Mediumwave Oddities - Geography

Think you know mediumwave? Are you good at geography? Do you like statistics?

Let's look at the geographical oddities of the mediumwave band for the United States. Information has been gleaned from current FCC records, and includes only US-licensed stations. 4784 licensed stations were used to compile these statistics from the FCC database dated July 14, 2010.

EAST

Did you know that 21% of all US-licensed AM stations are east of Florida? This one surprised me.

Which US station is the farthest east? Remember, east goes all the way to the International Date Line.

If you guessed a station in Maine, you would be wrong by a great margin. The farthest US station in the eastern hemisphere is KCNM-1080 (5KW), Saipan, Northern Marianas at 145.714E longitude. Next would be KGUM-567 (10KW), in Agana, Guam at 144.759E longitude. Three other stations in Guam are #3, #4, and #5 farthest east in longitude, west of the International Date Line.

So, how about the continental US? Are we there yet?

Think Carribbean. WSTX-970 (5KW), in Christiansted, US Virgin Islands is next farthest east at 64.693W longitude, and the most eastern US station in the western hemisphere. Five other US Virgin Islands stations are next.

Next comes a slew of stations in Puerto Rico, in fact 75 of them. The farthest east in Puerto Rico is WMDD-1480 (5KW), at 65.64W longitude.

Now we finally come to the continental US. The most easterly station in the continental US is WXME-780 (5KW), Monticello, Maine at 67.817W longitude. However, there is an application on file for a "NEW" AM station in Calais, Maine at 67.266W longitude which will take the title if it ever goes on the air.

But what about Florida, you ask?

Florida is not even close in the running. WWRF-1380 (1KW), Lake Worth, Florida at 80.072W longitude is the station farthest east in Florida. Astonishingly, there are 921 stations up and down the east coast of the continental US which are farther east than Florida's WWRF-1380, and 1007 stations farther east in total, clear to the International Date Line, all licensed to the US via the FCC.

Amazingly, 1007 stations (21%) of 4784 licensed FCC stations are east of Florida.

Which is the most easterly NPR (National Public Radio) station?

WFPB-1170 (1KW) Orleans, Massachusetts at 70.01W longitude.

Most of us know that "K" stations are west of the Mississippi, and "W" stations are east of the Mississippi, except for a few exceptions, like KDKA-1020 in Pittsburgh, PA and KYW-1060 in Philadelphia, PA and WOAI-1200 in San Antonio, Texas.

Which is the farthest east "K" station, east of the Mississippi River?

That would be KCNM-1080 (5KW), Saipan, Northern Marianas at 145.714E longitude. It is 7788 miles east of Wasington, DC where the FCC is located, and most definitely east of the Mississippi River. The most easterly "K" station in the lower 48 states is KYW-1060 (50KW), Philadelphia, Pennsylvania at 75.248W longitude.

WEST

Which US station is the farthest west?

We have two winners. KJAL-585 (5KW) Tafuna, American Samoa at 170.776W longitude and WVUV-648 (10KW), Leone, American Samoa at 170.776W longitude, both in the South Pacific and licensed by the FCC, some 7035 miles west of Washington, DC. They transmit from the same location.

Which is the most westerly station in the lower 48 states?

KBIS-1490 (1KW), Forks, Washington at 124.388W longitude. There are 72 stations farther west of this, all in Alaska or the Pacific Ocean.

Which has more AM stations, Hawaii or Alaska?

Hawaii has 30; Alaska has 40. Alaska is the winner.

Which is the most westerly Alaskan station?

KICY-850 (50KW), Nome, Alaska at 165.314W longitude. There are a total of 6 Alaskan stations that are farther west than the most westerly Hawaiian station, KUAI-720 (5KW), on the island of Kuai.

Which is the most westerly NPR station?

KOTZ-720 (10KW), Kotzebue, Alaska at 162.568W longitude.

Which is the farthest west "W" station, west of the Mississippi River?

The prize goes to WVUV-648 (10KW), Leone, American Samoa at 170.776W longitude. So much for WOAI-1200 in San Antonio, Texas! WOAI-1200 is the most westerly in the lower 48 states.

NORTH

Which US station is the farthest north?

KBRW-680 (10KW), Barrow, Alaska at 71.256N latitude.

Which NPR station is the farthest north?

Again, KBRW-680 (10KW), Barrow, Alaska at 71.256N latitude.

How about the continental US? Which station is the farthest north?

We have a tie. KVRI-1600 (50KW), Blaine, Washington at 48.954N latitude and KARI-550 (5KW), Blaine, Washington at 48.954N latitude.

How come a station in Maine isn't the farthest north?

The most northern station in Maine is WFST-600 (5KW), Caribou, Maine at 46.886N latitude. 180 stations are farther north than WFST-600, and all are scattered from Minnesota all the way to Alaska.

The geographical center of the lower 48 states lies outside of Lebanon, Kansas, in the middle of what used to be a hog farm.

Are there more stations to the north or to the south of this location?

There are 1814 stations to the north and 2970 stations to the south of Lebanon, Kansas.

SOUTH

Which US station is the farthest south? Think outside of the continental US.

Another tie. KJAL-585 (5KW) Tafuna, American Samoa at 14.357S latitude and WVUV-648 (10KW), Leone, American Samoa at 14.357S latitude. Coincidentally, these two stations are not only the farthest south, but also the farthest west.

Which is the most southerly station in the continental US?

WKIZ-1500 (250W), Key West, Florida at 24.567N latitude. The Florida Keys have 3 stations - 2 in Key West, and 1 in Marathon Key.

How about Texas? It's pretty far south.

The most southerly station in Texas is KVNS-1700 (8.8KW), Brownsville, Texas at 25.949N latitude.

And California?

That would be KURS-1040 (360W), San Diego, California at 32.694N latitude. Texas is much farther south than California.

How many stations are south of the continental US?

There are 118 stations south of the continental US, that is, south of Key West, Florida. All are in the Pacific or Caribbean.

The Mississippi River runs north and south through the country, dividing the US east to west approximately at St. Louis, Missouri (90.18W longitude).

Are there more stations to the east or to the west of St. Louis?

There are 1990 stations west of St. Louis and 2794 stations east of St. Louis. The majority of stations are to the east of St. Louis, in fact, 71% of them.

IBOC

How about some IBOC stats?

There are 293 licensed IBOC stations. Two are silent at the moment.

The most westerly IBOC station is KOTZ-720 (10KW), Kotzebue, Alaska at 162.568W longitude. It is also the most northerly IBOC station and the most westerly NPR station.

The most easterly IBOC station is WIPR-940 (10KW), San Juan, Puerto Rico at 66.141W longitude. It is also the most southerly IBOC station.

There are 128 IBOC stations west of the Mississippi River. There are 165 IBOC stations east of the Mississippi River.

Which state has the most IBOC stations?

California wins with 32. Runner up is Florida with 25, followed by Colorado at 17. New York has 16, and both Texas and Ohio have 15 each.

Which state has the fewest IBOC stations?

Several are tied. Kentucky, Mississippi, North Dakota, Nebraska, and South Carolina have 1 each. Arkansas, Delaware, Idaho, Louisiana, Maine, Montana, New Mexico, and Nevada have 2 each.

Which state has the most IBOC NPR stations?

Surprise! Alaska wins with 6. Alaska also has the most NPR stations overall at 9.

ERRATA

How many "K" call signs?

1907.

How many "W" call signs?

2877. The "W"s win by a huge margin.

We have a KAAA and a KZZZ, but no WAAA or WZZZ.

What are the oddest call signs?

Puerto Rico gets the win here. WA2XPA-680, WI2XAC-740, WI2XSO-1260, and WI3XSP-1260. These four are experimental synchronous stations. Usually AM synchronous station call signs are named the same as the host station, like KKOB-770 in Albuquerque, New Mexico, which runs one in Santa Fe, also KKOB.

Which state has the most stations?

