Cutting-edge diy projects

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Cutting-edge diy projects

Monthly Archives: July 2019

Expanding the 12 ft EME Dish

Posted on by Posted in Amateur Radio N2QG, David

As I had mentioned in the reflector discussion, my municipal permit allows my dish antenna to be up to 15 ft in diameter, so a project that will possibly precede the erection of the two towers is to expand the diameter of my EME dish from 12 ft to 15 ft.  I’ve been looking at how other hams have done it, and I think that the following are the best examples of what I would like to do:

This increase in diameter should have a theoretical gain change from 11.3dB to 13.6 dB at 1296 MHz.

I would be interested in knowing any experiences by other hams who have modified their dishes for larger D.  Anyone tried doing it to a Tek2000 dish?

 

 

 

 

Antenna Garden Expansion Plans at my QTH

Posted on by Posted in Amateur Radio N2QG, David

I have received approval from the XYL for expanding my antenna garden, so I’m planning the projects for the upcoming fall and spring.  NJ law allows me to put up a 70 ft tall tower (excluding the antenna) without interference from the township, so I’m planning to take it all the way to that height.

The tower next to the house can be supported against the outer wall of the house, and I’m intending to place a 6-element HF beam and a a large 2m/70cm EME array on top of that tower.  My limitation is a 16 ft boom so that I can keep within 15 ft of my property line.  That’s certainly enough for a large, high-gain array.

The second project is to elevate the current 12 ft microwave dish to expand my horizon.  This will need a very heavy-duty, self-standing tower because of the wind load presented by the dish.  I need to take some measurements and see what would be the best compromise between height and achieved minimum inclination, but I feel that will fall somewhere around the 30 ft range.

I’m currently looking at the specs of ROHN towers, and would love to hear feedback from current users under similar load conditions.

 

PS.  Finishing the power amplifiers for 1296MHz EME right now… see you soon on the Moon at 23cm!

Modifying a Tek2000 12ft Dish for Az/El Rotation with a SPID BIG-RAS Rotator

Posted on by Posted in Amateur Radio N2QG, David, Radio Astronomy

I am now concentrating the bulk of my ham activities in the microwave region, and have CW EME and amateur DSN as my top projects. My goal was thus to install a relatively large prime-focus dish to be moved by a heavy-duty Az/El rotator.

In this whitepaper I describe how I modified a Tek2000.com 12 ft TVRO mesh dish so that it can be moved by a SPID BIG-RAS Az/El rotator.

Location of whitepaper:  Tek2000 antenna on AzEl – N2QG

 

 

Using the Trivec-Avant AV2040-2 Military Wideband SATCOM Antenna in the Amateur Radio Bands

Posted on by Posted in Amateur Radio N2QG, David

It’s July 20, 2019, and I am invited to a private screening of the CNN Apollo 11 documentary, followed by a party with my fellow nerds, so I don’t really have time today to work the sats. It’s 102ºF outside, so not a good day to tweak the antennas either, but I nevertheless wanted to do something space-related to celebrate the 50th anniversary of the Apollo 11 Moon landing.

As a compromise, I decided to test a Trivec-Avant AV2040-2 SATCOM antenna indoors to see if it would be suitable as a portable antenna in the VHF and UHF ham bands.

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Published data are NOT protected by copyright!

Posted on by Posted in David

I was cleaning my desk today, and came across a folder containing correspondence about a legal threat that I received a few years ago from someone accusing me of copyright infringement.

The accusation was that I had used his published data in one of the figures in one of my books without his permission, and had thus violated his copyright.

For my figure, I had drawn a stylized graph which matched the data presented in his graph, but I didn’t copy his figure.  He acknowledged the fact that I had “changed the colors and style,” but insisted that the fact that he had placed a copyright notice meant that the data were his, and that anyone publishing a graph that matched these data would be infringing on his copyright.

Although presenting and contrasting previously published data are the basis for academic discussion, which is why it didn’t even cross my mind that I would be doing something unethical or illegal by presenting my version of the graph, I wanted to make sure.  Indeed, I was right – in the US, as in most parts of the world, ideas, procedures, and data that can be independently retrieved or replicated (i.e. which are not specific to the subjective viewpoint of their creators) are not subject to copyright.

I also checked with the European Copyright Code, which states that the following are not to be regarded as “expressions within the field of literature, art, or science” that can be protected by copyright:

  • Facts, discoveries, news, and data;
  • Ideas and theories;
  • Procedures, methods of operation, and mathematical concepts.

Furthermore, hearings regarding the US Database and Collections of Information Misappropriation Act of 2003 show that data are not protected under copyright.  It is clearly stated that while certain databases may qualify for copyright protection if they exhibit some modicum of creativity in the selection, arrangement, or coordination of the data, in no case are the data themselves copyrightable.

Bobby Glushko, now the Head of the University of Toronto Scholarly Communications and Copyright Office wrote a very nice article about this very question while the Copyright Program Manager at the University of Michigan.  The article is available online at:

https://deepblue.lib.umich.edu/bitstream/handle/2027.42/83329/copyrightability_of_tables_charts_and_graphs.pdf

Based on the explanations in the article, even if I had taken each single point of data in his chart, and just because it took him effort to acquire these data, it doesn’t mean that the data are subject to copyright protection.   This is because:

“Facts, data, and the representations of those facts and data are excellent examples of things that require much “sweat of the brow” to create, but yet still do not receive copyright protection.”

Please note that I’m not a lawyer, so don’t take any of the above as legal advise.  However, I hope this will be a good starting point for anyone who is threatened by a bully with a false claim of misappropriation of intellectual property based on use of published data.

 

 

Receiving EMWIN and HRIT Services from GOES-16 with XRIT

Posted on by Posted in Amateur Radio N2QG, David

 

CLICK HERE for a detailed writeup  with high-resolution pictures in .pdf format.

The GOES-East (GOES-16) satellite (GOES=Geostationary Operational Environmental Satellite) operated by NASA and the National Oceanic and Atmospheric Administration (NOAA) is exactly due south of my QTH and provides a view of Earth centered right at my longitude (75°W).

GOES-16 transmits two interesting direct services:

  • The EMWIN (Emergency Managers Weather Information Network) service contains weather forecasts, warnings, graphics, and other information directly from the National Weather Service in near-real-time.
  • The HRIT (High Rate Information Transmission) service broadcasts GOES satellite imagery data and other weather-related products.

I wanted to experiment with receiving these services from the GOES 16 satellite, and to do so, I added a small grid parabolic antenna to the Az/El boom that drives my 12’ EME dish. I purchased this antenna on eBay®. It is an Altelix WiFi 24dBi 2.4GHz parabolic dish with N-male connector that sells for $30:

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