In the video transmission spectrum there are three bands used by the media: 2 gigahertz, 7 gigahertz and 13 gigahertz. The preferred frequencies lie in the 2 gigahertz spectrum. Available to the media are 7 channels, 2 gig one through seven, divided amongst the tv stations. For example, WJZ primarily uses 2 gig channel 1 (which is where I used to work - hence the screen name 2gigch1).
Beyond the 7 media channels there are three reserved for government, channels eight through ten. On those frequencies police agencies can transmit their video back to a receive site for ground evaluation. Interestingly the media and police use the same gear, just the media uses the first 7 channels on the gear and the police use the last three. Therefore the police receivers can watch media transmissions and *gasp* the media can watch police stuff (though it would NEVER hit air!) I understand intake operaters in both cities were fascinated by Baltimore County's downlink of Joseph Palczynski's (sp?) standoff a few years ago.
Notably the government agencies are more likely to use omnidirectional antennas on their helicopters paired with directional "dish" antennas at their receive sites since they do not require long distance transmissions. Media birds use directional antennas slaved to a gps to keep them aimed to their receive site which produces much longer transmission ranges, limited mostly by earth curvature. To get a good signal from Ocean City to TV Hill means the helicopter has to fly around 2000 feet. Once west of Cumberland Roy had us up around 7000' to get a clean signal back. That was a bit unnerving....
At this time the 2 gigahertz spectrum is about to go to Nextel. The media will have to play in a much smaller band of frequencies. The answer of course is digital compression, but that means all new transmitters and receivers. Many dollars to be spent soon.
Also it is noted that the tv vans with telescoping masts use the same microwave technology described above. That is how you see local news going live all the time without paying for satellite time (which can be expensive).
Sadly you are unlikely to acquire the gear to 'listen in' on these transmissions since you need steerable receive dishes, expensive decoders and most importantly you need to be up pretty high in the narrow microwave path from the transmitter to tower.
