Near the flight path of several airports in southern California

Photogrammetry Based Ranging

This project is one of the more aggressive undertakings I have set out to pursue. Long term, I intend to set up a remote-controlled astronomical observatory on my property.

In the short term, however, I am going to construct two remote-controlled smaller but nevertheless precision telescopes with integrated CCD cameras in order to do range and heading measurements of high-flying aircraft in the air space above where I live. Of course such an activity must be noninvasive (no active sensors like radar or lasers!). Perfecting this instrumentation during daylight hours will serve as a prelude to making LEO and MEO earth satellite measurements at night time for my other orbit calculation interests.

You must look very carefully at the photo to the left in order to see the small aircraft in the picture. A close-up of this jet is shown in the picture below.

As already mentioned, the measurement instrumentation will consist of two precision telescopes which will be trained on the aircraft over head. Precision triangulation and image cross-correlations at the pixel level will be used to construct a mathematical model for the plane’s position and velocity vector.

Simultaneously directing two telescopes to simultaneously track a moving aircraft over head is a challenging task when faced with a finite budget! Calibrating the two telescopes (which will be separated by several hundred feet) could be fairly daunting- if it were not for my interest in astronomy. Calibration of the two optical systems will be done at night by making use of the star fields each telescope will see as a function of its respective right-ascension and declination settings. So long as the telescope mounts provide good pointing repeatability, this approach should solve what would otherwise be a very difficult problem.

Part I of this journey written about here.

One of the spotting scopes and one of the equatorial mounts are shown to the right. The telescopes will necessarily have to be fitted with CCD cameras, and the equatorial mounts will have to be fitted with servo drives. The servo drives will come as a natural by-product of my CNC machine work. Wireless control/telemetry will be required from each remoted telescope, but I already have Arduino-based WiFi up and operational with my local LAN. Additional considerations will be required to time-tag and transport the digital images from each telescope of course, so that precision triangulation can be performed, but this part of the project should not be too difficult based upon some earlier work I did for a previous client.

One of two equatorial mounts needed. Servo drives yet to be added.

One of the more intriguing elements of this project is that it entails multiple disciplines. Servo drives will be required for each of the equatorial mounts where my CNC machine will likely come in very handy. The same thing can be said of the CCD camera mounting hardware- where having my own CNC machine should help side-step otherwise potentially pricey hardware. Telescope optics are of course involved. Some elements of control systems will be needed to accurately steer the telescopes autonomously (as will later be used for my satellite tracking project). And there is of course other software elements (Arduino as well as desktop C/C++/C#) which will be required as well.