I have been licensed as a Ham Radio operator since 1970. After taking the Morse code test several times at the FCC office in downtown Los Angeles, was licensed as WA6ROC (finally!). Passed the Extra test in 1975 at the FCC office in San Francisco, while graduating from UC Berkeley (and operating W6BB). Lots of ham projects have been done over the years, so many that most have been forgotten. Some memorable ones:
· TexNet packet switching network— the first radio-based layer 3 routed amateur network. I designed the custom hardware, the layer 3 routing protocol, uninterruptable supplies, and FSK modifications for the RCA700 radios. Tom Aschenbrenner, then WB5PUC, wrote all the software (Z80 assembly). The system covered about 3000 miles at 9600 baud on the 445.1 MHz. backbone links, and had almost fifty 1200 baud 2 meter entrance links. At one time we had 2000+ users a month check into the system. It provided the first statewide email system in 1987 all radio linked, and provided virtually instantaneous email across the whole system. The members of the Texas Packet Radio Society (TPRS) provided lots of hours, construction, and donated equipment to construct all the nodes. The system was decommissioned in 2001. The system was described in a 3-part series in Ham Radio Magazine:
"The TEXNET Packet-Switching Network”
Part 1: System Definition and Design, Ham Radio, March 1987, pp. 29-31, 33-34, 37
Part 2: Hardware Design, Ham Radio, April 1987, pp. 29-34, 37-42
Part 3: Software Overview, Ham Radio, June 1987, pp. 53-58, 60-61, 63-65
· Windows development environment for the TAPR/AMSAT DSP-93 program. This provided a windows based assemble/link/download environment to develop DSP code for the DSP-93 board developed by Bob Stricklin, N5BRG. It was based on the TI TMS320. The environment also provided a graphical host for applications. I wrote a spectrum analyzer, oscilloscope, and function generator that worked by downloading DSP code to the TMS0320. This was described in the TAPR PSR.
· A 900 MHz spread-spectrum radio project. This used XINU and a TCP/IP stack written in C on a Motorola 68360 processor with a Qualcomm convolutional coder/decoder and a downloadable Xilinx FPGA for the baseband filtering. The demodulator was based on the Harris (now Intersil) 50210. The RF part of the design never got completed; but the baseband DSP, 802.1D bridge, HTTP based configurator, etc. all worked. It was cool in 1999, but it’s passé today. The project was described in:
“An Amateur 900 MHz Spread-Spectrum Radio Design”, Tom McDermott, N5EG, Bob Stricklin, N5BRG, Bill Reed, “WD0ETZ”, Proceedings of the 16th ARRL/TAPR Digital Communications Conference.
· A USB-based Vector Network Analyzer. It was published in the Jul/Aug 2004 issue of QEX magazine. The software continues to be updated with better calibration routines, improved display capabilities, etc. The current software and source code is available on the TAPR software library web site / VNA page.
· One textbook, a down-to-earth but (hopefully) adequately technical treatment of digital communications for amateurs:
“Wireless Digital Communications: Design and Theory”, 1996, TAPR, Inc.,