Radio Waves: Plant-powered Satellite Comms, BBC Pips, Filter Basics, and Replacing Shortwave

Radio Waves:  Stories Making Waves in the World of Radio

Because I keep my ear to the waves, as well as receive many tips from others who do the same, I find myself privy to radio-related stories that might interest SWLing Post readers.  To that end: Welcome to the SWLing Post’sRadio Waves, a collection of links to interesting stories making waves in the world of radio. Enjoy!

Many thanks to SWLing Post contributors Marty, Dennis Howard, Dennis Dura, Kris Partridge and Richard Langley and for the following tips:

Plant-powered sensor sends signal to space (

A device that uses electricity generated by plants as its power source has communicated via satellite—a world first.

[…]The device can inform farmers about the conditions of their crops to help increase yield, and enable retailers to gain detailed information about potential harvests.

It transmits data on air humidity, soil moisture and temperature, enabling field-by-field reporting from agricultural land, rice fields or other aquatic environments.

The extremely low power device sends signals at radio frequencies that are picked up by satellites in low Earth orbit. It was developed by Dutch company Plant-e and Lacuna Space, which is based in the Netherlands and the UK, under ESA’s programme of Advanced Research in Telecommunications Systems (ARTES).[]

The eccentric engineer: a tale of six pips and how the BBC became the national arbiter of time (Engineering and Technology)

This edition of Eccentric Engineer tells the story of the BBC Time Signal and how, over the years, it has just got more complicated.

Every engineer needs to know the time, if only so as to not miss lunch. Since 1924, many Britons have been checking their watches against the BBC time signal, known affectionately as ‘the pips’.

The history of the ‘pips’ is almost as long as the history of the BBC itself. The first transmissions from what was then the British Broadcasting Company began in late 1922 and soon afterwards there were suggestions of broadcasting a time signal under the control of the Royal Observatory at Greenwich – then the arbiter of time in the UK.

No one seems to have seen a need for this degree of precision, but early broadcasts did use their own ad hoc ‘pips’, marking the 8pm and 9pm news programmes with a time signal consisting of the announcer playing the Westminster chimes on a piano and later a set of tubular bells. This proved rather popular with listeners, who could now adjust their clocks and watches daily, so the BBC decided to invest in some more high-tech clocks from the Synchronome Company. These provided audible ‘ticks’, which the announcer then simply counted down.[]

What Is Replacing Shortwave? (Radio World)

A joint effort is necessary to bring the digitization of radio to a successful end

Analog shortwave will celebrate about 100 years of existence in 2028 when many hope 5G will have been properly defined, tested and applied, though broadcasting is low on its long list of perceived advantages.

It’s true that shortwave was typically a medium of the Cold War that peaked in 1989 and that afterward its listenership dwindled. Many international broadcasters gave up on it as the post-war transmitters got rustier and the energy bills kept mounting.

After all, when budget cuts are needed, no transmitter will go on strike or write to the press, as happened when the BBC World Service tried to unsuccessfully close its Hindi shortwave transmissions in 2011. In 2020 these broadcasts stopped, when committed BBC Indian listeners, writers and thinkers who opposed it in 2011 did not protest too much.

The slow death of shortwave has been blamed on the internet and satellite. As technology and content are inextricably linked, shortwave created its type of content that is no longer favored by the savvy FM listener, internet user and cellphone obsessed.[]

Filter Basics: Stop, Block and Roll(off) (Nuts and Volts)

A casual observer might think that wireless systems consist primarily of filters connected by the occasional bit of circuit! Block diagrams of transceivers often include as many filters as any other function. This is true at the system level, just as it is at the circuit level — and many circuits behave in a filter-like way, whether intended to be a filter or not! That makes understanding filter basics important for wireless success.[]

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16 thoughts on “Radio Waves: Plant-powered Satellite Comms, BBC Pips, Filter Basics, and Replacing Shortwave

