Talk:Beaglebone Spectrum Analyzer
Decided to take a stab at making a quick-hack mockup of a spectrum analyzer using a Beaglebone and and rtlsdr DVB-T dongle. Must be ready by Saturday morning for a presentation I am giving at the 2013 Danish Winter VHF meeting.
To begin with I will be using the default Beaglebone demo image available from the download site, namely Angstrom-Cloud9-IDE-GNOME-eglibc-ipk-v2012.05-beaglebone-2012.11.22.img.xz. The application software will be built using:
- Gtk+ for a simple GUI
The spectrum analyzer is working, see photo.
Som info and benchmarks for this completely unoptimized image:
- Automatically starts the application on boot.
- Startup time is somewhere around 2 minutes (from power on till application is running).
- CPU load is around 30% when doing 20 frames per second.
Used the spectrum analyzer mock-up for demo during my SDR talk at the 2013 Danish winter VHF meeting. It was very well received and people were very interested. There has also been a lot of positive reaction on Twitter.
Trying to build a custom image based on cloud9-gfx-image.bb and cloud9-image.bb.
Image successfully built and it boots in 6.3 seconds, see system-analyze output.
Gtk+ libraries are installed, not the devpacks. Same for libusb and ncurses. Git, gcc and pkg-config are installed as well. RTL dongle does not work well with this build (copied binary from other disk built using different version of the libraries).
Trying demo GNOME 2 image again, this time using a class 10 SD card (I was using class 4 previously).
Reduced autologin delay from 10 to 1 second.
Application is running within 45 seconds after poweron:
root@beaglebone:~# systemd-analyze Startup finished in 4784ms (kernel) + 7389ms (userspace) = 12174ms root@beaglebone:~# systemd-analyze blame 3583ms pvr-init.service 2166ms cape.service 1984ms connman.service 1958ms avahi-daemon.service 1932ms systemd-logind.service 1353ms xinetd.service 804ms console-kit-daemon.service 616ms console-kit-log-system-start.service 461ms udev-trigger.service 455ms systemd-modules-load.service 266ms systemd-remount-api-vfs.service 253ms dev-mqueue.mount 172ms dbus.service 164ms systemd-sysctl.service 159ms udev.service 130ms tmp.mount 129ms systemd-user-sessions.service 123ms sys-kernel-debug.mount 74ms systemd-tmpfiles-setup.service 39ms remount-rootfs.service root@beaglebone:~#
So, about 30 seconds are wasted on GDM and GNOME startup.