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Passive AM Monitor Antenna

At the place of my former employment, there is an issue with AM reception. The building is full of old, electrically noisy fluorescent light balasts, computers, mercury vapor parking lot lights, and every other electrical noise generator under the sun.  The second issue is that one of the EAS monitor assignments for two FM class B stations is WABC in NYC.  Under normal conditions, WABC puts a fine signal into the area.  Listening to it is not problem at my house, in the car and what not.  However, at the studio the station is audible, but terribly noisy.  Every time one of those FM stations  ran a required monthly EAS test originated from WABC, it was full of static and just sounded bad on the air.

The state EAS folks were inflexible as to the monitoring assignment.  “WABC is the PEP station for NY.  You should have plenty of signal from WABC at your location,” said they.

At one time, the studio had an active loop antenna (LP-1A) from Belar, which worked, but also seemed to amplify the noise.  I decided that the best thing to do was go big and ditch the preamp.  I made a diamond shaped receiving loop on two pieces of two by four by eight foot lumber.  I wound four turns of #14 stranded wire around this frame and made a 4:1 balun to feed the unbalanced 75 ohm RG-6 coax.

That cured the noise problems and for eight years, WABC sounded pretty good on the EAS monitor.

Fast forward to about a week ago.  The roof at the studio building was being redone and all the monitor antennas had to be removed from the roof.  The homemade loop was not in good shape.  The balun box was full of water, the lumber was cracking and falling apart, the insulation was degraded by UV exposure, etc.  My boss asked, “how much to make a new one?”  So I said something like forty dollars and a couple of hours.  He then said, “Make it so we don’t have to ever make another one.”

Music to my ears.  I started by checking my assumptions.  I made a model and ran NEC to see what the electrical characteristics for that size loop were on 770 KHz.   It came out better than I thought, about 1 ohm resistance and 282 ohms inductive reactance.  Fooling around a little more showed that roughly 1.3 uH inductance and 720 pF capacitance in a L network would bring this inline for a 50 ohm feed point.  Since this is a receive only antenna, that is not a prime consideration.  I am more concerned with noise reduction and maintaining at least the bi-directional quality of a loop antenna.

NEC 2 model AM receive loop

NEC 2 model AM receive loop

Then, I decided to get fancy.  What if the capacitance was put on the end of the loop to ground instead of the feed point.  That, in effect should make the loop directional off of the unterminated side.  Driving the feed point with a 9:1 balun would also bring up the inductance on the feed point.  Finally, grounding the whole thing with a separate ground lead might also get rid of some noise.

The final configuration looks something like this, which is essentially a top loaded vertical:

Low noise AM loop antenna

Low noise AM loop antenna

Now to build it.

Once again, I felt that a non-conductive support was needed, so I used two by four by eight foot lumber, but this time I painted them with oil based paint.  The side length worked out to be 5.7 feet per side, or 23 feet per turn for a total of 92 feet of wire.

I purchased 100 feet of PV (photovoltaic) wire (Alpha wire PV-1400), which is UV, heat, moisture resistant and designed to last for 30 years in outdoor, exposed environments.

For the balun box, I used a metal outdoor electrical box with a metal cover.  I put a ground wire jumper between the box cover and the ground common to maintain shielding.  I used a water tight bushing to feed the antenna wires and the ground wire into the box.  I drilled a 3/8 hole for a type F chassis connector.  Everything was given a little extra water proofing with some silicone based (RTV) sealant on all threaded junctions.

The spreaders for the wire windings are UV resistant 1 inch PVC conduit.  I drilled four holes, three inches apart in each spreader to run the loop wires through.

The balun is 7 trifiler turn of 24 AWG copper wire on an FT-43-102 toroid core.  Trifiler means three wires twisted together before winding the toroid core.

I used all stainless steal screws and mounting hardware.

The loop is terminated with a 500 pF, 500 volt ceramic capacitor to ground.  Once in place, I am going to experiment with this by jumping it out of the circuit to see what effect it has on noise and signal strength.  I may also try replacing it with a 200 ohm resistor and or a 1000 pF capacitor.

The assembly was pretty easy, although time consuming.  My four year old son helped me paint the wood and string the wires through the spreaders.

