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DRM broadcast (left) as seen via a KiwiSDR spectrum display.
Many thanks to SWLing Post contributor, Michael Bird, who shares the following news via Cambridge Consultants:
Digital launched, ever so long ago, with TV and radio. So what’s the big story? It’s that the last piece of the digital jigsaw is finally in place: a system called Digital Radio Mondiale (DRM), designed to deliver FM-radio-like quality using the medium wave and short wave bands.
We’re familiar with AM on medium wave and accustomed to the horrible buzz, splat, fade away and back again. But it does have a great advantage in that it will reach for hundreds of miles from a single transmitter. That’s a lot easier than FM or DAB, which both need transmitters every 30 or 40 miles. No fewer than 443 DAB transmitter sites are needed to cover the UK alone.
So take a modern digital scheme, apply some clever (and low cost) computing power, and you can get good sound for hundreds of miles. You get to choose radio stations by name instead of kilohertz, and you can even receive text and pictures. Emergency warning and information features are also built into DRM.
Great technology. But will it fly? Is it available for everyone?
The new news is that India, through its national broadcaster All India Radio, has invested in and rolled out a national DRM service, live today. Just 35 transmitters cover that large country. New cars in India have DRM radios in them now. Other countries like South Africa, Malaysia and Brazil are likely to follow India’s lead.
But something’s missing. The radios that can receive DRM are still prohibitively expensive, especially for those markets that would benefit most. So vast swathes of the world remain unconnected to the services that DRM can provide. Where’s the cheap portable that you can pick up from a supermarket to listen to the news or sport?
Cambridge Consultants has just held its annual Innovation Day, where we throw open our doors to industry leaders and reveal future technology. One of our highlights was the prototype of a DRM design that will cost ten dollars or less to produce, addressing that vital need for information by the 60-ish per cent of our global population that doesn’t have internet or TV. It’s low power, so can run from solar or wind-up.
This design will be ready in 2020, available for any radio manufacturer to licence and incorporate into its own products. We’re doing our bit to make affordable radios for every corner of the globe!
I must admit: there have been so many proposed low-cost DRM receiver designs that never came to fruition, it’s easy to be skeptical. I assume the $10/9 Euro design will be for the receiver chip only–not the full portable radio, of course. They plan to bring this to fruition in 2020, so we’ll soon know if they succeed.
Several readers have written recently asking about the DRM tests we mentioned in a previous post. These tests are being sponsored by the Budapest University of Technology from June 1, 2019 to May 31, 2020–thus, they’ve been on the air for several months already.
The programming, which was produced by Radio Maria, is being played in a loop–repeated over and over again. The signal is a modest 100 watts and is being transmitted via a 5/8 wavelength vertical on 26,060 kHz.
This is a low-power DRM broadcast using a very modest antenna, so I suppose it goes without saying that expectations should be in check. It’s a very long-shot for those of us living outside of Europe, of course. With that said, there are a number of KiwiSDR sites nearby Budapest:
You could certainly see the distinctive DRM signal on a KiwiSDR waterfall display, but I’m not sure how you’d decode it.
KiwiSDRs do have an IQ mode, however. I am very curious if anyone has ever used a KiwiSDR to decode DRM, perhaps, using Dream? Could the KiwiSDR IQ be fed into DREAM with a virtual audio cable?
Please comment–have you ever decoded DRM via a KiwiSDR site?
BUDAPEST, Hungary —Digital Radio Mondiale transmissions began from Budapest, Hungary, last June. Although two Hungarian broadcasters previously tested DRM on medium wave, the transmissions are the country’s first DRM trials on shortwave.
The Department of Broadcast Info-Communications and Electronic Theory at the Budapest University of Technology is conducting these latest trials. Csaba Szombathy, head of the broadcasting laboratory, is also head of the project, which will last for at least 12 months.
While the 11-meter 26,060 kHz frequency is well known for use in local broadcasting, it’s rarely implemented for international broadcasting. […] Researchers have also performed tests in this frequency to measure coverage and determine optimal mode and bandwidth on various occasions in Mexico and Brazil. The new Hungarian trials will add to this research.
Szombathy initially operated the transmitter with just 10 W of power into a 5/8-inch vertical monopole. Radio Maria, a Catholic station, is providing a 25-hour program loop, while a Dream DRM software-based encoder broadcasts the signal using AAC encoding. In spite of the low power, the program was reportedly received in the Netherlands.
