Electronic Interference Effects on Station Hardware/Data Logger/USB Cable

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The following are possible causes for electronic interface on Davis consoles and possible remedies:

A) RFI/EMI interference caused by defective AC power supply for VP2 console. If your VP2 was produced before March of 2009 you likely have a faulty power supply that is emitting stray electronic noise into the Data Logger.

Solution: To test, disconnect AC power from console and run VP2 console off internal batteries for a few days and see if dropout issues stop. If confirmed, contact Davis and request the improved OEM power supply for the VP2 console that eliminates this problem. All VP2 systems shipped after Feb. 2009 come with this new RFI free AC adapter that also includes a Ferrite core on the console end of the adapter power cable.

B) Lack of a surge protector power strip or wall plate that also includes line conditioning for your AC adapter Plugging your console power supply directly into a wall outlet is not a good idea, especially if your home has known AC line quality issues. To help prevent stray interference in the AC adapter, use a high quality surge protector/line conditioning power strip or AC wall plate. For additional protection, do not plug any other devices into this same strip or plate.

C) RFI Interference caused by other electronic devices placed too near the VP2 console and/or computer. Devices include Cell Phone chargers, Cordless Phone Base Stations, other rechargeable battery chargers etc.

Solution: Move all such devices at least 6 feet away from the VP2 console, USB cable and computer. Do not share your AC power source for your VP2 adapter with any of these types of devices. Preferably relocate these potential sources of RFI/EMI to another part of the house.

D) USB cable run longer than recommended 8 feet. Use of a non-powered/passive USB extension cable. If you have the need to extend the length of your VP2 USB connection to your computer, you must use a POWERED USB extension cable in order to prevent a loss of signal strength and quality. Davis warns that the USB cable from the VP2 console to computer should not be extended beyond the 8 foot length provided. A powered USB extension gets around this limitation by providing a transparent additional length with no degradation to the USB signal quality. In fact, the use of a high quality powered extension can actually improve the overall performance of the entire USB cable run.

Solution: Purchase a high quality powered USB extension cable available from many online retailers.

E) Using a USB Hub to Connect Your Data Logger to Your Computer.

Solution: Davis recommends plugging your VP2/Vue USB cable directly into your computer to avoid signal degradation and dropouts. A direct connection of your Data Logger's feed into a dedicated USB port on your Mac is vital to avoid signal level/quality related hangs and dropouts. RFI/EMI can also be introduced into the signal by some lower quality USB Hubs handling multiple USB devices, especially the non-powered variety.

F) Help Protect Your Station from Current and Future Interference!

Finally, as a preventative measure to guard against current and future problems with RFI and EMI interference, it is a good idea to install several clamp on Ferrite Cores to your USB cable. Ferrite is an excellent shielding material and when attached directly to the cable will help to filter and reject any stray electronic interference that may be radiating your USB cable from outside sources. The minimum installation would use two cores; one on each end of the USB cable run.

Davis recommends Part# 240-2245-ND which can be purchased from Digi-Key directly

Note: This document was originally published on the Lightsoft Weather Center LWC Forum in 2010.

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