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00J277 Repeater The HANDAR 544V (VHF) and 544U (UHF) Store and Forwatd Repeaters (shown in Figure 6) provide the capability of e"tending the range or distance from the remote siteS to the Base Station. By locating the repeaters on high elevation terrain, tall buildings, or towers, range is extended by the line-of-sight distanc~ between the repeater and the remote site plus the distance between the repeater and the base sta- tion. The HANDAR repeaters incorporate a unique store-and-forward fea- ture. Data is received from the remote site, stored momentarily, and then rettansmitted at the sa~e frequency. Consequently, only ODe frequency is required, unlike conventional repeaters that require two frequencies. This is especially advantageous because of the short supply of fuquendes available for this service (20 VHf; 8 lHF in the Unittd States of America). Moreover, there is no desensitization of the receiver from the transmitter, since both units are not on at exactly the same rime. Us e of only one applications but also place of two antennas. duple"er to operate on e"pens ive duple"er.. frequency not only simplifies radio license reduces cos t by requiring only one ant enna in Or, where only a single antenna is used with a two frequencies, it eliminates the need for the Another feature of the tiandar repeater is the capabil ity of switch selecting blocks of sensor II:: codes so that the repeater only responds to transmissions with those 10 codes. In multiple repeater systems this can prevent repeaters from interfering with one another. In additioCl, the tepeaters will ClOt respoCld ro noise or other interfering radio transmissions at the assigned frequency. The blocks of 10 codes arc selected by a series of switches on the repeater. If the sensor 10 codes need to be changed, as when other sensorS arc added in the future, users can simply reset the switches. The Handar repeaters are designed to be in a "power down" or "sleep" except when a signal is detected. This keeps the standby current drain down ro only 14 ma., thus, providing greater operating time for the battery before it requires recharging, or a smaller size solar panel if one is used at the site. The HANDAR Store and Forward Repeater can be installed in exist- ing repeater structures or installed in a ~~AR 405A Standpipe Tower with mast, antenna, and cables as shown in Figure 1. 14