Tag Archives: Bob Colegrove

Guest Post: Bob’s conundrum with the Radio Data System (RDS)

33 Replies

Many thanks to SWLing Post contributor, Bob Colegrove, who shares the following guest post:

A Conundrum with the Radio Data System (RDS),
or Why I Set the Clock Manually

By Bob Colegrove

There’s an old story about a man who owned two watches.  One watch ran but lost a minute every hour.  The other watch didn’t work at all.  He always wore the watch that didn’t work, because as he said, “At least it will have the correct time twice a day.”

First off, a couple of caveats.  This is not a definitive description of the Radio Data System (RDS).  I leave that to much more knowledgeable sources.  One detailed description is at https://en.wikipedia.org/wiki/Radio_Data_System.  Second, my experience described here is confined to the Eton Elite Executive and the XHDATA/SIHUADON D-808.  Other radios may operate differently.

I have surrounded myself with several multiband travel radios over the past year and enjoy them very much – each for different reasons.  Besides listening, I like to push buttons to see what happens.  The manuals?  At best they occasionally provide a clue.  I read them, eventually filling in the blanks on my own.

XHDATA/SIHUADON D-808

Basic RDS

What is RDS? RDS is a system which enables an FM station to transmit various fields of information such as date, time, call letters, frequency, and program information in text form.  The call letters are useful, but if you have a digital radio, you already know the frequency.  The name of the song and artist are particularly helpful if the DJ won’t tell you.  As for the date and time, well, I’ll get to that.

RDS is an international standard and Radio Broadcast Data System (RBDS) is the official name used for the U.S. version.  So why don’t we in the States just call it RBDS?  Probably because our radios aren’t made here.

Eton Elite Executive

The XHDATA and Eton allow the user to display four of the several fields comprising the RDS standard.  They each step through the same sequence, indicating a similar or possibly the same demodulator chip.

PS and RT seem to be freeform fields with stations providing whatever information they want to share.  Often the call letters and frequency are contained here, along with program content.  Clock Time (CT) is not displayed per se, but is used to set the radio time, and is included as part of the DATA field.  DATA is important; it has four elements, which should provide the listener with an indication of the call, day, date, and time being received by the radio.  The international RDS standard omits the call letters.

The RDS information transmitted by any given station may not contain all the fields identified above, including the time.  For example, stepping through the fields you may encounter “NO PTY,” “NO PS,” “NO RT,” or “NO DATA.” Consequently, you may tune in to a station broadcasting RDS and wait a long time for the radio clock to synchronize, which it never does.  The display of any content in the DATA field is probably the best clue whether CT is being transmitted.

It is interesting that the Eton is programmed for the US RBDS system, whereas the XDATA follows the international RDS system.  For the international system on the D-808:

  • “DATE” replaces “DATA” in the display.
  • The call letters are omitted from the DATE field.
  • The terms in the PTY field differ; for example, WRBS, 95.1 MHz, the PTY element displays “SOCIAL” instead of “RELIGIOUS MUSIC.”

International PTY RDS term on the XHDATA

US PTY RBDS term on the Eton

The Conundrum

The mischief all began when I got my XHDATA D-808 and tried to program the clock to automatically update using the RDS information off FM stations.  Minutes seem to display correctly, but try as I might, I couldn’t get the hours to register properly.  Then I bought an Eton Elite Executive.  It also has the RDS feature, so I tried again.  It appeared to work OK for a day or so.  Then the hour indication started to misbehave.  In addition to the clock, the Eton allows programming of time zones and day of the week.  I determined that the erroneous indication did not appear to be related to GMT, EST, 12-hour or 24-hour format settings.  In theory, if you try to set your radio to GMT or some other time zone, the RDS time from a local station should override it.

When I tested the radios side-by-side, the DATA field was fraught with problems on both radios.  Several local RDS stations containing CT were monitored.  The whip antenna was extended a tad, as the information may not reliably register with some otherwise clear audio signals.

  • When tuned to the same station, there were occasional inconsistencies between the two radios, presumably receiving the same exact information from the station.

 

  • Sometimes the hour would not advance on the XHDATA after minutes transitioned from 59 to 00.
  • Curiously, both radios might exhibit the correct date and time during the day, then at 1900 EST, several stations on both radios prematurely advance to the next day and date, and the hour would display incorrectly, completely unrelated to local hour.  Minutes may or may not be correct.  1900 EST happens to be 0000 GMT.  Are some station clocks running on GMT?

