Member Since: January 7, 2010

Country: United States

  • It gave me a chuckle to read this. I appreciate the support, and yes, there is a difference between building a life critical device and a hobby device.


  • I have indeed found this to be true. I live next to where the Hamvention is held each year. There are some fantastic people that are in the hobby.


  • I appreciate the encouragement. In this case, as I am operating in very low conductivity water (read not salt or brackish water), VHF and UHF will work. There is a gentleman that has tested devices in the 433Mhz and 915MHz ranges. With modern, high sensitivity RFICs it was possible to get a fully functioning submarine using a 433MHz transceiver. Using 915Mhz, he was only able to achieve about 3' (roughly 1m) in depth. While this is useful, it is not as useful as is required to operate a boat safely.


  • I appreciate you question, though I do ask for some level of civility in asking questions. I and others are happy to answer questions.

    As was mentioned, a VNA is a Vector Network Analyzer. It is used measure the performance of various radio frequency (RF) related parts and connections. It essentially sends out a signal that is a frequency sweep, and then it also listens to see if there is a return of that signal. The magnitude and phase of the return of this signal corresponds to performance parameters of the device under test (DUT).

    What I am doing with the LimeSDR is an application that was originally envisioned as a sample application. Is it fully equivalent to a $10k device, absolutely not, but is it better than having no device at all, for sure it is. While there are performance trade-offs, it still yields useful information.


  • Very true. With passion and a desire to learn, you can go very far. I have loved the freedom of being able to study diverse topics since I have left school. It has allowed me to be able to make connections across disciplines that would have been hard to find in a siloed approach.


  • It all depends on what one considers playing around and one considers learning. They are not mutually exclusive. I agree that one can take learning to various levels depending on their aptitude and desire to learn. Also note, that I am a degreed engineer, just in another branch of engineering. The overlap in the fundamentals is significant despite the application being different. As to my classmates appearing to be geniuses, well this why we went into engineering, to be surrounded with like minded people who were "different" :)

    As to playing around with Arduinos and not understanding how an actual computer works, I would contend that this may one of the the best way to get an understanding of what our computers evolved from. By studying these small microcontrollers one learns how memory is handled, how code is converted to machine instructions, and many other concepts are directly leveragable to a general CPU. In fact, Intel at one point in time had their Arduino board with chips that were x86 instruction set devices and had early Pentium level performance.

    I currently have a dev kit on my desktop that has a Cortex M7 in it, and as far as processing power is more powerful than our family's first personal computer (486DX2-66 with math co-processor). The cortex M7 part benchmarks at ~460 DMIPS vs about 45 DMPIS for the 486. It really is amazing what these microcontrollers can do now a days.


  • I suppose it all depends on if you read it 102 or 201. If you read it 201, then it comes out to 4/200 Ohm resistors in parallel, that then equals 50 Ohm load.


  • For MCAD programs, STEP/STP and IGES (though STEP/STP is becoming more popular) are the standard interchange file types. STL is used for 3D printing, but is not a very clean geometry when importing everything into a standard MCAD program. All the surfaces are represented by triangles.

  • That is like comparing bananas and bears.

  • This is not exactly what I had in mind when you asked me to come over to play Mario Cart!