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X10 PRO 3-Wire Noise Filter

Item # XPF

This product has been discontinued.

View all X-10 Pro products

Product Description

Designed to filter out most signals above a frequency of 300Hz by attenuating the voltage of these signals by a ratio of 40 to 1. For installation at the fixture or electrical panel.

Electrical devices such as TV, VCR, stereo, low voltage power supplies, computers, monitors and power/surge protection strips all have a tendency to "dump" electrical noise on the power lines.

Overview

Because line carrier products use the power lines as a communications path they are susceptible to interference. When noise is placed on the power lines it can attenuate, corrupt and/or block the signals being transmitted or received over the entire house.

Typically noise will cause intermittent operation of the receivers. An example would be if you can turn on alight from a transmitter but cannot turn it off from the transmitter or you can turn off a receiver but cannot turn it on. The offending device does not even have to be turned on, because a TV or computer still has their power supplies on the power line when they are turned off.

Noise on the power line is solvable. The proper way to trouble shoot for noise is to use an XPTT Test Transmitter and an XPTR Signal Strength Indicator. The XPTT is plugged in at the transmission point where it will transmit a constant line carrier "P1" on/off command. Taking the XPTR you go from outlet to outlet in the home and take a signal strength reading.

The XPTT transmits a 2V signal and the XPTR can detect from 2V down to 24MV. The lowest possible signal that can make a module respond properly is 100MV. As you go around the structure and you see a fluctuation in the signal you may have detected a noise-producing device. While leaving the XPTR plugged in you can systematically unplug a device (TV, VCR, computer or low voltage lighting power supply) and see if you detect any change in the signal amplitude.

Wire-in Filter
If the offending device is a hard-wired device, shutting off it's breaker is necessary to "unplug" it from the system. Then an XPF Wired-In Filter can be installed between the switch and the offending device OR at the breaker panel before that circuit. Wiring Diagram

Installing the XPF:
  • Shut off the breaker attached to the "offending device"
  • Disconnect the 120VAC supply from the offending device.
  • Connect the 120VAC to the Black lead of the XPF.
  • Connect the White Lead from the XPF to Neutral.
  • Connect the Red lead from the XPF to the offending device. This supplies power to the device.
Note: make sure that you do not exceed the 20A load rating.

More Info



 

How X10 Works

 
X10 communicates between transmitters and receivers by sending and receiving signals over the power line wiring. These signals involve short RF bursts which represent digital information.

X10 transmissions are synchronized to the zero crossing point of the AC power line. The goal should be to transmit as close to the zero crossing point as possible, but certainly within 200 microseconds of the zero crossing point. The PSC05 provides a 60 Hz square wave with a maximum delay of 100 µsec from the zero crossing point of the AC power line. The maximum delay between signal envelope input and 120 kHz output bursts is 50 µsec. Therefore, it should be arranged that outputs to the PSC05 be within 50 µs of this 60 Hz zero crossing reference square wave. .
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A Binary 1 is represented by a 1 millisecond burst of 120 kHz at the zero crossing point, and a Binary 0 by the absence of 120 kHz. The PSC05 modulates its input (from the O.E.M.) with 120 kHz, therefore only the 1 ms "envelope" need be applied to its input. These 1 millisecond bursts should equally be transmitted three times to coincide with the zero crossing point of all three phases in a three phase distribution system. Figure 1 shows the timing relationship of these bursts relative to zero crossing. .
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A complete code transmission encompasses eleven cycles of the power line. The first two cycles represent a Start Code. The next four cycles represent the House Code and the last five cycles represent either the Number Code (1 thru 16) or a Function Code (On, Off, etc.). This complete block, (Start Code, House Code, Key Code) should always be transmitted in groups of 2 with 3 power line cycles between each group of 2 codes. Bright and dim are exceptions to this rule and should be transmitted continuously (at least twice) with no gaps between codes. See Figure 2. .
. Within each block of data, each four or five bit code should be transmitted in true compliment form on alternate half cycles of the power line. I.E. if a 1 millisecond burst of signal is transmitted on one half cycle (binary 1) then no signal should be transmitted on the next cycle, (binary 0). See Figure 3.