In early September, Szombathy moved the antenna and transmitter to a slightly different location to improve coverage. He increased the power to 100 W.[…]
Many thanks to SWLing Post contributor, Mangosman, who shares the following:
The European Union as asking its member states to legislate the following, which Germany has just done today.
EU Vehicle Directive
This directive requires all new car radios sold in the European Union to be capable of receiving digital terrestrial radio, in addition to any FM or AM functionality which manufacturers may want to include. The code also grants EU member states the power to introduce rules requiring consumer radios to include digital capability.
Following its adoption by the European Council, the directive was published in the Official Journal of the European Union (OJEU) and came into force on Dec 20 last year. For the automotive industry, the key section of the European Electronic Communications Code is Article 113, XI:
“Any car radio receiver integrated in a new vehicle of category M which is made available on the market for sale or rent in the Union from … [two years after the date of entry into force of this Directive] shall comprise a receiver capable of receiving and reproducing at least radio services provided via digital terrestrial radio broadcasting. Receivers which are in accordance with harmonized standards the references of which have been published in the Official Journal of the European Union or with parts thereof shall be considered to comply with that requirement covered by those standards or parts thereof.”
The policy commences 21st December 2020 and applies to any vehicle with 4 or more wheels. It does not apply to amateur radio equipment. The radio must be able to display the broadcasters’ name.
Note the way the type of receiver is phrased is digital terrestrial radio, it does not specify what type. It obviously applies to DAB+ because there are many DAB+ transmitters in Europe, but could also apply to DRM. With the advent of Software defined receivers, it is easy to have both standards. This would then open they way for high frequency (short wave) DRM in most vehicle radios. Remember that there are now 1.5 million factory installed DRM car radios in India which has been achieved in 18 months.
This decision will open the way for all new radios to include DAB+/DRM in all markets except the USA/Mexico.
All-Digital on the AM Band? The FCC Might Allow It Soon
AM radio station operators in the United States may soon have the option of switching their transmissions to all-digital.
It’s not a done deal; but the concept is about to take a step closer to reality, because the Federal Communications Commission will consider a proposal at its next meeting that would start a process. It will take comments on whether to allow AM band licensees to make the switch if they want.
Ben Downs, VP/GM of Bryan Broadcasting in Texas, petitioned the FCC in March to initiate a proceeding to authorize the all-digital mode of HD Radio.
Allowing stations to use all-digital transmission is an idea that some broadcasters feel could give business-challenged AM stations in the United States new life or at least another option. Turning off their analog signals would mean that most existing receivers could no longer pick up that signal; but many AM broadcasters are currently heard on FM translator simulcasts now. And adding the all-digital AM option could open up new possibilities for them as the number of digital receivers in the marketplace continues to grow.
[…]Chairman Ajit Pai described the proposal in a blog post Monday: “Just as the FCC is trying to keep pace with changes in the market, so are AM radio operators, and the commission wants to give them as much flexibility as possible to compete in the digital age,” Pai wrote.[…]
The Radio World article mentions WWFD in Frederick, MD–a station that has been broadcasting AM digital for over a year. We posted a note about this last year and I even included a short recording/video with reception when traveling through the area.
Many thanks to SWLing Post contributor, Mike Ladd with SDRplay, who shares the following guest post:
Basics to decoding WEFAX using an RSP and SDRuno
by Mike Ladd
SDR I use: RSPduo from SDRplay using the Hi-Z input. Any model RSP’s can tune WEFAX transmissions. https://www.sdrplay.com/rspduo/
Antenna I use: Megaloop FX from Bonito. In an Inverted delta loop configuration pointed N/E-S/W. Any good antenna placed outdoors should be fine. It’s all about the SNR, not your S-meter reading. https://www.bonito.net/hamradio/en/mega-loop-fx/
Software:
SDRuno v1.32
SDRuno is an advanced Software Defined Radio application platform which is optimized for use with SDRplay’s range of Radio Spectrum Processing receivers. https://www.sdrplay.com/downloads/
VBcable (donationware) vPack43
Transfers audio, digitally from one application (SDRuno) to another (Black Cat HF weather Fax) with zero loss. https://www.vb-audio.com/Cable/
Black Cat HF Weather Fax (paid for use) beta 19
Decodes and produces images from the WEFAX transmissions from the output of SDRuno using a virtual audio cable.
