ALCO P25 System Is Up
Well I plugged in my scanner today and couldn't hear anything on the Alco trunk....I thought well I'll check for the data channel as I usually can hear some multipath distortion in the signal....and no Motorola data channel to be found. Its usually the strongest Motorola system in my area....so I found what I thought was Alco's data channel and then found it was San Francisco's system. I started scanning the range and did pick up some open-carriers that have the distinctive Motorola background hum. I'd known for some time Alco would be switching to a P25 system and expanding it to include Contra Costa County. So I guess it happened. I haven't determined yet if part of this system is using 700 Mhz or not for its simulcasting but its obvious the control channel data cannot be heard and I assume some type of subaudible tone encoding is taking place on the control channel muting the data audio behind the clear open-carrier I'm getting now. Guess that's the nature of P25 control signals...it would definitely sound like a multiplexed mess of data-voice channels....with a wide frequency spread....guess its gone subaudible to reduce that spread.
Now I have to buy a P25 scanner with a 700 Mhz bandplan.
Well I plugged in my scanner today and couldn't hear anything on the Alco trunk....I thought well I'll check for the data channel as I usually can hear some multipath distortion in the signal....and no Motorola data channel to be found. Its usually the strongest Motorola system in my area....so I found what I thought was Alco's data channel and then found it was San Francisco's system. I started scanning the range and did pick up some open-carriers that have the distinctive Motorola background hum. I'd known for some time Alco would be switching to a P25 system and expanding it to include Contra Costa County. So I guess it happened. I haven't determined yet if part of this system is using 700 Mhz or not for its simulcasting but its obvious the control channel data cannot be heard and I assume some type of subaudible tone encoding is taking place on the control channel muting the data audio behind the clear open-carrier I'm getting now. Guess that's the nature of P25 control signals...it would definitely sound like a multiplexed mess of data-voice channels....with a wide frequency spread....guess its gone subaudible to reduce that spread.
Now I have to buy a P25 scanner with a 700 Mhz bandplan.