Surf Diaries 2006

3 steps forward and 2 back...

Although the noise source for the radio Jove antenna was installed correctly, over the past few days we have noticed that it seems to be working erroneously.  The problem now is determining what exactly is causing the problem and how to fix it.  Briefly, the problem involves seeing very little variation in signal between calibration steps, where we should see the received signal roughly double at each higher step. 

In other news the noise generator for the CURT1 dish has been removed, fixed, and re-installed on the dish, and appears at this point to be working correctly.  Although a rough calibration method has been determined through daily solar scans and data from the SEC, a working noise source should allow for a more accurate calibration. 

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Yesterday we received the noise generator we ordered from RF Associates LLC in Honolulu, HI.  In addition to calibration of signals from the JOVE antenna, the use of the noise generator allows the user to determine background radio-noise levels.  This measurement is significant because it describes the 'noisiness' of the receiving site.  A good site would have low noise contribution from interference.  For some time on the project I have wondered how radio-loud or radio-quiet the Town of Ashland was and the noise generator allowed for that determination at 20MHz. 

 The following link illustrates this measurement using the SkyPipe software package.  Calibration levels have been labeled using Microsoft Paint. (You will probably have to view the picture at its highest resolution in order to read the font.)

http://i96.photobucket.com/albums/l176/repullin/RFNoiseLevel.jpg

 As you can see the 3^rd calibration level, antenna temperature of 173,000 degrees Kelvin, is roughly equivalent to our background measurement.  Generally the galactic background radiation is at a temperature of about 50,000 degrees Kelvin at 20MHz, and thus Ashland can be considered comparatively radio-loud.  Because solar bursts can be 12dB above background, this excessive noise should not be a problem in receiving solar signals. 

 This measurement was conducted at approximately 10:00AM local time, and is generally conducted at night, for more accurate results I intend to repeat the test at night. 

 Undoubtedly this has been a major improvement to the JOVE antenna and accurate calibration will allow for much better synthesis of Solar and Jovian data in the future. 

Posted by rpullin | Permanent Link

This week I have been busy working with the CURT 2 antenna located on the roof of Copley Science Center at RMC.  The polarity switch I spoke of in the previous journal has been installed does not seem to cause any significant signal loss at 20MHz.  The switch allows the conversion from anti-phase to in-phase without having to reconfigure the array.  More simply stated, the switch converts the signal from the shielding of a coaxial wire to the center wire, and the signal from the center wire to the shielding.

With the array left in-phase the beam pattern of the antenna coincides with the path of the sun across the sky thus allowing for solar observation.  We began recording data this morning at 13:00 UTC (09:00 EDT) and concluded at around 18:00 UTC.  During this time several bursts were recorded although it is unknown whether their origins were solar or local radio interference.

Concerning calibration of the CURT 2 antenna, a radio frequency (RF) noise generator was purchased early this week from RF Associates LLC, and should arrive in time for installation before the end of summer.  This equipment will allow for calibration of results recorded with the JOVE receiver, and works particularly well with the SkyPipe software package we have been using to record data. 

Additional solar scans at 1.4GHz are still being conducted daily at local noon (16:00UTC) in an effort to calibrate the CURT 1 dish. 

Posted by rpullin | Permanent Link

The past week has brought considerable progress to the project.  A switch was constructed that reverses the polarity of the CURT 2 antenna without having to physically alter the dipole.  This will reduce the time it takes to change the array from in-phase to anti-phase, and hopefully will increase the functionality of the antenna.  There was a concern that installing the switch could cause significant signal loss at 20 MHz, although for the moment this problem seems to be avoided with securely soldered connections. 

Steps towards calibration are also being made on the CURT 1 dish.  Three successful solar scans were conducted last week and matched with simultaneous radio flux data from Sagamore Hill, PA, USA.  Although the forecast is for scattered thunderstorms, if it stays sunny outside we should be able to conduct another scan today.  Additionally, steps towards improved alignment and pointing accuracy are also being made on the dish.

Posted by rpullin | Permanent Link

It is convenient that it would rain the week we planned to conduct daily solar observations.  By the end of the summer we should be able to point the CURT 1 dish without the aid of the sun's shadow, for now, we can hope for better weather. 

This week's forecast:

Posted by rpullin | Permanent Link

At local noon everyday (16:00 UTC) solar flux values are reported at 1.4 GHz by the SEC/NOAA.  As a result I am going to attempt to calibrate CURT 1 by continuously comparing the voltage received from solar observations at noon in Ashland, with flux density values reported online.  The level of correlation should illustrate the accuracy of the calibration.  For radio dim objects I plan to conduct several lunar scans.  The moon is much less variable than the sun and has a relatively constant radio flux associated with it.  Currently we are working on zeroing the telescope at zenith which should improve the pointing accuracy of the dish.

Posted by rpullin | Permanent Link

FIRSTLY: The following website provides a live view of the Keeble Observatory and Small Radio Telescope Project (SRT) named CURT-1.

http://spagnacam.rmc.edu/view/index.shtml(R-MC Campus Only)

I understand that the planning stage is a difficult part of each project.  I've heard it can take days before real progress begins to show itself, and I'm starting to believe it. 

Posted by rpullin | Permanent Link