I soldered all wire connections with 5% silver bearing solder.

When the whole thing was assembled, I tested it out with my Drake R8 receiver.  It performs much as expected, low noise, directional away from the terminated wire loop.  It does not appear to be too narrow banded either, as the stations on the high end of the dial were also received with good signal strength.

Next was loading it on the pickup truck, driving it in and mounting it on the studio building.  I got some funny looks from my fellow travelers, then again, I usually do.

For the ground, I purchased an eight foot copper clad grounding rod and pounded it into the ground at the corner of the building.  This area is always wet as it is the lowest area around the building and all the gutters drain there.  This is not be best RF ground, but for the purposes of this antenna, it should work fine.  I used about 28 feet of left over #12 stranded wire from the ground rod up to the balun box and connected it to the common ground point inside the box.

The frame itself is mounted on a standard wall mount antenna pole.  Stainless steel clamps hold the wood frame to the pole.

Once it was installed, I used my Kenwood R-2000 receiver to find the best mounting azimuth and locked everything down.  I also put a toroid on the RG-6 coax coming up from the rack room to keep any shield noise from getting into the antenna.

AM receive loop PVC wire spacers

AM receive loop PVC wire spacers

AM receive loop wood frame

AM receive loop wood frame

AM receive loop balun transformer

AM receive loop balun transformer

The tuning capacitor is in there too, behind one of the loop wires.

AM loop antenna installed on roof

AM loop antenna installed on roof

Antenna installed.  I did try substituting the 500 pF capacitor with a 220 resistor.  The signal strength came up somewhat, but the noise increased more, therefore the capacitor is a good termination for this antenna.

With this antenna, the signal from WABC is nice and clean and sound good on the FM station when a monthly EAS test is retransmitted.

What is 200 KHz divided by 400 KHz?

The standard FM channel in the United States, as defined by the FCC is 200 KHz (See CFR 47  73.201).  The occupied bandwidth of an FM IBOC signal, as created by Ibiquity, Inc, is 400 KHz.  See below picture:

HD radio trace on FSH3 Spectrum Analyzer

HD radio trace on FSH3 Spectrum Analyzer

A picture is worth a thousand words. Engineering types will understand this without explanation. For non-engineering types, here is your thousand words (or so):

On the left hand side of the screen is the signal strength scale.  Each vertical division is 10 dB.  This is not absolute signal strength, it is referenced to -20 dBm.  However, it gives a good relative signal strength for both the analog carrier and the IBOC carriers.  The analog carrier is centered on the screen, it slopes upward like a steep mountain, peaking at -50 dBm relative.  The IBOC carriers are on either side of the analog carrier, they are flat, approximately 75 KHz wide and peak approximately 20 dBm below the analog carrier (-20 dBc).  For some reason, likely the bandwidth and/or impedance match between the antenna, high level combiner and the two transmitters, the left IBOC carrier is actually peaking around -14 dBc.

The span, as noted on bottom right hand side of the screen is 500 Khz.  Each horizontal division is 50 KHz.  The entire span of the measurable signal is eight horizontal divisions, thus 400 KHz.

As noted above, the allocated channel bandwidth is 200 KHz, thus this station is exceeding it’s allocated bandwidth by 100%.  This is allowed under CFR 73.404, which is titled “Interim hybrid IBOC DAB operation.”

IBOC proponents will make the argument the FM radios work on something called “The capture effect,” which is to say that if two signals are on or close to the same frequency, only the stronger signal will be demodulated.  Thus, the IBOC carriers have no effect on the adjacent channels that they are interfering with so long as the adjacent signal is stronger than the IBOC carrier.  The argument is further carried forward by assuming that with a stations protected contour (60 dBu in most cases), the IBOC carrier will never exceed that analog carrier.

That is not necessarily true, especially in areas where terrain (and buildings, underpasses, unintentional directionality in transmitting antenna, etc) can attenuate signals close in causing the IBOC signal to become equal to or stronger than the adjacent analog signal.  This effect causes picket fencing.  Lower powered FM stations; class A, LPFM, etc, are especially vulnerable to this effect.

