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Random Radio Thoughts – September 2015

September 7, 2015


           Cris Alexander, CPBE, AMD, DRB

           Crawford Broadcasting Company

HD Radio Alerting

There are lots of good things going on in the HD Radio world these days, all of which couldn’t have come at a better time. Although HD Radio continues to make steady gains in the automotive sector, overall its growth had leveled out. Some stations have even turned their digital signals off for various reasons, many times because first-generation equipment has reached the end of its life and there is no budget for replacement or upgrade. That’s reportedly what happened with KOA here in Denver, which is really too bad. I miss hearing the news in HD quality on my way in every morning.

Announced the first week in September, DTS has acquired Ibiquity Digital for $172 million. This portends good things for HD Radio. DTS has announced plans to expand HD into a greater number of consumer devices and push for integration in mobile devices and home entertainment systems as well. And DTS very likely has the horsepower to push HD Radio past the point of “critical mass” in the automotive sector as well.

Unrelated to all that, stations all over the nation are implementing a technology that connects the HD Radio data stream to EAS. Once set up and working, alerts appear on the displays of current-generation HD Radio receivers. Even when off, such radios will “wake up” on receipt of an alert in much the way that many weather radios do when a weather warning is received.

We played “test pilot” at Crawford-Denver last month and found the implementation process to be straightforward and easy. In a nutshell, it required:

• Insuring that the exporter had the correct firmware version and upgrading if necessary
• Performing a firmware update on the Digital ENDEC EAS unit.
• Setting a few parameters, including the exporter IP address, in the ENDEC
• Setting a parameter in the exporter


The tail end of a test scroll at one of our Chicago stations. Sparc makes a number of good-quality, inexpensive portable and tabletop HD Radio models.

Once that was done, a triangle appeared on the display of the HD Radio receiver we were using for testing. Subsequent tests appeared on the screen (there was no “wake-up” with the RWT and RMT but there should be in the event of an actual alert).

Now, Crawford is rolling out this technology across the entire company with good results. It doesn’t require a lot of effort and it’s something that is of great benefit to the public and something we can promote. With an HD Radio footprint of 2,300 stations covering 90% of the U.S. population and a claimed 35% penetration of the new car market, there are a lot of folks out there with HD Radios (whether they know it or not). As DTS takes over, those numbers are only going to go up.

For Want of a Part…

In mid-August we took a lightning hit in Albany, evidently on one of the array towers at the collocated 50 kW transmitter/studio site. The worst of the damage was fairly confined to main and aux transmitters plus a couple of relays in the phasor controller. The automation computers and server had to be restarted to get them behaving right again, and we have an unknown issue with the large UPS feeding the engineering/transmitter room, but those things did not keep the AM/FM combo off the air. It was the transmitter issues that were the real kick in the head.

Our very capable engineering crew in Albany jumped right on the problem but without a lot of initial success. After bypassing the failed interlock relays in the phasor controller, the main transmitter was lit up like a Christmas tree with warnings all over the place and would not run at more than a few hundred watts. The aux would come on and make RF power but would not modulate.

The decision was quickly made to focus on the aux, since the issue with it was likely low-level and easily remedied. That was undoubtedly the correct course of action but it was anything but a quick fix. Our engineers found seven different issues requiring a handful of parts from the spares kit to get it running again. The aux is only 5 kW instead of 50, but at least the station was back on. The FM, which has separate programming and transmits from a site northwest of the city, was not affected.

With the pressure (somewhat) off, our engineers were then able to focus on the main 50 kW transmitter. Expecting the worst, what they found wasn’t really all that bad. The main AC power contactor, which bypasses the step-start resistor when energized, was burned out and physically broken. The transmitter would run at very low power but not more than a few hundred watts at which point the voltage drop across the step-start resistor would reduce the PA voltage below the operational threshold and light up the status panel in red.

It seemed a simple matter, then, of calling the manufacturer and ordering a replacement contactor. The problem is that particular model of solid-state transmitter, installed in the mid-1990s, has been out of production for a few years now and the manufacturer no longer has stock on the AC power contactor. In fact, the manufacturer of the part itself no longer makes it, so the transmitter manufacturer had to scramble to source something that would work. They did, after several days, find something, but it has a 9-10 week lead time. So the 50 kW AM in Albany will have to operate at 5 kW on the aux for more than two more months until we get the part.