RDS content obviously requires some attention at the station.  In the end, they are responsible for the information going out.  In fairness, with all that goes on in a studio and limited staffing, RDS content may not be a priority.  As an example:

  • Call letters in the DATA field for local WMZQ read KZQK, which is not assigned.

Conclusions

There are two main factors which may impinge on the accuracy of a radio clock when set automatically by the RDS:

  • Accuracy depends on the station transmitting it correctly.
    • With RDS set to the AUTO mode, there is a good chance that the clock will be updated repeatedly as the radio is tuned among various stations – not necessarily to the correct time.
      • For the Eton, the clock would reset each time when changing stations between WTOP (correct time) and WPRS (incorrect time).
      • For the XHDATA, the clock would reset each time when changing stations between WTOP (correct minutes) and WPRS (incorrect minutes).  In both cases, the displayed hour remained 00.
    • There is still the unexplained premature update of day and date by some stations observed on both radios.
  • Correct time depends on the radio’s RDS demodulator to interpret the incoming data.

Trivial?  Perhaps, but you may want to reconsider and program the clock manually, particularly if you depend on the alarm function of the radio to get to work on time.

Spread the radio love

“If Memory Serves Me Right, . . .”

24 Replies

Many thanks to SWLing Post contributor, Bob Colegrove, who shares the following guest post:

If Memory Serves Me Right, . . .

By Bob Colegrove

The radio in my ’61 Ford Falcon came with memory.

Memory features on portable radios have become increasingly popular in recent years.  I would say the subject ranks up there with antennas and batteries in many discussion groups.  Memory is really a matter of convenience; that is, the quick and easy recall of favored frequencies.

Mechanical Memory

Memory-capable radios are nothing new.  My very first multi-band radio was a Howard Radio Company Model 308 radio-phonograph console.  It was manufactured sometime in the late 1930s and came with four memories.  These were in the form of pushbuttons, which when pressed, quickly accelerated rotation of the variable capacitor to frequencies of local interest.  The radio even came with a set of call letter stickers for AM stations all over the country.  Memory in car radios goes back almost as far.  It was convenient when you were driving.

During daylight hours it wasn’t hard to find stations in the nearby radio listening area, so you could just twirl the tuning knob in the usual manner until you got to the desired station.  In lieu of push buttons, my mother marked the dial of her kitchen radio with red fingernail polish, WXLW, WIBC, WIRE, WFBM, WISH.  At night it was quite another problem, when the great ionosphereic mirror in the sky began to reflect radio signals from hundreds of miles away.  That’s when the buttons really became useful.  Being a mechanical system, you had to be careful; a hard press of a button would cause the mechanism to overshoot the frequency.

Digital Memory

The digital age brought with it the capability of adding electronic memory to the product, as well as much more precision.  My next experience with radio memory came in the mid-eighties with the Sony ICF-2010.  This radio has a matrix of 8 x 4 = 32 dedicated keys on the front panel, each key recalling one stored frequency.  Further, in the case of SW, the single-sideband and bandwidth settings can be saved.  I found the feature very useful and managed to keep many of the 32 memory locations occupied a good deal of the time, honestly never giving much thought to the need for more memory.

Memory matrix on the Sony ICF-2010.  In conjunction with the SHIFT key,
many buttons have a secondary function for scanning or band selection.

But today’s small multiband portables do not have the available real estate for a large matrix of memory buttons on the front panel.  It’s now done with a sequence of key presses or possibly rotation of the tuning knob.  Since the Sony ICF-2001/2010, there has been a race among manufacturers to include more and more memory capacity in their radios.  “If you build it, they will come.”  Below is a sample of the total memory locations in some popular portable radios.

I am reminded of a passage in Life on the Mississippi in which Mark Twain speculated about the continual shortening of the Mississippi River due to new channels flooding across its bends.  According to his extrapolation, in 742 years Cairo, Illinois will be joined with New Orleans.  Similarly, we may soon reach the point where memory capacity of a multiband radio exceeds the total number of available channels.  But memory is cheap these days.  I suppose it’s already on the chip, so why not make it available and tout it as a feature?

As a result of this large memory capacity, recalling a saved station can quickly become a problem.  First, if you have band-specific paging, you must ensure you are on the appropriate band.  On page memory radios, it requires that you first recall the page number and button on the number pad where you have saved the frequency.  In any event, you navigate through the stored locations mentally correlating location numbers with frequencies.