  1. Joe

    During Hurricane Sandy in 2012 wireless phone system was non existant along with cable tv. Got my news from AM radio till I could go outside to fire up portable generator in the shed. NYC tv broadcasters were telling everyone to get updates on the internet. Wired phone service was overloaded but I forgot about DSL
    But bought internet up on the computer, not much help for our aera. I had my Ham Radio equipment online but local airwaves silent. Thought Hams maintained this stuff for emergencies, shame on us. Later found out people along the coast of NJ had no communications for a week! Some places without power for 3 weeks. AM radio made me aware of sources of gasoline and the neighbors teamed up to keep all supplied with fuel. I beleive that doing away with AM stations totally would be a big mistake. Since Sandy most voice communications on has ham radio gone. Simple powerless crystal radios can receive AM. Hope the government thinks about that.

  2. mangosman

    Why would the Indians going to car dealers ask about DRM. I went through the specifications for all the variations of models of all the Indian car manufacturers. All but the cheapest version all had DRM radios as standard equipment. This is not media release this is real research, not asking a car salesperson’s view.
    Just remember that in 2 years there is now 2 million DRM equipped cars where the radio was installed AS standard equipment. The car price has not altered because of it.
    All India Radio has now transmitting cricket commentary on DRM only to a cricket mad country in addition to its normal programming. They are also simulcasting the AIR Gold FM programming. If you look at the power of the 235 FM transmitters over 100 W they are not very powerful, so have small coverage areas particularly when compared to the high power of the DRM transmitters. There was a planning meeting of all the stakeholders last month to plan how to promote DRM. It recently started at the cricket. Were you in Bengaluru in September last year and go to the cricket?
    You should also be aware that government plans in every country do not always run on time.

  3. mangosman

    How much power do you think digital radios use? The example I have seen on Utube used a DAB radio which didn’t have a digital signal to receive!
    The first DAB+ were guzzlers, 10 years ago were, but new portable radios contain lithium batteries like phones do. Now there are single chip digital radios. Remember that phones when they are on have to transmit every 15 min to identify their location.
    Digital radios installed in vehicles will go for a very long time!

    Nothing like the home of free enterprise using a system which requires broadcasters to pay xperi licence fees as do receiver manufacturers on each radio produced. DAB+ and DRM standards are free. All manufacturers have to pay for patents for the hardware and software design.
    Nothing like having to use the cell phone system to transmit to the radio logos to select broadcasters!
    Also all digital HD radio in the AM band still wastes lots of the transmitted power for the carrier as in analog. DRM does not have a carrier thus saving more than 70 % of the electricity.
    For a country which promotes itself as being technically innovative sticking with 1901 for AM and 1936 for FM technology with an upgrade to stereo in the 1960s is incredible.
    The FCC has made terrible decisions, NTSC analog colour TV, ATSC digital TV, no upgrade to 50 microsecond FM pre-emphasis and of course HD radio.
    Now that analog TV channels 2 – 6 are virtually empty, there is enough 100 kHz wide channels to fit every AM and FM broadcaster into the at spectrum with space to spare. In addition blackspots can be filled in using repeaters on the same channel. Then every broadcaster would be on a level playing field!

    Lastly I would rather have DRM in VHF band low, where there is no interference from any electrical devices or other broadcasters than AM stereo. If the stations had the programs surround sound is also available.

  4. rtc

    Thanks for your insight,mangosman.
    I’m not opposed to digital if it’s done right…which Ibiquity/iboc
    has not been with its $ monopoly from radio factory to radio station.
    If it were mandated one company-Ibiquity- would control all radio
    broadcasting in this country.
    All digital AM supporters will face an uphill battle from the Pentagon,EMA
    and Civil Defense folks because analog AM is here and it works
    despite its shortcomings.
    It *could* be improved if they allowed stations to go beyond the 10.2K
    bandwidth during the daytime…there is a local daytime-only station here
    that sounds like they are running ~12-13k bandwidth and it sounds much
    Bring back AM Stereo,too…it was great.

