Tag Archives: RDS

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

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.

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Aeronautical RDS: Ivan’s impressive collection of in-flight FM stations

Many thanks to SWLing Post contributor, Ivan Cholakov (NO2CW), who writes:

Last week I took an Eton Satellit with me on a flight from Tampa, Florida to Washington DC. The radio is very light, portable and packed with features. I have used an SDR radio before for inlight FM reception where I recorded audio, but this time I decided to only count stations with an RDS lock. With so many signals battling RDS is tricky to catch as every 10 seconds or so one station comes on top of another. The flight was just short of 2 hours and I divided my logs into three 30 minute segments. Not suprisingly looking into the technicalities I noticed RDS is commonly received from stations 50 -100 kW of power and tall towers.

Interestingly signals seem to be stronger a lower altitudes. My theory is that FM broadcast antennas heavily favor gain on the horizontal plane parallel to the terrain and send as little signal as possible out into space. I overlaid my logs onto three maps and also a video:

Click here to view on YouTube.

Impressive Ivan! I’m taking a flight later this month and might even try this with the FM radio built into my Moto G6 smart phone which also includes RDS (although I doubt reception can match that of the Satellit.

This is fascinating, Ivan! Thank you for sharing.

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Digitech AR-1780: unboxing, photos and initial impressions

[UPDATE: Click here to read our full review of the Digitech AR-1780.]

Yesterday, prior to heading out the door for two days of travel, I received the Digitech AR-1780 I ordered ten days ago from an Australian eBay vendor. I’m very pleased with how quickly the order was processed and delivered via the post. The radio arrived in a rugged mail pouch and was double boxed inside.
I’ve had no time to evaluate the radio’s performance yet, but I thought I’d post a few photos I took while unboxing the AR-1780.

There’s not much in the box: just the radio and an owner’s manual. There are no batteries, no charger, and no case or carry bag. That’s okay though as the AR-1780 takes standard AA cells and I have an assortment of bags that can protect it in my suitcase.

The buttons all have a responsive, tactile feel. The hard plastic chassis feels durable.

I really like the dedicated fine tune control on the right side of the radio.  Nice touch! But 7 VDC in? That’s an odd voltage for a power supply. That’s okay by me as I never use wall wart type power supplies due to inherent noise–rechargeable Enloop AA batteries are how I power all of my portables. Bonus! There’s also a dedicated external antenna jack! One odd thing, though, is the AR-1780 breaks the convention of having the volume control on the right side of the radio–it’s on the left instead. Last night, I tuned around the 31 meter band and the AM broadcast band.  I listened to the French language service of Radio Romania International from inside a noisy house–armchair copy.

The AR-1780 has an impressive 7 AM bandwidth settings: 6, 4, 3, 2.5, 2, 1.8 and 1 kHz. My radio defaulted to 2.5 kHz, so you’ll want to widen that to 4 or 6 kHz before listening to most broadcasts.

I really like the display–it’s compact, yet contains quite a lot of info and even has a dedicated line for FM RDS content.

This morning, I took a couple shots of the AR-1780 next to the venerable CC Skywave. The Skywave is slightly smaller in every dimension.

Stay tuned! Though this is a very busy week for me–with travels and total solar eclipse preparations–I plan to put the Digitech AR-1780 through the paces. I’ll try to post updates as I have time.  Follow the tag: Digitech AR-1780

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Richard’s initial impressions of the Sony XDR-S41D FM/DAB receiver

Many thanks to SWLing Post contributor, Richard Langley, who recently attended a conference in Paris and picked up a Sony XDR-S41D. Richard writes:

The workshop closed around noon on Friday so I spent part of the afternoon walking around the nearby Darty consumer electronics and appliance store.

I wanted to buy a DAB/DAB+ portable receiver just to see what Europe was doing with digital radio. I bought a recently introduced Sony XDR-S41D DAB/DAB+/FM(with RDS) receiver for 79€ (about 11€ off list price).

I can use it in North America to listen to FM and take it with me when I visit Europe for DAB/DAB+ as well as FM.

It has reasonable sound from its 8-cm speaker and pretty good stereo sound on headphones. It has an automatic search mode on both DAB/DAB+ and FM and creates a list of available stations.

In my hotel room in the 13th arrondisement, I could receive 46 DAB+ stations. One of the stations is World Radio Paris (WRP) and they provide English language programming 24 hours per day from BBC World Service, Public Radio International, Radio France International, and Radio Canada International, among others as well as their own programming.

Another available station was Medi 1, which just dropped its shortwave transmissions. I recorded some of the WRP programming:

Audio Clip 1 (MP3)

Audio Clip 2 (MP3)

There is no line output from the receiver but I was able to use the earphone output and crank the volume to maximum to get an acceptable recording level without noticeable distortion.

Happy with my purchase and can’t wait to go back to Europe again, say to England, to try out DAB+ there.

I also spotted three receivers with SW capability on the shelves at the Darty store:

  • Panasonic RF-3500 for 45€
  • Brandt BR200D for 45€
  • Brandt BR120A for 15€

You don’t see SW receivers in North American consumer electronics stores anymore and I’ve not spotted any in airport duty free stores lately either.

I’ve been listening to the XDR-S41D at home and it sounds pretty good on FM, too, and does a good job of displaying the RDS information although a character or two is sometimes cut off the end of the data but that could be the fault of the station. Need to investigate that some more.

By the way, the radio doesn’t come with a case but I found (just before I was going to toss it) that it just fits in the magnetic-clasp case of one of those Air Canada amenities kits that they give you in business class (see photo below).

That’s the second Air Canada item I have recycled. They used to use full-ear headphones with disposable foam covers. They were a perfect fit for the deteriorating covers on my old Sony noise-cancelling headphones. I’ve since upgraded to Bose. 😉

Thank you for sharing your thoughts, Richard! The Sony XDR-S41D sounds like a keeper for sure and is certainly compact enough to easily accompany you on travels to Europe. I was not aware of World Radio Paris either–I see they’re available via TuneIn, so I’ll add them to my WiFi radio station favorites!

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