CHESTER-On his first day on the job in January 1999, Carl Amaditz, Deputy Commissioner of the Division of Emergency Communications, called for a study on the problems first responders were having talking to each other by radio. Now, six years later, the most critical part of the work is about to fall into place. It is expected to be the most significant improvement ever made to radio communications in the county. By the end of next week, first responders will have the benefit of microwave communications, which will take the place of the old radio tie lines that were notoriously unreliable, Amaditz said. "It was a massive project," he said of the work done as a result of the radio study. To do the study, experts from RF Microsystems, a big defense contractor based in San Diego, Calif., moved to an apartment in Wallkill for six months in 2000 to study the county's communications full time. They prepared what are called propagation models to see what kind of service each part of the county was getting. The study was completed in February 2001 and made six recommendations, which the county legislature agreed to implement. Amaditz said all but one of the recommendations that have been put into place have already improved communications. But the final recommendation, to improve the "backbone" of the county's communications infrastructure, is only now falling into place. "We needed to improve the reliability of the towers," said Walter Koury, Commissioner of the Orange County Department of Emergency Services, of which the Division of Emergency Communications is a part. He said the circuits at the transmitting towers for emergency communications would get knocked out for hours, sometimes days. "That was unacceptable," said. "One hundred percent reliability is not possible unless you live in the Great Plains or some other place where everything is flat," Koury said. But the new microwave system will get as close to perfect as possible here amid the hills of Orange County. He expects radio reliability to improve to 99.8 percent. The county has eight communications towers. They are located in Woodbury, Warwick, Tuxedo, Mount Hope, Deerpark, Beacon, at the Sheriff's Office in Goshen, and at the 911 Center in Chester. There is a tower with limited capability in West Point. Amaditz is looking into installing a ninth tower in Blooming Grove. The "backbone" improvements cost slightly over a half-million dollars and has two phases. The first is the microwave upgrade to the towers in Tuxedo and Mount Hope that will happen by next week. The second is the upgrade to the towers in Beacon and in Warwick, which is expected to be completed by the end of the year. The county will then be able to tie in with the statewide communications system when that is up and running, Koury said. The other improvements, already made, include adding antennaes and transmitters to the Warwick tower, where coverage was spotty because Schunemunk Mountain is in the way; testing the Warwick tower for improvements; tying the high-band police polling channel to the Tuxedo tower; adding the Deerpark tower for paging services for emergency medical and fire responders; and tests, still ongoing, in Highland Falls.