ENGINEERING NOTE BOOK CHAPTER 2.

20. WiNRADiO 1500 AGC Defeat 10/14/99 - Like most receives the WiNRADiO 1500 has an Automatic Gain Control (AGC) that is always on.  The point of the AGC is to reduce the gain of the receiver in the presence of loud signals so that they don't distort in the detector stage.  For SETI this is an undesirable feature.  We want all the gain all the time.  A loud signal is never of interest to us.  The one drawback is that this will disable the signal meter on the radio control panel.  

The people at WiNRADiO have sent me the instructions in an e-mail and suggested that I publish the step-by-step modifications so that someone else may profit by my experience.  

19. RF Test Range 10/10/99 - I need to build a small stub antenna that I can drive with the Weak Signal Source and use it to test the received pattern of the main dish.  The problem is that the dish cannot be made to point down so that antenna must be place high enough so that it wont have to.  The antenna appearance must also be acceptable to my wife and still be as far from the main dish as possible.

This was accomplished by building a Flag Pole antenna that looks good and also flies the Flag Of Earth.

1. Purchase the following

• 1 - 14 foot 1 inch diameter dowel from the local hardware store
• 3 - pulleys
• 1 cleat
• 50' nylon line that will fit through the pulleys
• BNC connector
• Length of sealing tape from Ham Radio Outlet
• 2 swivels for the flag
• 3 Eye screws
• 21 cm antenna (BNC connector and short solid wire)

2. Paint the dowel

3. Attach the pulleys for the flag at 4 foot intervals (one at the top) and eye screws for the co-ax.)

4. Run RG-58 up through the eye screws and terminate at the BNC connector

5. Apply sealing tape to the BNC and plug in the 21 cm stub antenna.  More sealing tape.

6. Mount to the side of the deck   on a 45 deg angle for that nautical look and salute as the flag goes up.  Task Complete

18. SETI Net Dynamic Address 9/27/99 - 

SETI Net, the web site you are viewing now, runs on a computer in my home.  The SETI software and hardware also runs on this same computer.  You accessed this computer through a service called NameSecure that redirects HTTP requests to my computers dynamic IP address.  The IP address is assigned to my computer by my cable television company when I start the computer and log into the there system, it is a dynamic IP.

The problem is that NameSecure must be updated when ever my IP address changes or you, dear reader, will get a an error from you browser (we wouldn't want that to happen now would we?).  This happens if the cable company has to reboot there login server or if I have my computer off for an extended period of time - 1 or 2 hours.  If my computer is off for a short period the cable company doesn't know about it and lease on the IP remains if effect when I restart but if its off for a while SETI.Net will be dead to the world.

The application must do the following:

• Start - Come to life.  This could be as a result of the NT scheduling daemon "@" timing out.

• Get IP - Access the current IP assigned to the machine by my cable company.

• Log In - Log into NameSecure by sending the account and password needed.

• Test - Verify that the actual IP and the NameSecure IP match.

• Correct - If they match sign off.  If they do not match correct then sign off. 

• Log File - Update the log file and shutdown

Implementation:

1. Components.  Selected two Delphi components for the job.  I will use the Internet Commerce Kit (ickHTTP) component from devSoft  to handle the TCP/IP communications with NameSecure and an HTML 4.0 parser from Legitima Software (TLegHtmlParser).  These components were searched for and found through various Delphi web sites and were downloaded for evaluation.  If the projects works as well as expected I will have to pay for both of them.  Until then they both put up a 'nag screen' each time I start the application during development.
2. Organization. I will build a three state machine as follows:

1. CustomerCare -This state will fill in the domain name of SETI Net (which is SETI.Net) and a password previously given to me by NameSecure.  The domain name, password, and Submit command will be loaded into the ickHTTP component's PostData property.  The URL property will be filled with: 'http://updates.namesecure.com/cgi-bin/customer_care/authorize.cgi'.  The Action property will be set to ickHTTPPost.  This series of actions will cause the application to connect to NameSecure and send back the second page for the upDateCenter to analyze.
2. UpDateCenter - this state will parse the retuned page looking for an anchor tag  ("<a>") that has an HTTP reference ("href") to the NameSecure change_url page.  When found the URL will be sent back to NameSecure so that the third page (URLChange) will be sent back.  The necessary properties will be set into ickHTPP but this time GET will be used rather then POST to bring back the page.  This will bring the page in and start the URLChange state.
3. URLChange - The update state will pick up the IP address of the local machine and send it back to NameSecure to make the final change.  The results will be tested and an entry made to the log file.  The application will then dismiss itself.

3. Coding -   Purchased ick components and decided to use the XML parser that came with ick rather than the Legitima Software parser.  Added another component from the suite of TCP/IP components that is supplied with Delphi to enable access of the local IP address.

Initial prototype application operational.  More work will be required to build a reliable (the prototype doesn't handle exceptions) program that will run without user intervention.

 I won't be able to post the source because it will contain passwords and access codes necessary for operation. Task Complete

17. WinRadio receiving the Weak Signal Source 9/13/99 - I am seeing the following on the spectrum analyzer of the WiNRADiO Radio 1500 installed in the computer.  This doesn't seem right to me.  It looks like it s about 27 KHz wide.

Weak Signal Source (WSS) as viewed on the receiver (thumbnail).

  This is the WSS as viewed using my HP 141T Spectrum Analyzer, 2 KHz Scan width per division and 1 KHz Band Width.  This shows the signal to be about 4 KHz wide.  Still wider than I expected but that could be the limits of my test equipment.  

The WSS was routed through a 3 db splitter with one arm to the HP 141 and the other to a counter to make sure it was on frequency.

The next step will be to move the WSS a long way from the horn to make sure I am not simply overloading the front end of the WinRadio 1500.  This suggestion came from Paul Shuch of the SETI League ( www.setileague.org ). 

I attempted to move the WSS about a mile away but then it could not be found by the receiver.  I found that the WSS had 'hopped' down to the 11 harmonic, rather than the 12th and was out of band.  I guess I'll have to fix this before I go any further.   

The fix to the WSS turned out to be simple.  I simply compressed L1 as the directions suggested and made a better case to ground plane connection at the antenna and everything seems to work.  I noticed that the 11 harmonic is still present and only down about 3 db from the water hole 12th but it does work.

After fixing the WSS I moved it to the other side of the house to be sure that it wasn't overloading the front end.  The signal went way down in the mud but the shape remained the same - still about 27 KHz wide.  The next step is to contact WinRadio via e-mail for advice.

Problem solved 9/21/99.  The folks at WiNRADiO pointed out that I had the Resolution Bandwidth set to 17 kHz and therefore every signal would appear to be 17 kHz wide as it slid through the radio.  Makes sense.  On to the next problem.

16. WiNRADiO installed 9/5/99 - The WinRadio 1500 was finally installed after a long time doing other non SETI tasks.  It came right up. 

 Task Complete. 

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