[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 <aekalman at gmail.com> 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 <x> for one run, or LOOP <x> for
>       looping, where <x> 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 <aek at pumpkininc.com> 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 (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.
>>
>>