Goertzel_algorithm_2.ino

Working version running with simple serial display of direction based on tone phase. Need to add filter for second harmonic - reflections.

ino - 5.10 kB - 05/23/2019 at 00:15

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ddf_HW_v0.2.pdf

Updated hardware with overkill analog band-pass filter from the 1999 WA2EBY article. I thought it would be an interesting test to see if system performance could be improved with additional filtering.

Adobe Portable Document Format - 125.27 kB - 04/15/2019 at 07:15

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display options.jpg

The VFD is beautiful but I worry about washing out under sunlight. E-ink is really slow and not a good fit. Probably go with 4 digit LED or LCD. Any tips for getting better LED pix? I turned the ISO to lowest setting to get this.

JPEG Image - 2.93 MB - 04/07/2019 at 22:39

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VFD_DDF[1].jpg

Experimenting with an expensive display. I really need a heading readout at very least.

JPEG Image - 2.92 MB - 04/04/2019 at 05:31

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Puck Magnet Cookie Sheet.jpg

This is the cookie sheet ground plane with the prototype puck mounted antennas and antenna switcher. Because it'e unsymmetrical the cookie tin is not a good idea and the antenna and switcher will mount on the car. One step closer to in car testing.

JPEG Image - 2.23 MB - 03/30/2019 at 05:40

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20190328_153737.jpg

(Very rough) puck magnet prototype. Being lazy I went for silver epoxy to attach the PCB to the mounting magnet. Warning: the silver epoxy is really expensive and works great. The silver epoxy is conductive and I measured ~0.1 ohm beteen antenna ground and the magnet. The side mount SMA connector is crap and I'm going to spend the money on right angle, though hole jack.

JPEG Image - 2.16 MB - 03/28/2019 at 23:04

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V0.02_hw.pdf

Latest hardware schematic - see antenna switcher and BNC connector for a complete picture.

Adobe Portable Document Format - 96.34 kB - 03/26/2019 at 06:09

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HW Version 0.02.jpg

Pix of latest hardware.

JPEG Image - 2.55 MB - 03/21/2019 at 07:33

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20190317_161831.jpg

A cleaned up cookie sheet ground plane.

JPEG Image - 3.46 MB - 03/18/2019 at 00:02

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DDF_V0.02.ino

Latest and sloppiest Teensyduino code to date.

ino - 7.13 kB - 03/17/2019 at 23:01

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VID_20190315_115622.mp4

Display in operation. The white pixel shows direction and background color signal quality. Testing in a small room with metal furniture causing many reflections. Warning: annoying audio sound - beware!

MPEG-4 Video - 48.39 MB - 03/15/2019 at 19:02

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BNC_antenna_board.jpg

New PCB using BNC connector with though hole connection. Seems very sturdy. Now featuring PIN diodes!

JPEG Image - 3.83 MB - 03/07/2019 at 00:18

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DDF Scope Display.mp4

The upper trace is one of the antenna bias drivers turning on one of four antennas. The lower trace is the demodulated Doppler audio tone DSP filtered. The comparator output is overlaid showing Doppler zero crossing. You can see the lower signals wobbling around which I believe is me interacting with the RF reflections.

This is a terrible test lash-up and all of my signals are noisy. Must clean up.

MPEG-4 Video - 41.31 MB - 03/03/2019 at 23:57

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antenna_switcher.png

Selects an antennas based on input at P1. By selecting one of the four antennas in a rotating fashion a pseudo-Doppler tone is added to the received signal. The Doppler frequency is set by the rotation rate.

Portable Network Graphics (PNG) - 25.93 kB - 02/19/2019 at 21:42

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ddf_tester_tester.ino

Sorta stable pulse delayer script for Arduino.

ino - 469.00 bytes - 02/18/2019 at 10:22

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BNC-Antenna Mount.png

Board schematic for using a BNC whip antenna. Received signal appears on SMA side mount connector when the 1n4148 is biased on. Whip antenna is on the BNC connector.

Portable Network Graphics (PNG) - 7.54 kB - 02/18/2019 at 09:37

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