Further, even in areas where the analog carrier is stronger than the IBOC carrier, the noise floor has been moved from -100 dBm or so to -70 dBm, which is a 1,000 times greater.  To assume that raising the noise floor by 1,000 times will have no effect is, as they used to say in the Navy, making an ASS out of U and ME.  Mostly you, in this case.  This effects the receiver by making it less sensitive, it will also add noise to the demodulated signal as the elevated noise floor will show up as background hiss.  Even further still, higher IBOC carrier levels, as authorized by the FCC in January of 2010 can interfere with the stations own analog carrier.

According to the both Ibiquity and the FCC, which stated in the Notice of Proposed rule making, the reason for interim IBOC operations are:

iBiquity’s IBOC DAB technology provides for enhanced sound fidelity, improved reception, and new data services. IBOC is a method of transmitting near-CD quality audio signals to radio receivers along with new data services such as station, song and artist identification, stock and news information, as well as local traffic and weather bulletins. This technology allows broadcasters to use their current radio spectrum to transmit AM and FM analog signals simultaneously with new higher quality digital signals. These digital signals eliminate the static, hiss, pops, and fades associated with the current analog radio system. IBOC was designed to bring the benefits of digital audio broadcasting to analog radio while preventing interference to the host analog station and stations on the same channel and adjacent channels. IBOC technology makes use of the existing AM and FM bands (In-Band) by adding digital carriers to a radio station‘s analog signal, allowing broadcasters to transmit digitally on their existing channel assignments (On-Channel) iBiquity IBOC technology will also allow for radios to be ”backward and forward” compatible, allowing them to receive traditional analog broadcasts from stations that have yet to convert and digital broadcasts from stations that have converted. Current analog radios will continue to receive the analog portions of the broadcast.

Few if any of those goals have been met.  As far as the forward/backward compatible thing, it just isn’t so unless a person actually owns an HD Radio.  As noted in previous posts, few consumers have seen fit to purchase an HD Radio, nor have car manufacture’s taken to installing them en mass in new cars, so there is no forward compatibility.  Instead, we have FM radio stations interfere with each other and themselves in an attempt to “modernize” the audio broadcasting business.  This is a bigger problem for small, community radio stations that can neither afford to install the expensive, proprietary HD Radio system, or broadcast quality receivable signals with an adjacent HD Radio signal raising the noise floor by 1,000 times or more.

I can think of no other greater threat to free over the air broadcasting than HD Radio and the degradation of AM and FM services that comes with it.  The consumer has shown that they don’t care.  If given the choice between free over the air broadcasting that has mediocre programming and is full of interference, and some type of paid internet streaming service that sounds reasonable with good programming, they’ll go for the latter.

In short, some cobbed together digital modulation scheme is the last thing that radio needs right now.

Crown D75 monitor amp goes terminal

Happened the other day, took out the monitor speakers too.  I am not sure how this happened, but the production director reported that the speakers began making very loud squeal.  Somebody finally thought to turn off the amp using the conveniently located on/off switch on the front panel.

Crown D75 audio board burned open resistor

Crown D75 audio board burned open resistor

The two watt resistor is burned open.  Also, this got so hot it burned a hole in the circuit board below it.  Truth be told, I think this amp was about 25 years old and due to be replaced when the new studios were built out.

I’ve seen these Crown amplifiers self destruct in the past.

AM IBOC turn offs?

I have received an e-mail from occasional reader John, who comments that many of the Windy City AM’s have turned their buzz saws off. I note myself today, the same can be said for many of the NYC AM’s.  WABC has had their’s IBOC turned off for quite some time.  The latest to turn off is WNYC on 820 KHz.  Several people have noted the loss of noise on their signal this morning.

According to Ibiquity’s own website, only six AM stations in the NYC market are currently using IBOC.

What does this mean?

Could it be that management is finally realizing that the cure is worse than the disease?  The disease being alleged poor audio quality, and the cure being IBOC itself.

Where are, repeat, Where are all the dead birds?

