Portfolio for John Dalton

This is an incomplete portfolio of projects I have worked on.

The first real time prototype for 802.11a

World's first 802.11a modem

This photograph is of the world's first "802.11a" modem, on a bench at Macquarie University. I use quotes as when this modem was built the 802.11a standard did not exist. The modem was part of a collabration with the CSIRO and contributed to the writing of the 802.11a (WiFi) WLAN standard. The modem differed from the standard in that it used 16 tones rather than the 64 written into 802.11a.

The rack on the left is the baseband processing for the receiver. Each receiver subsystem is on its own Eurocard within the rack. The card on the bench is the baseband processing for the transmitter. It was built after the receiver so improved FPGA technology allowed the entire transmitter to be placed on a single Eurocard. The box on the bench at the back is an off the shelf bit error rate analyser. On top is the 5GHz radio receiver. In this particular photo the transmitter baseband is connected directly to the receiver baseband, so the radios are out of the loop. The coaxial cables exiting to the left of the picture are carrying clock and synchronisation signals.

I designed and built the transmitter, on the bench in front of the receiver rack, as well as the backplane of the receiver and the "BERT Interface" and "SYNC" cards in the receiver rack. I also designed the front panels for the receiver and was responsible for the cabinet, in which it is housed, and the associated power supplies.

CDMA/102.11b modems

The above is a prototype for a 802.11b modem, using a Least Mean Square algorithm for training the receiver despreader . At the time all 802.11b modems in the market were using fixed correlators for despreading and a RAKE receiver was state of the art in the lab. This modem was DSP based and operated at a rate of several hundred kilobits per second.

I was responsible for the design and construction of the entire system, including all hardware, firmware, software and DSP code. It was a solo effort in a small start-up company, apart from the late arrival of someone who took over responsibility for later versions of the DSP software.

The above is an update to the previous modem, with the addition of an FPGA. The FPGA allowed the system to operate in real time. The system was designed and constructed by myself. I had two people under me who helped with the writing of the DSP code and the VHDL for the FPGA, which I specified in detail.