Monitoring VK3RTV with a LED Display
This page details my experimentation with the local Amateur Radio broadcasts.
It discusses using a computerised monitoring system with a LED Display indicating that the Melbourne ATV Repeater VK3RTV is On Air or Off Air.
I purchased a USB LED Display $87 off ebay and connected it to a Linux computer.
I purchased a mono speaker $4 and usb audio adaptor $5 off ebay. This enables independent audio and volume control for the synthesised announcements.
I use the Elvin Event Router to connect the DVB-T on/off air checking script to the LED Display client.
There are two outputs from my monitoring system.
- A scrolling message on my LED display with an accompanying voice announcement.
- Play the following video to see and hear a demonstration of this.
- A tickertape message is emitted around my LAN to subscribed workstations.
- Screen shots of ticker messages on Windows 7 and Linux are given below.
Video of working LED Display
This is a video showing my LED Display with an actual notification that VK3RTV is on air from August 10 2013.
Screenshots of Ticker Events
The following screenshots shows how the VK3RTV checker notifications look on subscribed tickertapes running on my Windows 7 Desktop and Fedora Linux server.
The following screenshot shows a history of notifications as stored in sticker running on my Windows 7 Desktop. This history is from Monday November 5 2012.
Details of how to download a copy of AVIS Tickertape for Windows, OSX or Linux
may be found at:
At the antenna
On the computer connected to my DVB-T antenna I use a Kaiser Baas TV-Stick $50 as the tuner to monitor VK3RTV. I have tried a number of tuners and found that the TV-Stick will run 24/7 without dropping out. It is sensitive enough to detect the weak signal from the ATV repeater as some tuners are unable to receive VK3RTV.
See the LinuxTV web site for a list of support DVB-T dongles and the required kernel version.
I was required to install a DVB firmware file, for this specific USB dongle, to /lib/firmware.
The file is called dvb-usb-dib0700-1.20.fw.
As I have multiple devices connected to my TV Antenna. I am using a number of Kingray splitters. It appears that some strong VHF signals are going through the splitters and stopping reception of the ATV repeater.
By accident I found that using the UHF side of a VHF UHF Diplexer will enable reception of the ATV repeater downstream of the splitter(s). I have placed a diplexer between the output of the Kingray splitter and the DVB-T TV-Stick dongle. This must be acting as a high pass filter to remove interference before the repeater signal is being demodulated.
I wrote a simple bash shell script to monitor VK3RTV. It checks once every second for the repeater going on or off.
The script is written to work with the current 2 channel configuration ("2 services"). It will also work when a signal is detected but without enough strength to find the 2 channels ("filter timeout pid").
The above script calls scan and passes it the following /usr/local/bin/vk3rtv.conf file.
The script calls my Elvin producer named tick.
Details of my /usr/local/sbin/tick command line program may be found
on my Elvin page:
The tick program generates an Elvin notification that is feed through
my installation of the AVIS Event Router
The AVIS C client library maybe downloaded here:
I have made the source code for tick available here:
The led.c file is compiled and installed to /usr/local/sbin/led.
2014 Update: I have upgraded my computer and was introduced to the new systemd style of services. I added an atvchecker.service to my system by adding two files /etc/sysconfig/atvchecker and /etc/systemd/system/atvchecker.service.
The ATV Checker may now be started and stopped using:
At the LED Display
On the computer connected to my LED Display.
I modified the example C program that was supplied with the LED Display and added code to make it an elvin consumer.
I needed to compile the program on Fedora Linux and copy the image to Ubuntu as there is a critical bug open regarding the C client library.
The ledtickertape.c file is compiled and installed to /usr/local/sbin/ledtickertape.
Here in the script that calls espeak to synthesize any messages that accompany the LED display output.
A curfew is programmed between 10pm and 8am.
Here in the script that starts the ledtickertape consumer.