Tag: Radio

According to current planing, The Netherlands will have analogue FM until 20235. At least the commercial radio stations are licensed until that year. Our national and regional stations, both public and commercial, are already on DAB+ and essentially every such station now on analogue FM is already on DAB+. DAB+ coverage has improved too during the last few years. Is analogue FM useless or will it be useless soon? Not at all.

Disaster stations.

The regional public radio stations are designated radio stations to provide essential information during disasters. Older technology is often more reliable. It’s a great idea to have the FM network available during a disaster, just as a backup. For one thing, DAB+ will require GPS to be available to get multiple transmitters synchronised to the nanosecond. The FM transmitters for the regional network transmit on different frequencies and are not required to be synchronised accurately. Plus more people have battery powered FM radios in their emergency kits than DAB+ radios. All DAB+ radios can receive FM, but not all FM radios can receive DAB+.

Local stations

DAB+ multiplexes are designed to have 12 to 18 programmes per multiplex. A local station usually carries one programme and, unless we have large cities with dozens of stations, local stations will never fill a multiplex. DAB+ makes no sense for local stations. Just keep them on the FM band.A single studio close to a single transmitting site, that’s what local stations should be. We could have both commercial and public local stations.

Special purpose stations

When the FM band gets unused for the most part, we can finally have some room for stations that do not want or need to be on the air all the time, like campus radio, special event stations, churches or concert halls,. The same frequency could be used during school hours by a campus radio station, during the evenings by a concert hall and on Sunday morning by a church.

Radio Amateurs

In the early days, radio amateurs were allowed to transmit music on shortwave. This was before the widespread use of SSB, and speech was transmitted in AM mode. Ordinary home radios with shortwave could just receive these transmissions. While it is still legal to transmit AM on shortwave, transmitting music is not. It is technically even legal to transmit in FM stereo on the UHF bands, but also on these bands, music is taboo.

It would be great if music was allowed again on the amateur bands. You could add restrictions on the duration of music transmissions or let amateurs pay some form of copyright fee if they want to play music. Only when music is transmitted, you can really judge the audio quality of a transmission. If amateurs are on a section of the the FM band, ordinary people would occasionally listen in and they could be drawn to the hobby.

Unregulated Broadcasters

The Netherlands is one of the few countries where small stations, even hobbyists, can get a license to transmit on mediumwave (low power AM). You need to obtain several licenses and you need to pay copyright fees for music, but in principle it can be done. The same kind of license could be extended to the FM band, when that gets mostly abandoned by regular broadcasters.

Of course, radio pirates do not want to be legalised. For one thing, the copyright collecting societies decided long ago, not to go after pirate stations, because they were “criminal organisations” and they did not want to collect money from criminals. So if you are a pirate, you risk a big fine for transmitting illegally, but at least you are safe from the copyright collectors. And it is part of the culture to do things without a license. The fun would be gone if it was legalised.

It would probably help if the law was rewritten such that pirate stations are no longer considered “criminal organisations”, they just fail to pay some license fees. In that case the copyright collectors can go after them when they play music without paying a fee. Unregulated broadcasters would need to comply with power limits, they would need to use type-approved transmitters (as opposed to radio amateurs who can build their own) and they would have to stay within their section of the FM broadcast band. If they do all of this, they should be considered legal in principle, they just need to pay the required license fees. Criminal law should only be invoked when pirate stations cause real harm.

Back in the early 1980s, The Netherlands had four national radio stations and three of these were on mediumwave. They could be heard far outside our national borders. On the other hand, two Dutch language stations from Belgium could be heard throughout The Netherlands, as well as two French language stations from that country. That was not all you could hear though: there were a bunch of German stations and some English stations to be heard as well. BBC World Service was booming in on 648 kHz. During some years, we had some good pirate stations too.

Much radio listening still happened on mediumwave, as not all radios had the FM band back then and one of the national radio stations in The Netherlands was on mediumwave only. Starting in 1985, we got an additional national station (Hilversum 5) and it was on mediumwave only, but it took the frequency of Hilversum 1, which became FM-only.

