About Leviton's Intellisense System | Smarthome Home Automation Superstore

Leviton's new DHC receivers with Intellisense; deliver the reliability you depend on in powerline carrier home automation products -- even in applications where electrical "noise" is present on the AC line. And Leviton's Intellisense circuitry assures excellent noise immunity without reducing command signal sensitivity so that top performance of the DHC system is assured.

Leviton's new DHC receivers with Intellisense deliver the most reliable performance of any powerline carrier home automation products available today.

What is AGC?
AGC or Automatic Gain Control is a new enhancement available on certain X10 compatible products. It significantly enhances the ability to detect X10 signals in the presence of noise. Leviton's AGC claims to improve X10 signal reception to the point that signal bridges and noise filters are unlikely to be required in homes under 4000 sq. ft. HomePro AGC is of a different design than the Leviton AGC and may not be as sensitive.

Noise on the line -- a part of every electrical system

Powerline carrier home automation systems are easy to install because the home's existing AC wiring is used to carry command signals. However, in many homes, electrical interference can prevent receiver modules from operating properly. Electronic equipment found in virtually every household generates disruptive noise interference: TV's, VCR's, audio equipment, personal computers and peripherals, fax machines, electronic lighting ballasts and many other electronic devices.

How noise can disrupt powerline carrier systems
Powerline carrier systems transmit and receive command signals at the zero crossing of the AC power curve. That's because electrical noise is at a lower level here than at any other point in the cycle. The zero crossing point is the Signal Window where receiver modules listen for the special coded comman sequence. If the receiver hears a steady stream of signals in every signal window, it interprets this as random noise and does not respond.

Figure 1 shows a typical powerline carrier command signal.
Note that there are "empty" signal windows in the coded sequence.

Figure 2 shows what can happen when there's noise on the powerline
while a command is being transmitted. The noise fills in all the
signal windows, disrupting the coded sequence. As a result, the
receiver cannot hear the common signal and does not respond.

Amplifying the command signal may not solve noise problems
Problems from noise interference are more related to receiver sensitivity than to signal strength. The sensitivity of a receiver determines the minimum amount of signal it can recognize. In order to deliver reliable performance in a variety of applications, powerline carrier receivers must be sensitive to command signals that are lower than 1/10 of a voly (.100 volts). Boosting the command signal does not change a receiver's sensitivity. No matter how powerful the command signal is, the receiver will still be sensitive to noise that's only a fraction of a volt, and noise will still be capable of disrupting the system's operation.

Automatic Gain Control is needed, but not just any kind
Automatic Gain Control (AGC) is a special circuit that adjusts receiver sensitivity to help eliminate noise interference. While Automatic Gain Control can be very effective in reducing noise problems, some types of AGC cirtuis yield mixed results when it comes to overall system performance. Up until now, only a "non-gated" type of AGC was available in powerline carrier receivers. Non-gated AGC circuitry is not symchronized with the sugnal window. Instead, non-gated AGC desensitizes a receiver to high noise levels that occur throughout the entire AC cycle. Powerline carrier receivers are only affected by noise within the signal window, which is the lowest level of noise in the entire AC cycle.

Therefore, non-gated AGC desensitizes the receiver to accommodate high noise levels that do not even affect receiver performance. That means the non-gated type of AGC currently available can desensitize the receiver from noise to such a degree that it also desensitizes it to command signals. There are installations where non-gated AGC circuitry can create as many problems as noise does.

A New Built-In Feature Provides Outstanding System Reliability

Leviton's DHC receivers feature Intellisense, the right type of Automatic Gain Control
Leviton DHC receivers use Intellisense, a special gated type of AGC, to help eliminate hoise problems. The Intellisense gated AGC ciruit is ideal for powerline carrier systems because it only operates during the signal window when receivers listen for command signals. Noise levels in the signal window are never as high as they are during other portions of the AC power curve. Therefore, Leviton's Intellisense gated AGC will desensitize a receiver to noise signals with only a minimal reduction in command signal sensitivity. The result: Problems from noise interference are dramatically reduced without affecting overall system performance.

Leviton's new Intellisense is built into DHC wall-mounted switch and receptacle receiver modules. These modules are installed exactly the same way as they were before, and there's no change in their popular Decora styling, either.

NEW! DHC Dimmer Switch Modules with Intellisense plus enhanced performance features

Leviton DHC Dimmer Switch Modules not only feature Intellisense for outstanding performance and reliability; they also provide new performance features for added comfort and convenience.

Preset switching-- Turns lights ON at last selected lighting level instead of full brightness. Eliminates the need to continually readjust for a desired dimmer setting every time the unit is switched On and Off.

Soft ON/Fade OFF-- Starts lighting with a gradual rise to the selected brightness level, and gently fades lights when they're switched Off. Provides an eye-pleasing effect and helps extend bulb life.

DHC with Intellisense:

Cat. #	Description
2201WI	Incandescent Switch Module: Manual and remote switching and full-range dimming. Preset-switching feature turns lights ON at last selected lighing level instead of full brightness. Soft ON/Fade OFF feature starts lighting with a gradual rise to selected brightness level and gently fades lights off. Rated 500W max. 60W min. At 120V AC. Responds to ALL LIGHTS ON.
2202WI	3-Way Incandescent Switch Module: For use in 3-way switching applications. Same functions and rating as 2206WI, including Preset switching and Gentle On/Fade Off features.
2206WI	Wall Switch Module: Manual and remote switching of incandescent and fluorescent lighting, and appliances. Rated 20A 125V AC. Does not respond to Dim/Bright commands. Responds to ALL LIGHTS ON.
2207WI	3-Way Wall Switch Module: For use in 3-way switching applications. Same functions and rating as 4240W and 4240I.
2210I	Double-Pole Switch Module: Manual and remote control switching of pumps, air conditioners, heating units and other high amperage loads. Does not respond to Dim/Bright commands. Responds to ALL LIGHTS ON. Rated 20A 250V, 2hp. Available in Ivory only.
2240W 2240I	Duplex Wall Receptacle Module: Rated 15A 125V AC. Top outlet DHC-controlled, bottom outlet always live.
2245W 2245I	Duplex Wall Receptacle Module: Rated 15A 125V AC. Both outlets DHC-controlled.
2243W 2243I	Single Wall Receptacle Module: Rated 20A 125V AC.
2242W 2242I	Single Wall Receptacle Module: Rated 20A 250V AC.

Comparing Powerline Carrier Receiver Module Performance

NO AGC: High sensitivity means receiver will pick up
relatively low levels of noise as well as command signals.

THE RESULT:Noise may disrupt operation.

NON-GATED AGC, CURRENTLY AVAILABLE IN SOME RECEIVERS:
Sensitivity is reduced based on high noise levels outside the signal window.
This means sensitivity to command signals is also greatly reduced.

THE RESULT:Receivers may not respond to command signals.

LEVITON DHC RECEIVERS WITH INTELLISENSE GATED AGC: Intellisense
Gated AGC only operates during signal window when the receiver listens
for command signals. Sensitivity is reduced only enough to compensate
for low-level noise inside the box. Command sensitivity is still high.

THE RESULT: Optimum performance.