X10 Meter design advice needed


I am currently testing and reviewing Jeff Volp's latest design effort, the XTBM-Pro signal analyzer for X10 installations.

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We differ strongly on how the bargraph mode should operate. The Pro's bargraph mode is similar to how the discontinued ELK - ESM1 meter behaves with one difference. The last reading persists in the meter window. The ESM1 and other bargraph devices I am familiar with for measuring transient signal levels all revert to zero when the signal stops so this strikes me as a major exception to established display principles.

I realize that bargraphs that indicate state - fuel gauges, battery charge indicators, copier tray capacity indicators and the like all persist. But indicating a state of capacity is very different from indicating something that occurs briefly, like a sound level or an X10 transmission, and then is gone.

My opinion is that users will be confused by a bargraph that doesn't return to zero after the signal has "passed." To complicate matters, to keep costs low, there's no scale on the bargraph readout as there is on the ESM1, so all you see are two lines that say:

X: [][][][][] N: [][]

There's no reference to voltage or the fact that the X: scale runs from 0 to

10 volts and the N: scale from 0 to 1 volt. I've suggested changing the display to display actual voltage levels:

X: [][][][][] 4.5V N: [][] 0.1V

And I've also suggested that the low end of the scale be made more sensitive. My assumption is that if you've got a signal above 5V, you're in the money and don't really need to know how much stronger than 5V the signal is. Sort of like the old joke about actors: "If you can afford to go to Betty Ford, you don't really have a drug problem." (Your habit hasn't consumed all your money - yet.)

The meter is perfectly capable of reading those high levels in the alpha-numeric mode, but the bargraph mode is for quick and dirty signal level checks. That's why I think it should be extra sensitive in the low range: That's where people have the most X10 problems.

Other than this small design disagreement, the meter is smartly designed and executed and has some features that are remarkable. Using 2 way modules like the RR501, Jeff's new Pro meter can test the voltage levels of all the two way modules in your system and report them back to a control program like HomeVision or even to the meter itself using dim levels to communicate the remote voltage.

In addition, he's design the most useful bitmap mode I've seen, putting even the venerable Monterey Powerline Signal Analyzer to shame. Lynx had a meter that attempted to do what Jeff's unit does, but you needed an attached PC to use it. (-:

And wait, there's still more! He's built in a repeater check so that if you have one installed, each time you plug in the meter, it measures the signal strength of the repeated signal to the outlet being tested. Unlike the much more expensive Monterey, the XTBM-Pro's LCD is backlit, a boon for these old eyes.

Feedback on whether the bargraph should persist or reset to zero after an X10 command is received would be appreciated. If you know of a bargraph device that measures signals like X10 transmissions and "holds" that reading, I'd like to know that. My contention is that meters are designed with HOLD buttons for similar situations and that holding the reading is the exception, not the normal state of affairs.

-- Bobby G.

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Robert Green
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