[Pafgbt] BYU backend testing in GB

[Bill Shillue]

Karl, 

Thanks for the slides.  We have met many excellent people here at CSIRO, and I am sure that Brian will have a great interaction when he comes.

I am preparing my presentation and will include some of your slides.  I would like to know a little more  about the feeds.  If I understand correctly, there are three versions of the BYU dipoles: kite, GBT1, and GBT2.  We currently have kite installed.  GBT1 has been replaced by GBT2 before it was ever used, and GBT2 represents a more optimized version.  

Questions:

1. Why is there such a large change in the angles P3 and P5?  Do you attach any significance to these angles: ie does increase in P3 generally mean wider bandwidth?  What does p5 do electromagnetically?  I might guess that it allows you to increase the physical length of the dipole while having less coupling to an adjacent element?  But it is not clear how the angle affects the   single element dipole pattern.  What would happen if p5 was 98 degrees instead of 82 degrees?  Or do questions like this have no place since the computer optimization determines all...?

2. The last plot is a nice way to show the optimization.  There are three cases:
(a) kite at 20m spacing
(b) GBT2 at 20m spacing
(c)GBT2 at wider spacing

And the plot seems to show that
 (a) has higher Tsys/Aeff but good FoV
(b) has low Tsys/Aeff but less FoV
 (c) has low Tsys/Aeff and good FoV

Is that summary correct?  20 K seems very low.  Can  you explain how you get that?  What is the Aeff in that case?  Can you say what causes the large Tsys/Aeff of "Kite" at the low end of the band (1.2 GHz) while at 1.5 GHz it is so good (even better than GBT2?!)

Thanks,

Bill


-----Original Message-----
From: Karl Warnick [mailto:warnick at ee.byu.edu] 
Sent: Tuesday, April 23, 2013 5:12 PM
To: Bill Shillue
Cc: Brian Jeffs
Subject: Re: BYU backend testing in GB

Bill,

Per your request in yesterday's telecon, attached are slides for your talk in Australia. Have a great trip, and please pass on our greetings to the group there.

Karl

On 4/19/2013 2:49 PM, Bill Shillue wrote:
> ok for 4.30 pm
>
> One other issue I should bring up now...I was just talking to Bob Simon and he mentioned that he was expecting dipole parts from you.  He was wondering where that was at (knowing you have been traveling), but if he gets these very soon he might have time to get the work started before we travel next Thursday.
>
> Bill
>
> -----Original Message-----
> From: Karl Warnick [mailto:warnick at ee.byu.edu]
> Sent: Friday, April 19, 2013 3:43 PM
> To: Bill Shillue
> Cc: Brian Jeffs
> Subject: Re: BYU backend testing in GB
>
> Sure..
>
> On 4/19/2013 1:40 PM, Bill Shillue wrote:
>> Can we push this meeting until Monday 4.30 pm EDT 2.30  pm MDT
>>
>> A meeting I had at 3 pm got pushed to 3.30 ...
>>
>> Bill
>>
>>
>> -----Original Message-----
>> From: Karl Warnick [mailto:warnick at ee.byu.edu]
>> Sent: Thursday, April 18, 2013 12:01 PM
>> To: Bill Shillue
>> Cc: Brian Jeffs
>> Subject: Re: BYU backend testing in GB
>>
>> Works for me. My number is 801-422-1732, and I can conference Brian in (if the time works for him as well).
>>
>> Karl
>>
>> On 4/18/2013 9:57 AM, Bill Shillue wrote:
>>> how about Monday 4 pm EDT 2 pm MDT?
>>>
>>> I may be away from my office so if you provide a number I can call you there.
>>>
>>> Bill
>>>
>>> -----Original Message-----
>>> From: Karl Warnick [mailto:warnick at ee.byu.edu]
>>> Sent: Thursday, April 18, 2013 11:55 AM
>>> To: Bill Shillue
>>> Cc: Brian Jeffs
>>> Subject: Re: BYU backend testing in GB
>>>
>>> Sounds good. Either Friday or Monday should work for a call.
>>>
>>> Karl
>>>
>>> On 4/18/2013 9:51 AM, Bill Shillue wrote:
>>>> I can update you at the very end of this week (Friday between 4-5 EDT) or early next week about GB PAF status if you like.
>>>>
>>>> Interesting comments on ASKAP.
>>>>
>>>> Bill
>>>>
>>>>
>>>>
>>>> -----Original Message-----
>>>> From: warnick at ee.byu.edu [mailto:warnick at ee.byu.edu]
>>>> Sent: Saturday, April 13, 2013 3:05 AM
>>>> To: Bill Shillue
>>>> Cc: Brian Jeffs
>>>> Subject: Re: BYU backend testing in GB
>>>>
>>>> Bill,
>>>>
>>>> Thanks for the update. I hope your trip to CSIRO is worthwhile. I met with Carole Jackson here in Gothenburg (who is leaving CSIRO, by the way), as well as a number of other members of the worldwide PAF community. There were rumors of performance problems with the ASKAP front end at the meeting. The BYU/NRAO collaboration, while small in terms of total numbers of people involved, has been quite successful in terms of basic performance metrics such as sensitivity. I'll be interested to hear what you find after your visit.
>>>>
>>>> Keep us posted on the cryo LNA problems and schedule for GBT tests.
>>>>
>>>> Karl
>>>>
>>>>> Our team will be visiting ASKAP 4/25--5/11.  Tony Beasley is 
>>>>> encouraging us to be more outward looking, so this will be a good 
>>>>> opportunity for us to see the amazing work that they have done in Australia.
>>>>>
>>>>> Testing could in principle take place in GB after that, the latter 
>>>>> half of May.  However, there may be some issues.  The most 
>>>>> critical is that we appear to have some failed amplifiers.  This may not in itself prevent all
>>>>> the tests, but we have scheduled GBT test time in June.   If we can we
>>>>> would like to meet that date.  If the amplifiers have failed as we 
>>>>> suspect, we have been discussing whether we could repair 
>>>>> amplifiers and recover in time for the GBT test.
>>>>>
>>>>> My current thinking is that we will likely have to postpone the GBT test.
>>>>> This is all fairly late breaking.  We will know more by the end of 
>>>>> this week I think.
>>>>>
>>>>> I think it would be worth having a conference call with you to 
>>>>> discuss more, maybe next week?
>>>>>
>>>>> Bill
>>>>>
>>>>>
>>> --
>>> Karl F. Warnick
>>> Department of Electrical and Computer Engineering Brigham Young 
>>> University
>>> 459 Clyde Building
>>> Provo, UT 84602
>>> (801) 422-1732
>>>
>>>
>>>
>>>
>>>
>> --
>> Karl F. Warnick
>> Department of Electrical and Computer Engineering Brigham Young 
>> University
>> 459 Clyde Building
>> Provo, UT 84602
>> (801) 422-1732
>>
>>
>>
>>
>>
> --
> Karl F. Warnick
> Department of Electrical and Computer Engineering Brigham Young 
> University
> 459 Clyde Building
> Provo, UT 84602
> (801) 422-1732
>
>
>
>
>

--
Karl F. Warnick
Department of Electrical and Computer Engineering Brigham Young University
459 Clyde Building
Provo, UT 84602
(801) 422-1732