D-ATV training for 2018

This Saturday I held the annual entry-level D-ATV training for TV operators for BCARES, including some hands-on time with the new prtable ATV packsets I donated.


Thanks to Jim KH6HTV for his presentation on the Boulder ATV repeater.


Fairly soon I will add an upper-level class covering the portable repeater, quad box, and streaming ATV onto a network. We’ll also get into how to plan and run an event involving ATV. Stay tuned!

Oh, where did the sound go?

Generally we’ve used Sony cameras in the field for digital ATV, with an HDMI cable running from the camera to the TV modulator.

Last year I got a small, inexpensive CX405 model. I recently tried using it for the Boulder-area weekly ATV net, and no one could hear me. A little digging with the DVB-T test tool revealed that the audio stream was simply absent — no sound was being transmitted at all.

It turns out that newer Sony cameras don’t put out any audio through the HDMI cable (except during playback from a recording). Sony says (as of 2015), “There are no Sony Handycam models that can pass the audio through while recording the video. Again, both video and audio passthrough is only possible when the camera is on playback mode [actually, the issue wasn’t recording, but just live output out the HDMI jack, recording or not].”

This has not been an issue for older models such as the Sony CX430V and AX33.

Also note that the behavior of the Hi-Des modulators is to omit the audio elementary stream from the output transport stream (TS) when no audio is present on the HDMI input. The PID is still listed in the PMT, so the test tool can easily identify it as missing.

Another year, another antenna

Actually, this year it’s an antenna farm in the attic. After moving out of Boulder this summer from a townhouse to a free-standing house, I needed a new antenna setup.

I now have a pair of X50 antennas (one east, one west) for VHF/UHF along with a west-facing M2 UHF yagi for TV (the 440-6SS, 6 elements and about 36″ long). I used an upside-down dish mount arm to hang it up.


I can receive the WØBCR TV repeater in Chautauqua Park at -62 dBm with a very clean signal (at a distance of 16 miles), better than the direct reception I had when I was located in Boulder.


Until someone builds a house behind me, I have line of sight to Chautauqua as well as to NCAR (for the BARC voice repeater and the KCØDS D-star repeater).

For the X50 antennas, I pre-made a mount that I took into the attic in one piece:


which I then nailed down to the rafters:


I also installed an HF loop using an SGC-237 autocoupler, but I haven’t got it working yet.