There is no standard by which manufacturers implement memory.  On the Skywave SSB 2, D-808, and ICF-SW-7600GR, the number pad defaults to memory tuning.  For direct frequency tuning, you must first press FREQ on the SSB 2 and D-808.  The Tecsun radios on the other hand have toggling VF and VM modes, and you best be careful which one is active.  To recall memory on the PL-330, you can either spin the tuning dial to the channel or key the channel on the number pad if you can remember it.

To directly enter a frequency Sony ICF-SW7600GR, there are two extra key presses:
DIRECT before the frequency and ENTER after.

At this point I must ask, at what point does it become more convenient just to directly key in a 4- or 5-digit frequency?

One of the things to remember about radio memory, even the old push-button kind, is that it stores frequencies not stations.  If another shortwave station is broadcasting on a frequency you saved, that may be what you will hear when the frequency is recalled.  With some extra effort, the Sangean ATS-909X will allow you to record a memo (i.e., station call or name) with frequencies you have stored.  Just remember, this may not be the station you thought you saved.

As an aside, the C. Crane Skywave SSB 2 can scan the first page of AIR band storage (10 frequencies).  If you don’t have 10 frequencies of interest, simply duplicate some of them to fill out the page.  This is also a good way to prioritize a favored frequency.

ATS

If you use the auto tune system (ATS) the computer searches and memorizes all detectable signals for AM, SW, FM or possibly AIR – each band separately.  When it’s done, you’ve caught a net full of fish, and are then confronted with a memory bank full of frequencies, many of which you may not be interested in, but must tune through in much the same way as with conventional tuning.  Finally, there is no easier way to destroy a meticulously hand-programmed memory page than to hold a button down too long and inadvertently activate ATS.  How do I know that?

Keep in mind, ATS requires a broad-band antenna to keep the playing field level during the scan.  The whip is generally all I need.  In the dense population of FM stations along the US East Coast, a completely retracted whip is often best.  I find the Tecsuns best for adding or deleting frequencies after the ATS scan.

Enhanced Tuning Mode

Tecsun has introduced ETM in recent years.  It is interesting and useful.  The most recent incarnation is called Enhanced Tuning Mode (ETM+), and the manufacturer has dedicated 3 ½ pages of the PL-330 manual to explain it.  In essence, it operates on each band much like auto tuning storage (ATS), but protects whatever you have in the radio’s main memory, and allows you to store time-specific sets of frequencies in separate ETM pages.  This expands the total memory to whatever extent on-air stations are detected during each time period.  I haven’t been able to put a number on it.

This Tecsun PL-330 display indicates the radio captured 45 frequencies
on an ETM scan of international broadcast bands made during the 00 UTC hour.

ETM is a quick way to find out what’s currently on SW international broadcast bands.  ETM logs SW broadcast stations to memory and reports the total number of stations captured at a given time (think of it as a separate page).  The total number could be used to determine SW reception conditions by comparing it with a previously calculated average for the same period.  For AM and FM, the feature can be used to store stations at a travel location without affecting main storage.  Regardless of how you use ETM, there is a learning curve, as well as a need to be continually alert to what you are doing.

Virtual ETM

For any other radio with page memory, you can still have many of the advantages of ETM, as well as avoid the likelihood of accidentally wiping out your carefully programmed frequencies.  Here’s how.

ATS on most radios begins saving frequencies on the lowest numbered page.  Note that the lowest page on the SSB 2 is 1, while it is 0 on the D-808, and the first station on each page is at button 0 (bottom).  My experience in the highly congested AM and FM bands on the US East Coast is that an ATS scan will likely take up no more than four or five pages of memory.  Likewise, ATS for SW is limited to AM stations on the international broadcast bands and will not require many pages, even at night.  By manually programming your favorite frequencies beginning on the sixth page of a 10-page memory arrangement they will likely be out of reach of an ATS scan and your manually-saved frequencies will still be there when you want them.

The travel benefit also applies to virtual ETM.  An ATS scan performed at a different location using the lower pages will quickly put you in touch with local stations in that area and preserve your manually saved frequencies at home.

As an aside, I would also suggest that sideband frequencies be kept together on separate pages, as the SSB function must be engaged separately to detect them.  With SSB engaged, the C. Crane Skywave SSB 2 will recall the saved LSB or USB mode, but you may have to switch from one to the other on the XDATA D-808.

Example of virtual ETM for D-808 on the shortwave band.
Skywave SSB 2 would be similar.

Virtual ETM is not perfect.  This method does not provide all the time-specific paging that the Tecsun PL-330 has.  Also, there is a danger if your radio has an auto-sorting feature which might be inadvertently activated.  Lock the buttons on your radio when you turn it off or pack it up.

