 2:13 AM Nigel gm8pzr via time-nuts <
time-nuts@lists.febo.com> wrote:

> Spirent have indeed done a very good job of removing just about everything
> from the public domain.Having spent many hours a few years ago trying to
> find a copy of SimChan for the GSS4100 I also had to give up, despite
> finding references not that much older which indicated it had previously
> been readily available.I think the crunch came when a lot of Spirent gear
> hit the surplus market and perhaps affected sales of new equipment, so
> can't really blame them.
>
> I do have the user manual for the GSS4200, it doesn't seem to have a vast
> amount of detail but does cross reference in places to the GSS4100, which
> can also be directly controlled via GPIB, so I have now updated my previous
> GSS4100 file on Mediafire to include both.The file also includes some USB
> drivers, although I always used GPIB, plus a few Spirent App notes etc
> https://www.mediafire.com/file/di0jiayxlz0demg/Spirent_4100_4200.zip/file
> I've checked that the file downloads ok but any problems please let me
> know and I can try again.
> I never did come across a copy of SimChan so if you ever find that I know
> I won't be the only who'd be grateful for a copy:-)
> Nigel GM8PZR
>
>
> I am ** desperate ** for a User Manual for the Spirent GSS4200 GNSS
> simulator (e.g.,
> https://www.testequipmentconnection.com/54837/Spirent_GSS4200.php). That
> model is somewhat unique, in that it's one of only a very few that Spirent
> released that can/will run without an external "control" program. Using the
> manual from the GSS6100, I'm able to do a couple of things with the GSS4200
> over GPIB, but for the life of me I cannot figure out how to get the
> GSS4200 into a mode other than single-channel (it supports 6 channels, and
> has a single-channel mode). I suspect there is a command to do this, but I
> have not been able to figure it out.
>
> I have spent 8+ hours searching sites and archives, to no avail. Spirent
> has done a rather impressive job of locking down their support software and
> docs behind a paywall (and I wonder if they even have the docs for the
> GSS4200 any more). Any help is appreciated, I'm happy to give back if
> someone wants to snag another GSS4200 (around $700 used) and use it as a
> simulator.
>
> Thanks,
> ___
> Andrew E. Kalman, Ph.D.a...@pumpkininc.com
>
>
>
> *
> -Original Message-
> From: time-nuts-requ...@lists.febo.com
> To: time-nuts@lists.febo.com
> Sent: Sat, 24 Apr 2021 8:30
> Subject: time-nuts Digest, Vol 201, Issue 30
>
> ___
> time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send
> an email to time-nuts-le...@lists.febo.com
> To unsubscribe, go to and follow the instructions there.
___
time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an 
email to time-nuts-le...@lists.febo.com
To unsubscribe, go to and follow the instructions there.

[time-nuts] Re: 20210423: Introduction and Request for Spirent GSS4200 User Manual / Help

[Andrew Kalman]

So, an update. I was graciously provided with the User Manual for the
GSS4200 (thank you!). Having read through it and having played with my
GSS4200, I conclude the following:

   - My unit is functionally working (well) -- 10MHz clock was not far off,
   output levels are correct, etc., it is generating a signal where one should
   be.
   - Most of the "commanded" behavior I had been observing (using the
   GSS6100 user manual as a guide, issuing commands over GPIB) was the
   behavior of the unit when operating in GSS6100 emulation mode (single
   channel, ability to change the SVID, maybe the ability to change the week,
   etc.).
   - This GSS4200 has (sadly) only one scenario loaded in its NVM memory --
   "4200calibration" that is 10 minutes long. It basically outputs a
   single-channel signal on PRN 1, makes sense for calibration.
   - Based on my reading of the manual, at a minimum, if you have access to
   the utilities CD ROM, you can load scenario "libraries" (#sats, signal
   strengths, ground trajectories, etc.) and then run them (in a looping mode,
   if you want) on this unit. A combination of utilities (that work only over
   USB) load scenarios into the GSS4200.
   - Each scenario also includes the appropriate ephemeris and almanac info
   (provided by Spirent).
   - Scenarios must be under 5 minutes long.Dunno how the 4200calibration
   scenario is 600s long ...
   - The scenario and other file formats are not / not well documented.
   Spirent had a server that you would provide scenario requests to, and I'm
   guessing that it would generate the scenario file along with the
   accompanying ephemeris and almanac info, and crunch that all into a .scb
   scenario file. You can then use a provided utility to combine multiple
   scenarios into a scenario library that you can then load into the GSS4200.
   Note that there is no obvious way for a user to ** generate **  their own
   scenarios (or ephemeris or almanac).
   - GSS6100 emulation is "independent" of GSS4200 scenario operation. For
   example, the GSS4200 manual does not mention an explicit level command
   (that is part of the GSS6100's command set), yet the example scenarios
   alter the output level, so clearly the unit can do that.
   - So, the intended way to use this unit appears to be:
  - Obtain supplied/default scenarios (*.scb) or ones built for you via
  the Spirent web interface
  - Optionally combine them into libraries (*.scl) via the Scenario
  Selection Tool
  - Download them into the GSS4200 (max 512KB worth) using the Flash
  Loader Utility
  - Run the scenario via RUNS  for one run, or LOOP  for looping,
  where  is the scenario number.