Texas takes the prize with 298, then California with 250.

Surely New York is next, right?

No. New York is #8 ranked with 168. Florida (227), North Carolina (219), Tennessee (185), Georgia (183), and Pennsylvania (180) all have more stations than New York (168). Weirdly, New York ranks just above Alabama, which has 152.

Which state has the fewest stations?

That would be Delaware with 10, followed by Rhode Island with 15 and Vermont with 19.

Coming up next: Mediumwave Oddities - Transmitter Power

Note:

Station powers listed are for their daytime service. Nighttime powers may be lower in some cases.

Digital Radio Update

Let's take a look at the current state of the digital radio conversion process in a few selected countries around the world.

THE UNITED STATES


Almost a year has passed since I reported on The IBOC MESS In North America. Since then, hybrid-digital IBOC conversions (HD Radio) on the US mediumwave AM broadcast band have come to a near dead stop. There seems to be little excitement for new stations to jump on the Ibiquity AM bandwagon, what with a scattered amount of dedicated equipment available and marginal listener interest, not withstanding the large cash outlay stations need to get signed up and converted. Available receiving equipment seems to be a few clock radios, some home sound system type tuners, and car radios (which seem to be coming on strong). Portables have largely been ignored. Sangean had plans to make an intriguing little AM/FM model, the DT-600HD, however the AM band on this unit was to be traditionally analog. They dropped the product before it got to the marketplace.

Last year at August 27, 2009, we had 289 licensed IBOC AM outlets, per FCC files. As of this writing we have 293, and two of them are silent. This is a net gain of only four new registrations in the last 11 months. In the past year there have been reports of several stations switching off their digital signal due either to problems, interference complaints, or lack of interest, so the actual count of stations currently transmitting IBOC is almost certainly under 290. Using the figure 293 against the total number of licensed AM broadcast stations in the US (4786), the AM IBOC factor is 6.1%. At this rate, AM IBOC cannot sustain itself.


Then, there is the adjacent channel interference problem, particularly bad at night, which many still complain about. And rightfully so. Nightly, digital broadband hash continues here in the northeast and other parts of the country on the mediumwave band. Earlier this year, one evening after dark I was driving through Phoenix, Arizona trying to listen to local AM station KMVP (itself an IBOC station) on 860 KHz. It transmits at 1KW. Every time adjacent channel KOA-850 (another IBOC, at 50KW) out of Denver, Colorado peaked, KMVP was not receivable due to the digital hash. It was maddening.

Earlier this year, Ibiquity announced  2010 fire sale pricing (good through December 31) for new stations wishing to join the digital "revolution", with the stipulation that they be "stations eligible for discount pricing", whatever that means. The existing $25,000 main channel licensing fee was reduced to a remarkable figure of $10,500 if payment is made up front. Monthly payment plans (at an overall higher total figure) for those stations less able to scare up this kind of money all at once were also instituted. It seems that the original higher flow of incoming cash might be slowing down. Ibiquity claims that one new digital station goes on the air on the average of every four days. I guess this must mean FM, as the AM figures don't support this claim. It will be interesting to see if the fire sale continues into next year.

So what is the current market share for HD Radio in the US? A 7 month old Bridge Report hinted at it.

12/15/2009 Bridge Ratings: New Media's Effect On Radio Lessening

"HD Radio, though it reaches only about 650,000 people, is attracting 'considerable listening time' of about 11.5 hours a week", though Bridge says "that's down from previous surveys, attributing the change to a larger number of HD receiver owners, diluting the impact of the heavy users."

"Respondents were also asked what audio devices they use every day, with a choice of AM/FM radio, HD Radio, cellphone, satellite radio, and Internet radio. Nearly 90 percent of radio listeners also use a cellphone every day, while more than 44 percent use an MP3 player. About 35 percent listen to Internet radio every day, with satellite radio and HD Radio well behind."

6/30/2010 Bridge Ratings: Is Terrestrial Radio Ready for a Digital Future?

Things are not moving along very quickly. Back to mediumwave, we can only hope that Ibiquity eventually gives up on the mediumwave band, or the government does, or both, and they take the AM patient off of life-support.

Beyond our borders, several other countries have issued mandates to go digital for some or all of their radio broadcasting services. Let's examine some of their stories.

MEXICO


4/14/2010 Mexico Is Set to Elect IBOC

Information out of Mexico is paltry, and I have seen nothing new since April. It would seem that this is a done deal, with Mexico on the verge of adopting IBOC as their standard. Back in May 2008, a 200 mile wide border zone was established along the US - Mexican border allowing Mexican AM and FM stations to use the IBOC format to "take decisive action so that the country’s AM and FM radio stations in the zone located within 320 km of the northern border of Mexico can transmit at the same technological level so that they can provide the benefits of quality service to the radio listening public."

Supposedly, there are two, or six, or nine IBOC outlets, depending on what you read, and at least two more deeper down in Mexico itself in or around Mexico City (XHDL and XEDA). The two call signs I have seen reported along the US border are AM outlet XEEZ 970 Radio Palacios from Caborca, Sonora, and the other, an FM outlet, XHTY-FM 94.5 in Tijuana. The station news is all old news anyway and reported a long time ago, way back in June 2008. I have heard no other IBOC-rollout fanfare since then.

Suddenly in early 2009 Mexico announced that it intended to convert all AM radio station outlets to FM, country-wide, a wholesale disbanding the AM service. They even published a schedule of the conversion dates, to take place between August of 2009 and August of 2010 (see page 8).

Whether this eventually happens or not is anyone's guess, but you can bet on it not happening by next month. Local reports out of Mexico indicate that some regional areas have abandoned the AM mode, particularly in the southeast. The government's general idea, I think, was to force the big city AM outlets to convert to FM (and in the future, IBOC), and let the rural outlets languish and eventually disappear. However there was no lack of border blasters in southwestern Arizona, where I spent last winter. The Nogales to Tijuana border strip has a sizable number of AM outlets, but none running IBOC as far as I can remember hearing. Assuming I get to Arizona again this winter, I will pay more careful attention to what is coming out of Mexico. Needless to say, the AM to FM conversion in Mexico is coming along slowly. And IBOC even slower. So where does this leave Mexican AM IBOC?

Curiously, Mexico's announcement of being on the brink of voting to adopt the IBOC methodology is some months old now, with no action since. It seems they can't pull the trigger. Maybe they realize that it's just a whole lot of money and effort for no good end, at least on the AM side. Or maybe they are dragging their feet waiting to see what happens with IBOC in this country. IBOC may be on life-support for the mediumwave band in the US, but FM has greater presence. As of this writing, 1569 stations (8 not on the air) are shown with IBOC permits in the FM service. This is compared to a total of 9608 full-fledged FM stations on the air, commercial and non-commercial, 130 of them showing silent at the moment. Using the figure 1569 against the total number of licensed FM broadcast stations (9608), the FM IBOC factor is 16.3%. Still not a great showing. However, listenership seems to be coming around.

May 2010 FM HD Radio is Becoming a Fact of Life for American Radio (be careful with this news, it is an Ibiquity article)

CANADA


Canada (having wanted to go with the DAB standard) seems to be stalled on the whole digital radio broadcasting question, according to a recent article this month in Radio Magazine Online. The article reports that "government observers agree that the service has reached the end of the line....with DAB's imminent demise, increased demand for analog FM frequencies is taking place in Canada's urban areas."

IBOC, where for art thou?


"While posts in online Canadian radio forums suggest a preference for HD Radio among hobbyists, government regulators and industry representatives still treat the the option with caution. Canada's Communications Research Centre, a governmental research body with an advisory role on telecom policy, has developed its own coverage analysis tool dubbed COVLAB to evaluate digital radio coverage and spectral compatibility, rather than simply deferring to U.S. data. IBOC digital radio testing has been conducted in Canada since 2006, and the Canadian government has said that it will accept experimental HD Radio digital hybrid applications from licensed FM stations, though few stations have stepped up to do so."