The Tables in Figure 4 show the binary codes to be transmitted for each House Code and Key Code. The Start Code is always 1110 which is a unique code and is the only code which does not follow the true complimentary relationship on alternate half cycles. .

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[1] Hail Request is transmitted to see if there are any X10 transmitters within listening range. This allows the O.E.M. to assign a different Housecode if a "Hail Acknowledge" is received.

[2] In a Pre-Set Dim instruction, the D8 bit represents the Most Significant Bit of the level and H1, H2, H4 and H8 bits represent the Least Significant Bits.

[3] The Extended Data code is followed by 8 bit bytes which can represent Analog Data (after A to D conversion). There should be no gaps between the Extended Data code and the actual data, and no gaps between data bytes. The first 8 bit byte can be used to say how many bytes of data will follow. If gaps are left between data bytes, these codes could be received by X10 modules causing erroneous operation.

Extended Code is similar to Extended Data: 8 Bit bytes which follow Extended Code (with no gaps) can represent additional codes. This allows the designer to expand beyond the 256 codes presently available. .


NOTE 1 . X10 Receiver Modules require a "silence" of at least 3 power cycles between each pair of 11 bit code transmissions (no gaps between each pair). The one exception to this rule is bright and dim codes. These are transmitted continuously with no gaps between each 11 bit dim code or 11 bit bright code. A 3 cycle gap is necessary between different codes, i.e. between bright and dim, or 1 and dim, or on and bright, etc.

NOTE 2. The PSC05 Two-Way Power Line Interface cannot receive Extended Code or Extended Data because these codes have no gaps between them. The PSC05 can only receive standard "pairs" of 11 bit X10 codes with 3 power line cycle gaps between each pair.

NOTE 3. The PSC05 can receive dim and bright codes but the output will represent the first dim or bright code received, followed by every third code received. i.e. the output from the PSC05 will not be a continuous stream of dim and bright codes like the codes which are transmitted.


A Square wave representing zero crossing detect is provided by the PSC05 and is within 100 &s of the zero crossing point of the AC power line. The output signal envelope from the O.E.M. should be within 50 &s of this zero crossing detect. The signal envelope should be 1 ms (-50µs +100µs). See Figure 5. .
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Opto-Coupled 60 Hz reference output (from the PSC05)
Transmissions are to be synchronized to the zero crossing point of the AC power line and should be as close to true zero crossing as possible. The PSC05 is designed to be interfaced to other microprocessor circuitry which outputs X10 codes synchronized to the zero crossing point of the AC power line. It is therefore necessary to provide a zero crossing reference for the O.E.M. microprocessor.

It is likely that this microprocessor will have its own "isolated" power supply. It is necessary to maintain this isolation, therefore the trigger circuit normally used in X10 controllers is not desirable as this would reference the O.E.M. power supply to the AC power line. It is also not desirable to take the trigger from the secondary side of the power supply transformer as some phase shift is likely to occur. It is therefore necessary to provide an opto-coupled 60 Hz reference.

An opto-coupled 60 Hz square wave is provided at the output of the PSC05. X10 codes generated by the O.E.M. product are to be synchronized to this zero crossing reference. The X10 code envelope generated by the O.E.M. is applied to the PSC05 which modulates the envelope with 120 kHz and capacitively couples it to the AC power line.

Opto-Coupled Signal Input (to the PSC05)

The input signal required from the O.E.M. product is the signal "envelope" of the X10 code format, i.e.

High for 1 ms. coincident with zero crossing represents a binary "1" and gates the 120 kHz oscillator through to the output drive circuit thus transmitting 120 kHz onto the AC power line for 1 ms.

Low for 1 ms. coincident with the zero crossing point represents a binary "0" and turns the 120 kHz oscillator/output circuit off for the duration of the 1 ms. input. .

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Opto-Coupled Signal Output (from the PSC05)

The "X10 received" output from the PSC05 coincides with the second half of each X10 transmission. This output is the envelope of the bursts of 120 kHz received. Only the envelope corresponding to the first burst of each group of 3 bursts is available at the output of the PSC05. See Figures 6, 7, and 8. .


 

Source: X10 WorldWideWeb pages

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