I am reading up on American Bird Conservancy v. FCC. I must admit, I am a bit ignorant on all this bird v. tower stuff.  After all, in my 25 to 30 years of working in radio, in and around towers almost every day, I have rarely seen a dead bird.  By rarely, I mean I recall seeing exactly three dead birds at the base of towers.  One, a mysterious looking songbird under a 1000 foot tower in Harrisburg, PA.  Another, a Pileated Woodpecker that flew into a chain link fence.  The third was a half eaten dead crow that likely met his fate at the hands of the resident Red Tailed Hawk, who hung out on the tower looking for meals.

Even so, the FCC is going to hold hearings on this important matter, because it is so important.   They also have finished all their other work and have nothing else to do.

According to the web site Towerkill.com, millions of birds have been killed because they have flown into communications towers.  In the FAQ section:

Thousands of migrant songbirds killed in a night at a single 1000-foot high television tower

I couldn’t reach BioFile Services, the domain owner, on their cellphone for comment.

I have been to hundreds of tower sites in states up and down the eastern seaboard, California and Guam.  In all that time, I can only account for one bird that may have died by flying into a tower.  Were are all the other ones?  Surely, when they hit the tower, they fall almost straight down, on account of gravity and the other laws of physics.  That means the terrible carnage would be evident near the base of the tower, right?

The above mentioned web site states that tall towers that are in foggy areas and are lit at night pose the greatest risk.

Case in point:

1. WBNR, which has two 405 foot towers, is located along the Hudson River so it is often fogged in at night.  The towers have four levels of lights with flashing beacons at the 200 and 400 foot levels.  The site is also on a major N/S migration route for birds.  Further still, it has a lawn extending 200-300 feet from the base of all the towers.  This was the former studio location from 1959 until 1998.  In the ten years I worked there, I did not see one dead bird, nor has the tenant that lives in the building.  No employees that worked at the former studio location recall seeing any dead birds either.

2.  Mount Beacon, a group of 5 towers ranging up to 300 feet tall near the summit of mount beacon, around the 1200 feet AMSL.  Certainly these towers stick way up into the flight paths of migratory birds.  One tower is lit at night with a red beacon light and it is often foggy.  The area round the base of the towers is gravel/dirt and cleared away for at least 100 feet.  Still, no bird carcases.  Nearby, however, there is a group of Bald Eagles, which have taken up residence in some of the craggy rocks.

3.  Illinois Mountain, Highland, NY: Same story

4.  Clove Mountain, Unionvale, NY: Same story

5.  Mount Zion, Highland, NY: Same Story

6.  Helderburg Escarpment, New Scottland, NY which has towers for the following stations: WRGB, WRVE, WFLY, WYJB, WPYX, WGNA, WMHT, WTEN, and WXXA: Same Story

7.  Mount Equinox, Manchester, VT: Same Story

8.  Pico Mountain, Rutland, VT: Same Story

9.  WHP transmitter site, Enola, PA, six towers 410 feet tall: Same Story

10.  WGY tower site, Schenectady, NY: 620 foot tower, same story

11.  WHP-TV/WITF Harrisburg:  The only place I saw a dead bird at the base of a tower.

I could continue with the no dead birds found and include tower sites for WROW, WRZN, WDVH, WKZY, WXPK, WLNA, WKBO, WTPA, WIZR, WENT, and so on.

I would testify to these facts under oath.

There may actually be a few towers out there that are located in a position to inadvertently kill birds and that is unfortunate.  The majority of towers, however, are no more deadly to birds than other man made structures like houses and office buildings.  I can think of at least two dozen times that I have been working in the office or sitting at home and there is a great big “THUNK!”  Outside there is a dead bird under the window.  While that is regrettable, I am not going to take the glass out of my windows.

I also see many dead birds on the side of the road when I am walking or riding my bike.

Human pets, especially cats take a huge toll on wild birds.

Loss of natural habitat from development takes a toll on birds.

This is a Red Herring.  It is time to put this foolishness to bed and get back to the business at hand.

Radio Industry Technology Study

Wheatstone, Inc has sponsored a radio industry future technology study which brings into focus some of the connections between technology and radio business models.   It appears to be very thorough, polling radio professionals on all aspects of technology development and management.

