A Work In Progress

a comprehensive history of one man's dream

The DARTS Project is a quest that I have undertaken (along with many others) to develop rocket flight performance measurement equipment . Here is a brief documentation of the trials, failures, and successes we have had in this quest.

Remember that the pictures are clickable to bring up larger, bandwidth-eating versions.

The Beginning (1989-1990)

I first started thinking about tracking rockets with radio during this period. I was in engineering school at Oklahoma State University at the time, and was talking to some of the members of Tripoli Oklahoma about how they measured the altitude of their rockets. The answers I got varied from "we don't" to "we eyeball it". Being an electronics engineer in heart as well as vocation, I knew there was a technological solution to this problem.

I didn't know that it would become my life's work <grin>!

I began gathering literature: everything from the "Rocket Manual for Amateurs" published at Fort Sill in the 1950's to NASA Tech Notes describing tracking for sounding rockets. My initial desire was for a ranging-only device; my literature searches were focused in that direction. I didn't, for instance, read much radar material at that time, mostly just material on missile and spacecraft tracking. I realized much later that I needed to learn about radar, and it was only then that I plunged into reading all the radar books I could get my hands on.

I started looking for radio bands suitable for such a radio tracking device. Amateur radio bands were fine and available, but I knew that I needed wideband data to measure distance accurately. So, I looked to the mostly-unused UHF TV band.

I recently found among my old college junk a notebook that contains the foundations of DARTS.
From my August 18, 1989 notes:

UHF Varactor Tuner could be used at the ground station.

Channel 21 - 512.00000 MHz -> Transmit to Rocket
515.57945 MHz -> Transmit from Rocket

<Rocket Unit Block Diagram> (will scan & put up soon)

Second Frequency about is generated by mixing the received 512.0 MHz signal with the output of a colorburst crystal.

Altitude information is deduced from phase shift in a tone modulated on the 512 MHz uplink carrier.

<System Block Diagram> (will scan & put up soon)

To get 10m resolution:

tp = (d1+d2)/c = 20m/(3E8 m/s) = 66.67 nS => 15 MHz

To get d1, multiply counter output value by 10 (meters).

d1 = (66.67 nS)(n)(3e8 m/s)/2 = 10n in meters

Using a 16-bit counter, dmax =655350 = aprx 407 mi

It's interesting that except for the counter frequency (now 30 MHz), the details of this range measurement remain the same in DARTS to this day.

History Top
Generation I: Doppler Trilateration (1990 - 1992)
Doppler Demo Radar (1992 - 1993)
Generation II: FM/FSK (1993 - 1996)
Generation III: Pulse Microwave (1996 - )

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This document copyright Steve Bragg, KA9MVA. Updated: September 21, 1998