This is very frustrating, and it’s a situation that I have run into a number of times in recent years (although this is the first time I have encountered it with this particular manufacturer). I do understand that it probably doesn’t make a lot of fiscal sense for a transmitter (or any) manufacturer to keep stock on a $2,500 part that very seldom if ever fails, but I can’t see where a manufacturer can claim a device is “fully supported” if they don’t keep stock of – or at least keep tabs on where they can quickly lay hands on – such critical parts.

More and more these days, broadcast equipment manufacturers rely on other manufacturers for such items as power supplies and subassemblies. It reduces their costs to simply order up large quantities of switching supplies (or whatever) instead of tooling up and making them in-house. In going this route, however, they give up a certain level of quality control. They can use burn-in racks to test these devices and subassemblies before putting them in their equipment, but that only weeds out the worst of the lot. The president of well-known manufacturer of audio processing and telco/IP interface equipment told me a few years ago that vendor power supplies were his biggest support headache.

Even the top-tier of broadcast transmitter manufacturers is now farming out some of its major subassemblies. We only found this out when we took delivery of a 40 kW solid-state FM transmitter a few months ago to find that a number of items had broken their solder joints in shipment. That would never have happened in the day when this manufacturer made all its own boards.

The point of all this is that manufacturers are “outsourcing” more and more and those sources often dry up. If these manufacturers don’t either invest in a significant level of excess stock or take other measures to make sure that parts will be available when needed five, ten or even twenty years down the road, users like us are going to find ourselves in a situation just like I am in with the Albany transmitter.

If you have news to share with the Rocky Mountain radio engineering community, drop me an email at

Random Radio Thoughts – August 2015

August 1, 2015



           Cris Alexander, CPBE, AMD, DRB

                    Crawford Broadcasting Company

Crawford Island

As we head into the heat of August, the cool rains of May and June are a distant memory, but the evidence they left behind is still apparent in many locations. One such location is Crawford’s KLVZ (810) daytime site just north of Brighton.

That site is on the east bank of the South Platte and is unquestionably in the flood plain. When we rebuilt the site a few years ago with a new prefab (think “cellular”) building, we had to get a flood certificate showing the MBFE (minimum base flood elevation) and then build one foot above that. It’s a good thing, too, because on several occasions since the rebuild, flood waters have covered the site.

As May turned to June, the site was mostly under water. The water wasn’t flowing, so it wasn’t really the river out of its banks so much as it was overflow from adjacent quarry sloughs and saturated ground. As the water covering the site receded, however, the fun was just beginning as the South Platte was rising from upstream runoff.

 First picture

The new South Platte River channel at the SW corner of the KLVZ property. The breach that resulted in the flood is in the center background of the photo. The fence marks the KLVZ property boundary, what used to be dry ground some ten feet higher.

The KLVZ site has quarry operations adjoining it on the south and east sides. On the south side, the quarry operator dug out a slough to provide a place to pump water out of the mining operation. When constructing the slough, the quarry operator built a 20-foot berm across most of the south side of the KLVZ 15-acre property. This berm has provided a great and safe place to target shoot over the years!

As the site dried out and the river rose, it broke through the narrow spit of land between the river and the quarry slough. The swollen South Platte roared into the new channel, around our property on the south and following the slough around on the east. It washed out Weld County Road 6 where it crossed a drainage channel adjacent to the slough, leaving a 20-foot gap in the roadway with deep, fast water running below. The South Platte had forked right at the southwest corner of the KLVZ property and was running in two more or less equal flows and channels on either side of the site. The new channel rejoined the old a thousand feet or so north of the site, creating “Crawford Island.”

The river ran like that for most of July, and as the flow settled down into something approaching normal levels, it became clear that the new channel on the east side of the site was a permanent new channel. The breach in the riverbank had been scoured to a depth lower than the river bottom itself and with a width equaling if not exceeding that of the main river channel, so half if not more of the flow was permanently flowing through the new channel.

second picture

The same view after damming of the breach. The new dam is visible in the background. The sandy bottom is 10-12 feet below the site grade.

The good news for us was that the KLVZ site remained (relatively) high and completely dry, unaffected by its new island status. The bad news was that we had to take a circuitous route down miles of washboard dirt farm roads to get into the site from the west; the 20-foot gap in the pavement on WCR6 was a real problem for accessing the site. The other bad news was that the river flow was eating away at the southwest corner of the KLVZ property. We could see a foot or two of our land disappearing into the muddy water every day.

