This has been a problem for many years because the Station sits on top of the Pacific Crest along Highway 80. This station has a clear line of sight to both of the Tahoe’s main repeater sites. When Dispatch simulcasts the general announcements they use an East side repeater and a West side repeater to reach the most area for the entire forest, which are covered by those two repeaters. Because the Station can hear both repeaters it is causing heterodyne which garbles the transmission.
The Radio Shop has tried to mitigate this problem by shielding the antenna from the east, adding a VHF Yagi pointed to the West, and tone protecting the receiver all of which did not improve the signal. We have suggested doing Simulcast on a more North East Repeater which allows the station to be shadowed and only pick up the West side traffic but that will reduce the coverage for the South East side. ECC has been advised to only use tone 5 to communicate to Big bend or surrounding areas but only does so for single calls. The Radio Shop has tried installing a radio UHF link to dispatch but that removed their ability to scan other agencies and was dismissed. We are working on creating a link between Tone 8 to Big Bend rekeying a different Freq but that would require them to have a special channel on their radios different than the rest of the forest. We also have suggested that the station puts in a Forest Service Network and we could use RCoIP but the costs/ infrastructure was not feasible.
The suggestion to read the general messages twice would remove the heterodyne as for only one repeater would be used at a time. The another solution is to switch the Forest to an Eastside/ Westside frequency split having one side of the Pacific Crest work on Forest Net and the other on Fire net removing the interference while keeping the ability to Simulcast. We are researching the use of GPS Simulcast on multiple repeaters up on the Plumas but that solution is costly and untested which would fix stationary sites but could have unseen effects to outreached areas. The Radio personal will continue working on a fix and make suggestions to the Forest on what we can try. |