  5. arthur ascii

    Dab and drm receivers are waaaaay too current hungry !

    You’ll be lucky to get a few days use it of it
    compared to months or sometimes even a
    year on an old fashioned am rx and dry cells.

    In an emergency or shtf scenario you don’t want to be constantly worrying about
    charging in a drm or dab radio !

    1. rtc

      You are so right,arthur ascii.
      Everyone would have to have plenty of extra batteries,or a whole house generator,etc.
      which many people can’t or won’t do.
      Events like the storms in Nashville show that,like it or not,analog AM/FM is the fallback
      when all else fails.
      We were without power in the spring 2011 storms and a local AM provided local info we
      couldn’t get anywhere else…heard a lot of caller’s cell phones pop out,too.

  6. mangosman

    You haven’t commented on the success in India. 2 million cars in 2 years fitted with DRM in the factory prior to delivery. 600 million people covered with strong DRM signals including some with DRM only.
    No mention that DAB+ and DRM have almost identical transmission standards except for the frequency range and the data rates used. Therefore it is easy to make combined DAB+/DRM receivers. Fortunately all DRM receivers have a screen which can show pictures, not like the single line of scrolling text of most DAB+ receivers.
    As far as audio quality goes, firstly look at the source. All digital radio systems use lossy compression. This is fine if it only happens once, however if compression happens upstream and then decompressed the effect is horrible. Also are they using xHE-AAC compression which is much better at low data rates.

    5G is a poor technology because you have to use it in the 26 – 28 GHz range where the repeaters have to be a maximum of 900 m apart, the signals won’t go through heavy rain, wet leaves on trees, walls, hills…
    In addition the huge data rate is not required for radio! Each repeater then have to send the data to and from the Internet Service Provider. What happens if the electricity fails on the street!

    I agree with switching off MW because it uses AM. AM must have a carrier which is 67 – 100 % of the transmitted power depending on the volume of the sound. This carrier carries no sound information. It just wastes lots of electricity. It would be better to either go to DAB+ in areas of high population density or DRM elsewhere.
    RTC. Digital radio has nothing to do with Microsoft or even the greedy telcos.
    I bought a DAB+ radio about 10 years ago and the sound is much better than MW-AM and using my newer hand held DAB+ radio, i go on long walks, headphones on listening to the good stereo on DAB+ from an AM broadcaster.
    Lastly you all forget that both DAB+ and DRM can transmit stereo sound, images, indexed text, electronic program guides and even updates to GPS in vehicles to route around road closures. All of which can be used in Emergency Warning System which can be isolated to a defined area

    1. Keith Perron

      Success in India of DRM. Well that is debatable. When I was there in December buying some Royal Enfield parts and checking the car markets in Chennai & Mumbai. Yes the 600 million figure sounds impressive, but not so impressive when you talk to Tata & Hindustan. None of the dealers I spoke to told me they almost never get anyone asking about the DRM radios and are more interested in bluetooth.

      The introduction of DRM radios in cars in India was because the car companies get money from the government. AIR (All India Radio) spent millions converting sites to be able to transmit in DRM. But since late last year AIR has been under the spot light for the million spent, but not being able to show results.

      The car I rented in Chennai was a Tata Altroz. Yes, it did have a DRM receiver. The DRM receiver did work and worked well. But only 50% of the time. In the parking lot of the hotel. it was fine, when driving it it another story. Signal kept being lost. On the drive from my hotel to the Royal Enfield factory, which was about 1 hour drive the signal strength was between 2 and 4. And when it was it was choppy and under 3 nothing. Not impressive. Outside the city center it was even worse.

      The only time I have ever heard DRM work well with no interruptions was about 15 years ago when Babcock and the BBC did a test for a DRM conference. And in Vanuatu where one of the local stations receives DRM from Radio New Zealand for relay.