"So industry opinion on IBOC's potential in Canada is checkered at best. With many stations moving away from AM altogether, and interference concerns among those who remain, AM HD Radio is probably a nonstarter."

Exactly what I've been talking about. Canadian reader Greg writes:

"DAB failed in Canada because there was almost no public awareness of it and virtually no receivers on the market that could receive it. I never saw anyone selling or even advertising DAB receivers, and never even heard any mention of the service anywhere except on radio hobbyist sites and mailing lists. Canada's DAB system was a bit different than that adopted in the U.K., operating on a different frequency band. I wonder if it would have been more successful had we adopted the British standard, which would have enabled us to use receivers designed for the U.K.?"

7/7/2010 Canada DAB Shut Down

Outside of North America, at least four more countries are either entertaining or have adopted Digital Audio Broadcasting (DAB) or Digital Radio Mondiale (DRM) schemes. Europe and many parts of Asia have gone or are going with the DAB or DRM schemes.

Also see:

Digital Radio Mondiale Home Page
Country Information for DAB, DAB+ and DMB

BRITAIN


Britain is an interesting story, in and of itself. The government is going gangbusters for DAB "Digital Britain" via the Digital Economy Act, and pushing it as hard as they can. However, the public and the pundits are panning it for now as "not ready", if ever. The government stipulates that the 2015 switchover "will go ahead only if 50 per cent of radio listening is via 'digital platforms' by 2013." Many say that will never happen by that soon a date, and that the switchover should be delayed for a period of ten years or more. At the forefront is the BBC. The BBC's digital radio stations now cover 86 per cent of the country (signal pattern coverage). The corporation has built 50 transmitters in the last year and plans 60 more in the next year to increase coverage to 90 per cent. Of course, nationwide, the thrust is mostly FM.

Whether their switchover happens by 2015 is the guess of the decade. Figures published showed that the audience share for digital radio in Britain – including listeners on digital TV and the internet – is rising at a record rate, up to 24 per cent from 20.9 per cent in the previous quarter (first quarter, 2010).

We shall see, if we all live long enough. No IBOC for Britain.

There is lots of interesting digital conversion news out of Britain:

7/22/2010 More On The Digital Economy Act

7/8/2010 Digital Radio Speech by the Culture Minister, Ed Vaizey

7/8/2010 Relax. Digital radio switchover will now never happen

5/23/2010 Digital radio switchover gets poor reception

4/8/2010 Say goodbye to your transistor radio, digital switchover is coming

9/9/2009 Britain Mulls Over Digital Radio Transition

6/16/2009 Digital Britain: Analogue radio switch-off set for 2015

INDIA


India is going with DRM, and All India Radio has just ordered a fair amount of equipment. All India Radio is also big into shortwave, much of it used for national regional service. On mediumwave, transmitters there tend to be big boys - 100KW, 200KW, and 300KW to extend the coverage area. On the books are 34 new MW transmitters, upgrades to 36 existing MW transmitters and the purchase of 5 SW transmitters and other associated equipment. Interesting, I see no mention of FM in here.

7/1/2010 All India Radio tender notice for DRM digital transmitters

4/10/2010 Indian government approves country’s digitalisation plan using DRM

AUSTRALIA


Australia has gone with the DAB+ method, a variation of DAB. All commercial and public service broadcasters are now broadcasting digital radio in Sydney, Melbourne, Brisbane, Perth and Adelaide. Australian commercial digital radio services switched-on progressively in May and June 2009 in the five state capital metropolitian areas. The public service broadcasters switched on 1 July 2009. A recent report revealed, "....the industry recently released figures indicating there were already nearly 500,000 people listening to digital radio across those markets."

"There are no plans at this stage to switch off AM and FM radio services", the report said. It continued on, "As there is an estimated five radio devices per home, listeners must be given time to change over all of their radios before any discussion of the switch off of analogue services. In addition, planning needs to continue for the switch on of digital services to the rest of Australia outside of the five metropolitan capital cities."

"It is expected that it will be some years before digital radio is extended to the bulk of the Australian continent. Australia's vast distances and low population density are not well suited to the propagation characteristics of DAB+ and it is therefore likely that a standard other than DAB+ will be adopted for serving areas outside the major cities."

At the moment, it looks like IBOC has lost out here. Australia may use DRM to fill in the nether regions if DAB+ doesn't work out.

Digital Radio In Australia (Wiki)

Digital Radio FAQs For Australia

7/19/2010 ABC Radio Is Now Digital (including AM outlets)

5/5/2010 Digital radio trial to begin in Canberra

8/13/2009 Rollout Of Digital Radio In Australia (announced in 2007)

BRAZIL


Brazil is huge. Ibiquity has done IBOC testing here, and the HD Radio system has been used on a trial basis by a number of commercial broadcasters since 2005. Brazil is the second-largest radio country in the world in terms of station count, behind the United States. Brazil has more than 3,000 commercial stations and about an equal number of low-power community radio stations. This would be huge profit for Ibiquity.

"Brazil's target date for full roll-out of an IBOC approach to digital radio is the year 2016. The Congress of the Brazilian Association of Radio and Television Broadcasters is expected to make a standards announcement by the end of this year or in early 2011. However, there is also interest in Digital Radio Mondiale's DRM30 and DRM+ technologies. The possibility exists that the country will adopt different standards for AM, FM and shortwave."


"While AM and tropical-band shortwave remain important in large swaths of Brazil, DRM may be better positioned than Ibiquity's HD Radio AM for these wavebands, according to anecdotal comments on Brazilian digital radio message boards, blogs and press accounts. Yet HD Radio has more receivers on the market than does DRM. If regulators opt for DRM on AM and for HD Radio on FM, there is a concern that the rollout could be delayed by the manufacturing time necessary to produce dual-standard receivers, according to these accounts. Ibiquity publicly has supported the use of DRM30 for shortwave services in Brazil. It also supports the concept of multi-system tuners capable of receiving both HD Radio on AM/FM and DRM on shortwave."

IBOC is at the doorstep here, but not through the door yet. Again, like Australia, the rural regions may need to adopt the DRM technique for the AM service. We will soon see what Brazil decides.

5/27/2010 Brazilian Broadcasters make public open letter in support of DRM

5/12/2010 Brazil Could Pick Digital Standard in 2010

IBOC INTERNATIONAL

According to the Ibiquity web site, there are a handful of other countries testing and evaluating IBOC digital radio as of this writing. They are: Argentina, Austria, Canada, Chile, France, Hong Kong, Indonesia, New Zealand, Nigeria, Phillippines, Poland, Switzerland, Thailand, and Ukraine.

Ibiquity International

The AM Broadcast Station Self-Inspection Checklist

AM Broadcast Station Self-Inspection Checklist (Sept. 2009)


As a mediumwave DXer and a person interested in radio in general, you might be interested in what the FCC requires of mediumwave AM broadcast stations in their day-to-day operation. A document exists, called the AM Broadcast Station Self-Inspection Checklist. The FCC has developed it to assist broadcast station management in conducting a self inspection of their station. It provides an opportunity for the broadcaster to review and correct any deficiencies associated with the operation of a station without an actual on-scene visit (and citation!) by the Commission. Some interesting entries are to be found, and I will cover them in this article.

STATION LOGS AND RECORDS

First of all, the paperwork. Stations must keep logs and records. What is the difference, you might ask? What goes into a log and what goes into a record?

Section 1B. STATION LOGS/RECORDS:

STATION LOGS include entries pertaining to equipment status, equipment calibration, the Emergency Alert System (EAS) and, when applicable, the recording of tower light outages.

STATION RECORDS include, but are not limited to chief operator designations, equipment performance measurements and AM Directional field strength measurements.

Station logs and records are to be retained for a period of two years.