Black Cat Uno UDP
UnoUDP allows you control SDRuno’s VFO frequency from within Black Cat HF Weather Fax scheduler. This is done over a virtual com port pair using a virtual com port emulator. http://blackcatsystems.com/download/UnoUDP.zip
VSPE or COM0COM
VSPE is a paid for use app. COM0COM is completely free. Either one of these applications will work. A virtual com port emulator allows you to create a virtual com port. The pair will internally link Black Cat Weather Fax decoder to SDRuno’s using UnoUDP as the transport protocol.
This document is not a definitive guide to the WEFAX protocol, the process of decoding WEFAX images or reading a synoptic weather chart https://youtu.be/kzfNSvQREu8. This is only a collection of information that I have found scatter throughout the internet and re-compiled into a document, this document. Expect typographical mistakes, inaccuracies, or omissions.
WEFAX is an analog mode for transmitting monochrome images. It was the predecessor to slow-scan television (SSTV). Prior to the advent of the commercial telephone line “fax” machine, it was known, more traditionally, by the term “radio facsimile”.
Facsimile machines were used in the 1950s to transmit weather charts across the United States via land-lines first and then internationally via HF radio. Radio transmission of weather charts provides an enormous amount of flexibility to marine and aviation users for they now have the latest weather information and forecasts at their fingertips to use in the planning of voyages.
Radio fax relies on facsimile technology where printed information is scanned line by line and encoded into an electrical signal which can then be transmitted via physical line or radio waves to remote locations. Since the amount of information transmitted per unit time is directly proportional to the bandwidth available, then the speed at which a weather chart can be transmitted will vary depending on the quality of the media used for the transmission.
Radio fax data is available from the web on sites such as the ones hosted by the National Oceanic and Atmospheric Administration (NOAA). https://tgftp.nws.noaa.gov/fax/marine.shtml Radio fax transmissions are also broadcasted by NOAA from multiple sites in the country at regular daily schedules https://www.nws.noaa.gov/os/marine/rfax.pdf. Radio weather fax transmissions are particularly useful to shipping, where there are limited facilities for accessing the Internet.
Black Cat HF Weather Fax is a program that decodes WEFAX (Weatherfax, HF-FAX, Radiofax, and Weather Facsimile) transmissions sent from fixed locations around the globe.
A fax is transmitted line by line, typically at a rate of 120 lines per minute, or half a second per line. For example, to send a weather chart, you would start in the upper left corner. You would send the value of that pixel (dot), black, white, or perhaps a shade of gray. Then you would move over one pixel to the right, and send that pixel, and so on, until you reach the edge of the chart. Then you’d move all the way back to the left edge, and move down slightly, one line, and repeat the process.
Each pixel is converted into a certain audio frequency or tone. By convention, a tone of 1500 Hz represents black, 2300 Hz represents white, and frequencies in-between represent shades of gray. So if you listen to a fax transmission, you’ll hear the different tones as each pixel is present. For example, listen to a chart with mostly white background being sent. You’ll hear mostly the high pitch 2300 Hz, and some lower (1500 Hz) blips as each black pixel is sent. When a horizontal line is sent, you’ll hear a long half second burst of 1500 Hz, since the line is all black.
The transmitting station frequency modulates the carrier. That is, when a black pixel is transmitted, the carrier shifts down 400 Hz. When a white pixel is transmitted, the carrier shifts up 400 Hz. For a medium gray pixel, it stays on the assigned frequency. This is how most fax transmissions are made. Since we’re tuning it in SSB, it sounds to us as if the station is transmitting a variable frequency audio tone. The two processes are identical. This accounts for the confusion regarding what frequency to tune the radio to in order to properly decode the fax transmission. Different stations list their frequency in different ways. It is important to remember that a black pixel produces a 1500 Hz tone, and a white pixel produces a 2300 Hz tone within the AUX SP.
The setup works as follows. SDRuno demodulates the received signal. The demodulated audio is piped from SDRuno using virtual audio cable and sends it to the HF weather fax decoder. HF weather fax decoder receives this audio from the virtual audio cable that was demodulated from SDRuno and processes it, producing a picture on the screen
HF weather fax decoder can also set the VFO (tune) frequency of the RSP in SDRuno. This is done over the virtual com port pair using the UnoUDP application as the transport.
