SUG Minutes 29 April, 2015
In attendance: Jim T, Chuck, Shing, Wes, Tom, Jim Sky, Dick
Station reports
Wes – plans to be off the air for a month or so this summer – to upgrade his radio room and given the heat of the summer – install the TFD polarimeter.
All observers are urged to keep an engineering log and update their system drawings for the SUG site.
Spectrograph Network The education proposal being submitted by Shing et al includes money for 5 years for development of clusters of radio spectrographs. The goal is to establish a cluster of 5 stations each year. Each cluster will include stations located within tens of km of each other. Software and hardware will need to be developed as well as data archiving and analysis capabilities. Funds may also be available to upgrade and standardize existing SUG network stations. We should learn by years end if this proposal has been accepted. During the coming months we will begin to develop the cluster system design in the hope that funding will become available. Adding to the challenge is the obvious fact that technology is rapidly changing – with many new offerings in terms of software defined radios (SDR). The experience and expertise of the current SUG station operators will be key to developing a successful network concept.
Spectrograph data from the 28 February storm is awaiting cross correlation analysis by Francisco to determine the time offset between similar spectral features at different stations. It is unlikely that this observed time offset is caused by computer clock timing errors at any of the stations. Tom, Wes (and Wes for Dave) reported that their station timing errors are less than 1 second.
Spectrograph and SkyPipe Data Archiving Jim Sky and Baptiste continue working on methods and procedures to archive “Jove/SUG” spectro data in France. Some of the detailed work underway involves file conversion and developing transmission protocols so that spectrograph stations are not burdened with any additional work while making data available for the archive. In addition to the French system we are aware of various archiving opportunities in the US and within NASA, such as the PDS and VWO. It was suggested that before proceeding too far in detailed development of a system to meet the French requests, that an archiving architecture be developed which will assure that no unnecessary duplications of effort are required so that our data are available for both French and US systems. The data archiving architecture should also integrate with the spectrograph station clusters, if that grant is forthcoming. Chuck will set up a telecon during the MOP meeting to allow discussion of these opportunities.
Polarization switching and time synchronized spectrographs Jim Sky is continuing work on software mods to allow use of a polarization switch in front of an FSX spectrograph. He is also looking at what will be required to sync all of our spectrographs using GPS timing. Those that want the upgrades will send their FSX machine for a brief Hawaii vacation. The DDS ADC PIC module will be upgraded to accommodate both mods. A polarization switch will be added to each machine.
The actual GPS sync timing mod will likely be completed sometime in the future – now I only plan to add a connector wired to the PIC for input of the GPS timing code. When the timing mod is fully implemented a new PIC will be installed (or perhaps the PIC code will simply be updated). I would also like to upgrade the early FSX (1, 2, 3) machines to a new 12 bit ADC at the same time I add the polarization switch – this will make all the FSX machines similar, using the same PIC code.
New SDR developments Jim Sky has received the AirSpy radio (thanks Chuck) which is apparently capable of outputting a 10 MHz wide spectrum. This $200 unit will be evaluated for RF performance and software compatibility with RSS. Jim also told us about a Cuban ham operator who is experimenting with a standard RTL dongle. The basic dongle is capable of outputting a 2 MHz wide spectrum but he is stepping the center frequency in 2 MHz increments to synthesize a wider spectrum display – apparently sampling a total of 10 MHz at about 7 times per second. Jim Brown continues to experiment with two different dongles, one the unit purchased at SARA and the other a Nooelec unit which is supposed to have superior performance.
Jim Brown’s antenna performance Jim and Dick have been working to evaluate the efficiency of the extended LWA antennas in use at HNRAO. Basically the goal is to estimate the antenna temperature delivered from the fork style antennas to the active balun amplifiers. Jim has measured the galactic background temperature using a Jove dual dipole array. At the same time he has measured the GB temperature delivered to the input of the spectrograph at 20.06 MHz.. This temp was 1.18Mk. Since we know the gain of the active baluns (19 dB) and the intervening cable loss (3.1dB) we can compute the antenna temperature at the input to the active balun. The result is that the LWA forks appear to be over 50% efficient. This is much higher than expected. It may be that the droopy forks have better noise pickup close to the horizon – hence raising the antenna temp a few dB above that measured with the Jove dipoles. We plan to investigate this possibility by orienting one set of LWA forks in the horizontal plane – instead of their present 45 degree down droop.
Phase Plane Dave continues to work on populating the phase plane with data from the last apparition. He is reading Jovian activity periods at several different frequencies – a mind numbing task I am sure. This work is in collaboration with Chuck who I understand has provided Dave with some of the UFRO fixed frequency data from the TP array.
END OF SEASON
This was the final meeting of the SUG for the 2014/2015 observing season. Thanks to all who have contributed their observations to the listserve and the Jove archive.
In particular thanks to all who have joined in the SUG telecon discussions.
Beyond Jupiter and the Sun, members have observed scintillations of Cass A and possibly Virgo as well as interesting ionospheric propagation effects. The future of spectrograph observations looks exciting with more stations coming on line with polarization measurements. New equipment is becoming available which may make useful spectrograph observations possible for less money.
Antenna developments including the TFD and LWA antennas are yielding improved frequency coverage. Software upgrades have kept us connected with improved capabilities.
Dr Shing Fung has brought welcome scientific expertise to our group and we all extend our thanks for his promoting the vision of an expanded network of spectrographs in the years to come.
We will reconvene a few weeks before the next observing season starts in the fall.
dick
Next SUG Telecon TBD (844)467-6272, 352297#