Building iHeart LA's Temporary Deer Park Transmitter Site

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This is the third installment of a series documenting how iHeartMedia Los Angeles is being impacted by the spectrum repack. Read part one and part two.

Because Video Rd plays such an important role in the Deer Park system, it was necessary to get the communications link between the two going as soon as possible. The link between the Poole Building and the post office had to be made to work as well.

We hired a local contractor to build an antenna mount up on the top of the ice shield on the post office. Fortunately, we did have a clear view of Deer Park, but really only from one spot.

What I refer to as the “sun room” holds our 950 antennas, which look directly back at our studio facility in Burbank, along with the 5.8 Gig dish that looks back at Video Rd.

We got this set of antennas and radios up and running early on, since it provides the “backup” communications with Burbank. If Video Rd is completely dead (for some horrible reason) we can use our 950 links, plus backup audio processors to generate the composite. 

Nautel delivered the transmitters at the end of April, and those and their three associated racks went in right away.

One of the ideas that our own Matt Anderson brought up from San Diego was feeding two exgine cards by setting their IP addresses to the broadcast address of the particular network they live on, and then telling the exporter to send E2X packets to that address. He had done this in San Diego, but the difference here was that the two exgine cards were at separate sites. How would this complication affect the performance? 

Early on, we started working on that. Our new site was going to have HD Radio, and naturally, we wanted the time delay to match.

The radio link between sites carries a trunk that has eight different VLANs — four of which are small ones associated with HD — specifically for the E2X packets. This idea ended up working pretty well, except that we really didn’t have any way to manipulate the varying amount of time it would take for packets to transit the system. 

On the other hand, our IP MPXp units could be manipulated using the configurable buffer depth. Quite a bit of time was spent trying to match these up so that the HD timing was right on; unfortunately that part didn’t really work. 

We ended up adding Inovonics Justin 808 units at Video Rd for all four stations; by their placement, we got them to correct the HD delay on normal transmitters, as well as the new rigs at Deer Park. (That was another consequence of the “slave” nature of Deer Park vis-à-vis Video Rd.)

As this work was going on in-doors, Wireless Infrastructure Services was finishing up their work with the top of the tower, which they had to strengthen, and the of course the removal of the old pole, and the batwing. They used a crane to do this.

Literally the day after that work was completed, WIS accepted delivery on our behalf of the Axiom antenna.

Com Plus was hired to do the actual antenna and transmission line installation, and they made fast work of it despite the fact that they had to take "days off" from our project to do other work they had previously committed to — on tight deadlines. As you are all aware, tower crews are now in high demand, and they’re all working long days to try to accommodate all this work. We had some foggy days during this process as well, which caused all tower work to stop.

As the antenna was going up we took delivery of the combiner from Shively. The company had to modify its original design, and that caused a delay of about two weeks on the delivery. Fortunately, that delay had no material effect on the timeline.

With the combiner and antenna installed, and the transmission line connected, it was time for our regional SVPE Tom Cox to come up to “slug” the antenna. Turns out ERI had already done it at the factory, and we found that the tuning was optimized. That’s an obvious advantage to having the pole design done at the same time as the antenna — they were able to take the effect of the proximity of the pole in to account, and effectively match the antenna, at all four frequencies, quite well. The highest reflected power we’re seeing is about 65 watts with 9300 forward.

Naturally, part of this process, was to do occupied bandwidth and intermod measurements at the end of the construction. That information was then passed on to our engineering office in Tulsa, who then completed our license applications. Those were already granted.

PERFORMANCE IN THE FIELD

With the site construction effectively done, we did driving tests in the field at night and found the coverage from Deer Park to be very much like the Video Rd site. 

As I write this I can tell you that we did our first “run” of the site during the daylight/weekday hours, in order to accommodate tower climbers up on Video Rd., on June 13. The results were good — not a single listener commented via phone, email or text. No one seemed to notice anything, which is, of course, what we were hoping for. 

The Deer Park transmitters sound identical to those at Video Rd and even the HD delay matches up. Our goal is to be able use this site at any time and any day, and so far at least, it looks like we’ll be able to do that.

A couple of more mentions: Andy Huynh and Matt Anderson are both younger members of Engineering, and both participated extensively in this project. Who says young people don’t want to work in radio engineering??

Also thanks to Maurice Mischook, a senior member of our engineering staff here in Los Angeles, for all of his work on the project. 

In case you've missed the first two parts of the series, check them out — part one is found here and part two here.

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