If your radio had longwave too, you got a bunch of foreign stations: from France, Luxembourg, the UK, Germany and some other countries. After sunset, the mediumwave band came to life and if you took the trouble, you could hear radio stations from all over Europe. These were some of the main national programmes of those countries, hence it was quality stuff. BBC Radio 1 played the latest British pop songs, weeks or sometimes months before they were allowed to enter our country. Radio Moscow once had a Dutch language service on mediumwave, one of the few international broadcasters to have one, along with South Africa (that and an even more objectionable regime and that was on the 16 meter band on shortwave). But at night the mediumwave band was indeed used as another shortwave band, on both sides of the Iron Curtain.

If you had a good radio and you were skilled with the rotating ferrite bar antenna, you could often pick up two different stations on the same channel. Hearing stations outside Europe was a challenge though, as there were many more European stations occupying those frequencies. Today it’s relatively easy to pick up North Africa for example.

And of course many, many countries had a presence on shortwave. Back in the day, the 49 meter band was chock full of stations, whatever time of the day you listened. Most European countries were all there, all the time. Higher shortwave bands, like 25m, 19m and 16m gave you the more distant stations. Shortwave was not listened to by everybody though. But everybody got exposed to mediumwave during day-to-day listening. And everybody occasionally heard foreign stations, if only unintentionally.

We are less exposed to radio stations from other European countries than we were a few decades ago. Since 2003, the FM band in The Netherlands was reorganised and it became very overpopulated, reducing the opportunities to hear foreign stations on that band. DAB has a far shorter reach across the border than FM used to have. We have internet radio now, but some countries (in particular the UK) reduce their internet radio streams to within their own country. With true broadcast radio, there’s nothing between you and the station you want to hear, that can be controlled by governments. You can add jamming stations, but you can’t take radio propagation away. Compare that to the many links that exist between an internet radio station and you.

Exposure to radio stations from other European countries was a good thing, even if you were not intentionally listening to them. It created an awareness of a being part of a larger Europe. In most places in The Netherlands we have access to over 50 stations on DAB+, but many of these are non-stop computer generated playlist stations without a soul. BBC World Service is actually available on DAB+ in The Netherlands, which is a good thing. But this will only last as long as somebody pays to have it there. And we should have German and French voices as well, plus something from Belgium. Some of those more-of-the-same popular music stations can really be missed and be exchanged for existing foreign radio stations. I know,this is not how commercial radio works. But why should everything work according to the rules of commercial radio?

The UK is the last country with a significant presence on mediumwave in our part of Europe and it will likely stop by the end of this year. Nobody will bring mediumwave back. But maybe the EU should facilitate airing public radio broadcasts outside national borders, to replace what mediumwave used to do for us naturally. There’s spare capacity on some DAB+ multiplexes, like that of our national public broadcaster NPO. It carries 10 programmes, 2 of which will likely be axed by the end of this year. You can easily have 12 programmes with good audio. Why not get some Belgian, French or German stations there?

Today’s single-chip radio tuner chips make it possible for hobbyists to construct decent quality broadcast receivers. One chip that has been around for 15 years or so is the Skyworks (formerly known as Silicon Labs) Si4735. This chip contains a full LW/MW/SW/FM radio tuner from antenna to audio. It requires a microcontroller to control it, for example the 8-bit AVR processor used by Arduino. There are many hobbyist and open-source designs based on this chip. The Si4735 is an SDR radio internally, it does all filtering and demodulation on its internal DSP. There is a custom firmware blob for it that can demodulate SSB. However, this firmware blob is not open source. The AVR sends the Si475 its commands to tune to a specified frequency and set its other operating parameters, The AVR controls the display and the user controls of the radio. There are many ready-made Chines radios designed around this chip (or the Si4732) and an Arduino/AVR. This chip gives nearly continuous LW/MW/SW coverage up to 30 MHz.It is also the main part (or the final IF filter/demodulator) of nearly all world band radios currently on the market.

