The actual MDT frequency for Schenectady is 857.7375 MHz. however it is useless to listen to. It is just straight 24 hours of 'buzzing' noises. Plus, if it's the same type of system that can be found in Colonie, Albany City and Albany County, then it is either 128-bit or 256-bit encrypted (as recommended by the good folks from the National Crime Information Center).
There isn't any voice traffic on that frequency, nor does the city have the ability to use it for voice traffic if the MDT system happened to fail. I have heard in the past when a car in the field either has a problem running a plate or can't log into the computer at all they switch back to COUNTY-1 (155.190) and get the data & information there. COUNTY-2 (154.800) is just used by the Sheriff's Department now, but every now and then you may hear another agency in the county pop up on the channel. The county still pretty much uses their number scheme that was assigned back when most of the law enforcement agencies still used COUNTY-1 & 2 so it's pretty obvious when it isn't a sheriff on 154.800.
Kevin