ZL2UHF 2m Beacon now running JT4D
Posted: Tue Mar 11, 2014 4:43 pm
After over 30 years of near continuous operation the ZL2UHF 2m beacon on 144.275 MHz developed a serious fault at the end of last year. Given its age it was decided replacement was the best option, and in Janurary a replacement beacon was installed and soak tested using the old FSK-CW mode.
On Feb 28th the JT4D digital mode was enabled, which now opens opportunities to experiment with weak signal digital modes using the popular WSJT software.
The new beacon consists of a ZLPLL board driving a 2m power block with a controller baord containing a more powerful Atmel micro and GPS receiver to get exact timing which is a requirement for all WSJT modes.
JT4D is being transmitted for the first 47 seconds of each minute followed by a CW ID. Note that the lowest JT4D frequency is zero beat for 144.275 MHz
For anyone interested JT4D was chosen over JT65 mode as it was easier to generate with the chosen PLL, and it will generally be more successful for those with lower stability radios from the 70's and 80's era. It also seems to be more popular for beacons in Europe so seemed like a logical place to start.
Some pics of the beacon during its construction phase before covers were installed shows its simplicity (and potential to add other bands in the future...) :
As an interesting experiment I tested a screw driver in the back of my FT817 and got -9dB decodes I ended up with a short piece of wire and progressively started to trim off 1cm at a time until decodes stopped at -16dB. After increasing the WSJT audio gain (right hand slider in the waterfall screen and disabling AFC) I can now decode the beacon at -22dB and -23dB (some at -24 but not as reliable)
The scary thing is for most of this experiment I was just listening to static!
So far the beacon has proven to be stable enough that planning has started to deploy a similar upgrade at Waipuna Ridge for the 144.271MHz ZL2WHO/B 2m beacon. Work is also underway to add a 1296 beacon at Waipuna so next summer DX season there should be a number of new and exciting signals to decode.
For additional information about the controller you can read more at http://zl2bkc.com/projects/multi-beacon-controller/
73,
Wayne
On Feb 28th the JT4D digital mode was enabled, which now opens opportunities to experiment with weak signal digital modes using the popular WSJT software.
The new beacon consists of a ZLPLL board driving a 2m power block with a controller baord containing a more powerful Atmel micro and GPS receiver to get exact timing which is a requirement for all WSJT modes.
JT4D is being transmitted for the first 47 seconds of each minute followed by a CW ID. Note that the lowest JT4D frequency is zero beat for 144.275 MHz
For anyone interested JT4D was chosen over JT65 mode as it was easier to generate with the chosen PLL, and it will generally be more successful for those with lower stability radios from the 70's and 80's era. It also seems to be more popular for beacons in Europe so seemed like a logical place to start.
Some pics of the beacon during its construction phase before covers were installed shows its simplicity (and potential to add other bands in the future...) :
As an interesting experiment I tested a screw driver in the back of my FT817 and got -9dB decodes I ended up with a short piece of wire and progressively started to trim off 1cm at a time until decodes stopped at -16dB. After increasing the WSJT audio gain (right hand slider in the waterfall screen and disabling AFC) I can now decode the beacon at -22dB and -23dB (some at -24 but not as reliable)
The scary thing is for most of this experiment I was just listening to static!
So far the beacon has proven to be stable enough that planning has started to deploy a similar upgrade at Waipuna Ridge for the 144.271MHz ZL2WHO/B 2m beacon. Work is also underway to add a 1296 beacon at Waipuna so next summer DX season there should be a number of new and exciting signals to decode.
For additional information about the controller you can read more at http://zl2bkc.com/projects/multi-beacon-controller/
73,
Wayne