   - So, I'm kinda stuck here. I want the GSS4200 available for a quick and
   consistent validation of the proper operation of GPS receivers. For that,
   at a minimum, I need some complete scenarios (the default ones supplied
   with the unit would be alright) that I can load into the unit to run in
   looping mode. There are 18 default scenarios, 3 each (different power
   levels, stationary vs. moving, etc.) for six cities: Boston, LA, Tokyo,
   Hanover, Seoul and Shanghai.They all run at various dates in 2003,
   suggesting that the GSS4200 was released around that time.
   - My unit only has the one calibration scenario (PRN 1 only, standard
   output level) loaded ... I'm not really clear on the usefulness of a single
   channel of GPS signal.
   - This unit differs from more modern units like Spectracom/Orolia GSG
   series units in that the newer units allow you to generate your own
   scenarios, and they pull ephemeris and almanac data directly from the
   internet. Plus more channels and constellations, more interference and
   other simulations, etc.

So, I conclude that without the full GSS4200 utilities disk, I'm kinda
stuck. :-(

--Andrew

----
Andrew E. Kalman, Ph.D.


On Fri, Apr 23, 2021 at 1:15 PM Andrew Kalman  wrote:

> Hello.
>
> [SNIP]
>
> I am ** desperate ** for a User Manual for the Spirent GSS4200 GNSS
> simulator (e.g.,
> https://www.testequipmentconnection.com/54837/Spirent_GSS4200.php). That
> model is somewhat unique, in that it's one of only a very few that Spirent
> released that can/will run without an external "control" program. Using the
> manual from the GSS6100, I'm able to do a couple of things with the GSS4200
> over GPIB, but for the life of me I cannot figure out how to get the
> GSS4200 into a mode other than single-channel (it supports 6 channels, and
> has a single-channel mode). I suspect there is a command to do this, but I
> have not been able to figure it out.
>
> I have spent 8+ hours searching sites and archives, to no avail. Spirent
> has done a rather impressive job of locking down their support software and
> docs behind a paywall 

[time-nuts] 20210423: Introduction and Request for Spirent GSS4200 User Manual / Help

[Andrew Kalman]

Hello.

This is my first post. I'm an EE who also dabbles in ME and CS. My first
real job was at SRS (Stanford Research Systems), where I designed the
look-and-feel and functionality of the SR560 (still in production, wow!),
albeit with John Willison's help on the cascode front-end aiding this
freshly minted EE. Since then I moved to the aerospace and IoT industries.

I currently use, maintain and upgrade instruments from HP/Agilent, XL
Microwave (I love their frequency counters), SRS, Adret, Spectracom and
others, plus some mid-70's audio as well.

I am ** desperate ** for a User Manual for the Spirent GSS4200 GNSS
simulator (e.g.,
https://www.testequipmentconnection.com/54837/Spirent_GSS4200.php). That
model is somewhat unique, in that it's one of only a very few that Spirent
released that can/will run without an external "control" program. Using the
manual from the GSS6100, I'm able to do a couple of things with the GSS4200
over GPIB, but for the life of me I cannot figure out how to get the
GSS4200 into a mode other than single-channel (it supports 6 channels, and
has a single-channel mode). I suspect there is a command to do this, but I
have not been able to figure it out.

I have spent 8+ hours searching sites and archives, to no avail. Spirent
has done a rather impressive job of locking down their support software and
docs behind a paywall (and I wonder if they even have the docs for the
GSS4200 any more). Any help is appreciated, I'm happy to give back if
someone wants to snag another GSS4200 (around $700 used) and use it as a
simulator.

Thanks,
___
Andrew E. Kalman, Ph.D.a...@pumpkininc.com

President
Pumpkin, Inc.
750 Naples Street
San Francisco, CA 94112  USA
tel: (415) 584-6360
fax: (415) 585-7948
web: http://www.pumpkinspace.com

*The information contained in this email message is intended only for the
use of the individual or entity to which it is addressed and may contain
information that is confidential. Furthermore, this information may be
protected by Federal law relating to confidentiality (42 CFR Part 2)
prohibiting any further disclosure. If the reader of this message is not
the intended recipient or the employee or agent responsible for delivering
this message to its intended recipient, you are hereby notified that any
review, dissemination, distribution or copying of the communication is
strictly prohibited. If you have received this communication in error,
please notify Pumpkin, Inc. immediately by telephone, email or fax and
return the original message to us via the means by which it was originally
delivered. Thank you.*
___
___
time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an 
email to time-nuts-le...@lists.febo.com
To unsubscribe, go to and follow the instructions there.