A couple weeks ago I tested my 1.7 GHz transmitter/receiver and found that they did not work well enough to be usable. The problem appeared to be interference (which isn't surprising in New York), but could have also been some kind of device failure or mis-configuration.
I had selected 1.7 GHz specifically to avoid interference. Most wireless video transmitters operate at 2.4 GHz, but using that frequency in an urban environment would be foolish (given the proliferation of wireless ethernet, microwave ovens, and other devices at that frequency).
Other common wireless video frequencies include 5.8 GHz, 1.2 GHz, and 900 MHz. I would choose 5.8 GHz (since it's not a very crowded frequency), but that frequency is obstructed by many materials and is not good for non-stationary transmitters. (This table provides a useful summary.) So, I'm left with 1.2 GHz and 900 MHz.
After looking at various websites offering 1.2 GHz and 900 MHz wireless video systems, I've settled on this transmitter and receiver.
If that doesn't work, I suppose I'll try 1.2 GHz or a more powerful 900 MHz transmitter. (or a tether!)