SDRuno can internally emulate a Kenwood TS-480, UnoUDP sends the Kenwood TS-480 serial commands via UDP over the virtual com port pair in order to set the frequency selected from the HF Weather Fax Scheduler option over to SDRuno.
You will need to install and configure the following applications.
1: A virtual audio cable.
2: A virtual com port emulator (If you would like HF Weather fax to communicate with SDRuno).
3: UnoUDP (If you would like HF Weather fax to communicate with SDRuno using the virtual serial emulator).
4: HF Weather Fax.
5: A simple wire antenna placed outdoors.
Virtual Audio Cable:
A virtual audio cable allows you to pipe the audio from one application (SDRuno) into another application (a decoder like HF Weather Fax) digitally. I will assume SDRuno is already installed with your device attached and functioning properly.
You can now download a virtual audio cable package. If you already have a virtual audio cable package installed, you can skip to the next section. If you don’t have a virtual audio cable application installed, you only need to choose one and install only one of the two that are available.
Close any running apps, install the virtual audio cable and reboot your computer. When your computer boots to your desktop, your computer will now have a virtual audio cable pair installed on the system.
You can verify it the installation by going to your Control Panel and double clicking the Sound icon. VB-Cable and Virtual Audio Cable will only install a single virtual audio cable pair, one is for the input (Recording) and one is for the output (Playback). A single pair is all that is needed (as shown below).
Virtual Serial Port:
A virtual com port emulator is only needed if you would like Black Cat HF Fax decoder the ability to tune the station in SDRuno when you double click a station name in the HF Fax Decoder scheduler.
Please use the links provided (additional PDF’s and YouTube videos) on Page 2 of this document for an installation / configuration walkthrough.
Download the latest HF Weather Fax beta package and the UnoUDP application from the link provided on Page 2 of this document. I suggest making one main folder called HFfax and two subfolders within HFfax for each of the applications. One folder is for the HF Weather Fax Decoder and the other folder is for the UNO UDP transport application.
Double click the HF Weather Fax beta ZIP file you downloaded and extract the full contents of this ZIP into the folder you created on your local drive. Right click the “Black Cat Weather Fax” EXE file and send a shortcut to your Desktop.
Double click the UnoUDP zip file you downloaded and extract the full contents of this ZIP into the folder you created on your local drive. Right click the “UnoUDP” EXE file and send a shortcut to your Desktop.
You should have two shortcuts on your desktop, One for the decoder and one for the transport app.
Black Cat UnoUDP:
HF Weather Fax needs a way to communicate with SDRuno, this is done via UnoUDP and the virtual com port emulator.
Launch UnoUDP with the above configuration. Set your UDP Receive port to 58084 and your UDP send port to 58083. UnoUDP must be left running in the background, this will control SDRuno. You can minimize the application or right click the shortcut and have UnoUDP auto minizine on launch.
You should see a Firewall popup prompt asking permission to allow UnoUDP to pass data within the system. You must allow this traffic to pass or external control of SDRuno will not be possible from the HF Weather Fax decoder scheduler.
Assign 1 of the 2 com ports from the virtual com port emulator to UnoUDP (the 2nd com port will be assigned to SDRuno). My com port pair is Com 1 and Com 2, SDRuno uses Com1 and UnoUDP uses Com 2.
Black Cat HF Weather Fax:
HF Weather Fax needs to be configured in order to communicate with UnoUDP, this is done via the UDP settings. Click “Edit” and “Preferences” Set the UDP Send port to 58084 and the UDP Receive port to 58083.
You should see a Firewall popup prompt asking permission for HF Weather Fax to pass data within your system. You must allow UDP traffic to pass or external control of SDRuno will not be possible from the HF Weather Fax decoder scheduler.
SDRuno:
SDRuno needs its Output assigned to the Virtual Audio Cable. The output can be changed via the RX CONTROL panel, clicking the SETT. button on the top left and clicking the OUT tab.
SDRuno needs a com port assigned so it can be externally controlled. The serial port is assigned via the RX CONTROL panel, clicking the SETT. button on the top left and clicking the CAT tab.
