ACT CO-SITE INTERFERENCE FILTERS

TWO OR MORE FREQUENCY HOP RADIOS OPERATING IN A COMMON SITE CREATE A SUBSTANTIAL INTERFERENCE PROBLEM BECAUSE CONVENTIONAL FIXED FILTERING TECHNIQUES WITHOUT FREQUENCY AGILITY CANNOT BE USED TO SUPPRESS IT. A NEW ENABLING TECHNOLOGY CALLED ACOUSTIC CHARGE TRANSPORT (ACT) HAS GIVEN RISE TO A FAMILY OF PROGRAMMABLE FILTERS THAT HOLD PROMISE FOR REDUCING THIS INTERFERENCE PROBLEM. THE PROGRAMMING TIME FOR THESE MINIATURE FILTERS IS LESS THAN 100 USECS, THE TECHNOLOGY EXISTS TO PROGRAM THE CENTER FREQUENCY ACROSS THE 225 TO 400 MHZ BAND AND THE BANDWIDTH IS PROGRAMMABLE TO VALUES LESS THAN 25 KHZ. THE STANDOFF DYNAMIC RANGE OF ACT PROGRAMMABLE FILTERS IS IN THE 85 TO 95 DB RANGE FOR THE 25 KHZ CHANNELS. THIS DYNAMIC RANGE IS INADEQUATE FOR THE VERY DEMANDING CO-SITE REQUIREMENTS. THIS PROGRAM WILL UPGRADE THE PRESENT FILTERS WITH A PROGRAMMABLE MATCHING NETWORK AT THE INPUT IN ORDER TO INCREASE THE STANDOFF DYNAMIC RANGE AND SIGNIFICANTLY DECREASE THE NOISE FIGURE. THE OBJECTIVE OF THIS PROGRAM IS TO PRODUCE A PROGRAMMABLE FILTER IN A SMALL MODULE THAT CAN BE ADDED TO PRESENT FH RADIOS TO ALLOW THEM TO MEET THE CO-SITE REQUIREMENTS. THE PHASE I EFFORT WILL PERFORM EXPERIMENTS WITH EXISTING DEVICES TO EVALUATE THE FEASIBILITY AND PRODUCE A DESIGN FOR A MODULE TO BE DEVELOPED IN PHASE II.