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Simple, low-cost FMCW radar

A basic radar system makes radar accessible at low cost for experiments with rangefinding & navigation of autonomous aircraft or spacecraft.

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This project was created on 06/30/2014 and last updated a month ago.

Description
This relatively compact, cheap, simple FMCW radar operates in the spectrum around 5.8-6.0 GHz and is aimed at lowering the barrier to entry for experiments with radar and general education around RF/microwave electronics. It is capable of speed measurement, rangefinding and SAR imaging (with appropriate moving antennas or a moving vehicle.) It is potentially applicable to experiments with autonomous aircraft (or spacecraft) altitude-finding, SAR imaging/mapping or navigation as an alternative to (or in addition to) other sensing techniques such as GPS, ultrasonics, LIDAR or barometry, without some of the limitations applicable to those technologies.
Details

Frequency-modulated RF is generated by the Hittite HMC431 VCO at top left, at about 5.8-6.0 GHz, amplified by the HMC476 MMIC gain block at top left, and split in half by the Wilkinson divider at top center. Half the RF output from the divider is amplified again and sent to the transmit antenna connector at top right.


The local oscillator, from the other side of the splitter, is amplified again and applied to the LO port of the Hittite HMC219 mixer at bottom center. The reflected RF from the receive antenna comes in at bottom right, where it is amplified by the Hittite HMC717 6 GHz LNA and the amplified output is applied to the mixer.

A couple of pi attenuators are used, after the VCO, before the mixer LO port and after the mixer's IF output, to "tune" optimal mixer LO level and overall performance, although I haven't fixed certain values for these attenuators yet, space for them is left on the board.

IF filtering, amplification and signal processing, along with generation of the 0-10V modulation signal for the VCO, are done on a separate board. More details to come, as design, fabrication, revision and testing progresses.

Components
  • 1 × Hittite HMC431LP4E 5.5-6.1 GHz GaAs/InGaP HBT MMIC VCO (voltage-controlled oscillator) with internal output buffer
  • 1 × Hittite HMC717LP3E 4.8-6.0 GHz GaAs PHEMT MMIC LNA (Low-Noise Amplifier)
  • 1 × Hittite HMC219AMS8 4.5-9.0 GHz GaAs MMIC double-balanced mixer
  • 3 × Hittite HMC476MP86 0-6.0 GHz SiGe HBT MMIC gain block (amplifier)
  • 3 × Molex 0732511150 50 ohm SMA socket, board edge end-launch style to suit 1.6mm PCB, specified up to 18 GHz.
  • 3 × Susumu PAT1220-C-3DB-T5 Susumu 0805 PAT series 50-ohm pi attenuators, specified up to 10 GHz. I will tweak actual values later.
  • 30 × Assorted capacitors, resistors, a couple of LEDs, 3.0V LDO and a couple small FETs.
  • 4 × Several assorted opamps - LM358, MCP6001, OPA2228s, MAX477 Various functions - IF video amplification, triangle-wave oscillator, DAC output gain, active filters
  • 1 × Microchip MCP4921 SPI 12-bit DAC for VCO modulation waveform synthesis - arbitrary function.

Project logs
  • New video is up!

    a month ago • 0 comments

    NOTE: This is an 8-minute video, I know it is slightly longer than the 5 minutes requested by the THP judges. I think you'll still get some valuable substance and overview of the project work thus far if you stop watching at the 5 minute mark... so hopefully they are not too strict about an extra couple of minutes. Hope that's OK :)

    Please enjoy, and feel free to let me know if you have any comments or questions! :)

  • Productive day.

    a month ago • 0 comments


    See, you can see just how productive my desk is today! (I swear it's not usually this bad!). I guess you could call this a behind-the-scenes "how it's made" sneak-peek.

  • Gain block schematic

    a month ago • 0 comments


    This is the schematic of my HMC476 "building block" module for prototyping. I'm going to have everything on GitHub for public open-source consumption shortly, but right now, you can enjoy a pic :) Please do comment if you have any questions. :)

View all 22 project logs

Discussions

Jasmine wrote 2 months ago null point

Hello Luke, I think you have most of what we are requiring for the next round of The Hackaday Prize. The only thing I can't see is links to code repositories or software libraries. And remember to mention any licenses or permissions needed for your project. Best to document that information in the project details. Thanks for entering and good luck!

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Luke Weston wrote 2 months ago null point

Hi Jasmine, I will put an update up and some code online this weekend. :)

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rafael.menezes wrote 3 months ago null point

If you need help with the algorithms, I have some background.

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J Groff wrote 3 months ago null point

I wonder if the ultrasonic processing firmware would function with tweaks to constants?

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pfeffer.marius wrote 3 months ago null point

Have you thought about the legislations over the world ? Would be realy nice if this could be used worldwide.

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Adam Fabio wrote 3 months ago null point

Nice work Luke! I love those Hittite chips - though they can get pricey! Thanks for entering The Hackaday Prize - with 10 project logs, you're doing a great job keeping the updates coming in! Don't forget about the video, and good luck on your way to Space!

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Luke Weston wrote 4 months ago null point

I will probably start with some PC-based experiments building on the prior similar work of Greg Charvat and Tony Long, but I would also like to eventually have the ability for a lightweight, cheap embedded microcontroller system to digitize the signal and extract basic information such as speed or altitude for use in autonomous navigation of a vehicle such as a quadcopter or other UAV, autonomous altitude control etc. But this kind of software is one of the least mature, least developed parts of the project at this time. Thanks for your support :)

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zakqwy wrote 4 months ago null point

Sounds like a great plan. There are a number of industrial products out there that use FMCW radar systems for level monitoring in liquid/solid applications; while the firmware is always locked down and proprietary, the manufacturers often share some details of the echo processing system. Worth a bit of research to get you started I'm sure.

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pfeffer.marius wrote 3 months ago null point

Sounds great ! Currently it's not easy (and cheap) to measure the distance to the ground from UAVs which is realy helpful for autonomous landing or collision prevention.

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zakqwy wrote 4 months ago null point

Great project! I'd love to learn more about your plans for echo processing. Any algorithm details?

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