Regular Japanese DRM Broadcast

 

After years of working on getting ready for DRM, it has not quite sunken in that we are now doing regular DRM broadcasts to Japan.  These Sunday broadcasts at 12120KHz at 1057-1156UTC are being eagerly received across the country.  Many listeners use software defined radios (SDRs) to tune us in.  These radios are hardware combined with software running on a PC or a laptop.  Many listeners have sent us proof of reception with screenshots similar to the one shown above.  The narrow peaks are normal analog broadcasts.  The wide "Bart-head" is the DRM signal from KTWR.  Not only does that signal carry audio, but it also has text info such as the station ID and a short message that scrolls across the receiver display.

 

Most of the early listeners to this broadcast have been shortwave radio enthusiasts.  Japan seems to have more SW hobbyists per capita than any other country on the planet.  They were actually the ones who encouraged us to start these broadcasts.  Most hobbyists will tune in a broadcast they have not heard before once or twice for short times to get a QSL card or other souvenir from the station.  However, we have been greatly encouraged by the fact that these listeners listen to the entire program.  They tell us how much they enjoyed hearing the programs for their content, not just the signal quality.

 

We do pray that this experiment expands to more days and more countries in the near future.  This technology allows people to clearly hear the gospel while using 1/3 the power of analog broadcasts.  The power savings allows us to expand the ministry to more people groups.

ANT2A is Up

After a little over a week since it fell, ANT2A is back up in the air and coonected to TX7. We are very grateful for the volunteers who worked hard with us to get the job done. The Lord also gave us some good weather for antenna work.  The antenna worked well last night and the transmitter tuned easily to the new hardware.

One difficult part of the repair was in the slew switch. (It looks a bit like a lunar lander in the photos.) When the antenna fell, it bent some components in the switch that were made out of large copper pipe fittings. The riggers were able to make new parts which worked out well.

Now that this work is complete, we can consentrate on building the antenna switch matrix.  The control software work has progressed very well.

Major Detour

For the past several weeks, we had been working hard on the antenna switch matrix.  It would have been really helpful if we had that already in operation.  We were hoping to have part of the matrix operational in early May, so that we could increase the power for a TX7 broadcast.

Last week, ANT2A had one of its cable swage clamps fail.  This caused one end to fall to the ground.  This sort of thing tends to break many insulators and cables.  We had to use jumpers to connect TX7 to ANT3 and reconnect TX2 to ANT2B.  This allowed us to continue our normal broadcast schedule.  Without the matrix, we also had to do our Japanese DRM broadcast on TX6 and ANT1 instead of TX7 and ANT2A. 



 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The antenna has been reassembled and is now back up in the air.  We are still working on repairing the slew switch and its input transformer.  The slew switch is what controls the direction that the radio waves go when they leave the antenna on their way to the listeners.  The transformer is the set of wires needed to adapt the signal from the transmitter to the antenna system.

 

Once repairs are complete, we can resume work on the matrix hardware.  In the meantime, we do have a short-term visitor who is working on the control software.  We should have a usable software system by the end of the week. 

 



Progress

There have been various points of work these last couple weeks.

1) Fabrication and placement of Matrix complex. The 'feed line beam' (or hanger) has been constructed. This is a massive 40 foot beam that Jim has welded together.  This will be the beam where the feed lines from the building will come to and then be distributed to the matrix.

2) The PLC has been fabricated and tested with an antenna switcher. The micro switches and relays have been added. It was great to see a switching test - it took only 8 seconds for the switch to change from A to B. The seven switchers have been fit and are now on the pad.  There are three more switchers that will need the frames fabricated and then readied for the matrix. 

 

3) In preparation for the coming frequency period antenna two has to be fitted for transmitter seven.  This is pre-switcher matrix broadcasting.  Because of the amount of programming we are putting on TX 7 we need to use antenna two and the old A/B switch.  By the end of April the antenna matrix first stage will take the place of the A/B switch and switching between antenna two and three.

And on March 30, 2014 as the new season begins KTWR will be broadcasting it's first DRM broadcast - in Japanese.

Moving Right Along...

It's great to be able to show things coming together.

Paul has completed substantial work on the retaining wall of the pad.

We have seven switchers now that have been mounted to the stands.

The switch control box has been connected and we've been able to test the switch and establish a switching time. (There are still a couple microswitches to be installed and wiring to be completed.)

Four of the mounted switchers have been moved to the pad. Now we can show a good picture of the matrix coming together. 

Stay tuned...

Boxed In

The final delivery of the antenna switchers arrived at the site today. They were all crated and boxed up quite effectively by the HCJB team in Elkhart. There was no damage at all to the cargo.

Work continues with the switcher stands and mounting the switchers. We now have a good assembly line as switchers are mounted on the stands.  

Jim is even boxed in as he completes the rest of the stands.

Hmmmmm... do you have an idea of an upcoming project?

Arrival

Just a very quick update this week.  The antenna switchers arrived in port last week.  The first truck delivered the first six switchers today. Hopefully the rest will follow very soon.