Project Page.
Note: Only a FEW of my projects are listed here, will add more when I make pictures.
One of the more intersting items is called "HackRF". Which is a SDR Transceiver (10Mhz to 6Ghz)
Link to HackRF is here.
Other projects include DSP, FPGA, and Optical Correlators (JTC).
* My first DIY Laser, MOPA (Master Osc. Power Amp) -- Circa 1998/1999.
* Nd:YAG laser at 1064nm wavelengh - can burn a hole in the side of a beer can.
* External Power Supply, Once I find it, will post pictures here.
* Uses the polished inside of a Coke can as amplifier mirrors.
* Wrote C programs to design Laser power-supplies and PFN's, see:
* Code is here, bottom of page: Sam's Laser FAQ. Laser power supply theory and math is at beginning of this page.
* This link will take you directly to the spot on the above page. You'll see the reference to my name here (and my old IBM email address).
Engineering:
Instead of trying to time when the light pulse is in the amplifier, I used a PFN
to "stretch" the amplifier pulse to such a length in time it was assured to amplify
the main pulse. Certainly simplified the design. Built on a optical rail from a
grocery store laser scanner. Optics was designed to make small "zoom" lens,
(not adjustable) to put spot of impact (smallest dia. spot) at about 4" from front of lens assy.
The external PS/PFN probably puts ~100 amps of a HV on a aircraft coax cable, (computed this once)
but due it's less-than 1-millisecond in time, it's does not melt the wire. Recharge time
was something like a minute. Should also mention that this is all analog tech, and cable
length matters, and probably made it too long. There's a 1/4"-20 hole on the bottom for a tripod
mounting.
(PFN = Pulse Forming Network)
* RADAR, Synthetic Aperture Radar (SAR), Short Range.
* Highly modified version of project found in the book: Small and Short Range Radar Systems.
* Book on my main page, by Gregory L. Charvat (http://glcharvat.com/tincan/).
* Uses Raspberry Pi (Linux OS) for switching between modulators.
* First pic shows first version, the vertical component is a "directional coupler and diode detector".
* Second pic shows external modulation via Waveform Generator and my new portable oscilloscope.
* Second pic shows radar in final 19" rack mount chassis. Radar is in test.
Engineering:
Radar was modified several times. In it's final configuration, I moved to external modulation, and
one form of internal modulation. (So I can use a precision Arbitrary WaveForm Generator, and any waveform
the generator can make.) Added a High-Powered Amp on a second and top board, that increases RF to
250 milliwatts. Amp board is not installed (yet).
* Beagle board (Linux OS) married to an Arduino sub-processor via the I2C bus.
* Wrote software in C for both devices, the Arduino is used for it's A-to-D converters.
* Basically it poles the Arduino board for a channel of A-to-D and returns the analog value.
* Arduino board somewhat hard to see, it's under the beagle board. Wired for 12vdc.
* Nice HW/SW and I2C project...
* HSMM node, now known as "HAMNET". Uses WRT-54gl WiFi High speed data network board.
* HAMNET (or HSMM) was developed by a group of hams in Austin, Texas for ECOMM.
* Here again used sub-processor board (Arduino) and a 433 Mhz receiver that listens for
* a data stream, once it's receives the right data stream (coded), it will do a hard reset
* to the WRT-54gl board. For use on top of towers where access is limited.
* AKA "Drive-by" remote hard resets.
* Notice the conformal coating and the heat sinks to with-stand the HOT Texas summers.
* WRT-54gl runs a small Linux OS.
* Mounted in outdoor box.
* Remote Wide-Band Receiver, All Mode, 0.1 Mhz to 1700 Mhz. Accessed via TCP/IP Link & remote SW.
* Used Cheap USB receiver and HF up-converter board for the HF portion of the band, (0.1-30 Mhz).
* Raspberry Pi board (Linux OS) that switches antennas (HF or VHF/UHF) and to put audio on the TCP/IP port.
* All mode: AM, FM, SSB, digital modes. Frequency Tuning is also done via remote SoftWare.
* For accessing signals (RF) in remote areas -- anywhere on the planet via internet.
* Other than the Power Supply assy, and Coax Relay Board, it's all built from COS components.
* Mounted in outdoor box.
Engineering:
Used switching power supplies, so enclosed power supplies in a "Altoids" tin, with a fan for cooling
in hot Texas summers. Under the fan is copper window screen -- soldered to make a Faraday cage.
Note the use of ferrite torriods (beads) that are for RF "quiet" operation. Many of the wires
are shielded, plus shielded ethernet cable. Believe I also put extra filters on the power supply outputs.
* Analog Computer: This is the "Chaos Theory" demo, aka "The Butterfly Effect".
* See: MIT News, Edward Lorenz.
* Circuit Web Page is Here.
* Displays on oscilloscope, in X-Y mode.
* Always had a interest in Analog Computers, and built one. I believe analog tech is beautiful!
* This analog computer is solving three differential equations (the weather) in parallel!
* Does absolutely nothing, no purpose at all, just demo's the "Chaos Theory" science. Still cool IMO.