STATION IDENTIFICATION


This is a hot topic with me. Stations seem to identify less and less. There are stations (ESPN Radio, Radio Disney, are you listening?), which never seem to identify with call signs, making our task as mediumwave DXers a little more difficult. What is the rule? Well, here it is spelled out in exact terms:

Section 1D. STATION IDENTIFICATION:

Station identification shall be made at the beginning and ending of each period of operation, and hourly, as close to the hour as feasible, at a natural break in program offerings. The identification shall consist of the station's call letters immediately followed by the community of license. Any reference to additional communities must be made after the community of license. The name of the licensee, or the station frequency, channel number, or both, may be inserted between the call letters and community of license. No other insertion is permissible. Simulcasted AM and FM stations may identify jointly if owned by the same licensee.

Not much room for ad-lib here. Stations must identify at least once per hour on the hour, and in a strictly defined format. Exclaiming, "ESPN Radio!", "Radio Disney 1650!", "Power 101!", or "K-Lite 107!" cannot be used for the official identification. They must state the station's call letters and community of license at minimum. Optionally, they may insert the owner's name, or frequency, or channel, or all of these. Finally (capitalization mine): "NO OTHER INSERTED INFORMATION IS PERMISSIBLE." What's so hard about this?

ALL ABOUT BROADCAST TOWERS


A tower is a thing of beauty to the radio aficionado. Somebody even produces a tower calendar. Ah, the mediumwave broadcast tower! Think of it! Stately, striped sentinels with strobe lights flashing, they number thousands and thousands across the country, each emitting invisible waves of electrons through the late night air, spanning that mysterious thing called "the ether" to deliver communication to unknown distant masses. It conjures up thoughts of far-away points on the landscape, souls crouched in cramped corners with headsets fixed in the dark of night, straining to make sense of distant babble through static crashes and heterodynes. That would be me. The whistle of a far off freight train gives the same feeling of wonder. So, back to the broadcast tower - what is the broadcast station's responsibility?

Well, any tower over 200 feet tall or even if under 200 feet and an impediment to aircraft navigation must be registered (FCC Form 854). It also must be lighted and painted. We've all seen the lighted towers of AM broadcast stations. Ever wonder about those lights? What happens when one goes out? Who checks to see if they are burning, and how often?

Section 2C. TOWER LIGHT OBSERVATIONS:

The lighting on tower structures is to be observed at least once every 24 hours either visually or by observing an automatic indicating device; or alternatively the licensee/tower owner may provide and maintain an automatic alarm system to constantly monitor the lighting on a structure. All automatic or mechanical control devices, indicators, and alarm systems are required to be inspected at intervals NOT TO EXCEED 3 months.


Relief here, maybe, for the engineer. As of 1996, responsibility for tower lighting (and painting) lies with the owner of the structure, not necessarily the station licensee. However, at least a human doesn't have to go outside once a day and look to see if the lights are burning. An electronic monitoring device can perform the task. However, then the MONITORING DEVICE must be inspected at least every three months! Note: A recent directive relaxes this requirement to a year.

More on tower painting:

Section 2D. PAINTING/LIGHTING:

The station authorization and/or tower registration specifies the painting and lighting requirements for your operation....The licensee must make certain that the number and placement of paint bands and lighting match exactly with that shown on the station authorization and/or tower registration. The licensee/tower owner should also be aware of the requirement to clean or repaint tower structures as often as necessary to maintain good visibility to aircraft.

Exacting detail is found in FCC Form 715-715A:

Antenna structures shall be painted throughout their height with alternate bands of aviation surface orange and white, terminating with aviation surface orange bands at both top and bottom. The width of the bands shall be equal and approximately one-seventh the height of the structure, provided however, that the bands shall not be more than 30.48 meters (100 feet) nor less than .46 meters (1 1/2 feet) in width. All towers shall be cleaned or repainted as often as necessary to maintain good visibility.

All high and medium intensity lights shall be synchronized to flash simultanously at 40 pulses per minute. The light system shall be equipped with a light sensitive control device which shall face the north sky....

Additionally, Form 715-715A goes into great detail on the positioning and intensity of tower lights.


Section 2D, PAINTING/LIGHTING finishes by saying:

....One of the most common problems associated with tower painting is the feedlines that are on the outside legs of a tower. In many cases, the tower is painted correctly, but the solid black colored feedlines defeat the purpose of the painting by covering the outside legs of the tower. The licensee/tower owner should make certain that the feedlines are also painted in such instances. This does not apply in cases where the tower is authorized for strobe lighting.

To wit: If you run your feedlines up the outside of the tower leg, paint the feedlines to match the tower striping! So that's what they call that red color on towers: aviation surface orange.

And let's not forget to notify the Federal Aviation Administration when the lights go out:

Section 2E. FAA NOTIFICATIONS:

The tower owner/licensee is to notify the Federal Aviation Administration (FAA) at (Phone: 877-487-6867) within 30 minutes of the observation of an improper functioning or extinguished top steady burning light or ANY flashing obstruction light regardless of its position on the structure. Such improper functioning beacons include non-lighted beacons as well as those that are lighted, but non-flashing. Notification is to also be made immediately to the FAA once the beacon or steady burning top light is returned to service. Notification is not required when side light outages are observed....

Bottom line: you have 30 minutes to notify the FAA if your top tower light or one of your flashing lights goes out!

TRANSMITTER POWER


Lots of rules exist about checking and maintaining station transmitter power and purity of signal. Stations are granted the privilege to transmit at a certain output power. How much leeway do they get to be over or under powered?

Section 4A. POWER:

All AM stations are to maintain antenna input power between 90% and 105% of that authorized.

Interesting, we are allowed no more than 5% over and 10% under. Accordingly, a 50KW station can actually run between 45KW and 52.5KW and still be in compliance. I wonder how many 50KW stations push the envelope and run that extra 2.5KW? Or more?

Section 4A continues on, concerning failure to maintain a minimum power level (90%):

....The power is to be maintained as near as practicable to the station's authorized power. In the event that it becomes technically impossible to operate at authorized power, a station may operate at reduced power for a period of not more than 30 days without specific authority from the FCC. If operation at reduced power will exceed 10 consecutive days, a notification must be sent to the FCC, Media Bureau, Washington, D.C. 20554, no later than the 10th day. If normal power is restored prior to the expiration of the 30 day period, the licensee must notify the FCC upon restoration of normal operation.

It's kind of like highway speed limits. The cops will ticket you for going more than 10 mph over and let you by at 5 mph over. You will also get ticketed for going to slow on certain roadways, i.e. 35 mph in a 55 mph zone.

So how exactly does a station measure its power level accurately to assure compliance with the FCC?

MEASURING POWER

Okay, we need to check the power. Do we just read it off a meter on the console and log it? Well, perhaps.

Section 4B. DIRECT vs INDIRECT METHOD (of monitoring power output):

The antenna input power of AM stations must be determined using the direct method. However, the indirect method may be used on a temporary basis when it is not possible or appropriate to use the direct method due to technical reasons.

Direct Method. Two possibilities are allowed here:

1) Employ a suitable instrument for determining the antenna's input power directly from the RF voltage, RF current, and phase.

2) Calculate the product of the licensed antenna or common point resistance at the operating frequency and the square of the indicated unmodulated antenna current at that frequency, as measured at the point where the resistance has been determined.

Indirect Method.

Apply the appropriate factor (they mean efficiency factor here) to the input power to the last radio frequency power amplifier stage of the transmitter, using the following formula:

Transmitter output power = Ep x Ip x F

Where:

Ep = DC input voltage of final radio stage.
Ip = Total DC input current of final radio stage.
F = Efficiency factor of the transmitter.

The value of the efficiency factor, F, is to be determined and a record of its value is to be maintained and available upon request. Licensees must make certain that all duty operators know which method of power determination is being used and how to calculate the output power based on that method.

Furthermore, how does a station ensure that its signal is clean and meets prescribed standards?

MORE PAPERWORK


Not only must a station monitor power and other parameters, but it must have procedures in place on how and when to do it.

