Ive been talking about my qrm on 137 khz for some time and have long suspected the ABB/Landis/Gyr/Hunt mechanical electrical meter as installed by the electrical power company on their side on the incoming 2 phase supply -
They use remote data collection using the power lines at a very low data rate- with a "Turtle" module installed inside the meter - aka
http://www.barronelectric.com/energy/turtletech.html and "The Turtle module is installed in the meter at your house and the consumption information is sent to a Turtle receiver at the nearest electrical substation, using the power lines. From there, the information is delivered by phone to the Turtle software in the Electric Meter Shop, where the information is processed for the billing department. The entire process takes about 27 hours to complete, thus, the name “Turtle”.
Its a low bit rate device - trouble is it was injecting wide band old style car ignition noise at some S7 and radiating using the house wiring - Noise was audible at some strength from 70-500Khz. The electrical company much to their credit didnt blow me off - especially when I held a Eton style SSB rx near the meter and when the guy unplugged the "EVM" turtle device and the noise dissapeared - he tried different models, capacitors etc but unable to clear.
The final resolution was the electrical supply company to completely remove this device from inside the meter and will now come round and "read' the mechanical meter once a month - a backwards step in their view money/time savings but they agreed that this PLT system in incompatiable with my noise level needs.
just a heads up if your encountering a similar noise....
I now have a much better s/n down on 137
Laurence KL 1X Wasilla Alaska
WE2XPQ
Hotmail: Powerful Free email with security by Microsoft. Get it now.
=
|
|
