KG2PM SETI Radio Telescope Project

Test Log

Revision April 22, 2004

Initial test of installation - Saturday, June 24, 2000

The receiver is set at 1420.5 Ghz.

The telescope has received its initial test. In the evening, Mike and I installed the feed, LNA, and receiver. The LNA gets power right out of the receiver. The receiver was modified slightly so that we could pull a DC signal from the signal strength meter and run it to an F connector. The DC signal then runs through a coax cable to a Tektroniks oscilloscope. Then we simply ran a power cord to the receiver, which has a built-in power supply, for the initial test.

Back in the shack, we turned on the oscilloscope and set it to read the DC voltage coming from the antenna installation. We then used a sweep generator to send out a very weak source to see if our scope could detect it. It did, quite easily. The scope displayed nominal reading with no signal applied, and a very definite signal response with the sweep signal generator source.

For the time being, this system will continue to use the DC voltage as the source for analysis. We are awaiting the installation of the Radio Sky Publishing's Data Collector Lite, which uses a dc voltage fed to the computer through an analog to digital converter circuit. This will allow us to generate graphs of the voltage variations, and we can begin to start defining the noise of the system. We also intend to test the system on natural objects known to exist and accessible to small telescopes. In this way, we are attempting to duplicate the approach used by the University of Indianapolis Radio Astronomy Department.

The real work comes now. Radio Astronomy seems to be a matter of spending a great deal of time getting the system to hear something other than its own noise, and if you can get it right, then you just might hear some radio sources in the cosmos. For SETI it is even more difficult because we don't know if the signal we're looking for even exists, and we're not sure how to recognize it if it does. And it may be in a form our telescopes can't detect as yet.

August 27, 2000 Software and A/D Converter Tests

At the present time, tests are being conducted on an analog to digital converter and software which will be used in the data logging and analysis phase of the project.

The a/d converter was made from a Maxim 187 a/d chip according to specifications supplied by Jim Sky of Radio Sky Publishing. The schematic for the a/d converter is here.

The software is Data Collect Lite, also by Radio Sky Publishing. Info on the software is here. At this point, technical problems are being sorted out, and info will be posted here as available.

August 27 Power Supply Problems

The project receiver, the SDR1000, has a built in power supply. In tests with the sweep generator and oscilloscope, an ac ripple was detected in the output. This noise level is not acceptable for our project, so the internal power supply is being bypassed. The receiver has a plug for an external DC supply. An external supply is being installed, and further tests will continue to see if the AC ripple disappears.

September 1, 2000 Argus Telescope EL29 Now Operational

The telescope is now operational and capable of making readings. The AC ripple problem was solved with the installation of an external power supply with better filtering. Although the initial ripple is reduced, we think we still detect a small ripple, and will add a little more filtering to the output for safe measure.

The Data Collect Lite software is still not working correctly with the Maxim chip A/D converter, so we installed the Radio Shack PC interface multimeter (#22-805) and accompanying ScopeView logging software to the system. The telescope is now capable of taking voltage measurements from the receiver/LNA and logging them onto the computer. Since we are not yet looking for information in the form of a modulated message, this sytem is capable of detection of a carrier, or hopefully, an other-than-noise signal. We will also test the multimeter A/D with Data Collect Lite, and continue to troubleshoot the Maxim chip A/D converter.

The next step is to test the system against some astronomical objects. We will use Radio Sky Publishing's Planetarium Software to locate known objects in the 1420.5 MHZ neighborhood and see if the scope can detect them as they cross its beamwidth. If we can detect them, then we will know the telescope is functioning properly.

September 16, 2001 - New Receiver to be installed

The Argus EL29 telescope has not proven useful after a year of admitedly intermittent testing. The scope responds to test signals emitted by our signal generator but to date has not detected even a hint of astronomical rf. Mike, N5LHM, has recently donated a new receiver which he obtained in his routine searches for interesting high tech equipment on the surplus market. The new receiver is a MicroTel Series 1200 Wide Range Receiver, designed for testing microwave antenna systems. It covers 950Mhz to 150 Ghz. In it's present condition it appears functional but the analog tuning dial needs a new cable installed, which is presently being done. Once the dial is repaired and the receiver calibrated, the MicroTel 1200 will replace the SDR1000 data receiver currently installed. The MicroTel is capable of detecting CW, pulse, or square wave modulated signals. We need to devise a way to connect the output to the computer and hopefully to a DSP program for weak signal detection. We may continue to use the Radio Shack Multimeter and Scope program for tests, but for the actual recording of astronomical signals, the DSP approach will almost certainly be necessary. The receiver may also require addition LNAs.

February 25, 2003 - After many months away from the project, I am now getting back to the radio telescope. The Microtel receiver discussed in the previous paragraph but has not been able to be calibrated. Attempts will be made to get it functional, but for now it is definitely a laboratory project. In the meantime, I have decided to put in a new SDR1000 receiver, since I have several of these to work with. This will be done within the next month. The LNA also needs to be tested because the system was flooded out during a thunderstorm. It should be waterproof, but we'll see when we throw the switch.

Final Entry April 22, 2004

This marks the last entry for the Argus Station EL29 Test Log. Repairs on the system have not been made due to a lack of time and funds. In addition, recent thunderstorms brought down the wooden structure holding the dish, so the project is in complete disrepair.

I am still intensely interested in the SETI project and will devote myself to exploring some of the more theoretical and methodological problems of the SETI Search. For now, I will leave the hardware science to those already doing an excellent job on the experimental side of things, namely the talented amateurs of the SetiLeague and the professional radio astronomers of the SETI Institute. I will post ideas on SETI procedures, methodolgy, and theoretical concerns on this site and on the SETILeague site as they deem useful.

KG2PM

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