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!
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.
Last night I gave a presentation on digital ATV to the Adams County ARES (R1 D1) team including a live demo of a portable transmitter and my quad receiver box. It was the 90th anniversary of the first modern TV transmission (7 Sept 1927).
I also talked about streaming TV signals over a network using several different hardware devices and technical approaches. This week YouTube introduced ultra-low latency for live streams. I tested it at home over my wired network, and found that end-to-end latency from camera through RF and conversion to an IP stream, out to YouTube, and back to my browser, all happened within about 2 seconds. That’s fantastic!
In this case I was streaming through a Matrox Monarch HD. I’ve also tested an Epiphan Webcaster X2 but it kept changing the stream latency back to “normal” (15–30 seconds!). I have confirmed with Epiphan that this is an issue that will need to be addressed by a firmware revision.
YouTube live streaming gives us an option when RF alone can’t deliver the picture to a distant command post — provided that we have a suitable internet connection where we operate the ATV receiver. (One catch, however, is that only folks with some type of Google or YouTube account can be invited to watch a private stream, while an “unlisted” stream is accessible to anyone who has the URL.)
See the slides from my presentation: DATV for ARES Sept 2017
Another year’s gone by, and football season is coming soon. We use the CU home games (planned events) to prepare our members to run TV for emergencies. Here I am explaining how DVB-T works. At far right I have some equipment to demo; I usually leave a transmitter up during the class (it’s off to the left of the picture, watching the attendees :-).
Thanks to the Boulder Office of Emergency Management for the use of their facility. See the BCARES web site for more information on how we serve the community.
Last week I gave a presentation and demo to the Boulder Emergency Squad (BES). They operate drones (“unmanned aerial vehicles” or UAVs) for county emergencies, such as swift-water search and rescue efforts. One issue they have is downlinking the video from the drone. We discussed how digital ATV could be used to backhaul video from the drone pilot/controller to a command post some distance away. This is needed because the drone pilot must have a line of sight to the drone, and so may have to move some distance away from a command post.
The presentation was largely the same as the one I gave last fall to the Arapahoe County ARES group.
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.
I demonstrated the digital quad box for BARCFest attendees and attracted lots of interest. I had two TV backpack transmitters of my own placed in corners of the building, plus a signal from Jim KH6HTV showing home video, plus a video input from a stationary drone camera belonging to Allen KØARK (the receiver is the white device on the far left of the table; it is connected directly into the HDMI switch).
On the right I have a laptop receiving the video stream over an Ethernet network, using a Monarch HD streaming appliance (the silver part in the middle of the quad box).
The embedded HDMI switch makes it easy to substitute video sources into the quad processor as well as choose which images are shown on monitors or fed into the streaming device.
This past week I deployed a new quad DATV receiver box in support of public safety exercises.
Built around an 8×8 HDMI matrix, the box can substitute other video sources as inputs to the quad processor; below, we have two TV channels and the output from a drone camera on the monitor.
The switch also allows output of both quad and simplex pictures to any of several monitors or a laptop or other streaming appliance. During this exercise we experimented with streaming the quad box’s output over a private local wireless network.
Note that I’ve moved to using HV-120 receivers from Hi-Des; these are powered by 12v instead of 5v, have channel ID and manual channel up/down buttons on the front, and have a new, much improved remote control.
Thanks to Mark KØLRS who worked with me on the video setup.
Yesterday a team of eleven BCARES members provided nearly eleven hours of digital ATV coverage at the GOP debate in Boulder, assisting the University of Colorado PD and the Colorado State Patrol who ran security for the event. In addition, we provided video to the Boulder County EOC for about six hours with the help of two more members who staffed our cube there. Here one of our cameras operates near the VIP entrance.
For this event we extended our reach across campus to a much greater degree than ever before. Pretty much all the coverage areas did not have a strict line of sight back to the stadium; instead, we depend on reflections off the stone faces of campus buildings to help get the signal to the receiving antennas.
We used the same TV antennas at the football stadium that we’ve used for actual football games. Here our quad box is showing the two early cameras; we went to four cameras later in the day. The quad output was streamed over IP through the campus network to the command post, providing a view of protesters as well as VIP arrivals and departures.
By increasing the DVB-T forward error correction (FEC) coding rate to 1/2 or 2/3 we were able to maintain a low power level (300 mwatts) in most locations even in the face of interference from commercial TV production trucks with their powerful satellite uplinks. For some locations close up against buildings, we need to raise the level to 1-2 watts to maintain a good signal.
We used the BCARES portable VHF voice repeater for the first time, installing it on one of the tallest buildings where it can cover the entire campus. Here Mark KØLRS finishes programming it before the event.
Many thanks for the hard work of Mark KØLRS, Dave KIØHG, George NØRUX, Doshia KBØNAS, Mark NØXRX, Ron KCØNEV, Tom KDØUI, Ron K2RAS, Bill KDØYYY, Steve WBØNFQ, Steve KS3FOX, Jerry NØOUW, and Joe KCØJCC!
This Saturday 9/12 I and six other members of BCARES ran digital ATV cameras at this year’s first home football game at the University of Colorado. This marks our first all-digital ATV operation providing TV for situational awareness to the CU police department.
This operation was also our first use of the new HDMI-based quad box, allowing up to four digital ATV channels to be combined in high definition. The resulting output was streamed over an IP network from the press box to the command post located away from the stadium.
While the stadium has fixed cameras, our mobile cameras allow the CU security team to focus on areas around the stadium that are not well-covered as well as to get close-ups of incidents as they happen, particularly on the move. For BCARES, supporting CU football offers us a great training opportunity as well as a safe environment to prove out new technology.
The DVB-T transmitters were able to work with and without line-of-site to the antenna location on top of the press box using only 300 mW while sending a perfect 720p picture at nearly 6 Mbps.
Thanks to Mark KØLRS, Dave KIØHG, George KAØBSA, Pete WB2DVS, Tom KDØUOI, and Bill KDØYYY for all their hard work!
KØDVB-TV 