Then in late July, a contractor showed up and started building a dam across the breach. They brought in truckload after truckload of recycled concrete and dumped it into the breach. With that base in place they started bringing in dirt, hundreds of tons of the stuff. Within a few days, the new river channel was down to a trickle and we were able to get our first look at what had been left behind – a ten-foot-deep, 20-foot-wide and 100-foot-long area that used to be our property. The perimeter fence posts were dangling by the fence wire some 20 feet out into what had been the new channel. The ends of several ground radials could be seen trailing away from the cut bank into the sandy bottom some ten feet below. We lost over 2,000 cubic yards of soil.

Aside from relocating the perimeter fence in that corner back up onto solid ground and doing our best to bury those radial ends in the sand, the KLVZ site is no worse for wear. The station stayed on the air throughout both the initial flood and the river split. We lost power for a few minutes while Xcel relocated a pole that had been swallowed by the new channel, but the station was able to operate from the night site while the power was out.

Now we have to wait on Weld County to rebuild that section of WCR6. We’re told that it will be November. I guess it could be worse!

If you have news to share with the Rocky Mountain radio engineering community, drop me an email at

Random Radio Thoughts for September 2013

September 7, 2013

Cris Alexander, CPBE, AMD, DRB

Crawford Broadcasting Company

It’s hard to believe that another Colorado summer is already just about in the books. I trust that each of you completed your outdoor projects while we had the good (and hot!) weather. Now, think snow!

New Array Protection Rules

Last month, the FCC enacted a new set of rules, most of which are contained in Part 1, for protection of broadcast directional antenna arrays from pattern disturbances caused by nearby antenna support structures. This has been a long time in the works and is, in fact, part if MM Docket 93-177 (if that tells you anything about the origins).

My company was part of the “AM Directional Antenna Performance Verification Coalition” that was largely responsible for driving the drafting of the moment-method proof rules that were enacted a few years ago. The Coalition has remained in existence from that time since, and one of the things we were pushing for was a new set of omnibus rules that would protect broadcast directional antennas from all nearby antenna structures, not just wireless, cellular and other broadcast towers. As of August 14, those new rules became a reality, and they were placed in Part 1 to make them applicable to all services authorized by the FCC.

Here are the new rules in a nutshell:

  • Construction of any tower taller than 60 electrical degrees at the AM frequency constructed within one wavelength of a non-directional AM station will require notification and study. Predicted or resulting pattern disturbances of more than 2 dB will require detuning.
  • Construction of any tower taller than 36 electrical degrees at the AM frequency constructed within the lesser of 10 wavelengths or 3 km of the AM station will require notification and study. Predicted or resulting pattern disturbances in excess of the licensed standard pattern will require detuning.
  • Modification of towers within the above-specified distances that would change the height of the tower by more than five electrical degrees at the AM frequency, or for detuned/insulated towers, the addition or replacement of one or more antennas or transmission lines, will require notification and study.
  • Antenna supporting structures on buildings within the distance screens need not make notification or be studied unless the antenna support alone exceeds the 60- or 37-degree threshold for non-directional and directional antennas, respectively.
  • Moment-method analysis shall be employed to determine the expected pattern disturbance.
  • Pre- and post-construction measurements of monitor points can be used in lieu of moment-method analysis for stations licensed using a conventional proof.

One of the provisions that Crawford Broadcasting Company pushed for in these new rules was a way of dealing with existing pattern disturbances from nearby antenna supporting structures that were not required to notify, study and detune under the old rules. This encompassed just about everything except wireless and cellular, including two-way, paging, amateur radio and public safety.

In short, the county sheriff could put up a tower across the road from an AM antenna for its dispatch communications and not have to do a thing with respect to protecting the AM array. This happened more than you might think, and broadcasters were in most cases left holding the bag, either having to pay out of pocket to detune the other tower, readjust/re-proof their array or operate under an STA with parameters at variance for as long as the other tower was in existence. Crawford has one such situation on Mt. Scott in Portland, with a county tower right across the road that really wrecked the back side of our station’s directional pattern.

The FCC heard us and included a provision in the new rules that within a one-year window following the enactment of the rules, an AM licensee can submit a showing that its directional pattern has been disturbed by a tower construction or modification that occurred prior to the enactment of the rules. If the showing proves a pattern disturbance in excess of 2 dB for ND or standard pattern for DA, the FCC will order the tower owner to install detuning apparatus.