      If you look DRM. In reality Radio New Zealand International is really the only one using DRM perfectly. They use DRM as a lower cost means of relaying programming to the Pacific, which is far cheaper than satellite. They will continue to do so for perhaps the next 5 years. But there are a number of Pacific Island Nations who are having mobile networks upgraded as a very fast rate.

      First time I went to Gilbert Islands in 2009 mobile data was terrible and on the main island there was almost no signal and it was very expensive. In 2017 that all changed.

      DRM reminds me of BETA. There were a few countries where BETA did well, But BETA SP went on to be successful in the professional industry and BETA in the consumer industry died off.

      1. RonF

        > “None of the dealers I spoke to told me they almost never get anyone asking about the DRM radios and are more interested in bluetooth.”

        I’ll just say that this, and the comment about reception quality, lines up with my own experiences spending some time (1-2 months each) in India during 2016 & 2019 – mostly around New Delhi / Guguram, but with a fair bit of travel around the northern & central parts. I mentioned some of my experiences with DRM there to AlanH in, IIRC, early 2017 – but, as usual, he refused to believe it over his usual emphatic interpretation of press releases. (I’m pretty sure he still believes All India Radio will turn off AM by August 2017! 😉 )

        1. Keith Perron

          Sadly for AIR (All India Radio) DRM is the least of their problem. The management structure is such that you can have as many as 10 doing exactly the same job. The other issues is its over inflated staff.

          During a motorcycle trip I was doing around Uttar Pradesh and Bihar regions, which border Nepal and Bangladesh. At night I would use the motorcycle battery to power inverter to charge a laptop and phone. The radio I had with me had DRM. It did manage to work. But sadly with sometime like DRM if you don’t have a good enough signal it keeps cutting out.

          I love DRM, but all the years the wasted at the beginning and with major manufactures pulling out. The writing is on the wall. Also don’t forget is the broadcasters and manufactures still behind the DRM Consortium pull the money. Well bye bye.

          Back in 2008 Sangean lent me for a few weeks a prototype DRM receiver that had work on. It was nice, it worked well, but then they decided the market wasn’t big enough to justify the expense to have it go in production. Its now sitting in their museum, which you can visit if your in Taipei. Its very interesting.

          Another footnote on Sangean. The ATS909x price here has had a dramatic drop. The few official dealers in the electronics area that carry the the 909x have cut the price to 2000NTD (around 65 USD). When i asked why they said they are clearing out what stock they have and that once these are gone there will be no more.

      2. mangosman

        The following power is the power of the simulcast transmitter
        Chennai has 720 kHz AM at 200 kW of carrier,
        To prevent interference during simulcasts the average DRM power is only 6kW on 729 kHz
        A second AM transmitter on a different site near Chennai is 783 kHz at 20 kW DRM because it is not a simulcast transmitter.
        Mumbai has 558 kHz AM at 100 kW
        567 kHz DRM at 3 kW
        1044 kHz AM at 100 kW
        1053 kHz DRM at 3 kW
        Note: there is DRM only transmissions at 1530-1630 daily except Sundays which would allow full power to be used. Did you listen at this time?
        The TATA car has a short twisted wire rod antenna which is much too short. When AM was king, cars used a telescopic aerial from the fender which would have been around a metre long? In more expensive cars it would erect using a motor when the radio was on.

        As far as bluetooth goes, was it to be able to make phone calls whilst driving hands free?

        The mass publicity for DRM is yet to start, but is being planned. There is no point unless the transmission network is fully operational complete with stereo sound, emergency warning system for a double monsoon country so to also to be able to show maps and Journaline. You have to make it more attractive otherwise no one will buy. Once there is enough receivers in the market you can then market the new technology and when users find it in there cars they can demonstrate it to others, particularly when the international cricket is on. The cricket has returned to the radio.
        Radio New Zealand Pacific are doing it right by producing program completely in digital and compressing the audio prior to a digital studio-transmitter link. They however need to upgrade the compression to new xhe-AAC.