Conclusion

Apart from simply listening to the radio, it’s still entertaining to press buttons and see what they do – something like an electronic Rubic’s Cube.  I will go as far as to put a half dozen favorite AM and FM stations into memory.  I may enter a DX frequency or two I want to check out periodically.  That said, there are a limited number of storage locations beyond which memory ceases to be convenient, and for me the number is well short of what is generally available.

On the other hand, ETM or virtual ETM opens some useful possibilities if you take one of these small portables on travel or want to do a quick scan to see what’s currently on shortwave.

No radios were harmed in the preparation of this blog.

Spread the radio love

Guest Post: Here Come the Lithiums

17 Replies

Many thanks to SWLing Post contributor, Bob Colegrove, who shares the following:

Power Play – Here Come the Lithiums

by Bob Colegrove

I have belonged to several radio-oriented user groups in recent years and can’t help noticing how often the subject of batteries comes up.  It’s almost a sub-hobby within the hobby.  There are a couple of reasons for this, first is the unending quest for the ultimate cost-effective, everlasting battery, and second, it’s a rare opportunity for most of us to tinker in an increasingly complex world of technology.

Lithium batteries offer a sustainable voltage output well into their discharge cycle and can deliver a higher rate of current than alkaline batteries.  They are somewhat lighter in weight than alkaline batteries – 2.5 oz. versus 5 oz. for D-cells.

Considering the fast pace of technology, lithium batteries have been with us for a comparatively long time, this in the form of cell phone and camera power, not to mention a host of electric appliances.  Most of these batteries have limited purpose, that is they have been developed and packaged for just a few applications, thus resulting in an incredible variety of sizes and shapes, and no doubt a host of frustrations due to obsolescence.  It’s somewhat reminiscent of the early days of transistor radios which ran on a wide array of zinc-carbon batteries.

Perhaps I have been asleep at the wheel, but it has only come to my attention recently that lithium chemistry has begun to backfill the standard battery sizes we have long been familiar with, namely AAA, AA, C, D, and even the PP3 standard 9 volt.

I have been running along quite successfully for more than 10 years on AA NiMH technology on several portable radios.  Although these run at a slightly lower cell voltage of 1.25 Vdc, the one-for-one substitution of these for alkaline chemistry has seldom been a problem in terms of performance.  In most cases, newer radios are provided with an alkaline/NiMH-NiCad setting to compensate for the difference in voltage.  Even the venerable Sony ICF SW7600GR, for which alkaline batteries are assumed, seems to operate equally well either way.

My problem has always been the larger power consumers running on D-cells – the Sony ICF 2010 and Grundig Satellit 800 to cite two examples.  A fresh set of NiMH batteries put the 2010 on the cusp of poor performance.  Lithium batteries having a sustainable single-cell voltage of 1.5 Vdc now provide a possible alternative to a steady diet of costly alkaline cells.  Even more attractive, some are equipped with a USB-C connector and can be recharged without a dedicated charger.

In the figure above, a set of four lithium D cells are connected simultaneously through a 4-lead USB-C harness and USB charger (not shown).  Many of the brands include the harness with a set of batteries.  I have added a USB multimeter, which I find very useful to monitor the progress of the charge, but this is not necessary.  This particular meter can also show accumulated capacity.  However, it should be noted that, unless batteries are charged one at a time, charging rate and capacity will show the total values for the number of batteries being charged.  I would also recommend that the USB charger be rated at least 3 amps.  In the figure below, one of the USB-C leads is connected at the top of the battery.  The built-in LED flashes during charge and remains on when the charge is complete.

Cost is an equally important consideration.  There is a lot of hype in the marketing department about how many times these batteries can be recharged.  The key compound preposition here is “up to,” and as long as they use those words, they can make the number anything they want to.  That said, it simply won’t take more than a few cycles for the cost-benefit cusp to be reached in favor of lithium batteries.

I am just getting started with this.  Although the batteries came highly recommended for the portable radio application, I can make no judgment at this time as to their ultimate quality or convenience.  It just seems like the next logical way to go.

There are some things to remember when choosing lithium batteries.  Not all lithium batteries are rechargeable, particularly smaller sizes.  Some do not come with the built-in USB-C charging jack, so a separate charger intended for lithium batteries will be required.  D size batteries are also available at 3.6 Vdc/cell.  There may be other options, so watch out.  Be sure to thoroughly check the features of any batteries you consider.

