So, your BCD436HP is displaying Unknown in the Depatment window.
For the first few days of monitoring with my new BCD436HP, I was seeing "Unknown" displayed in the Department window upon receiving transmissions when monitoring the Arkansas Wireless Information Network (AWIN) and could not understand why. For background, AWIN is a P25 system used by state and local agencies throughout Arkansas. For example, I could be monitoring what I thought was Little Rock PD and suddenly Unknown would appear and the conversation would clearly be the Arkansas State Police. It was befuddling.
I was in range of known AWIN sites and recognized the voices and call signs of several agencies, effectively monitoring channels downloaded from the RadioReference database. Many of these "Unknown" department transmissions interfered with what I wanted to monitor.
With a few suggestions from forum members and some tinkering in the Sentinel software, I determined the cause to be a setting where I had the ID Search function turned On. Upon changing the setting to Off, the Unknown department traffic disappeared and normal transmissions resumed. This made me happy. Could there be a benefit to leaving the ID Search function in the on position? Why, yes indeed.
Some of our colleagues actively seek to identify new talk groups in use by various agencies. Thus, enthusiasts who activate ID Search and report their findings to RadioReference or forum moderators perform a service to the rest of the monitoring community.
For those who are happy listening to established channels and talk groups, simply set ID Search to Off and blissfully scan. For the more adventurous, turn ID Search to On, note your findings, and share with the forum.