Rocode >> Hobbies >> Amateur Radio
Amateur Radio Experimentation
This page details my experimentation with the local Amateur Radio broadcasts.
It specifically details my IT related amateur radio interests.
Further details regarding my other interests in amateur radio and telecommunications may be found on my personal web site communications interests page.
I have commenced studying for my Amateur Radio License via the
Radio and Electronics School.
I own a Uniden Bearcat Scanner and can receive the local VK3RML voice repeater on 146.700 MHz. I have heard nets on Monday nights discussing and transmitting SSTV pictures.
Here is a brief menu of what is detailed below.
Here are some external Amateur Radio links.
TV Antenna Distribution
I have a rather complex antenna wiring layout from the antenna socket to the many DVB-T appliances. I installed a VHF and UHF diplexer between the antenna socket and the first f-type splitter. With only the UHF side of the diplexer connected the strong VHF signals are attenuated before being put through the two amplified splitters.
I connect my DVB-T appliances using RG-6 coaxial cable from my antenna splitters. There is no replacement from the usage of decent coaxial cable to give the maximum signal available from VK3RTV at your receiver. The better cable allows you to have more room for losses in your antenna connections and still receiver the repeater. The digital signal is either received successfully or you will not be able to tune your receiver and need more signal.
I use two antenna splitters. The first is a 2 Way TV VCR Antenna Signal Amplifier Booster Splitter from Radioparts for $38. The second is a 4 Way TV VCR Antenna Signal Amplifier Booster Splitter from Radioparts for $55.
The two Kingray antenna splitters must not be 100% linear when used in series. I have tried using the splitters on there own, with a low VHF bandstop filter and with a VHF/UHF diplexer. Only when using the diplexer was VK3RTV received through the two splitters.
It appears that some strong VHF signals are going through the splitters and stopping reception of the ATV repeater. My set top box would complain that the Digital ATV signal had to much noise and it could not decode the ATV repeater.
Unfortunately using the UHF side of the diplexer causes a much higher attenuation of the VHF TV channels. The Seven Network on 177.6 MHz is closer to being unwatchable. There is the occasional slight digital breakup during poor reception conditions. I would have preferred to use the low VHF bandstop filter as this gives okay reception of the Seven Network but no reception of VK3RTV.
TIP: Without the diplexer inserted before the amplified antenna splitters I was unable to receiver VK3RTV after the second splitter.
Watching VK3RTV1 and VK3RTV2 using Mythbuntu Linux
The Melbourne Digital Amateur Television repeater is called VK3RTV.
The VK3RTV official website contains live streaming of the repeater.
The repeater is configured with 2 multiplexed DVB-T digital television channels being VK3RTV1 and VK3RTV2.
The ATV repeater uses the frequency of 446.5 MHz which is not a standard Australian channel. As a result many digital tuners may not support this frequency. Many tuners skip from channel 12 to channel 27 and may not have manual tuning. VK3RTV transmits at 446.5 which is around channel 16.
Here are the transponder details for VK3RTV here in Melbourne, Australia. Included in my Melbourne_Transponders_File.
Use the scan command, when VK3RTV is on-air, to collect the channel information for use in tuning Mythbuntu.
The following data was generated by issuing this scan command.
scan Melbourne_Transponders_File > channels.conf
The following screencast shows how to configure Mythbuntu to receive VK3RTV1 and VK3RTV2. I tune all freeview channels as I use the channels.conf file with the channels from all 7 Melbourne transponders.
UPDATE: After installing Mythbuntu 12.04 the built-in frequency search may be used to tune VK3RTV. A copy of channels.conf is no longer required. I will prepare another screencast showing how to use the frequency search feature to easily tune VK3RTV1 and VK3RTV2.
I purchased a Leadtek Winfast DTV Dongle Gold USB TV Tuner from mwave.com.au for $40.
The Leadtek Winfast DTV Dongle Gold USB TV Tuner box comes with Windows software but this is unable to tune the frequency of VK3RTV. However, using Mythbuntu Linux, the WinFast DTV Dongle can successfully decode VK3RTV1 and VK3RTV2.
The signal strength of the ATV repeater is very low and not all the DVB-T receivers will lock on the repeater. I have tried a few other DVB-T dongles without success.
I connected a RG-6 coaxial cable from my antenna splitter to the Winfast DVT Dongle.
Within MythTV RTV1 and RTV2 do not have a logical channel numbers, as shown in the above screencast, I manually enter 350 and 351 to match my set top box.
Here are a number of screenshots of local amateur television stations as received via the VK3RTV repeater using Mythbuntu Linux.
Further details about my installation of Mythbuntu may be found on my ASRock Demonstration page.
VK3RTV is ON or OFF Air Checker
UPDATE: This has been replaced by my new Raspberry Pi checker.
I have connected DVB-T television to my computer network and check when VK3RTV the Melbourne Digital Amateur Television repeater is switched on or off.