I would close by warning that lithium batteries come with safety caveats regarding their transport, handling, use, charging, and disposal.  These precautions are all well stated in the literature, which should be followed with an abundance of caution.  Of note is the fact that not all chargers support lithium batteries, and their capability should be checked as well.

Click here to check out these Lithium D Cells on Amazon.com (SWLing Post affiliate link), or explore other brands.

Spread the radio love

Bob’s Bespoke “Rack of Radios”

8 Replies

Many thanks to SWLing Post contributor, Bob Colegrove, who shares the following:

A Rack of Radios

by Bob Colegrove

You simply cannot have enough radios – a principle I learned a long time ago.  The difficulty occurs when it comes to storing them and yet having them at the ready when necessity calls.  Turns out several of my portables fall within a dimensional range that they can be conveniently stored in a rack on the table.

I would like to say I made a project out of this choosing a fine hard wood for construction, carefully routing each divider into a finely milled slot, tastefully finishing the whole thing off with appropriate stain and varnish, and perhaps lining each slot with felt of finest virgin wool.  However, never having been one to let form triumph over function, instead, I found a couple empty cracker boxes of the right dimensions, made a few cuts with a hobby knife, and applied some hot glue.  Whalla!

Wait a minute.  Is that an unused slot at the end?  Hmm!

I love it, Bob!

I mean, you know those cracker boxes just wanted to become a custom radio rack–! I say save the fine wood working to build the shelf upon which you’ll place your bespoke cracker box radio rack. 

Thank you!

Spread the radio love

Radio Nostalgia: Bob’s first radio

8 Replies

Many thanks to SWLing Post contributor, Bob Colegrove, who shares the following guest post:

My Very First Radio

By Bob Colegrove

Sears and Roebuck Co., Silvertone, Catalog No. 8003, Model No. 132.818-1

I don’t remember much from 1949.  I was seven years old and still in the first grade.  I do remember being gifted a radio by my mom and dad on my birthday.  It was a Sears and Roebuck Co., Silvertone, Catalog No. 8003, Model No. 132.818-1.  I don’t really remember asking for it.  I’m sure mom and dad did not have a clue as to how consumed I would become with radio over my lifetime.  In truth, this was not the radio that got me totally absorbed, rather that function would be filled in 1958 by the Howard Radio Co. Model 308 combination MW/SW radio-phonograph console which had been relegated to the basement in favor of the TV set.

In 1949 television was on the cusp of success, and AM radio was still the one-way Internet of its time.  I recall my mother listening to countless soap operas during the afternoon.  The Howard was still in the living room and we listened to all the popular programs at night.  Anyway, the Silvertone was mine.  It took up residence in my room and I could independently explore the wonder of five local stations broadcasting in Indianapolis at that time.  There were no parental guidance settings on the Silvertone, nor was there any need.

The Silvertone was not a world-class radio with all the sensitivity, bells and whistles I would later desire.  Below WXLW, 950 kc it was deaf.  It was, in fact, one tube short of an “All American Five.”  However, one of its four tubes was dual function, if you counted the detector.  It was what was called an “ac-dc” radio.  This meant it could be powered by either 110 Vac or Vdc.  Granted, there were a couple communities in the US which were still serviced by dc power at this late date, but that fact certainly did not warrant advertising.  The whole thing always seemed to me no more than a marketing ploy on the part of manufacturers to cover for the lack of an expensive isolation transformer in the circuit.  Given the fact that electrical standards of the time did not provide for polarized outlets and power cords, these things could be quite hot, and it’s amazing so many tinkers, myself included, are around to talk about it.

One Tube Short of an “All American Five”  

The dial was very crude, and the tiny tuning knob swept all 107 available channels in a 180-degree twist of the variable condenser.  My mom, always handy with a paint brush, took to marking favorite stations  with a dab of nail polish.  1430 kc was WIRE and 1070 kc was WIBC.  Perhaps she got the idea from Bill Halligan who used little red dots on the controls to indicate the setting that would likely produce some noise.

The printed media were sizeable and substantive in the 1940s.  The Indianapolis Star’s morning edition for Friday, April 13, 1945 was particularly mournful as the U.S. woke up to the news that the president had died the day before.  I was later given to understand that many stations broke from the normal schedule for a few days to play somber music.  Notwithstanding, the first section still bore the quintessential hourly radio program schedule from 6 am to midnight for each of the four local stations.  We always kept clippings of station logs for each day of the week.

