LPFM Puts Digital Radio to Work [with VS300LP]
Radio World, Ralph Martin, KVCB(LP), 09.20.2017
The author is education director for Vacaville Christian Schools Radio Conservatory.
No doubt, many low-power FM station operators entertained the thought of HD Radio broadcasting early on. That’s the way it was with us at KVCB(LP), an LPFM grade-school radio station owned by Vacaville Christian Schools in Vacaville, Calif.
However, we believe KVCB was the first LPFM actually to implement HD Radio (and as I write there is only one other, WGVV(LP) in Rock Island, Ill., listed in the FCC database with hybrid digital authority).
Radio World asked me to share our experience and observations as an LPFM broadcasting in digital.
We were really excited when we received our initial, analog construction permit from the FCC. We had a feeling like we could do it all. I call this stage the “dream mode.” And oh my, can motivated people dream!
Of course, reality soon set in, and we were focused on just getting on the air. Building an LPFM radio station is costly — even if all of the work is done by volunteers. We certainly had great volunteers! Parents of students were driving copper rods into the earth for our ground system, installing a mast for the antenna and running cables. Even the transmitter equipment rack was welded together by a student using metal scraps from his uncle’s ranch.
As for me? I’m the station’s chief engineer, operations manager, broadcasting instructor — anything I’m needed to be.
Actually, I’m not an engineer at all; by profession I’m a full-time music teacher. But in the world of LPFM, that qualification sometimes has to be good enough. It meant sleepless nights studying; it meant weekends on the roof learning how not to look down when installing and field-tuning an antenna. I’m not complaining, though. Building the station was fun. I was committed to it, and I loved every single minute.
All said and done, we were on the air about nine months from the time our construction permit was granted.
Then came the realization that once a station is built, the real work begins. A radio station has to be fed programming constantly, and my students took it from there, producing shows to fill the broadcast day.
Everything was running fine, but only in analog.
THE MOVE TO HD RADIO
Two years later, the HD desire was still there for us. Radio is moving the way of all other forms of media, and I wanted our students to be a part of the movement.
With the huge generosity and commitment of our school and community, we were able to acquire the necessary HD Radio equipment. From there it was back to “construction mode.”
We began installing the additional equipment, adding an antenna bay to raise the gain and running additional studio feeds. The kids were ready with additional programming. We were broadcasting in HD by March 3, 2017. The feeling of turning on the HD Radio system for the first time was very much the same emotion as when the transmitter was first fired up. Fellow LPFMers will relate to that.
We’ve found several benefits of HD Radio:
1. In HD Radio mode, the service is more consistent. Dropouts due to tropospheric ducting and multi-path cancellation can be a serious issue for LPFM stations, with their low power and low antenna height. The digital signal appeared to react a bit differently from the analog within our service contour — filling in spaces for each other as the receivers blend between them. In fact, at times the HD works in places where the analog signal struggles. The result is a more consistent signal throughout our community. For those with HD Radio receivers, the overall listening experience improved tremendously.
2. Additional sub-channels (HD2, HD3) provide increased options for our listeners. Our HD2 is dedicated to student-produced music and sound art. Called “Sound Art Central,” the channel allows the kids to experiment with recording nature and adding sounds to create soothing and sometimes dramatic effects. The VCS Radio Symphony and Jazz (our student orchestra) provides student compositions and orchestrations. Lots of creativity and a very interesting channel.
Our HD3 is a lower-bandwidth mono channel we call “School Connect.” It focuses on school news sports and art performance announcements as well as broadcasting schedules for all three channels. As filler we’ll use classic radio shows from the early days of radio.
3. Increased interest and heightened perception that come from being a station on the cutting edge of broadcast technology.
We have also experienced some challenges:
1. The single-bay antenna we were using was inadequate for our purposes. We needed to add a second element to increase the gain so the transmitter could handle the additional power requirements. Also, our antenna system needed to be well tuned with a better than 1.1:1 match.
2. There is a diversity delay needed so that the HD1 and analog timing mix perfectly. This was just a matter of playing a digital and an analog radio together in a room and adjusting the analog delay until the echo was gone. It was quite easy to accomplish. The sub-channels don’t have the blending feature so no synchronization is needed for HD2 and HD3.
3. Processing the HD1 audio to match the sound of the analog counterpart is important for LPFM stations. Our low power and low antenna height cause car radio receivers to blend between the two signals often as our listeners travel to the edge of our coverage area. It can be very annoying if the mixing analog and digital signals sound too different. A good matching sound creates smooth transitions and really improves the listening experience over just the analog alone.
Budget will be a consideration for any operation, and especially LPFMs. Of course not all will be able to afford it.
But it may be possible to bring the price tag for HD Radio well below the $30K mark. I’m encouraged by Nautel’s new combined importer/exporter units, which should significantly cut the cost going forward.
It’s also important to note that LPFM stations are exempt from the continuous yearly licensing fees for multicasting. Xperi/HD Radio requires a one-time $5,000 that can be split into a few yearly payments interest free. It’s my hope that manufacturers are open to making HD Radio with sub-channels more affordable for community and school LPFM broadcasters. The future success of HD Radio will require including everyone at the “digital table.”
So what do I think of LPFM HD Radio overall? I love it. The benefits are huge and the few pitfalls were fun to overcome.
Most of our challenges were due to the fact that we were the first LPFM station to adopt HD Radio technology; we were essentially breaking ground as we go. This leads me to my final point: I found little documentation or discussion on the web about LPFM upgrading to HD Radio. What little chatter there was in the LPFM community seemed to be somewhat negative. There seems to be a longing by some radio folks to keep things analog; others would complain that the digital transition for FM in the U.S. should have been done differently.
Jampro two-bay JLCP antenna
Nautel VS300LP transmitter
Nautel VSHD digital exciter
Nautel Exporter Plus
Nautel Importer Plus
Breakaway One PC-based audio processing
As in all debate between well-meaning people, there are good points to ponder. I only ask that we LPFM operators begin opening up the discussion to include LPFM’s place in the digital landscape regardless of how it develops. There are almost 2,000 LPFM stations across the country! I think we are certainly sufficient in numbers to get the ears of broadcast equipment manufacturers, the FCC and Xperi to work toward making the upgrade even easier and more affordable. It could be win for everyone. We should at least accept any offer to sit at the discussion table.
I thank the great folks at Nautel, Xperi and the FCC for listening and helping. Without you we couldn’t have made the upgrade.
The station website is www.vcsradio.com