Certain private roads (like the road my condo complex is on) aren't listed in the database, and obviously the unit won't know of any roads that were recently constructed. We tried to get the unit to navigate us to a newly constructed mall in Elizabeth, New Jersey, and found ourselves completely off the map once we got to the closest exit. Navtech and Datus expect that by 2006 all the roads in the United States should be in their database, and they hope to begin working on maps for Europe and other parts of the world once they can get around localization problems and language issues in their software.

Getting there
Depending on the complexity of the route, it may take a minute or so before the unit has calculated all the turns and markers to your destination. My daily 33-mile trip back and forth to New York City from my house takes about 45 seconds to calculate, for example. But there's no need to sit and wait -- you can start driving while the route is still being calculated.

Once the route calculation is complete, the PNA begins prompting you to your destination. As you approach each turn, the PNA notifies you with all the information you need by voice and screen display to navigate the route to your destination. The PNA alerts you by voice to upcoming turns when you are less than one mile away, less than one-half mile away, and immediately as you approach each turn. After completing each turn, you're immediately notified visually, as shown in Figure G, and audibly as to the distance and direction of the next turn. You can also repeat the last instruction and re-calculate the distance to the next turn by hitting the Enter key.

FIGURE G

After completing each turn you're immediately notified visually and audibly as to the distance and direction of the next turn. Click picture for a larger image.

The PNA's voice synthesis is pretty sophisticated, but it isn't perfect. It uses text-to-speech, so it pronounces everything literally. If the text-to-speech algorithm doesn't understand a word, it spells out each letter. For example, if the screen displays "Rt. 24" it will say "Ar-tee twenty-four" as opposed to "Route 24." You would think that the dictionary would understand common street name abbreviations, but it doesn't. The speech engine also has problems with certain kinds of ethnic names -- for example, one town in New Jersey, "Mahwah," which should be pronounced "Mah Wah," is pronounced "mwahhhhh."

The PNA also has a tendency to talk very fast, and will start jabbering like crazy if you have markers that are close to each other, even if you're going straight on the same road. This happens on the New York City West Side Highway, where the actual name of the road changes very frequently (at least according to Navtech's data). However, after using the unit for a few hours you do begin to understand its dialect. The nice thing is that if you get totally confused by what the PNA says you can still see the instructions on the screen or repeat the instructions.