My interest in baseball grew over the next couple years, and the Silvertone played an important role in my keeping up with the local AAA team.  The static on a summer night was atrocious.  Further, in those days, the broadcasters were not compelled to fill the air with chatter between pitches.  There were no recitations of mindless statistics and no color commentators to describe the nuances of sliders and curve balls.  Consequently, between pitches there were often long pauses of nothing but dead air.  If you happened to tune in during a pause you had little idea where WISH, 1310 kc was on a hopelessly crude dial.

Most minor league broadcasters did not travel with the team.  When the team went on the road, they used an old Model 15 clickety-clack Teletype machine in the studio.  A local guy at the distant ballpark would observe a pitch or play, and quickly type a cryptic message on his Teletype.  On the radio you would first hear the receiving Teletype spring to life in the studio as the message came in.  The announcer would quickly interpret it, and then embellish the play with some excitement as best he could.

Teletype Model 15
Copyright Museums Victoria (Licensed as Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/)

During those times, it was not too uncommon for the Teletype to suddenly go down during the game.  What to do?  An announcer was suddenly left to his own creativity to fill in airtime.  Possible solutions were to describe the lengthy process of extricating a stray animal from the field, or a sudden cloudburst and consequential rain delay.  An intrepid announcer went on as nothing happened, making up the play-by-play over the interval.  Invariably, when the Teletype came back up, he found himself not quite in sync with the game and possibly a few runs behind.  At that point the challenge was to patch in the necessary play and go on to complete the game to the satisfaction of an otherwise unsuspecting audience.

Well, after 73 years, I’ve seen my share of radios.  In the meantime, the Internet has made it possible to DX the entire world at any time on a fifty-dollar Kindle – excellent fidelity, no interference, no noise, no fading.  But, after all these years, I still cherish those static-filled ballgames and teletype machines heard on the Silvertone a long time ago.

Quietly Waiting for the Next Pitch

Spread the radio love

Guest Post: Calculate Station Distances Using Excel Formulas

7 Replies

Many thanks to SWLing Post contributor, Bob Colegrove, who shares the following guest post:

Calculate Station Distances Using Excel

By Bob Colegrove

Introduction

On occasion, I’ve wanted to know just how far away a station was from my home.  I’ve never been much of a contester, but I know distance can play a part in the results.  There are a number of Internet cites which let you enter latitude and longitude information and then calculate the distance across the surface of the earth.  These are alright on an occasional basis, but I often wind up getting the data mixed for the two locations, and it is not handy when you want to make several measurements.  Here’s a way to generate the distance from your home to thousands of stations with just a little effort.

Many years ago, armed with my faded knowledge of high school trigonometry, I used Excel to calculate the surface distance between any two points on earth.  I managed to find the spreadsheet (file dated 1998) which has no fewer than 11 steps in the algorithm.  Although it worked, when I came back to it a few months later to make a change, I couldn’t remember my thought process.  There are Internet sites which develop earth surface calculations in highly esoteric terms and heavy-duty math.  But life is short, and I wanted to cut to the chase.  There are, in fact, several formula variations which have somehow managed to distill all this down to a neat single-cell calculation, and they seem to work very well.

Construction

The spreadsheet figure below is the simplest form used when you have decimal latitude and longitude data as input.  The convention is to use negative numbers for the Western and Southern Hemispheres.  Home is your reception location and all other locations are compared with that to determine the distances.  If you’re curious, the home location (yellow cells) used in these examples is the monument marking the geographic center of all 50 US states in Belle Fourche, South Dakota.  Google Maps is one easy source to determine the exact latitude and longitude of any point on earth.

To calculate the distance between any two points on earth, copy the formula below directly into a cell, then change the reference cell names as appropriate, and you’re ready to go.

=ACOS(COS(RADIANS(90-$B$5)) * COS(RADIANS(90-B9)) + SIN(RADIANS(90-$B$5)) * SIN(RADIANS(90-B9)) * COS(RADIANS($C$5-C9))) * 3959

$B$5 and $C$5 are the cell references for your home address (yellow in the figure above).  Of course, the dollar signs indicate these data remain fixed in each calculation.  B9 and C9 are corresponding latitude and longitude for the example radio station, WTOP (green).  Change these four cell locations as necessary.  The constant, 3959, at the end of the formula is the average radius of the earth in miles.  Use 6371 if you want kilometers.  The data cells in Columns D and E are populated with the formula and produce the result. These values are dynamic and can be replicated down the columns for the rest of your station location data.

Degrees, Minutes, and Seconds Format

The US FCC on-line database contains latitude and longitude tower locations for medium wave stations in Region 2, North, South, and Central America.  However, coordinates are in degrees, minutes, and seconds format and must be converted to digital format for calculation of distances.  The conversion process can also be done in Excel.