Section 4G. MONITORING PROCEDURES:

The licensee must establish monitoring procedures and schedules for the station. Monitoring procedures and schedules must enable the licensee to determine compliance with operating power, modulation levels, AM modes of operation, and where applicable with antenna tower lighting and AM directional antenna parameters. Licensees should be able to provide upon request made by the FCC, the monitoring procedures and schedules they have established for each station. In the event that an AM broadcast station is operating with a mode of operation not specified by the station license, then the station operation must be terminated within 3 minutes or the station output power must be reduced sufficiently to eliminate any excess radiation. This includes AM Directional stations with parameters or monitoring points out of tolerance with the station authorization.

Additionally, the directive states:

....In the event that an AM broadcast station is operating with power in excess of 105% of authorized, or with excessive modulation, then station operation is to be terminated within 3 hours, unless corrective action is taken prior to that time.


All right, it basically boils down to this: A station must have a monitoring procedure in place (obviously written), and a schedule in place for when to do it. They must monitor, at minimum, the power output, modulation level, AM quality, antenna lighting, and antenna directionality. And if their monitoring shows that they are out of compliance, they must shut down within three minutes, or at least reduce power to bring them back into compliance! The only exception is if power is exceeded or modulation is excessive - in which case they have three hours to terminate operation.

FREQUENCY

A station is licensed to transmit on a specified frequency. Along with measuring power output, a station must also ensure that it is on frequency. How accurate is it required to be?

Section 4C. FREQUENCY:

The carrier frequency for monophonic transmissions or the center frequency for stereophonic transmissions may not depart more than 20 Hz from the assigned frequency.

Tune across the broadcast band some night when conditions are good and listen for heterodynes. On any given channel there should be none, ideally. You have to listen carefully. Listen for that faint, low "whump, whump, whump" beat note caused by one station being ever so slightly off frequency, usually only a matter of cycles. 20 Hz offset is too low to hear as a tone. It is more of a rapid, dull thump-thump-thump, 20 times per second. If you hear a tone, a station is way off frequency, much more than 20 Hz (cycles). Surprisingly, you will find some.

MODULATION


Over-modulation is sometimes a no-no, too much over-modulation is a definite no-no. It results in distortion of recovered audio when the signal is demodulated, and worse, interference to stations on nearby frequencies due to the spurious byproducts. Here's what the FCC has to say about it:

Section 4D. MODULATION:
In no case shall the amplitude modulation of the carrier wave exceed 100% on negative peaks of frequent recurrence, or 125% on positive peaks at any time.

Slight over-modulation on the positive portion of the waveform is sometimes used for a more punchy sound, and works within limitation.

Any time you exceed 100% modulation on the negative portion of the waveform, it is clipped because you can't have less than zero carrier signal; that clipping generates high order harmonics that cause sidebands far outside of your intended channel and will interfere with other stations above or below the operating frequency.

POWER CHANGES FOR DIFFERENT TIMES OF DAY

Back to station output power again. If a station's service is not "Unlimited", it will generally be required to operate at different power levels for daytime, nighttime, and possibly even during the "Critical Hours" period. Critical Hours are the first two hours of daylight after sunrise and the last two hours of daylight before sunset.

Of course throughout the year, sunrise and sunset times are changing every day, therefore, stations must be constantly updating the times when they change power levels. The FCC is very specific on this. Let's see what this section of the document has to say:

Section 4I. POWER CHANGES:

Most AM stations utilize more than one power mode of operation. In addition to the normal authorized daytime power many stations operate under the reduced power pre-sunrise service authorization (PSRA) and post-sunset service authorization (PSSA)....Some stations will have reduced power nighttime operating authority and a few stations have a specified critical hours reduced power authorization. The times when power changes are to occur are clearly shown on the station authorization and in readily available sunrise/sunset tables.

(See http://www.fcc.gov/mb/audio/bickel/srsstime.html for a table of the sunrise/sunset times for your area).

Any unauthorized departure from an operating schedule will be considered as a violation of a material term of the license. It is the responsibility of the licensee to maintain calibrated time keeping devices, power switching devices and other equipment necessary for the timely change in power to occur as authorized. In addition, should the station be operated with more power than authorized for that time of day, then all operation is to be terminated within 3 minutes. The logging of power mode changes is not required unless the station is operating out-of-tolerance with any operating parameter. However, licensees are encouraged to do so.


As already stated, the FCC is very specific on power changing. Stations must keep accurate timing and change their power accordingly and on time. They must determine (on their own), their local sunrise/sunset time and change power precisely at that time. If they are out of tolerance by as little as three minutes, THEY MUST SHUT DOWN OPERATION. This is a stringent requirement. Violation of this requirement is a violation of the terms of their license. I would venture a guess that there are more than a few stations that are not changing power exactly on time. I know of some locals that are most definitely not within the three minute window.

So there you have it - the FCC's basic checklist on how to run an AM broadcast radio station. Hope you enjoyed it.

LINKS

Other FCC self-inspection checklists

Review Of The Tecsun PL-380 DSP Receiver

       -With emphasis on mediumwave reception
       -And comparisons to various radios

       -by RADIO-TIMETRAVELLER

       Purchased From: Anon-co (eBay)
       Price: $45.99 + $24.00 shipping ($69.99 total)

       Serial#: 369-2010-0202-752 03/2010

INTRODUCTION

The Tecsun PL-380 DSP Digital Receiver is one of the newest offerings in the ultralight-sized category of pocket receivers. It uses the industry's first fully integrated, 100% CMOS AM/FM/SW/LW radio receiver chip, the Silicon Labs Si4734. It tunes the longwave, mediumwave, shortwave and FM bands, and uses the latest in software-based digital signal processing to provide an outstanding choice of filter selectivities of 6 KHz, 4 KHz, 3 KHz, 2 KHz, and 1 KHz, minimizing interference. This little receiver is truly a quantum leap in technology.

Coverage:

       Longwave coverage: 153 - 513 KHz
       Mediumwave coverage: 520 - 1710 KHz (9 or 10 KHz split)
       Shortwave coverage: 2300 - 21950 KHz
       FM coverage: 64 - 108 MHz

This review is lengthy and quite technical in places. It is purposely slanted toward the mediumwave DX enthusiast, mainly because I am one and that's why I bought this radio: to further pursue this hobby of mediumwave DX. Virtually all of what is said in terms of functionality and technical specification can also be applied to the shortwave and FM sections of this radio.

SHIPPING AND ARRIVAL



This is my first radio purchased directly out of China (Hong Kong), so I was a little nervous. Seller Anon-co sells these and other radios via eBay. It has been a good experience and exceeded my expectations. Purchase is easy through Pay-Pal. Joyce, the sales agent for Anon-co, contacted me via e-mail within 24 hours of my web purchase introducing herself and asking my preference of color for the radio. Three styles are available: silver, grey, and black. I chose the black one.

The radio was shipped out of Hong Kong within 48 hours via air post. A tracking number was provided for the parcel, shipped by a Hong Kong shipping company. The radio arrived 13 days later in New York via US Postal Service registered mail.

The PL-380 is physically small, fits in a shirt pocket, and is just a little larger (by 5/8 inch width and height) than my Kaito WRX911. It was packed in a Tecsun box, the box itself in a heavy duty bubble-wrap envelope. Radio size is 5-1/4 inch wide x 3-3/8 inch high x 1 inch deep. It arrived in good shape, complete with Hong Kong stamps on the envelope for the stamp collector.

ACCESSORIES

The PL-380 comes with a nicely equipped accessory package. Accessories include a nice zippered cloth case with inside pocket and small foldover pouch for earbuds, an external antenna wire with mini connector and curtain clip, earbuds, 3 NiMH batteries (1000 mAH), a USB charging cord, and a manual.

