I installed my improved antenna assembly the other night. Though I would get weird occasional connection issues, I was pretty happy with the results. However when I fired up my Handibot today it would not show up on my network. Even in AP mode I had problems. I could see it but connecting to the FabMo network would fail. I opened up the electronics bay and suddenly I could connect to the FabMo. Once connected I could close the electronics bay and use the Handibot. It was all very strange.
So, I did a little research on the web. The FabMo is built around an Intel Edison. There are apparently two types of Intel Edison. One which uses an internal antenna and one which supports an external antenna. Both modules have the connector for an external antenna. However Intel's documentation states...
From page 13 of Intel's documetation
Intel® Edison Compute Module Hardware Guide:
Quote
3.7 Integrated chip antenna or u.FL connector for external antenna
The Intel® Edison Compute Module has an integrated dual-band 2.4/5 GHz antenna built onboard. The onboard
antenna is used primarily for small form factor plastic devices. For larger devices or a device which has a metal
enclosure, another version of Intel® Edison is available with an industry standard u.FL connector for attachment to
an external antenna. This will allow the end-user to locate the antenna for optimal performance.
Note: The internal antenna versions also have a u.FL connector on the board, but it is only used as a
manufacturing test point. Do not connect an external antenna to a board with an internal antenna.
My FabMo is pretty clearly an internal antenna Intel Edison. There is a big internal antenna on the board and it works best with no external antenna and the electronics bay open.
There is not a lot of clarity out there about what happens if you attach an external antenna to an internal antenna Edison. I can imagine interference issues between the two antennas as well as power issues causing both antennas to be weak.
Some folks online claim that an internal antenna Edison can be turned into an external antenna Edison by removing the black 0 ohm resistor near the external antenna connector. Comparing photos of the internal and external antenna boards this made a lot of sense. The chief difference between the two is the population of the internal antenna and a few resistors. The black 0 ohm resistor nearest the U.FL connector connects the U.FL and the internal antenna. Removing it should render the internal antenna in-opperable. Since I am fairly decent at soldering I figured I could remove it and if necessary reattach the 0 ohm resistor without damaging my Fabmo.
Internal antenna Edison. 0 ohm resistor circled in red.Well, I gave it a try and so far I am getting much better results. I can now turn my Handibot off and on and it fairly quickly shows up over the network without having to place the Handibot right next to the base station. I seem to get pretty consistently 4-5 bars of signal. When it does dip in signal strength it drops to 3 bars instead of all the way down to 1 bar. I am cautiously optimistic that I have resolved my connectivity issues.
DISCLAIMER: I am not advocating that you modify your FabMo. This is difficult soldering and you may very well destroy your FabMo board if you try to disconnect the internal antenna. I have nearly 25 years of experience working at the intersection of software and hardware. I am a strong solderer and I am willing to pay for a new FabMo board if I kill it. My results are positive so far, but this is just an experiment. At some point I may decide this made no difference and reconnect the internal antenna.
Edited 4 time(s). Last edit at 11/24/2016 05:37AM by Collin.