Another single-chip radio tuner is the TEF-6686, designed by NXP. This chip contains a very capable FM tuner, along with LW, MW and SW. SW coverage is limited to 27 MHz (not 30) and there is no way to do SSB. As microcontrollers are now predominantly 32-bit, the TEF-6686 radios (and some newer Si473x designs too) uses an ESP32 microcontroller. One such open-source design was provided by PE6PVB https://www.pe5pvb.nl. This design has found its way to numerous ready-made Chinese radios too.

There is also the Skyworks Si4684, a complete FM/DAB+ radio on a chip. PE5PVB designed a very capable DAB+ radio around it, using this chip, an ESP32 and a colour display. As the ESP32 does slide show decoding and display, the software uses nearly all the flash of the ESP32, so the FM side of the chip cannot be accessed using the current software. Unfortunately, there are no ready-made Chinese versions of this radio yet. DAB+ is not a thing in China and many markets these Chinese radios get exported to.,

As interesting as these projects are, they leave the nitty-gritty radio stuff to a closed-source DSP and the open-source part is only about user control and sometimes RDS decoding or decoding of other digital data that comes with the radio signal. The Pico Rx project is different though. See https://github.com/dawsonjon/PicoRX There a Raspberry Pi Pico does all the hard work of an SDR in software. It uses minimalistic front-end circuitry (a set of analogue multiplexers to act as an IQ mixer and some frontend filters) and uses the on-board circuitry of the Pico itself for the rest, including A/D converters and the I/Q oscillator signal generation. This circuit gives you a capable all-mode HF receiver (0-30 MHz), optionally with a spectrum display. All the DSP stuff is done on the Pico, which is a fairly powerful dual-core 32-bit microcontroller in its own right. The radio can run on batteries and draws little current.

At least since the 1970s, portable world band radios have covered the FM broadcast band (and of course mediumwave). People would purchase a radio to listen to shortwave broadcasts when on holiday, but they could also use it as a normal radio while at home. Back in those days there was no internet and international phone calls were prohibitively expensive. Shortwave was often the only viable way to receive information from your home country.when you travelled abroad. Some countries even ran a service to alert specific persons about an urgent situation at home, like an unexpected death. Radio Netherlands was such a station and my father and I were very keen never to skip this broadcast for a single day.

The market for shortwave receivers has decreased and shortwave listening has shifted from the broadcast bands to the amateur bands. There are far fewer stations broadcasting on shortwave and the ones that remain are mostly either religious propaganda or China Radio International. In the western world. any interesting broadcast could be listened to more conveniently via the internet.

But as any avid shortwave listener knows, you do not listen to shortwave broadcasts just to get the information, but for the thrill of receiving a signal from a great distance, especially if that signal was not supposed to reach you at all. For example if a religious broadcaster beams from Australia to India, but the signal takes the next hop and reaches Europe too.

If you live in an apartment with no real possibility to have an outdoor antenna, portable radios are the way to go. Even a nearby park in your home town gives you better reception than when you are at home.

None of the world band radios currently on the market has DAB+, but I think it should be included for the following reasons:

• If it was a good idea back then to have FM, why shouldn’t we have DAB+ on today’s world band radios? It’s the main broadcast band in many European countries.
• Some EU countries (but not The Netherlands) have laws that require all broadcast receivers to support digital radio. Apparently this is not widely enforced for shortwave radios, but why can’t we just have DAB+ on some of these radios anyway?
• Nearly all DAB+ radios also receive FM, but it is almost always implemented very poorly in terms of usability. One of my Sony DAB+ radios has excellent FM reception, but it mutes for over a second when you tune, even if just one 50 kHz step. This makes it impossible to explore the band by manual tuning. Some other radios refuse to stop on a station that’s too week, but they could hear the station if you do manage to get on that frequency eventually. The least thing we need is a DAB+ radio where the FM band can be manually tuned the same way as on traditional radios. And how much more DX-friendly could we make the DAB-side of things? In terms of manual tuning and useful information to identify a multiplex?
• When I’m actually travelling, I would want to pack one radio and have coverage of both local DAB+and the other bands such as mediumwave, shortwave and FM. Plus SSB on the amateur bands.

