In my previous post, I posted the raw footage recorded from the Nexø II onboard cameras. These videos give an excellent qualitative indication of how well the video downlink worked. I have now also processed the received telemetry data and have a more quantitative idea of the performance.
During the last year or two, you may have heard me talk about rocketcam or rocket-cameras, teasing with pictures but without providing too many technical details. Actually, it all started with a cryptic tweet I posted on October 23, 2016:
I have a plan. pic.twitter.com/pboLyN4oK6
— Alexandru Csete (@csete) October 23, 2016
In October last year I learned about the UT-100 series of DVB-T modulators available from a company in Taiwan. At that time I have already been working with software defined video broadcasting; however, I still found the idea of a small USB-stick modulator very appealing for use with embedded devices. In this post I have collected my notes about setting up and testing the UT-100 modulator on Linux.
A lot has happened since I posted my ugly hacks required to take advantage of the H.264 compressor in the Logitech C920 webcam. Gstreamer 1.2 now includes a uvch264src that can be used to read H.264 encoded video stream from the camera eliminating the need for an external capture application.
A few closeup photos showing the eCAM32 3.2 megapixel camera mounted on top of the Gumstix Overo Water, mounted on the Tobi expansion board.
As promised in my last post, here is a quick demo of the eCAM32 3.2 megapixel camera connected to the Gumstix Overo Water. I am presenting two videos, one showing the setup where the eCAM32 camera board is mounted on top of the Gumstix Overo Water, the other one being a screen cast demonstrating some of the most common settings of the camera. I am using the Tobi expansion board because it has Ethernet interface allowing me to stream H.264 encoded video to a host PC running linux.
As I mentioned in my previous post, I had only had limited success with the Caspa VL and Logitech UVC cameras. While both cameras work with the Gumstix, the Caspa seems to take poor images while the Logitech USB camera performance is limited by low USB bandwidth. Therefore, I have decided to try my luck with cameras from e-Con Systems.
I’m happy to report that I am now able to encode video on the Gumstix Overo Water using the DSP in the OMAP3530. It wasn’t difficult to make it work but it took several attempts at building the kernel before I got it right and, as you might know, cross compilation takes time.
A year has passed since we had a Gumstix Overo based video recorder onboard an amateur rocket and it is time to resume working on it. This time I will continue towards the original goal, namely live radio transmission of video encoded using the built-in DSP.