I connect my Ubuntu Linux PC, running as a Zental Router, to the roof top antenna using a usb Leadtek Winfast DTV Dongle Gold USB TV Tuner from cpl.com.au for $28. It connects directly to a USB port on the ASUS Eeebox PC. Some detailed instructions on installation may be found on LinuxTV.org here. I was required to manually download a firmware file to enable the dongle.
I have found this to be the best dongle to receiver VK3RTV. I have used other dongles including Kaiser Bass TVStick and Pinacle PCTV nanoStick. They receive the Freeview networks okay but have less success with the local Amateur TV repeater.
TIP: The supplied Microsoft Windows software for the Winfast DVT Dongle is unable to tune the frequency of VK3RTV. DO NOT try to use this adaptor with the supplied software.
I connected a RG-6 coaxial cable from my antenna splitter to the Winfast DVT Dongle.
Using Ubuntu the Winfast DVT tuner is successfully able to lock on to VK3RTV1 and VK3RTV2.
I wrote a simple bash shell script to monitor VK3RTV. It checks once every 10 seconds for the repeater going on or off. As my computer has two DVB-T dongles installed I specified adaptor 1 ("-a 1").
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").
TIP: I use adaptor 1 ("-a 1") as I have two adaptors installed. Otherwise you may omit the adaptor option to use the default adaptor 0.
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
I start the bash script on boot in /etc/rc.local. When it detects a change with VK3RTV it will produce an Elvin notification that is displayed on any tickertape that is subscribed across my Local Area Network (LAN).
Here is a photo of my AVIS router with the second DVB dongle visible on top of the ASUS EeeBox PC. A RG6 coax cable from the antenna splitter is connected using two right angle adaptors.
The DVB dongle does not need to be inserted to the same PC as the AVIS Router. It is done here for convenience. The Elvin producer tick could be used to send the notification, from the PC with the DVB dongle, across the LAN to the AVIS Router.
The following screenshot shows how a VK3RTV checker notification looks on a subscribed tickertape running on my Windows 7 Desktop.
The following screencast shows a real notification when VK3WWW started to use VK3RTV1 on 25th January 2012 at 7:40pm for the weekly WIA News broadcast. The screencast includes a web browser placed on the VK3RTV homepage to show, via live streaming, the ATV repeater coming on air.
The following screenshot shows a history of notifications as stored in sticker running on my Windows 7 Desktop. This history is from Wednesday 18th January 2012 and shows the weekly WIA News broadcast at 8:00pm.
Repair of Mac TV Dongle.
My housemate's EyeTV DTT TV Tuner Stick on his Mac broke. The USB Connector on the dongle detached from the PCB.
The retail cost for the USB dongle is $125. As a result we ordered a replacement USB 4 Pin 4P Male Panel PCB Connector Plug SMT pack of 3 on ebay for $2.
Using my Weller SP25D soldering iron I inserted the new USB Connector as shown in the photo below.
I had to remove the broken pins ends that were still inserted in to the PCB. I then soldered the 6 pins on the new USB Connector to the PCB. There are 4 signal pins and 2 mounting pins.
The TV Dongle is now in working order again and can receive VK3RTV using the EyeTV software package running within OS X.
You will find the DVB-T manual tuning by right clicking on the channels list of EyeTV. Then enter 446500 and select a bandwidth of 7 as shown.
TIP: If you get Signal "No" then check if VK3RTV is operational. This may be done by checking the website streaming. Otherwise this indicates you do not have a signal from your antenna.
Watching VK3RTV1 and VK3RTV2 using a DGTEC set top box.
I use a DGTEC DG-FV7200 to watch the local ATV repeater. I enter 446500 khz manually and VK3RTV1 and VK3RTV2 may then be found on logical channels 350 and 351 respectively.
I connected a RG-6 coaxial cable from my antenna splitter to the DGTEC.
Here are some snapshots taken of my DGTEC with VK3RTV1 and VK3RTV2.
These snapshots of my DGTEC with VK3RTV1 and VK3RTV2 were captured using a Pinnacle Instant DVD Recorder.
Raspberry Pi and Amateur Radio.
During 2012 the new educational and experimentation Linux credit card sized computer called Raspberry Pi ( http://www.raspberrypi.org/ ) was made available internationally for purchase.
The Raspberry Pi Model B has built in Fast Ethernet and Two USB 2.0 ports. It retailed for £21.60, plus a clear case for £3.99 and £4.95 shipping via PayPal.
A number of Linux distributions are available for download ( http://www.raspberrypi.org/downloads ) and are usable with Raspberry Pi.
I have installed my first Raspberry Pi Model B as an Elvin producer that
checks for VK3RTV going On Air or Off Air.
Episodes 41, 42 and 43 of AmateurLogic TV featured the Raspberry Pi.