In this case, the inclusion of the coordinate hemispheres, N or S, and E or W is important.  Whereas, the hemispheres in the decimal example were signed + or -, the inclusion of the appropriate letters here is necessary.  Cell L5 reads

=IF(H5=”S”,-I5-(J5/60)-(K5/3600),I5+(J5/60)+(K5/3600))

and cell Q5 is similar for longitude, except “W” is substituted for “S.”  These formulas are then replicated in columns L and Q for each data item.  Columns R and S contain the distance calculation formulas as described above.  Line 14 is not necessary, but can be used to see if your formulas are correct; that is, the distance from home to home should be zero.

Let Excel Get the Information for You

What follows is for anyone tired of copying cumbersome latitude and longitude data.  Unfortunately, it only works on the current version of Microsoft 365 Excel, and apparently goes off into the big cloud in the sky to instantly download the information.

  1. Enter the town followed by either the US state, Canadian province, or other country name (Column A).
  2. Copy these locations to the next column (Column B).  The cells in Column B will become temporary geography cells.  Note:  As shown above, the data have already been converted to geography format (Step 4).
  3. Make sure you have all the geography cell locations selected (Column B).
  4. On the Data ribbon select Geography.  A map icon will appear at the left of each cell, and the state, province and country will be truncated.
  5. For the first latitude (Cell C7), enter =B7.Latitude; likewise, =B7.Longitude in Cell D7.
  6. The formulas in C7 and D7 can be replicated down your list.
  7. Columns for miles and kilometers (E and F) can be added using the distance formula as described above.

The geography data (Column B) cannot be replicated.  If you want to add data later, you will have to reapply the geography format for the new data.  Or, latitude and longitude can still be inserted manually for any additional entries.  The geography data (Column B) are not needed beyond this point and can be deleted or hidden.

Note:  I logged on to my first mainframe computer in September 1976 and have never ceased to be amazed at what these confounded things can be made to do.  I tried as best I could to trip the system with small, obscure towns in faraway places, as well as duplicate names.  I finally succeeded with a relatively large city, Ulaanbaatar, Mongolia.  To be fair, I tried to get it to accept alternate spellings.  So, if you need that one, you’ll have to enter it manually.

Medium Wave Example

This example is for medium wave DXers in Region 2, the Americas.  It makes use of the FCC AM database at https://www.fcc.gov/media/radio/am-query.  The database currently contains more than 24,500 entries, many of these are duplicate entries for stations using different daytime and nighttime powers.

  1. Download the database as a pipe-delimited text file.
  2. Import the file into Excel.
  3. Create additional columns to convert the latitude and longitude data from degree-minute-second format to decimal as described above.
  4. Add some rows above and enter your home coordinates in decimal.
  5. Create another column to calculate the distance from home to all the stations, again using the base formula above.
  6. Hide any columns in the FCC database that you don’t need.
  7. Finally, by creating an Excel table from all of the data, except your home location, you can do some on-the-fly filtering.

The example below shows some of the stations near our example home in Belle Fourche, South Dakota.  The Distance column on the right has a filter applied to limit the listing in the table to stations within a 150 mile radius, that is, it only lists potential daytime stations.  You could also use the conditional formatting feature of Excel to highlight the same information in the unfiltered data.

Shortwave Example

The AOKI log, http://www1.s2.starcat.ne.jp/ndxc/, has listings for all of the recent broadcasting cycles, B21, A21, etc.  The Excel format files are zipped for download, and include the latitude and longitude of each station.  Unfortunately the coordinates are not only in degrees, minutes and seconds, but they are all mashed together in one cell for each listing.  Excel to the rescue again.  Select Text to Columns in the Data Tools portion of the Data ribbon.  This feature will allow you to divide the single column into four columns each for latitude and longitude, that is, degrees, minutes, seconds and hemisphere.  Then you can use the conversion formula to change degrees-minutes-seconds to decimal.  Note that the first three digits used for longitude are minutes (they go up to 180); the remaining numerical columns have two digits each (up to 60 or 90), and the hemisphere columns (alpha) one character each.

Accuracy

Here are a few things affecting accuracy:

  1. The constants 3959 or 6371 used in the formula for miles and kilometers are generally accepted averages for the earth’s radius.  The difference between the equatorial (longer) and polar (shorter) radii is about 13 miles.
  2. If you are using town locations in your data, remember that the actual distance to the tower in that town is likely to be different.  The FCC and AOKI data are assumed to be station tower locations.
  3. Some decimal sources of latitude and longitude data have less resolution, which could lead to a slight error.