According to Josh Gordon:

While it is hard to predict which of the radio industry’s newest business models will succeed in generating new revenues, we can better anticipate the winners by measuring how fast the technologies that enable them are being adopted.

To find out, we surveyed the radio professionals involved in all aspects of technology management (engineers, and operations and technical management). The results reported in this study can serve as a benchmark for managers to evaluate their own organizations’ progress.

The first graph is telling:

Wheatstone Technology Survey Results

Wheatstone Technology Survey Results

Almost everyone believes that the internet will play a greater role in radio (and all media).  This goes against the “radio with its head in the sand” idea that can be found in some corners of the internet (I’d provide a link, but the site has turned on a paywall).

The question is, what are management type people doing about it.  Some have good ideas on how to bridge the gap between making money the old fashioned way; selling spots, to making money the new way; brand imaging,  media promotion and personal contact through new media.  While it is generally agreed that radio stations should stream their audio, many, if not most, make little or no money on this.  If radio is going to make some revenue on internet applications, obviously some new ideas are needed.

Unique local content seems to be the most sought after, things like local news podcasts, or new music, e.g. studio sessions with up and coming band and musicians, locally produced shows that are area specific, etc. Put a 10 second sponsorship in front of those and people will get the message.  Other things like value added contests that can only be heard on the internet.  Interactive radio station apps that have streaming, now playing, recently heard features that link to a .mp3 store for iPhone and Android operating systems.  Text link adds on radio station web pages, etc.

On the flip side of this, huge, great amounts of bandwidth will be required if the internet streaming is going approach the same number of off the air listeners.  Depending on the how the radio station has the stream set up, anywhere from 20 to 64 kbps of data transfer is needed for each listener.  For a station in a large metropolitan area, multiply that by 500,000 to 4,000,000 listeners at any one time and data gridlock ensues.

On the in house side, the red hot, cutting edge thing these days is AOIP (Audio over IP), which Wheatstone is heavily invested in with its E console series.  While some might not think of AOIP as a traditional internet application, it none the less uses the same transport protocols as other internet applications.   AOIP offers some great advantages over other routing systems, as both private (internal) and public (wide area) networking can be used to transfer audio in real time.  Of course, this is not as easy as plugging the new computer into an ethernet jack, it takes more planning than that.

Wheatstone has published an excellent white paper on Network Design for Ethernet Audio.  Well worth the read.

As AOIP technology develops more, web streams could come directly from the console and be customizable according to destination.  Further, IP logging can create stream user profiles and customizable greetings, listening preferences and so on.  This would require that the web streaming server be in house and the studio facility have enough bandwidth to handle all of the outgoing streams and other content.

Certainly an in house IT/Web developer will be needed to manage and maintain such a system.

You can download and read the entire studio at Alethea/Wheatstone Radio Survey.  The cliff notes summary is this:

Finding #1: Almost all radio tech people believe the Internet will play a bigger part in the future of radio.

Finding #2:Of the new revenue generating technologies, streaming a station’s signal has the biggest earning potential.

Finding #3: Technologies that require little or no capital investment are being deployed at similar frequencies by both stand-alone and group owned stations.

Finding #4: A technology gap is emerging as stand-alone stations deploy revenue generating technologies requiring investment at only half the frequency as group owned stations.

Finding #5: The revenue generating technology that most group owned stations plan on deploying next is a mobile app, while for stand-alone stations, it is broadcasting in HD Radio, with mobile apps coming in a close second.

Finding #6: There is a big divide between radio stations that are now, or will soon be, making money from streaming their signal over the Internet, and those who likely never will.

Finding #7: The day will come slowly, but in 15 years a majority of radio stations expect they will have more online listeners than RF listeners.

Finding #8: Despite the expected decline in over the air listeners, few stations expect to turn off their transmitters.

Finding #9: Three years from now, radio station technology will be more IT centric with more automation, as well as more networking between stations, IT networks, and office and audio networks.

Finding #10: Three years from now, the stability of each radio station network will be more important, as will networks with no single point of failure.

Finding #11: Three years from now, more audio consoles will be networked together. Also, the bandwidth of those networks will be required to increase.