  7. Keith Perron

    The piece by Ruxandra Obereja made me laugh. I’ve met her few times. The best was to describe her is an civil servant who will stay to the end no matter what. Not because she believes in what she is doing, but rather clinging on to her huge retirement package.

    Ruxandra Obereja use to in the Romanian Language Service of the BBC World Service. When the BBC was making cuts, she was one of those people that because of seniority they were unable to get rid of. She was too young for the golden handshake, but had enough seniority to just bump someone else.

    When she was elected at VP of the EBU (European Broadcasting Union) in 2009 the BBC was pushing for her to get elected to the role so as that way she would no longer be on the BBC’s payrole. Her salary now is from the DRM Consortium, which gets its budget from the broadcasters involved and other public funds across the EU and others.

    If you read the piece in Radio World and go back over the last 10 years and read every press release issued by the DRM Consortium. Its as if she cut and paste bits and pieces from each of them.

    Personally I love DRM. But its been over 20 years and it really hasn’t move. Like Mark pointed out when DRM works, it works well. Sadly the majority of DRM broadcasts don’t even come close to where it should be.

    Investing in DRM now would be like investing in new DVD technology. When I look at how many manufactures and broadcasters were involved in the consortium 20 years ago compared to now. It makes me think of SONY holding on to BETA right to the very end.

  8. Mark

    Who knows, perhaps 5G is intended to be some sort of Population control? Some kind of Climate Change reversal attempt ? seriously though, I think a lot more research should have been done on 5G, why the big rush ?

    DRM impresses me in the fact that the distances it can cover on little power are truly amazing, for instance, I can at times receive CRI perfectly which is transmitted from China @30 Kw and I can struggle to Decode Radio Romania International DRM here in Ireland despite RRI being a much stronger signal, I can successfully decode CRI at a much reduced power levels.

    Now the bad, all DRM transmissions are crap quality with that God awful digital highly compressed digital ringing noise, it’s just terrible stations decide to favour efficiency over Audio quality because DRM is capable of much more than 16 Kbps that’s the one real issue I have with DRM, give me analogue any day. Then there’s the all or nothing signal like DAB which is crap also, better Audio quality but all or nothing signal.

    These decisions to change everything to Digital are because more and more people are using apps and those that make these decisions to shut off analogue probably never used MW or SW in their lives and use spotify and tune-in-radio all the time.

    The BBC are trying to save money by spending millions on a digital network, how do you save money by spending millions ? they’re “committed to a digital future” and see no place for MW, they closed many MW stations in 2019 and at least 20 more in the coming months and next you know there’s be hardly any English speaking MW station. On their adds, they advertise “online, on digital, on FM” and don’t even mention MW any more.

  9. rtc

    Mr. Ebel is right as rain.
    In addition let’s replace All the bad old analog with Digital (which is Always better, they say).
    But then who do we pay?
    With Digital you gotta always pay.
    And pay.
    And pay.
    I am so weary of misinformed digital types hyping it… .
    If it ain’t broke don’t fix it,not the Microsoft Corollary,if it
    ain’t broke,break it.
    Gee,our analog ears still work pretty good.

  10. Adam Ebel

    Sorry to disappoint you, but 5G is not going to be a good source for radio communication since it requires cell phone towers everywhere even out in the ocean where there are no cell phone towers. 5G is not the best alternative for short wave radio. Maybe DRM (Digital Radio Mondale), but not 5G. I am already seeing that 5G is a health hazard for most users, and using 5G for alternative radio communications is just pushing it beyond boundaries. 5G uses milliwaves which there have been numrous reports that it’s killing the honey bees, the birds and other wildlife, because the milliwave RF radiation is too intense that it’s not really nature friendly. 5G needs to be replaced with something else, and no, it’s not going to replace radio communications. We need to keep on using short wave radio high frequency waves for world wide communications for years to come. I am not going to support the 5G agenda, sorry, maybe some other alternative cell phone service. Plus owning a 5G device is more expensive than owning and listening to a analog or digital (DRM) short wave portable radio. Let’s keep the hobby going!


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