THE PHILIPS SCD 589 baby monitor's parent and child units (top), and nightlight feature (bottom).

Price we paid: $200

What it is: A digital baby monitor that uses the 1.9-GHz frequency band, a different band than is used by other baby monitors. The new frequency, reserved exclusively for voice-only applications by the Federal Communications Commission, is called DECT, for digitally enhanced cordless telecommunications.

The frequency band used can affect interference, probably the biggest complaint among baby-monitor users. When a monitor uses the same frequency bands as other wireless products in the home, including cordless phones, home networks, and even appliances such as microwave ovens, its sound may be plagued by static or buzzing, ultimately making it difficult or impossible to hear your child. (See our tips on wireless interference for more information.)

Because so few devices yet use the 1.9-GHz frequency, the chance of interference in that band should be minimal. In addition, Philips claims the SCD 589 monitor will not experience interference from any other device, calling it a "guaranteed zero interference" monitor.

We devised a worst-case scenario to test the SCD 589, placing three models within 20 feet of two new Philips 1.9-GHz DECT cordless phones to see if they would interfere with each other. We also tested other attributes that are important in a monitor, such as battery life.

What we liked: The SCD 589 lived up to its claim of being free of interference, even in our extreme test. There was no interference heard on any of the phones or baby monitors in our test.

The SCD 589 also had some nice, if hardly essential, features the other models in our tests didn't. Those included a nightlight; an "intercom" that allows the parent to speak to the child remotely; and an alarm that sounds when the temperature in the child's room goes out of a certain range that parents can set.

What we didn't like: At $200, this model is among the most expensive monitors we've ever tested--though three others we're currently testing cost nearly as much. Battery life was only good, though the batteries on both the parent and child units of this monitor (and some others) are rechargeable and can run on AC power, as well.

Bottom line: The Philips SCD 589 is an excellent monitor overall. Its bevy of features may appeal to some parents--and seem superfluous to others. Unless you live in an area with lots of potential interference, a less-expensive digital model may be a better choice. Consider spending the premium for the SCD 589 only if you've tried other new monitors and have been unable to fix a persistent interference problem.

If you're unsure about interference, buy a less-pricey digital model that's not in the same frequency band as the other wireless products in your home, and consider models with more than two channels. Save the receipt (or include a gift receipt) in case of trouble. We're testing a number of other monitors now, including moderately priced models, and will post the Ratings on this site in the coming months.