[Pafgbt] PAF/GBT progress report

[Rick Fisher]

Brian, Richard,

Thanks for your follow-up on the GBT/DAQ interface.  As I mentioned some 
time ago, use of the PAF on the GBT will require a greater degree of 
interface formality than we've used with the 20-meter tests.  I hope you 
don't find this too intimidating.  It's not as daunting as it might look 
at first, and I'll be happy to guide you through the process based on my 
experience with interfacing the ADLink DAQ.  We'll be assigned a software 
engineer from the GBT Monitor and Control group to handle their end of the 
interface, and I've sent an email to the head of that group, Mark 
Whitehead, to get the ball rolling.

The heart of the GBT/PAF interface definition will be a Modification Request 
(MR).  I've attached a copy of the MR web page that we used for the ADLink 
interface.  Again, don't be intimidated by the length of the document, 
some of which is boiler plate and some background to get everyone on the 
same page.  The subsection that you'll tend to focus on is 4.3 and 
particularly 4.3.2, which defines the socket message protocol.  We can use 
the message definitions that you have already defined as a starting point 
and add anything needed to complete the interface definition.  The ADLInk 
interface was pretty simple, and I'd expect yours to be similar, expanded 
mainly to accommodate the greater capability of your device.  In the 
ADLink implementation I defaulted the vast majority of setup parameters 
that we didn't expect to change from the GBT control system just to 
simplify the interface.

That said, we need to try hard to make the interface definition as 
complete as necessary before signing off on the MR since this defines the 
scope of work for the GBT software engineers in managing their time for 
the coming three-month quarter.

I'm happy to share any of the code from the ADLink DAQ interface, but it 
will be pretty tedious to reverse engineer the code to figure out the GBT 
interface.  I'll send you the code, but let's start with your socket 
message definitions to define the sections 4.3 of the new MR.  Since we'll 
probably use the same frequency synthesizers as L.O.s for your new 
receiver and sampler clocks (if needed), the current GPIB interface will 
probably remain the same or nearly so (section 4.3.1).

One thing I did for the ADLink system was to write a graphical user 
interface (GUI) that used the same message protocol as the GBT interface. 
This serves double duty as a test generator for the messages and as an 
operator's console for use of the data acquisition system and PAF in the 
lab and outdoor test building.  The GUI is shown in Figure 2 of

http://www.cv.nrao.edu/~rfisher/ArrayFeed/paf_adlink_stand_alone.html

It's written with the Python WX module tool kit.  I'll send you my code 
and help modify it for your application.  You'll see that I put all of the 
ADLink setup parameters in the GUI for testing purposes, but that may have 
been overkill.

We'll also need to add some parameters to the PAF receiver FITS file 
definition to accommodate your system's setup information.  The aim there 
is to archive every bit of information needed to interpret the data from 
the PAF/DAQ without reference to memory or hand-written notes.  Part of 
the code suite is a FITS file generator in the form of a socket message 
server.  We'll steal this from my code and modify.

Enough for now.  Feel free to ask questions or suggest ways to make it all 
easier.

Regards,
Rick

On Tue, 6 Nov 2012, Brian Jeffs wrote:

> Rick,
>
> Sounds like great progress.  It will be very helpful for us (Richard) to 
> have your GBT/ADLink interface code so he can see how closely he can 
> adapt his DAQ interface to match your control protocols.  Hopefully 
> there will be a minimum of new functionality required.
>
> Thanks,
>
> Brian
>
> On Nov 6, 2012, at 9:55 AM, Rick Fisher wrote:
>
>> A short progress report on the PAF/GBT project:
>>
>> Paul Marganian (in Green Bank) and I have written and tested the first
>> version of the interface between the old ADLink PAF data acquisition
>> system and the GBT monitor and control system.  First-draft instructions
>> for starting the ADLink DAQ system and observing with it on the GBT can be
>> temporarily found at:
>>
>> http://www.cv.nrao.edu/~rfisher/ArrayFeed/PAFonGBT.html
>>
>> http://www.cv.nrao.edu/~rfisher/ArrayFeed/paf_adlink_stand_alone.html
>>
>> Comments welcome.
>>
>> The other major component yet to be added to the GBT control system for
>> PAF testing is a coordinate system for offsetting the GBT position on a
>> rectangular grid centered on a celestial radio source.
>>
>> Adapting the GBT/ADLink interface software to the new BYU
>> spectrometer/Correlator should be considerably easier than writing this
>> first interface from scratch.
>>
>> --------
>>
>> Also, Richard Black at BYU sent me a sample raw data output file from the
>> spectrometer mode of the new BYU spectrometer/correlator/beamformer along
>> with initial documentation on this system.  Aside from a couple of
>> detailed questions, it looks like we have read and plotted the first
>> spectra correctly at NRAO.
>>
>> Thanks to Paul and Richard!
>>
>> Regards,
>> Rick
>>
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