So I just took my exam in RF Devices and Circuits and as I sat down at my desk I realized I made a big mistake. On my note card, I had an equation as [math]\Gamma \left (d \right)=\left |\Gamma _{o} \right |e^{j\theta _{L}^{}}e^{-2\beta d}$$[/math] instead of [math]\Gamma \left (d \right)=\left |\Gamma _{o} \right |e^{j\theta …
Author Archives: Brian
Synthesizer Working
It turns out that the synthesizer was in fact damaged. I swapped it out and here’s the result: A nice 870MHz signal. Update 10:00 PM: The synthesizer probably failed because it was heated to long during the soldering process. Most likely it wasn’t the soldering of the synthesizer itself that did it but my need …
Synthesizer Not Working
Synthesizer still not working. I checked that there aren’t any shorts between the exposed paddle underneath the IC and any of its pins. Ground and power is everywhere it should be. The loop filter is pulled up to 3.3V though it should be around 1.8V when it’s locked in. It’s not shorted to 3.3V so …
JTAG Problem Fixed
Well, I figured out what was wrong with programming the ARM from JTAG. The RESET line on the JTAG connector is accidentally routed to the RESET_OUT signal on the ARM instead of the RESET_IN line. I pulled up the pin and added a jumper to the corrent pin and it works fine. On to testing …
Multilateration Mainboard Populated
I finished populating the mainboard and mounted the receiver cards on it. Here’s what it looks like: I’m having a bit of a problem programming it. It programmed just fine the first few times I tried but now it work take at all. The CPU is running because I can see its serial output and …
01-30-2009
I received the mainboard and began populating one test board by hand. When I got to the first inductor, I was awed by how awesome the little guy was! This is an 3.9nH inductor in an 0402 package making to 20×40 thousands of an inch or a little larger than a grain of sand.
Making Ringtones for Jailbroken iPhone 3G in Ubuntu
Making ringtones for your jailbroken iPhone in Ubuntu is easy using SoundConverter. I’m going to assuming your iPhone is already jailbroken and you know how to upload files to it (usually with openssh). First thing to do is make sure the Universe repository is enabled by going to System->Administration->Software Sources and checking “Community-maintained Open Source …
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01-21-2009
Yesterday I priced out all the parts for the multilateration system. Nearly everything is available from Digi-Key with the exception of the LNA, an oscillator, and an SMB connector that I have to get from Mouser and an RF splitter from Mini-Circuits. One thing I like about Digi-Key’s website is that they don’t have alot …
A Fix, a Tweak, and Out The Door
It turns out there was an error on the board that I managed to catch in my final sweep of the board. Now I’m wondering if there are any other unfixed gremlins waiting between the traces to bite me. Oh well, nothing to do but get it in hand and see if it works as …
Multilateration Board Complete
I completed the design for the multilateration system today. At least I hope I did 🙂 . I was quoted at $120 a board which is not bad for quantity 10 with a 5 day turn around. Here’s what the completed board looks like with all layers turned on. Next thing to do is generate …