A Week of Data Communications Planning

by Ken Schrock

November 20, 1998

16 Nov

Began web search for reviews on wireless LAN hardware. Also began researching the radio frequency bandwidth requirement for direct sequence spread spectrum bandwidth and waveform. Contacted friend at NASA Marshall that works with rocket telemetry for some suggestions.

Began web search for network throughput analysis software. Compared module for tool we already have to another tool that is cheaper. Can't tell if either has required capability.

Talked with FAA facility people about letting us put a computer and antenna on the on building roof to see if we can use radio system to replace ground lines that the phone companies charge us for every month. Installed on South side of TRACON roof. Asked for FAA to run network cable to my office.

Started looking to borrow spectrum analyzer to measure signals at the antenna.

17 Nov

Took packets from network "sniffer" program and moved from PC to Sun workstation. Later I'll sneaker-net the files from the private Intranet to the Internet on a floppy. It seems low tech, but it keeps the two networks completely isolated. Our Intranet is directly connected to the computers that run the nation's Air Traffic Control system.

After I got out of my astronautics class I checked out a book from the college library on spread spectrum theory. Read section on modulation technique our borrowed equipment uses.

Took the Sun workstation, gave it a new network number so it won't work unless it connects through the wireless LAN.

FAA had a better route to run the network cable from my office to the North side of the roof. Moved the antenna and connected to my Sun.

The Sun came and connected to the network at the building 6 miles away. Started transferring files to check maximum data rate.

18 Nov

Data rate from wireless LAN is less than one-fourth of expected. Asked FAA to put an antenna up in the Center Control Tower antenna floor (100 feet higher than TRACON roof).

Got to look at several sites to mount the antenna on the Center Tower. One catwalk was 130 feet up with an open grate floor. If you dropped a nut or bolt it would fall a LONG way down through the holes in the grate.

Got antenna moved, took Sun workstation from my office and sat it up in the antenna access room.

19 Nov

Data rate on the wireless LAN is not much better than when it was on the TRACON roof.

Took borrowed spectrum analyzer and connected to our wireless LAN antenna. Drew picture of what screen looked like and wrote all numbers down for analysis when I'm at my desk. Found an odd waveform that I didn't expect to see, will need to compare to theory and figure out the reason.

20 Nov

Borrowed another spectrum analyzer and went to the antenna on the other end of the connection. It's on the roof of a different five-story building. Glad we have the network cable run down to one of our offices. Need to get the cable ordered and then run from the Center Tower to one of our hubs.

With this new spectrum analyzer I can't even see the signal coming from the Center Tower. I know it's there because I can reconnect the computer and get data. Another mystery to solve. . .