You’re on Your Own

You may have noticed the examples shown in the figures all have multiple station locations. My thought in doing this was provide some test for accuracy and secondly to provide a seed for developing the spreadsheet into a more inclusive log of stations. There is likely enough basic Excel knowledge among the folks gathered here, and each person will likely have an individual preference in designing a spreadsheet. Nevertheless, the spreadsheet shown in the figures can be downloaded by clicking this link.

The first sheet shows Figures 1 and 2 from this article; and the second sheet, Figure 3. The link in Cell I2 of the second sheet describes how to use the geography feature of Microsoft 365 Excel. The third sheet is a recent copy of the FCC AM database (Figure 4). To facilitate storage and downloading, only stations from 530 kHz to 600 kHz are included. Numerous unused columns from the FCC AM database have been hidden; so you can still copy the full, pipe-delimited FCC database into Columns A through AH. The FCC database has been converted to an Excel table; the Home location is not part of the table. Try substituting your own location for Home (Cells AI2, latitude and AJ2, longitude) and setting a distance filter from your home in Cell AK4. In the example, the distance filter has been set limiting the list of stations to less than 600 miles from our example in South Dakota. Note also that the Conditional Formatting feature on the Home ribbon has been used to highlight stations less than 100 miles from home.

If you have any interest in developing your own spreadsheet, perhaps you can comment on what you have done, or provide the rest of us with something I have missed. Hopefully, I have provided enough information to get you started.

Spread the radio love

Guest Post: Control of Electromagnetic Radiation (CONELRAD)

11 Replies

Many thanks to SWLing Post contributor, Bob Colegrove, who shares the following guest post:

Control of Electromagnetic Radiation (CONELRAD)

As recalled by Bob Colegrove

In his comment on my recent posting, Tinkering with History, Mario noted the dial on the featured radio, the General Electric P755A, sported two small triangles, one between 6 and 7, and the other between 11 and 14.  He noted that these were civil defense markers intended to show the frequencies of 640 kHz and 1240 kHz, respectively, and that these were characteristic of AM radios produce in the US roughly between 1953 and 1963.  Since two full generations have been born and raised to adulthood since that time, and I can’t find any related posting here, I thought it might be useful to bring this subject to light.

In spite of otherwise economic prosperity and general wellbeing, these years were nevertheless filled with anxiety about the prospects of all-out war.  Children of the time (myself included) were being shown how to hide under their school desks, and some of their parents were going so far as to construct air-raid shelters in their basements, and stock them with enough provisions to supposedly outlast any catastrophe.  So it was that CONELRAD came into being in 1951.  The idea was, that in case of a National emergency, all radio and TV stations would go off the air, and only certain medium wave radio stations would stay on either 640 kHz or 1240 kHz.  They would remain on for a few minutes and then other stations would take over in a round robin arrangement – this to deter homing by hostile bombers.  Needless to say, quickly changing over transmitters and antennas to one of these two frequencies did not bode well for the equipment and there were many failures in subsequent tests.  Note that, as originally conceived, the system did not provide for local weather emergencies or other situations.

The banner photo at the top of this posting shows a portion of the Hallicrafters S-38E receiver which conformed to Government law of the time required for marking all AM dials.  An S-38E just like it was my first genuine multi-band radio in 1959.  Assuming good alignment, the dots next to the CD triangles indicated the 640 kHz and 1240 kHz frequencies.  When a test came on, you didn’t have to fish for it, since CONELRAD was the only service transmitting.

Going back to the radios described in Tinkering with History, GE took this one step further.  The figure below shows a portion of the dial on a GE P806A.  Note the nub on the outer edge of the dial under the triangle at 1240 kHz.  There is another nub on the edge at 640 kHz.  Together with the raised triangular dial pointer molded on the cabinet, they provided a braille system, so that someone visually impaired could easily tune to a CONELRAD frequency.

As technology improved, CONELRAD transitioned to the Emergency Broadcast System (EBS) in 1963, and subsequently the Emergency Alert System in 1997.  A more thorough description of CONELRAD can be found on Wikipedia https://en.wikipedia.org/wiki/CONELRAD.  Reprint of an April 1955 Radio & Television News article describing the construction of a transistor CONELRAD receiver is at https://www.rfcafe.com/references/radio-news/conelrad-radio-television-news-april-1955.htm.

Spread the radio love