Finding #12: The top reason group owned stations bought an AoIP network was to reduce maintenance costs. The top reason for stand-alone stations: to share talent.

Finding #13: At stations that have installed an AoIP network, more than a third of stand-alone stations found installing it harder than anticipated, while only 16.7% of group owned stations found installation harder than anticipated.

Finding #14: At stations with an AoIP network, more than one in four stand-alone stations and one in three group owned stations report latency problems.

The study is a good indication of where technical managers see growth.  One thing that internet sites like Pandora have shown, radio broadcasters cannot sit back and be content with the status quo.  Without technical innovation and some outside of the lines thinking, radio will be bypassed by newer more interactive media services.

Something to ponder.

Solar Cycle 24 brings better Shortwave Listening

Because of the utterly depressing selection of programming available on the standard broadcast (AM) band, lately I have been getting my radio fixes on higher frequencies.  Shortwave Listening can be a fun way to hear all sorts of things, from the very retro Voice of Russia interval music, which makes me want to go check on my survival bunker, to the almost comical Radio Havana, “Broadcasting from the free Americas,” depending on what your definition of free is, the number and type of programs are almost limitless.  Whether or not one believes the conspiracy theories posed by Alex Jones, listening to that program can give you the hebegebees (see above note about survival bunker).

Most of the shortwave broadcasts in this country are religious shows.  One can listen to Catholic Mass every morning at 8 am on WEWN, if so inclined.  I don’t think it actually counts as going to church, though.  There are several other shows on US shortwave, like Le Show, which appears to have a copyrighted on the phrase “this is a copyrighted feature of this broadcast,” but you have to hunt around for them.  WBCQ offers a variety of programs, likely the the lowest ratio of religious programs on any privately owned shortwave station in the US.

Don’t expect to find the old stalwarts, the VOA or the BBC to have very good signals in the US.  Both those agencies severely curtailed shortwave broadcast to the US starting around 2000 or so.

There is also a smattering of shortwave pirate broadcasters clustered around 6.925 KHz, which can be entertaining in their own way.

A good website that lists all the shows in English by hour and frequency, is short-wave.info.

Solar Cycle 24 is heating up, with excellent propagation last week and continuing on this week, I was able to hear some pretty rare stations.  Even better, we are in the early stages with the peak predicted sometime around 2013.  I even heard one wag predicting that the coming solar cycle jives with the recently popular “The world will end in 2012” theme.  With the long winter months ahead, I have been tuning up the shortwave listening post in my house.

I am going to be doing a multi-part post on how to set up a good shortwave listening post, how to get around local electrical noise issues, antennas, grounding, receiver selection and so forth.

Cracked Battery Terminal

File under some new everyday. Yesterday, there was an area wide power outage in Woodstock, NY. The backup generator failed to start, however, WDST remained on the air until the UPS batteries ran out several hours later.  Then my cellphone rang.  Alas, yet another Sunday on the job.

Upon arrival, I found the power had just come back on, so the DJ (yes, there was a live person in the studio, on Sunday) was restarting the NextGen system and getting the station back on the air.  I restarted the rest of the servers, streaming computers and what not.  While I was there, I figured I might as well see why the generator didn’t run.

Pressing the start switch led to the “click, click, click, click…” which normally indicates the battery is dead.  Deciding that I should dig a little deeper, I got the volt meter out.  Battery voltage, no load 13.8 volts.  A normal reading.  Flick the starter switch and measure the battery voltage again, under load 13.7 volts.  Hmmmm, now that is not what I suspected.  If the battery were bad, the voltage should drop down under load.

Cracked Battery Terminal

Cracked Battery Terminal

I grabbed the negative cable and it came off in my hand.  Another one of those “ah ha!” moments.  Upon closer examination, the terminal connector is cracked in half.

Cracked Battery Terminal

Cracked Battery Terminal

I went to the local Ford dealership and bought a heavy duty truck battery cable.  Since the battery itself is six years old, I decided to bring it and have it checked, and sure enough, the battery was going bad too.  Rather than suffer through another power outage without generator, I went ahead and replaced the battery.

Why the terminal cracked in half in the first place, I don’t know.  Perhaps it was over tightened, or some type of manufacturing defect.