MANUAL

The manual, in English, contains 29 pages. It is well-written with an acceptable amount of Chinese-English speak. Included in the radio description are many graphics showing how to use the various functions. The inside front-cover has a nicely detailed block diagram of this innovative digital receiver for the technically curious. Studying it, you can see this radio has few parts outside of the Silicon Labs' Si4734 DSP micro-chip. See the accompanying photo in the FILTERS AND SELECTIVITY section showing the radio disassembled and you will see what I mean.

SETUP

The radio requires 3 AA batteries, like my Grundig YB 300PE. Battery level is displayed on the screen as it is for the PL-600, and is accurate for either NiMH batteries (~1.2 volts) or standard alkalines (~1.5 volts). A simple key press toggles the display between alkaline or NiMH so that your current battery level reads accurately. The NiMH batteries are chargeable right in the radio using the USB adapter cabled to a computer. Charging automatically shuts off when finished. Battery consumption is very low, and batteries should last a long time especially if headphones are used.

Anon-co checks out each radio before shipping to make sure they work, a nice service. The radio also came preset for the North American mediumwave split, 10 KHz. Again, a simple key press toggles between 10 KHz and 9 KHz splits. The long wave band (153 KHz - 513 KHz) was already activated too, and can be activated or deactivated by key press.

The clock is easily set by a combination of a key press and rotation of the tuning dial, done while the radio is off. 12 or 24 hour formats are available. The clock can be made to show while the radio is in operation if desired.

No other setup was required.

QUALITY AND ERGONOMICS



The PL-380 build and fit quality is excellent, and better than the PL-600. The telescoping whip antenna measures 19-1/2 inches when fully extended, and is stout and of nice quality.

Buttons, though small, give a nice solid click when pressed, and have a stiff spring behind them. A somewhat loud tone is also emitted for each button press, but is easily silenced by a simple key action. Unlike the PL-600, lettering on the radio's buttons is on top of each button itself and it will be interesting to see at what age and usage the lettering begins to wear. The keypad is layed out in correct telephone pad-style format, with the zero key at the bottom center. Brilliantly, there are no tedious menus to wade through when changing core radio settings. Simple 2nd function key presses accomplish this. Excellent design.

A small (1-3/4 inch) front-firing, round speaker is on the left front. Sound through the small speaker is trebley at best. Use headphones, this is not a boom box.

The left side of the radio has a headphone jack and a 5 volt DC input connector, the connector being like those found on many digital cameras. Curious. I'm not sure how you would hook it to another 5 volt power source other than a computer, though a cable from an old digital camera could be stripped and cobbled up.

Two ridged, thumb-wheeled styled knobs protrude edge-wise from the right side of the radio. They are tuning and volume. They each have stepped-detents and seem a bit delicate. Be gentle when using them. I have seen one report in the Yahoo Ultralight group where a user's tuning wheel broke loose off its shaft.

On the back of the radio is a flip stand for elevating the PL-380 if set on a flat surface. The PL-380 also comes with a handstrap. The battery compartment cover is not hinged, but removable, and could be easily misplaced.

THE LCD DISPLAY

The display is clear and easy to read, and contrast is good. Backlighting is yellow, with perhaps a tinge of green, like the PL-600. It can be activated at any time by a key press, or turned on or off permanently.

A key lock button can be pressed to lock all controls on the radio. When locked, a small key is displayed on the LCD.

By pressing the Display button, found just under the Power button, the clock, alarm time, temperature, or received signal strength indicators can be made to show in turn along with the tuned frequency. Stop at the one you wish to be continually displayed.

The clock and alarm read in hours and minutes only, no seconds. A single timer is available which can activate the radio for up to 90 minutes when the alarm is triggered. You can also set the alarm to produce a buzzer-like sound.

A sleep function can turn off the radio after up to 120 minutes. By default, on first power up the radio starts in sleep mode and will play for 30 minutes before shutting off. A "30" will show on the display for the first few seconds. This can be defeated by a key press so the radio stays on permanently after power up.

Temperature reads in either Fahrenheit or Celsius. Cleverly, the software tests the mediumwave split you have selected (9 KHz or 10 KHz), and displays Fahrenheit if you have chosen the 10 KHz split or Celsius for the 9 KHz split.

For the longwave, mediumwave and shortwave bands, received frequency is displayed in kilohertz. For the FM band, received frequency is displayed in megahertz.

Memory operations are displayed in the received signal strength indicator area, at the upper right.

The PL-380, like the other ultralights using the innovative Silicon Labs' Si4734 DSP micro-chip, has a unique signal strength indicator display, the likes of which old radio buffs like me would never have dreamed possible back in the 1950s and 1960s during the waning era of vacuum tubes and analog signal strength meters. Learning of this when the Grundig G8 Traveller and Tecsun PL-300 came out, I was very excited to one day see this in action in addition to wanting to move along and try these new designs. I avoided these initial production attempts due to the so-called soft-mute issues inherent with their design software. The PL-380 has toned down the soft-mute attenuation. But more on that later.

THE RSSI AND SNR DISPLAY

When the PL-380 is tuned to the center carrier frequency of a broadcast station, the carrier strength in dBµV (dB above 1 microvolt) and the signal (+noise) to noise ratio in dB is displayed in the upper right corner of the LCD display. These are commonly called the RSSI (Received Signal Strength Indicator) and the SNR (Signal to Noise Ratio), respectively. The RSSI figure displayed is relative of course, and should not be confused with any published figures of signal strength like those available from V-Soft Communications, or seriously compared with private calculations for receivable stations in your area. Actual received signal strength is highly dependent on local terrain, daylight/nighttime conditions, transmitter antenna pattern gain, receiver antenna, ground conductivity, and other factors which make it impossible to accurately fix through calculation.



It is important to note that the RSSI indicator (marked dBµ on the display) is not the same measurement as dBu, the figure commonly used in recent years by the FCC for measuring electric field intensity of AM broadcast stations at prescribed distances. dBu [lowercase "u"] is electric field intensity, always in decibels above one microvolt/meter (and the same as dBµV/m). dBµV, on the other hand, using the Greek letter µ ["mu"] instead of u, is voltage expressed in dB above one microvolt into a specific load impedance, commonly 50 ohms. The PL-380 measures and displays dBµV, not dBu-dBµV/m.

Signal to Noise Ratio (SNR) is the ratio of (a) the power of the desired signal plus the noise to (b) the power of the noise. The (S+N)/N ratio is usually expressed in dB.

RSSI indications, as displayed on the PL-380, can range from 15 to 63 dBµV. Per Scott Willingham, one of the Si4734's designers, "The RSSI readings are referred to the pins of the chip, which are the inputs to the LNA. In the Tecsun radios operating in the MW band, this is also the voltage across the loopstick. In SW bands, the Tecsun ULRs use a preamp/LNA on the circuit board between the whip antenna and the Si4734. In that case, the RSSI readings reflect the signal at the output of Tecsun's external LNA."

Displayed SNR indications can range from 0 to 25 dB. About SNR measurements, Scott Willingham related that, "The SNR figure is calculated by a proprietary DSP algorithm, and neither the RSSI nor audio output directly play a role. The input to the algorithm is the filtered IF signal before audio demodulation. It is really more of a carrier-to-noise ratio than directly an audio noise measurement. Obviously, in AM it is bounded between 0 and 25 dB. The motive for computing and providing the number comes from implementing better station search capabilities; the display is just a nice byproduct."

At 0 dB SNR, a weak signal at best, soft-mute is at maximum attenuation according to the Si4734 programming manual. A great discussion thread on PL-380 soft-mute exists on the Yahoo Ultralight group.

Soft-mute, a further lowering of the audio level of the received signal when it drops below a prescribed strength, is undoubtedly meant to provide a more comfortable listening experience for the casual listener and not the DXer. The idea is to relieve the listener from all that nasty low level "static" and "interference", or as Silicon Labs states: "The soft-mute feature is available to attenuate the audio outputs and minimize audible noise in very weak signal conditions."