I recommend running the RSP in LOW-IF mode, this is selected via the MAIN panel. This reduces the need to track separation between the Tuned frequency and LO (local oscillator) https://youtu.be/Fsns4P3JxrM
LOW-IF mode also minizines the LO being placed outside of the desired preselect filter of the device in use, Remember the preselect filter is automatically enabled based on the LO frequency https://youtu.be/w-vkiVp7Q4E
I also recommend leaving the IF AGC enabled and placing the RF GAIN as high as possible without causing an ADC OVERLOAD warning within the MAIN panel. If an ADC OVERLOAD warning appears, back the RF GAIN down.
Launch SDRuno. Set the mode to USB and the filter width to 2.8k
HF weather fax will not set the mode or filter width at this time.
Click the Sked button in Black Systems HF Weather Fax. A current WEFAX transmission schedule will appear. Stations listed in White are either scheduled to transmit or about to transmit based on your computers clock. Stations show in Grey at the bottom of the list are currently off the air or not transmitting.
In the Freq Offset: box enter -1.9 and hit enter (Reason for this is on Page 5).
Click any of the stations listed in the Fax Transmission Schedule and it will automatically tune SDRuno to the correct frequency.
Black Cat HF Weather Fax folder will have a file named “Black Cat HF Weather Fax Docs” Please view this file to understand some of the advanced features available.
Your first decode (Without UnoUDP)
Launch Black Cat HF Weather FAX.
Launch SDRuno.
Navigate to the Memory Panel (MAIN panel and click the MEM PAN button)
Right click the Memory panel and select “Open bank”. Navigate you C drive telling SDRuno the location of WEFAX.s1b
Double click any of the frequencies shown within the WEFAX bank and SDRuno will set the correct mode and tune that station. My WEFAX.s1b file defaults to the Hi-Z port. If your device lacks a HI-Z input, navigate to the port section within the memory panel, double click the stations port you want to edit and change it to the correct port that’s available or in use for your device. Right click the memory panel and “Save bank” to save the changes.
To use my SDRuno WEFAX frequency bank properly. The MCTR button must be enabled within the RX CONTROL panel, enabling this option allows you to double click and tune a station that is stored within the WEFAX bank. Make sure the LO is not locked in the MAIN panel (LO LOCK).
If a decoded WEFAX image looks blocky or skewed or possibly pixeled, I recommend that the lock output fractional resampler option is enabled in SDRuno. You can enable this from the RX CONTROL panel, clicking the SETT. button on the top left and clicking the OUT tab.
I hope this document helped guide you in getting started with decoding WEFAX transmissions from around the world. I am sure I missed some key features, remember this is only a primer/basics to decoding WEFAX. I do have an accompanying video located here
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In the 1950s radio was declared mortally wounded by TV. But then FM with its new music rescued it, becoming one of the most successful technologies and platforms ever. Radio survived and thrived but AM should have died at the hands of the nimbler, younger and more attractive FM.
Only it did not and the medium reinvented itself by using presenter-led programming, commercial music and sport. In the United States it took until the end of 1990s for the FM and AM audiences to be equal and to this day the big AM stations are going strong, bringing in the ad dollars.
REASONS
Still, it’s undeniable that the whiff of decline has enveloped AM in the past two decades. The reasons are well-known: Analog medium wave doesn’t always deliver the best sound, it can suffer from interference, it can behave annoyingly different by day and night and even by season. Medium wave mainly appeals to a maturing population (a global phenomenon, considered shameful by some!) using aging receivers (this is bad!).
[…]
THE SOLUTION
Recently cricket fans were able to enjoy an open-air demonstration of three different DRM programs on one frequency ahead of an important match in Bangalore. The fans also received data (stock exchange values) available on radio screens. This demonstrated that digital DRM is a game changer for medium wave.
In DRM the crackling audio disappears as sound is as good of that on FM. The electricity consumption and costs decrease, the spectrum is trebled and reception, even in cars (as available in over 1.5 million cars in India currently) is excellent, too.
If it is so good then why isn’t DRM medium wave conquering the world faster? Maybe it’s about confidence in a new platform. Broadcasters and governments need to market DRM digital radio once signals are on air in their countries.
As for receiver availability and their costs, let us remember how many receivers were on sale in the 1970s when FM was taking over the world. Nowadays, many listeners consume radio in their cars rather than sit in front of a retro looking wooden box. Digital receivers (DRM alone or DRM/DAB+) are a reality and a bigger push for digital would help with volumes sold thus bringing down the prices.[…]
