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Power consumption and RF lab testing

We are preparing now for the first production run of the Mesh-Potato units. There are still some modifications we want to make before starting the production. One addresses power consumption. The prototype I’m working on draws 2.47 Watts at 12.3 Volts with radio on, phone on hook, Ethernet and Batman running (3 nodes), ssh remote shell connected via wireless. When the phone is off hook the power consumption increases to 3.26 Watts. Without FXS port the MP draws 1.9 Watts. While that is a pretty low power consumption compared to other WiFi devices (a Linksys WRT54GL draws 3.6 Watts at best) there is still room for improvement which should be finished by the end of next week.

I have also verified that the MP runs fine when fed with 15 Volts over 55 meters of AWG24 Ethernet cable using passive PoE. (That doesn’t imply 55m is the limit, I just didn’t have a longer cable to test). You can feed the MP with up to 20 Volt DC using the spare Ethernet cable pairs 4-5 (blue, blue-white=positive) and 7-8 (brown, brown-white= negative). Other WiFi devices that use passive PoE are the Ubiquiti Picostation, Nanostation and Bullet which are using the same layout. Hence you can use the same power injectors or power supplies.

Since the Mesh-Potato as a VOIP device may not necessarily have a Ethernet cable running to it, we have also implemented the option to feed it via the phone cable. The FXS port of the MP has 6 contacts, the pairs 1-2 and 5-6 can be used in the same way. However the maximum cable length may not be that long as phone cable usually has less inductor cross section.

I’m currently working at the CSIR in Tshwane/South Africa.

I could get access to a really professionally equipped radio lab here – network and spectrum analyzers up to 40GHz! Impressive! That gear costs more than just a fortune!

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