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NEW MEMBER? Please introduce yourself here
Hello all, apparently I've never bothered to introduce myself.
I'm an Embedded Field Application Engineer specializing in embedded systems and security. I work for a little company who, among other things, sells and supports SiLabs parts.
Pleased to be here! |
Nov 08 2017, 8:53 PM |
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NEW MEMBER? Please introduce yourself here
Hello all, apparently I've never bothered to introduce myself.
I'm an Embedded Field Application Engineer specializing in embedded systems and security. I work for a little company who, among other things, sells and supports SiLabs parts.
Pleased to be here! |
Nov 07 2017, 10:28 PM |
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EFR32WG Range Test
Excellent information. Thank you. |
Oct 28 2017, 4:26 PM |
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EFR32WG Range Test
Hi dasimon,
Thank you for the comments and feedback! |
Oct 28 2017, 4:25 PM |
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EFR32WG Range Test
Hi dasimon
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Oct 28 2017, 4:25 PM |
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EFR32WG Range Test
Hi andrasbiro, I went with 2FSK based upon my understanding of this knowledge base article: http://community.silabs.com/t5/Wireless-Knowledge-Base/Modulation-choice/ta-p/144373
While I didn't have a spectrum analyzer handy, I do know that the 2.4 GHz band is very crowded in the middle of a big city.
Is there a particularly recommended modulation scheme for low-bandwidth applications in very noisy environments? |
Oct 28 2017, 4:25 PM |
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EFR32WG Range Test
Thanks jose! I think I'd like to see if I can get a kilometer at some point! |
Oct 28 2017, 4:25 PM |
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Posted
EFR32WG Range Test on Projects
Below are the conditions and results of some range tests performed with a pair of BRD4151A +19.5 dBm EFR32MG WSTK boards. Tests were performed in the most glorious of non-scientific manner befitting of real-world conditions.
The range test application was flashed to the boards and I verified that it was working properly:
Next, a bit of data from the BRD4151A Reference Manual is required: 3.3.4 Inverted-F Antenna The BRD4151A Radio Board includes a printed Inverted-F antenna (IFA) tuned to have close to 50 Ohm impedance at the 2.4 GHz band. 3.3.5 UFL Connector To be able to perform conducted measurements Silicon Labs added an UFL connector (P/N: U.FL-R-SMT-1) to the Radio Board. The connector allows an external 50 Ohm cable or antenna to be connected during design verification or testing. Note: By default the output of the matching network is connected to the printed Inverted-F antenna by a series component. It can be connected to the UFL connector as well through a series 0 Ohm resistor which is not mounted by default. For conducted measurements through the UFL connector the series component to the antenna should be removed and the 0 Ohm resistor should be mounted (see Chapter 4.2 Schematic of the RF Matching Network for further details).
The inverted-F antenna is actually quite great but I felt like going for something a bit more excessive.
For starters, we need to modify things a little. Here is the 0 Ohm resistor mentioned above under a scope:
This resistor must be rotated 90 degrees anti-clockwise to the trace leading to the U.FL connector: (It looks messy but it's just a couple square millimeters of flux reflecting light from the scope)
Two, 2.4GHz antennas were chosen (because they were what I had lying around and because both happen to have the aforementioned requisite 50 Ohms of impedance).
For the transmit side, an 8 dBi omni-directional antenna:
And for the receive side... a 24 dBi parabolic directional grid, which I'm sure everyone has in their junk drawer at home:
The pigtails and coax cable likely introduce a non-negligible amount of insertion loss but it was decided that I would just see how it worked out in lieu of a bunch of math.
A suitable location was required with significant distance of unobstructed line of sight which proved very difficult to find in my locale. (The local airport was very confused about exactly why I wanted access to their runway and hung up on me.)
Fortunately, water is pretty flat and a nearby lake had a 535 meter clear path:
Cables were connected:
I managed to con my significant other into standing on the opposite side of the lake holding the omni-directional antenna and pressing the start button on the transmitter side.
Antennas were approximately 1.5 meters above ground level and were aligned optically (I pretty much just took a best guess). Boards were configured to use the minimum data rate and maximum receive sensitivity. FCC regulations were complied with to the best of my ability and understanding.
Results were quite positive and very consistent. All transmitted packets were received!
A more thorough write-up may follow as I'm curious to find out what the practical range limitations are! |
Oct 28 2017, 4:25 PM |
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Setting up Range Test Application on EFR32
Hi mapleleafs,
I realize your post is a bit old but I figured I'd comment anyhow in case someone chances upon it at a later time.
Having done some range test stuff myself I can tell you that the height of the antenna can certainly make a difference, performance wise.
Some of it has to do with the wavelength of the band you're operating on, in this case the 2.4-2.5GHz range of the ISM band.
The formula for wavelength is:
Where: c = speed of light in vacuum, a constant ~ 300,000,000 meters/sec
It's usually a good idea to keep your antenna at least 1.5X to 2X times the wavelength above ground or your photons are going to do all sorts of silly things.
1.5 meters is a nice number because it gives a standard baseline of comparison that is easy for most humans to manage (it's about 5 feet) without an antenna mast.
Some of it also has to do with radiation patterns:
With sufficient height, you're less likely to be bouncing the strongest part of your "lobes" off of the ground in a way that would interfere with ideal operation.
For the most part, any obstruction will tend to reduce ideal performance, some more so than others.
Will your module explode if it's 5cm above the ground? Probably not, but it's certainly not ideal and you won't see optimal performance.
As for your second question, I think I recall that the WSTK uses something like an LP3878 regulator, so I would suspect you should be fine with a single cell Li-ion. Just be careful, those 18650s can often source a LOT of current (some up to 40A), so don't short it out! |
Oct 28 2017, 4:25 PM |
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Gecko Lights
I too am curious about this magical driver library.
I was working on porting the FastLED library over to Gecko for a while but if you've got something functional it would be great if you could share! |
Oct 28 2017, 4:12 PM |