STL paths

I learned this one the hard way, all climates and terrain are not equal.   An important detail when planning a Studio to Transmitter Link.  The RF STL  is usually in the 950 MHz band, although lately people have been using 2.4 and 5.8 GHz unlicensed systems with good results.  What works well in the northeast, for example, might not work that great in Florida, where tropospheric ducting and multi path can create reception problems.

One example of this happened in Gainesville, Florida.  A station there had a 15 mile path over flat ground with tall towers on either end.  It had full line of sight and Fresnel zone clearance.  Ordinarily the signal strength was -65 dB, which is about 25-30 dB of head room for the equipment being used.  However, in the mornings, most often in the late summer early autumn, there would be brief drop outs of a few seconds.  After two years of suffering through the mysterious morning drop outs, we finally rented a plane and flew the STL path, only to discover there was a swamp right in the middle that was not on the topographical map.  On those mornings when drop outs occurred, it was surmised that dense fog would rise up, causing the RF path to bend and creating multipath at the receive antenna.  Since it was a Moseley Starlink, the digital demodulator would unlock due to high BER.  The signal strength never moved off of -65 dB.

Of course, had this been an analog STL, it would not have dropped out, although it may have gotten a little noisy for a few minutes.

950 MHz STL path study

950 MHz STL path study

I have learned to be very conservative with my STL path analysis, using software tools like RF Profiler to look at the theoretical path, but also surveying ground obstacles like trees and building, which are not accounted for in the USGS terrain database.  There are several RF software programs out there that will do the same thing.

Last week, when a station manager insisted that an STL path was possible from a proposed new studio location, I deferred to the path study, which showed only about 50% Fresnel zone clearance.  While it was true that the path is less than a mile, and it is also true that one can see the top of the transmitting tower from the roof; trees, buildings and even an access road create problems which could potentially cause STL drop outs.  We are not going down that road again.  The station manager, who’s background is in sales, was told to find another location or order a TELCO T-1.

Everything is fine, why do you ask?

I found this picture of Bob Struble’s vacation last summer:

HD radio flagship

To the uninitiated, this might seem quite alarming; boat sinking, rigging all ahoo, this poor guy waiting rescue or certain death.  But to understand what is going on here, you have to see the whole picture.   Things are not what they seem, in fact, it’s designed that way:

The rest of the story

All this time, I have been lamenting the technical flaws IBOC, when really; its supposed to do that.  Holy cow!  All these years of wondering, “What the fuck are they thinking?” and decrying HD Radio, especially AM HD radio.  Boy am I embarrassed.  Makes me want to do this:

Baghdad Bob Bob Struble latest quote, brought to bold typed prominence on the pages of Radio World magazine:  “Consumers now expect to see album covers when they listen to music.”  I think he means album art, but anyway.

You mean to tell me HD radio is failing because of lacking album art!  Of all the Bob Struble quotes, to prominently feature this one in their article makes me think 1) the editors at Radio World have a sense of humor, or 2) they have a sense or irony, or both.

So anyway, there you have it: Album Art.  The rest of the so called technical flaws are “design features” that will enhance HD radio in the long run.  They’ve got us right were they want us.

Axiom


A pessimist sees the glass as half empty. An optimist sees the glass as half full. The engineer sees the glass as twice the size it needs to be.

Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the Government for a redress of grievances.
~1st amendment to the United States Constitution

Any society that would give up a little liberty to gain a little security will deserve neither and lose both.
~Benjamin Franklin

The individual has always had to struggle to keep from being overwhelmed by the tribe. To be your own man is hard business. If you try it, you will be lonely often, and sometimes frightened. But no price is too high to pay for the privilege of owning yourself.
~Rudyard Kipling

Everyone has the right to freedom of opinion and expression; this right includes the freedom to hold opinions without interference and to seek, receive and impart information and ideas through any media and regardless of frontiers
~Universal Declaration Of Human Rights, Article 19

...radio was discovered, and not invented, and that these frequencies and principles were always in existence long before man was aware of them. Therefore, no one owns them. They are there as free as sunlight, which is a higher frequency form of the same energy.
~Alan Weiner

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