There is a whole section in the new rules covering installation of antennas on AM towers, both directional and non-directional. These are mostly common sense. On an ND radiator, if the base resistance changes by more than 2%, the AM licensee must file a 302-AM specifying the new resistance and base current. If installing on a tower in a conventionally-proofed directional array, a partial proof will be required. If installing on a tower in a moment-method proofed array, the base impedance of the tower must be measured and if it departs by more than 2 ohms and 4% from the modeled resistance and reactance values, a new moment-method proof will be required.

So what’s the bottom line? What can broadcasters expect as a result of the new rules? First, a lot of commonplace short monopoles, building tops and other support structures used for cellular/wireless won’t even come into play because they are below the 60/37-degree threshold, and the wavelength-based distance screen will take care of many more. Since more licensees are brought under the jurisdiction of the protection rules, the additional structures may somewhat offset those eliminated by the new height/distance screens.

The structures that are within the screen are likely to really cause pattern issues, and those will have to be studied. My advice is to pay attention to them. When you get the letter from the entity hired by the tower owner/licensee to do the study stating that the construction has been studied and determined to be no factor, respond quickly with a request for a copy of the analysis. Look at the model yourself and see.

Remember that site in Portland I mentioned? Here is a peek at the standard (red), undisturbed (green) and disturbed (blue) patterns, the latter two from moment-method models. Note that the forward nulls on the pattern disturbed by the county tower across the street (blue) are actually rotated forward by quite a bit, a new set of rear nulls has developed and the whole back lobe has filled out, exceeding the standard pattern. This reflects what we have seen in the field, and it’s a good illustration of why measuring just the monitor points is many times not good enough to detect serious pattern disturbances.



If you have news to share with the Rocky Mountain radio engineering community, drop me an email at


Random Radio Thoughts for June 2013

June 5, 2013



Random Radio Thoughts

Cris Alexander, CPBE, AMD, DRB

Crawford Broadcasting Company


The Future of AM

There has been a lot of traffic lately on the future of the AM band. Some of this was triggered by FCC Commissioner Ajit Pai’s AM improvement push, but there has been a good bit of impetus from within the industry as well.

One example of the internal debate has to do with the call for an “analog sunset” for AM stations, much like occurred with television a few years ago in the DTV transition. Testing at a couple of stations in the 100% digital mode produced generally positive results, which proponents (including several of my friends and respected colleagues) have used in support of their arguments for an analog sunset.

Personally, I disagree, and for a number of reasons. Primarily, I am concerned that digital receiver penetration remains fairly low and while the number is growing, the slope of the transition curve is shallow; it will be a long time before we hit 75% or even 50%.

Some would argue that were an analog sunset looming out there at some definite date, receiver manufacturers and automakers would be compelled to include digital decoders in even their standard equipment offerings, but I really don’t think so. With market forces driving virtually everything these days, the more likely course of action in my view is to simply drop AM from radios and entertainment systems altogether – after all, the “digital dashboard” offers so many other choices for listeners that it’s likely AM wouldn’t even be missed by a large segment of consumers.

Other debate topics include moving AM stations to low-band VHF TV channels. This would, in my opinion, have less chance of success than an analog sunset since there are zero receivers out there now and no templates from which to build.

While I am a firm believer in digital AM (have you listened to a digital AM station, one that is doing it right?), I don’t see digital as the savior of AM. Instead, it’s going to take high-demand content to save the legacy broadcast band. Ratings bear this out on a continual basis: people listen to what they want to hear regardless of which band it is on and regardless of whether it is digital or analog.

KOA here in Colorado remains one of the highest-rated stations in the market with little or no signs of erosion. People listen because KOA offers the programming they want. I could say the same about KFI and several other stations in Los Angeles, KYW in Philly, WOR in New York, WBAP in Dallas/Ft. Worth, KKOB in Albuquerque… the list goes on. And behind those front-runners are several others in each market that do well financially because their niche programming fills an audience need. Our own KLTT in Denver, KCBC in San Francisco and KBRT in Los Angeles are three such examples. We didn’t just spend several million dollars building out the new KBRT facility in Southern California because we had some cash lying around. We did it because it is a financially successful station with in-demand programming and a loyal audience.

So what is the future of AM? I think that’s up to us, the broadcasters, to a large degree. If we offer in-demand content in a qualitative way, the listeners will be there. The content is for station ownership and management to figure out. The quality – that’s our part of the equation.

The FCC can and should help (and I think it will with Commissioner Pai providing the push) by providing some rule changes. The “ratchet clause” has got to go. Ditto for the community of license coverage requirement (it needs to be a lower required percentage to permit site changes). And we need to take a good, hard look at the normally protected contour as well as skywave service area protection – the current rules with regard to those two parameters are completely out of step with the current environment.