Long suffer the mediumwave DXer, as static and interference and low level signals are his bread and butter and the secret to gaining new DX. Luckily for him a weakly received signal is still there, though attenuated, and may in fact be perfectly readable if not for the soft-mute. How do we recover it?

A general consensus indicates that tuning 1 or 2 KHz off frequency and advancing the volume control will compensate for the muted audio. This is the theory: When you tune off the center frequency of the carrier it causes the signal to noise ratio to drop to zero (in fact it does), and the software responds by fully engaging the soft-mute, stabilizing any pumping audio possibly caused by multiple and different strength stations on the same frequency. At that point the volume is manually raised to counteract the soft-mute reduction.

Sometimes it works. Sometimes not, in my experience. Raising the volume also raises the background noise level and sometimes I don't see any beneficial signal recovery. Many times I have found if you stay tuned on frequency, wait a few seconds and rotate the radio around a bit to either peak the desired signal or null the offending one, the soft-mute seems to settle down and disengage, allowing reception of the weak signal. So try this too.

Maximum soft-mute attenuation for the PL-380 is 6 dB. As measured, the soft-mute threshold is actually 3 dB (SNR reading) and the slope is 2 dB/dB. This means that there is no soft-mute effect at all for SNR readings of 3 dB or more. Below 3 dB SNR, the audio is attenuated 2 dB for every dB decrease in SNR, up to a maximum of 6 dB when SNR reaches its minimum reported value of 0 dB, as such:

       3 dB SNR: 0 dB audio attenuation (the threshold)
       2 dB SNR: 2 dB audio attenuation
       1 dB SNR: 4 dB audio attenuation
       0 dB SNR: 6 dB audio attenuation

On a separate issue, a different person in the same group reported a generally high and somewhat constant RSSI value (dBµV) across segments of the mediumwave band. I have noticed the same effect here in the general frequency neighborhood (let's say plus or minus 40-50 KHz) of the local powerhouse stations, where RSSI values will hang at a value of perhaps 20-40 dBµV with an SNR of 0. I can only attribute this to a kind of front end "desense", ahead of the filtering, as I don't know what else might cause it. When you get far enough away in frequency from the overly-strong signals, the effect vanishes.

The RSSI and SNR displays update every two seconds, however the radio itself responds to realtime changes much faster than this. For example, when rotating the radio to null a station's signal, you may notice that soft-mute kicks in before the SNR display reaches 2 dB. This is because the display has not reached its update cycle yet. This is not a problem, but just something to be aware of if you are using the displays for positioning the radio.

ANTENNAS



The PL-380 employs a rather short ferrite bar antenna (3-1/8 inches in length) for the LW and MW band frequencies. FM and shortwave employ the telescopic whip antenna. Signal nulling is excellent and as good as any radio I own, as good or better than the renowned WRX911.

Interestingly, WRX911 nulling was improved dramatically here by the removal of the telescopic whip antenna's connection to the circuit board which was found to be interacting with its ferrite loop and worsening its ultimate nulling capability. Per the block diagram, the PL-380 also connects its whip to the AM tank circuit, as the AM side of the Si4734 chip is also used for shortwave AM tuning. The connection is made through a so called "SW LPF" (low pass filter), funneling the shortwave band signals to the AM tank circuit. I wondered if there would be interaction with the whip causing a degradation of mediumwave nulling and maybe some false "signal enhancement".

I did an experiment by taking the PL-380 outside away from household noise and attaching about ten feet of wire to the telescoping whip. Tuning to distant outlet WGY-810 in Schenectady, NY (186.3 miles distant), the signal to noise ratio (and audible signal strength) increased by a factor of 7 dB when the wire was attached to the whip versus when it was not. It seems there is at least some interaction between the whip and mediumwave reception, as was the case with the WRX911. In the case of the PL-380, however, even with the whip extended a full 19-1/2 inches it is probably minimal, a matter of a couple of dB and hardly noticeable.

Further, coupling this unit to a passive loop to enhance sensitivity is a rather strange experience, and unlike any other ultralight or other radio I own. Passive loops seemed to tune rather broadly, making it a bit difficult to find a signal peak. Loose coupling seems to work best, and finding the "sweet spot" of best signal transfer is difficult.

My homemade Q-Stick device, the 4-Inch Tunable Ferrite Bar featured on RADIO-TIMETRAVELLER last September, couples even more poorly than the passive loop does to the PL-380. Again, in close proximity, tuning is upset and even more skewed and undefined. I often can't find a signal peak at all when tuning the external ferrite bar. All in all, the PL-380 exhibits some strange coupling tendencies. You will have to experiment with your passive loop or ferrite tuning device to see what works best for you.

Reports in the Yahoo Ultralight group suggest that Tecsun has tweaked the stock AVC for the Si4734 chip so much that it results in "unvarying volume over many conditions", which in turn makes it hard to determine a signal peak when coupling to passive devices. See this discussion.

SENSITIVITY

The sensitivity of the PL-380 is good and markedly better than my little Sangean DT-400W ultralight. It approaches the PL-600's sensitivity throughout the mediumwave band, though it tends to be down a little more at the lower end. Reports speak of the low tank coil inductance as curbing sensitivity on this unit, particularly at the lower frequencies. Ranking four radios for sensitivity, arbitrarily ranking the Kaito 1103 at a ten since it is the most sensitive, they would rank thusly:

       Kaito 1103: 10.0
       PL-600: 9.5
       PL-380: 8.0
       DT-400W: 4.5

The PL-310, on the other hand, a previously manufactured DSP ultralight receiver using the same Si4734 chip, had a longer loopstick and better sensitivity than the PL-380, as witnessed by others. Unfortunately, reports of its heavy soft-mute signal attenuation have steered me away from it.



So what to do if you want more sensitivity? Short of using a cranky passive loop or Q-Stick device, the answer for improved sensitivity seems to be hacking into the unit and replacing the PL-380's ferrite bar with something longer and tuned correctly. This has been hashed about in many posts in the Yahoo Ultralight group. A 7.5 inch ferrite bar has been used with very good results.

All-in-all, I don't find the PL-380's sensitivity that bad. It is certainly not dead, and better than many other ultralight receivers. It is obviously no Kaito 1103 or even a Tecsun PL-600, but it can hold its own with many others.

Get up early some morning just before sun up and take the PL-380 outside and away from household noise. Put your headphones on. You will find a world of distant DX stations fighting with each other for dominance on nearly every channel. And better yet, use the 2 and 1 KHz filters to slice that interference and IBOC nastiness out of existence.

TUNING

No chuffing or dropout is apparent when tuning the radio, and tuning is very smooth once you get used to the detents on the tuning dial. The days of chuffing and signal masking while tuning are about gone for digital radios, I hope.

Two tuning speeds are available, slow and fast. They are as follows:

       Longwave/slow: 1 KHz per detent
       Longwave/fast: 9 KHz per detent

       Mediumwave/slow: 1 KHz per detent
       Mediumwave/fast: 9 or 10 KHz per detent, depending on split

       Shortwave/slow: 1 KHz per detent
       Shortwave/fast: 5 KHz per detent

       FM/slow: 10 KHz per detent
       FM/fast: 100 KHz per detent

Slow or fast tuning speed kicks in automatically depending on how fast you spin the tuning wheel. It takes some getting used to, to get the feel for how fast you can spin the tuning dial before the radio goes into fast tuning mode. It is annoying at first and will catch you off guard till you learn the feel.

Direct entry tuning couldn't be easier. Punch in a frequency, like 8-5-0, and it instantly tunes to 850 KHz without having to press an additional "enter" key, or a "period" key twice. Such a simple feature makes a huge difference. Kaito, Eton, are you listening?

General shortwave band selection is done by the "carousel" method. Press the "up" or "down" arrow keys to take you to the band you desire. Or, just punch in the frequency on the number pad once you have arrived on a shortwave band. It is simplicity at its best.

The PL-380 has several different scanning modes. See the MEMORIES AND SCANNING section for a further description.

