Detail description of work have done.    AG6JU   Niko Takahashi

 

   

 

216MHz, 150MHz, 401MHz, directional finding receiver.

video example of how this unit being used ( youtube link )

  

 

Car Battery disconnect  , when engine start battery voltage exceed threshold it connect relay, disconnect when battery voltage drop  ( when engine stop ) after time out. 

   

   

   

   

Receiver production tuning, adjustment fixture, did PCB layout, wrote firmware to run tester.

 

   

actual usage for above fixture for testing, adjusting, fimrware programming of receive unit. 

using spectrum analyzer with tracking generator to adjust front end, local oscillator coils.

 

   

 PCB example RF circuit. 

 

 

 

Video of how this unit works ( youtube link )

 

 

 

 

 

 

 

 

 

 

 

VHF, UHF  CW receiver for direction finding.  layout PC boards, design circuit, wrote firmware in C.

video example of how this unit is used on 401MHz ( youtube link ) 

 

 

 

 

VHF, UHF  CW transmitter for Animal locating ,power 100 mW, and it has motion detector sensor 3 axils silicone, hall effect sensor.   ( PCB layout, RF design, firmware programming in c )

 

 

216MHz CW transmitter for locating person. Fractional PLL,  100 Hz step.  25 mS pulse, 10 mW , FCC part 95 certified   ( PCB layout, RF design, firmware programming in c )

    

 

 

 

216MHz CW receiver for directional finding, fractional PLL for 1st LO.  1kHz Step.  minimum discernable signal  about   -145dBm     ( PCB layout, RF design, firmware programming in c )

 

        

 

 

250MHz fundamental mode,  Inverted Mesa crystal Oscillator crytsal is made by KDK Nagasaki , Japan.

Schematic of 250 MHz fundamental Mode Inverted Mesa Oscilator.

 

Frequency / temerature  variation of 250MHz inverted Mesa oscilator

 

 

layed out PCB for  GPS to Radio adopter device, and assisted run of initial production.     ( PCB layout, RF design, firmware programming in c )

 

 

designed GPS tracking device and 150MHz FSK radio transmitter with ublox GPS module.  ( PCB layout, RF design, firmware programming in c )

PLL TX, TCXO reference OSC 0.5 ppm -40 to + 60 deg C, PIC microprocessor, National Semi Integer PLL IC,  100 mW PWR output.

 

 

 

designed full automated wildlife annimal tracking system. 216MHz,  PCB, and firmware    ( PCB layout, RF design, firmware programming in c )

PIC microprocessor, PLL with TCXO reference,  15 mW output, 3V 15 mA during TX, between TX 16 uA.

         

 

 

 

redesigned CTCSS and DCS Tone encoder and decoder

 

 

 

data transmitter  VHF, UHF

 

 

Solidworks sheet metal design

 

 

desinged plastic injection mold case and aluminum machined case for tracking transmitter using 3D CAD Solidedge V12

         

 

 

 

designed VHF, UHF tracking transmitter for LPRS ( FCC Parts 95, Parts 90 Certified ) use for law enforcement tracking.  Fractional PLL, 100mW  3.3 V  80mA     ( PCB layout, RF design, firmware programming in c )

 

 

   

desinged VHF, UHF  SSB/CW receiver for direectional finding. Fractional PLL, TCXO ref. Dual conversion 2.2kHz wide 10.7 MHz 1st IF, 455kHz 2nd IF

layed out PCB, firmware in 'c'  PIC microprocessor.  Designed Aluminum stampted metal case.

 

 

desinged VHF, UHF transmitter for small annimal

 

 

designed VHF, UHF PLL transmitter for locating. wrote firmware, layed out PCB , clock speed of 1Khz for low powe consumption.

 

Designing 900MHz transmitter for tracking.

developed 900MHz PLL CW beacon transmitter and receiver , FCC Parts 15 device.

   

 

 

 

GPS based animal tracking prototype.

designed  GPS based tracking transmitter, include GPS receiver and VHF, UHF  transmitter.

it send out modulation AFSK   1200 BPS  APRS packet   or     +/- 1.1 radian 800 bit per second  / manchester coding.

 

 

 

GPS based integrated vehicle navigation system.

developed Navigation system combined with data gathering ability using Alps , Co. Ltd. 's digital map ( Nagoya Japan ) , I got licensing from Alps for detail of data format , and made navigation parts using their map, this map is raster map rather than conventional vector map which are more commonly used in automobile navigation system map.

The system is build on frame work based in IBM PC compatible industrial computer, it runs on TNT DOS extender operation system for reliability as test equipment, rather than windows operation system. DOS extender is technology similar to DOS , but it enable to access full capability of Intel 386 or higher class processor since it is running under protected mode. By using preexisted hardware, developing time was shorter than other wise build special hardware.

 

 

 

Radio repair technician

worked as two way radio repair technician parts time during student, repair almost all the make of Amateur and commercial radio, including HF, VHF, UHF radio, component level trouble shooting, testing.

 

 

1992  Doppler shift based radio direction finder.

build radio direction finding equipment, this is based on Doppler shift effect, has 8 antennas in circle, 16 LED to tell which direction the radio wave is coming from. Used discrete component, designed antenna switcher, build and trouble shoot the system. This was develop as volunteer effort ( unpaid ) for Utah Sates University for high altitude balloon tracking and recovery, which was used as relay radio signal, take high altitude picture, etc.

the circuit consist of 8 vertical antenna placed in circle, and one of them is selected by PIN diode switching matrix to connected to receiver, and by switching each antenna sequentially in circular order, it simulate if the antenna is rotating around center of 8 antenna circle, this create doppler shift in incoming signal, and appear as FM modulated wave at receiver, its frequency is same as rotating speed of the antenna, by comparing phase difference between rotating antenna and modulated wave, it an determine direction of the signal is coming from.

I used PLL circuit to lock both modulated wave, and signal feed into antenna switching, but DSP process will be better way, specially when more than one signal is arriving from different direction, with PLL lock circuit, it had difficulty locking onto signal with multipass.

 

 

Avionics technician

worked as radio technician to repair component level of small general aviation air craft radio and its navigation system , this include VOR, COM, ILS, Transponder, DME, autopilot, ADF.

 

 

 

some manufacturing experience:

 

Able to program JUKI 750 series Pick and Place machine  using flexprog , can transfer the PCB CAD data to JUKI placement position data. know how to trouble shoot, maintain. hold certificate from JUKI video of  Juki 750 ( youtube link ) toubleshooting laser height adjument JUKI 750 ( youtube link )

familiar with DEK stencil printing machine

know how to use Heller Oven for SMT soldering

programed Computerized Production Test setup using visual c console program.