There are reasons why DAB+ isn’t included on world band radios:

• DAB+ is only a thing in Europe (and not even in all EU countries) and a few select other countries like Australia. It’s not used in China, where all manufacturers are and not in the USA, where China’s biggest export market is.
• Radios made by Tecsun (the largest manufacturer), have a numeric-only display. A DAB+ radio needs to be able to display station names. Tecsun radios don’t have RDS on FM either, even if they contain a tuner chip that demodulates the RDS bitstream..
• Some radios do have 14-segment displays for station names (like the Sangean ATS-909x), even some DAB+ radios do, but for serious DAB+ support you are practically required to have a matrix display. Matrix displays require a more complex CPU to control them and they cannot stay on while the radio is off. Many portable world band radios display the time when they are off, which is very practical when you use your travel radio as an alarm clock. The CPU needs very little power to maintain a 7-segment display.

There is a whole cottage industry in China that produces longwave, mediumwave, shortwave, FM receivers based on the Si4732 or TEF6686 tuner chips, combined with a colour matrix display and an ESP-32 microcontroller. Some of these have numeric keypads, some of them have airband coverage and some combine the Si4732 (that can do SSB) and the TEF6686 (that has better overall AM and FM reception) in one radio. Some of these designs are open-source. There is a separate open-source design based on the Si4684 that receives DAB+ (even though the chip can do FM, this is not enabled). There are SDRs based on the Raspberry Pi Pico, that can receive 0-30 MHz in all modes with little more than a Raspberry Pi Pico, some analogue multiplexers and frontend filtering.

The chips exists, the designs exists, so why shouldn’t some hobbyist throw an Si4732 and an SI4684 in one box to create some half decent world band radio with DAB+? Or turn the Raspberry Pico Rx into a capable receiver for 0-30 MHz and pair it with the Si4684 for DAB+ and FM?

Te Tecsun PL-680 may be the last truly analogue world band receiver ever produced. It still has analogue IF filters and an analogue demodulator. Newer radios like the PL-880 use the Silicon Labs Si473x DSP chip for IF filtering and demodulation instead.. It was introduced in 2016, almost 10 years ago. Its very similar predecessor, the PL-660, dates back to 2010.

It shares some desirable features with the Sony ICF-2001D (or ICF-2010).

• It covers the same bands, including the air traffic control band.
• It has two IF bandwidths on longwave, mediumwave and shortwave.
• It has a decent synchronous detector. Not nearly as good as Sony’s, but certainly very useful and better than the one that comes with some DSP radios..
• It has a a very smooth tuning knob, capable of tuning in 1 kHz steps.
• It’s very easy to tap a frequency on the keypad.

The only thing that’s really missing is the 32 dedicated preset buttons. Of course, the Tecsun has tons of presets, but you need to use the V/M button or page buttons to get to them.

For a start: I really hate the variable tuning speed as is used by default. But hold down the STEP button for a second or so and the radio will stay in slow tuning mode, which means 1 kHz steps. It will stay that way until you change batteries. I switched the mediumwave to American mode, so I can monitor the band segment between 1620 and 1710 kHz, where some pirate stations may be heard. Now that manual tuning is in 1kHz steps anyway, it does not matter if the fast steps are now 10kHz instead of 9.kHz. The PL-680 has absolutely mute-free manual tuning, something the less expensive DSP-based radios like the Tecsun PL-330 cannot offer.

For SSB we have a 1kHz tuning step plus an analogue clarifier knob (and it does have selectable LSB and USB). It’s a really nice radio to tune around the ham bands.SSB has good audio without any wobble and without the distortion at the onset of each word, as many of the more modern DSP-based radios have.

It performs very well on shortwave. Of course it does not play in the same league as the legendary ICF-2001D, but what radio does?

The PL-680 runs on four regular AA batteries, which may be alkaline or NiMH, which I prefer to the modern 16850 LiIon cells.All in all a very nice radio to have around and to enjoy listening to.