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Weak FabMo WiFi Signal?

Posted by Collin 
Weak FabMo WiFi Signal?
November 21, 2016 11:45PM
I just got my FabMo upgrade board installed this weekend. It works well in AP mode when the computer is nearby, but I had a heck of a time connecting it to the my WiFi network. I eventually discovered that if I moved the Handibot right next to the base station I could get it to connect to the network. It took me a while to think to do this since the basestation is line of site across the garage and gives a strong signal to any other device in the garage. I have since upgraded to v1.3.1 but it seems to make no difference for the connectivity issues.

Does anyone else seem to have a very weak WiFi signal with the FabMo?

Re: Weak FabMo WiFi Signal?
November 22, 2016 03:05AM
Yes, this is a real weakness of the fabmo platform right now. My shop is at the back of our property, not very large and even with a wifi extender I get nothing. All my laptops and tablets get it fine but fabmo is all like I can't see it. I just operate in AP.
Re: Weak FabMo WiFi Signal?
November 22, 2016 12:46PM

using a handibot 1, you're also facing the extra challenge of communicating wirelessly with a card enclosed in a metal case (the handibot 2 has a clear acrylic electronics enclosure). To overcome this, your card included that extra antenna. You might try moving the antenna to another location on the tool and seeing if that helps with your signal.

Re: Weak FabMo WiFi Signal?
November 23, 2016 02:38AM
I mounted a larger antenna in the now unused USB port on my Handibot. It seems to get better range. I get 4-5 bars now most of the time. Until inexplicably I don't and it drops to 1 bar or starts to have connectivity problems (I guess that's 0 bars). Then it pops to life and works fine. Strange.

- Collin
Re: Weak FabMo WiFi Signal?
November 23, 2016 02:41AM
I tried to attach images, but attachments seem broken on this forum.

Edited 1 time(s). Last edit at 11/23/2016 02:50AM by Collin.
open | download - IMG_0150.jpg (114.7 KB)
open | download - IMG_0157.jpg (75.1 KB)
Re: Weak FabMo WiFi Signal?
November 23, 2016 10:29PM
Yes attachments are broken. Everyone sticks stuff in Dropbox and links.
Re: Weak FabMo WiFi Signal?
November 24, 2016 04:06AM
Trying again from Dropbox...

Antenna Mount Front
Antenna Mount Side
Antenna Mount Back
Handibot Antenna Back
Handibot Antenna Close Up

Amazon links for parts :

SMA Panel Mount
U.FL Mini to SMA Cable

The mount press-fit into the USB-B hole in the Handibot. I fashioned a piece of MDF to fit the former USB adapter hole with a notch in the middle to fit the SMA mount cable. I used the existing USB mount screws to tap into the MDF. I have a jar of random screws and found 4 small screws to affix the SMA mount to the MDF. None of the screws were wood screws but they seated firmly enough into the MDF for this. The result is sturdy. It looks professional but doesn't modify any of the original Handibot parts.
Re: Weak FabMo WiFi Signal?
November 24, 2016 05:08AM
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:


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.
Re: Weak FabMo WiFi Signal?
November 24, 2016 11:41AM
Great info Collin, I certainly appreciate it even though I don't think it will help me as I've acualy been in electronics too long. No micro mini for me.
Re: Weak FabMo WiFi Signal?
November 24, 2016 01:54PM
Amazing work Collin! We're all discussing this here at hq--

It would definitely be great to improve reception--I tend to run in AP mode in my shop at home as well for signal reasons.
Thanks for opening up this discussion!
Re: Weak FabMo WiFi Signal?
November 28, 2016 02:02AM
Brief update...

I've played with my Handibot v1 + FabMo for a number of hours this weekend and it's working great with my upgraded antenna and resistor mod. I am getting 3-4 bars consistently with an occasional droop to 2 bars. I'm not sure why it droops occasionally but there is a lot of wireless going on both in my home and nearby. The important part though is that connectivity has been solid and responsive even at 2 bars. (I incorrectly stated I get 4-5 bars above, but on closer inspection the meter maxes out at 4 bars.)

It would be interesting to try the stock external antenna with the resistor mod, but I've been having fun playing around with the Handibot so I haven't tried.

Good job on FabMo. It's great that my Handibot finally has a brain onboard.

- Collin
Re: Weak FabMo WiFi Signal?
November 28, 2016 09:45AM
Glad you're enjoying it! If you're feeling adventurous--take a look at some of the other apps that we've been working on: [github.com] just download the .fma file and install from the dashboard. I've been having fun with the fabmo-graph app lately: [www.youtube.com]
Re: Weak FabMo WiFi Signal?
January 25, 2017 10:16AM
Hi...i am a new user here. As per my knowledge this is the problem of the fabmo platform right now. My shop is at the back of our property, not very large and even with a wifi extender I get nothing. All my laptops and tablets get it fine but fabmo is all like I can't see it. You should try to operate in AP.

low-cost pcb assembly

Edited 1 time(s). Last edit at 02/17/2017 04:13PM by JaseSerre.
Re: Weak FabMo WiFi Signal?
December 31, 2017 03:27PM
Just want to say I did this with a Handibot Adventure Edition. Works great. Used a hot air rework station, but I think you could probably just snap off the resistor with a needle nose if you really wanted to.
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