I would encourage you to be on the lookout for a Notice of Inquiry or rulemakings in these areas. File comments and reply comments. You can have a voice in the proceedings and perhaps influence what happens.

AM radio can have a bright future. It is up to us to make it so.

If you have news to share with the Rocky Mountain radio engineering community, drop me an email at


Random Radio Thoughts

April 2, 2013


 Random Radio Thoughts

Cris Alexander, CPBE, AMD, DRB

Crawford Broadcasting Company


Automobile Antennas

In my job, I travel a lot. And in those travels, I rent a lot of cars, which gives me a good bit of exposure to the various entertainment system offerings of domestic and foreign automakers. Most rent cars have the “standard equipment” package, meaning no premium sound, but from time to time I get lucky and find an upgrade installed in my rental.

It’s always interesting to listen to local radio as I drive around the various markets in rent cars. In most of the markets I am well acquainted with the signals, ours and our competitors’. For the most part, I know what the coverage areas should be, and I have at least some awareness of signal problem areas.

One trend that I have seen in the last couple of years is the low-profile antenna. This often takes the form of a “blade,” a “rubber duck” or “dimple” on top of the vehicle. Some of these antennas, particularly the blade style, apparently incorporate AM/FM and satellite radio in the one package.

There are, I’m sure, all kinds of reasons for the move to low-profile antennas, including aesthetics and aerodynamics, but whatever the reasons, these antennas do not – cannot – perform as well as a “regulation” antenna or even in-glass wires such as were popular in vehicles ten or more years ago. The laws of physics dictate that received field strength is directly related to antenna aperture. Reduce the aperture and you reduce the signal capturing ability of the antenna and the signal level delivered to the input of the receiver.

Because of its long wavelength, AM, more than FM, suffers from the reduction in antenna size. I would find it very interesting to pull the antenna lead out of the radio in a vehicle with a low-profile antenna and connect it to the external input of a FIM. My guess is that the signal level delivered is many dB below the incident field strength. Microvolts are likely delivered to the radio rather than millivolts, reducing the reception range of any station being tuned, likely to the detriment of the radio station.

To add insult to injury, automobile manufacturers are increasingly making use of microprocessors and other noise generators in their products. As a result, a goodly portion of the noise with which signals, particularly AM signals, must compete now comes from within the vehicle itself. It’s the perfect storm – reduce the signal level of the desired signal by drastically shrinking the antenna aperture, and at the same time increase the noise level in the overall environment with CFLs, microprocessors and plasma televisions as well as the local noise level within the vehicle.

Back in January, I rented a 2013 Ford Explorer, a very nice vehicle that had a “glass cockpit” with touch screen controls for just about everything, Ford’s “Sync” system and premium sound. I thought I’d hit the jackpot as I was pulling out of the rental garage. But it didn’t take long for me to figure out there was a problem. As I drove around L.A., even powerhouse stations KFI and KNX weren’t noise-free, and our own 50 kW signal seemed marginal in some locations. On several occasions, in locations where signals were noisy and weak sounding, I stopped the car and got out with the FIM… and measured 5 mV/m plus signal levels, which should have been absolutely solid. At one such location, I shut the engine off and noted probably a 10 dB improvement in the signal-to-noise ratio of the demodulated signal. The car itself, presumably the engine computer, fuel injector signals and even the fuel pump motor were definitely big parts of the problem.

Just last month, I rented a Dodge Journey with the standard sound system package. It performed very well. I noted that the antenna was more in the “rubber duck” category than “blade” or “dimple,” so there was presumably more aperture and thus more signal to work with.

And then in late March, our chief engineer in L.A. was driving a Scion rental with a Pioneer premium sound system installed. That vehicle had a “dimple” antenna. Its AM performance was abysmal, with the receiver unable to maintain an HD lock on even the strongest signals, and the FM performance wasn’t much better with the HD lock in and out (and multicast signals out more than in). I’m sure the Sirius/XM reception worked just fine.

Like it or not, this is the mobile reception environment we must live in these days. As radio engineers, we are inevitably going to field complaints from managers, programmers, sales people and listeners about “signal problems” that did not previously exist. My bet is that many of these will be directly attributable to low-profile automobile antennas and electrical noise generated within vehicles. Short of drilling holes and mounting real antennas on these vehicles, I’m not sure what the answer is.

If you have news to share with the Rocky Mountain radio engineering community, drop me an email at


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