FILTERS AND SELECTIVITY



Selectivity is nothing short of astonishing on this little radio. Five selectivity widths are available, digitally filtered of course - 6 KHz, 4 KHz, 3 KHz, 2 KHz, and 1 KHz. Gone are the days of ceramic filters, good. The AM Bandwidth button at lower left controls the filter setting using a carousel type method.

Audio recovery of weakly received signals is excellent and intelligible even in the 1 KHz bandwidth setting of the filter. And the benefit of using the lower bandwidths of 2 and 1 KHz are better signal to noise ratio, thus better signal recovery when receiving weak DX. I have tuned signals with this radio that were very weak but perfectly intelligible in the 1 KHz setting when they were not apparent in either the 4 or 6 KHz filter settings. So use the 1 or 2 KHz filter width when scanning for weak DX.

Offset tuning can sometimes be used to pull in a weak station that can't otherwise be received on frequency, perhaps due to adjacent channel interference or muddled audio. Switch to the 1 KHz or 2 KHz filter and detune the station by 1 or 2 KHz. The audio will brighten, usually imparting better clarity. Raise the volume some, to counteract the soft-mute. There are few receivers that I have known which can carry off intelligible audio at such narrow filter widths. The PL-380 can.

AUDIO

Audio quality is fair with the speaker and good using headphones. Don't expect to set this radio on a garden table and get yard-filling, full range volume. Use your boom box for that. Headphones are the key. They are the DXer's choice.

MEMORIES AND SCANNING



The PL-380 has 550 memories. Longwave, mediumwave, and FM each have 100. Shortwave has 250. Memory operation is simple. Tune to a station, press the memory key (VM), press again to reconfirm and store. Use the tuning wheel to scroll through memory slots when in memory mode.

Easy Tuning Mode (ETM) is an automated band scan type of operation which automatically scans and stores receivable channels into the Easy Tuning Mode memory, separate from regular memory. The manual states that the longwave, mediumwave, and FM bands have a total of 100 storage slots, and shortwave 250. While in the band of your choice, hold the ETM button down until the scan starts. Stations above a prescribed strength will be saved in ETM memory. A handy function, but almost identical to ATS, below.

Auto Tuning Storage (ATS) automatically scans and stores stations just like Easy Tuning Mode does, only uses regular memory. Makes me wonder why they even included ETM as another scan type operation. The difference appears to be that you have a full range of 100 memory slots for each band (longwave, mediumwave, FM) versus 100 total. Shortwave is the same, at 250.

Scanning within any band is simple, and fairly effective, though the lock thresholds are set a bit high. Press the VF key to start/stop.

Memory scanning is also available through the VM key.

SIGNAL SPURS AND IMAGES

As noted by others, the PL-380 has some spurs. The one usually reported is the strong one, a 2 KHz heterodyne on 620 KHz. I found numerous other heterodynes of low to medium strength on 560, 820, 850, 880, 920, 1010, 1280, 1420, 1430, and 1570 KHz.

Also, I'm hearing some sort of broad digital hash between 570 and 580 KHz, and a strange digital mixture fighting with a weak station on 590 KHz.

I have not detected any images in the MW broadcast band.

NOISE IMMUNITY

The PL-380's LCD display is fairly clean. Touching the display produces a barely perceptible amount of digital hash, about the same as the Tecsun PL-600. The Sangean DT-400W produces a noticeable amount of hash when you touch the digital display with your thumb.

RFI susceptibility is about the same for the three radios. Moving the radio about the house near sources of RFI produced the usual buzz in all. A computer will introduce a sizable amount of digital hash into all three radios.

THE PL-380 IN USE



As stated, the PL-380's sensitivity approaches the PL-600's throughout the mediumwave band. However, you will never notice it by hurriedly flipping through the band. If you take your time in tuning, use the narrow filters, rotate your radio and allow soft-mute to settle down and disengage, you may be as pleasantly surprised as I was.

First, let me say that sensitivity comparisons were done near mid-day to avoid any enhanced nighttime propagation.

At the high end of the MW band, usually weak CHTO-1690, Greek Multicultural Radio Toronto (1KW at 98.4 miles), is perfectly receivable on the PL-380, and about equal to the PL-600. Conditions on this one vary greatly throughout the day. I have had occasion where the PL-380 had the stronger signal by a small margin.

At the low end of the MW band, CIAO-530, Brampton, Ontario (1KW at 120.1 miles) is weak but readable, and the PL-600 excels here. WJR-760, Detroit, MI (50KW at 286.2 miles) is barely readable, but above the noise, a good catch for an ultralight without help from a passive loop. Neither the 530 KHz or 1690 KHz channel (let alone WJR-760) can be received at all on the Sangean DT-400W ultralight without help from a passive loop.

Nulling signals on this receiver can be an interesting experience if the station's signal strength at maximum null results in an SNR of 2 dB or less. At the 2 dB threshold the soft-mute kicks in and the signal drops off most abruptly, giving a false sense of having nulled the signal. Keep your eye on the SNR display when nulling, or tune 1 or 2 KHz off frequency, turn the volume up and null again, listening for the center of the fade. Remember, the SNR display may lag a little before it catches up.

Now for the selectivity test. A major problem here is local station WYSL-1040, which beams a whopping 20KW daytime signal in here with a level of some ~76 dBu - the strongest signal on the MW band here at the farm. With an antenna pattern pointed roughly northward, at some 4.25 dB gain in that direction, its effective radiated power is equivalent to some 53 kilowatts aimed right at me, and less than five miles away. It literally overwhelms receivers plus or minus 20-30 KHz either side of its frequency.

CP24 Radio 1050 (KHz), Toronto, Canada (50KW, ex-CHUM), across Lake Ontario, a distance of 105.0 miles, is the only station even capable of putting a up a fight with WYSL. All the rest are either too weak or too distant. I can usually detect the presence of CP24 in the WYSL splatter with the PL-600 using the narrow filter (4 KHz), however identification is difficult to impossible. Using the PL-380 and nulling WYSL carefully, it is perfectly readable using the 2 KHz and 1 KHz filters. This is an astonishing feat which impressed me very much!

SUMMATION



The Tecsun PL-380 is a technological wonder in a small package, and all for $45.99 + shipping. It is an experimenter's playground if you are into high technology, and a keeper for me.

Sensitivity is adequate in my opinion, and if you are patient with a passive loop it can make a positive difference. Remember, overall it is no Tecsun PL-600 or Kaito 1103 in the sensitivity department, but it is way ahead of a lot of other standard ultralights.

Selectivity is unmatched, perhaps in any radio under $1000 except for other Si4734-based receivers. Nulling is excellent. Audio is good. Ergonomics are simple, and the receiver is easy to use without tedious menus to navigate. 550 memories, not that you will use them, but they are available.

Four different scanning options. Two tuning speeds, and a real volume control. The display is bright and easy to read. If I could change a couple of things, I would add some up and down frequency slew buttons and perhaps beef up the tuning dial to be more like the PL-600 or Kaito 1103, getting rid of the detent. The detent is fine for the volume control.

Soft-mute is at a minimum in this radio, and I didn't find it objectionable once I got used to it. 6 dB of audio reduction is not a lot and can be defeated with some finessing of the radio, making it a non-issue in my opinion.

The radio has a fair amount of spurs, and some digital hash on a couple of channels. These are annoying. This is not the cleanest radio.

All-in-all, the PL-380 may be the ultimate ultralight receiver as of this writing, and a competitor to some larger models for mediumwave reception. The first company that produces a radio using this Si4734 chip with the soft-mute defeated, the thresholds lowered, AVC adjusted, and includes a matched, 6 to 8 inch ferrite rod is going to have a real DX machine on their hands.

LINKS

For the technically curious, an excellent treatise on calculations and measurement of electric field intensity, received voltage, and power density, see:

Calculations and Measurement

A excellent description of signal to noise ratio can be found here:

Signal to Noise Ratio