New DRM tests on 954 kHz planned from the Czech Republic in 2022

It was announced recently that České Radiokomunikace (CRA) in the Czech Republic has obtained a license from the Czech telecoms regulator (ČTÚ) to conduct a DRM test on 954 kHz in the city of České Budějovice in the south of the country.

The transmitter will have a power of just over 3kW which means it may be heard across Europe at night. The 954 kHz is one of the medium wave frequencies where the (AM) programs ČRo Dvojka and ČRo Plus were broadcast until the end of 2021.

CRA wants to use the test, among other things, to determine the scope and energy efficiency of broadcasting in the DRM standard. Both the 16 QAM and 64 QAM, the two common modulation schemes in DRM, will be tested. The operator will use an existing Transradio medium wave transmitter into which they will integrate a digital modulator.

The DRM system has long been touted as the digital replacement for AM on the Medium Wave and Short Wave bands. In 2003 and 2006, the Czech public broadcaster ČRo conducted a series of DRM tests on medium and short wave so these new tests should be seen in that light.

DRM has gained a foothold in countries like India but the take up has been slow elsewhere in the world.

New Android App for decoding DRM digital radio broadcasts

 

On the 13th of April 2021, a company named StarWaves announced the release of a new Android app called DRM SoftRadio. The app allows a user of a Software Defined Radio (SDR) to listen to any DRM digital broadcasts on an Android smartphone or tablet.

DRM or Digital Radio Mondiale is the global digital radio standard used for digital transmissions on medium wave and short wave in several countries. 

Some of the features...

Languages: English, German, Simplified Chinese

Convenient frequency tuning and DRM Service selection

Journaline, DRM’s advanced text application, allows to interactively browse through latest news, sports and weather updates, programme background information and schedules, distance learning/RadioSchooling text books, travel information, and much more

Free tuning to any DRM broadcast frequency

Supports all DRM frequency bands – from the former AM bands (LW/MW/SW) to the VHF bands (including the FM band), depending only on RF dongle functionality

Graphical spectrum view to check the signal on the tuned frequency

For live reception, an SDR RF dongle must be connected to the device’s USB port (with USB host functionality). The following SDR RF dongle families are currently supported, along with a range of specifically tested models:

Supported SDR receivers...

Airspy HF+ family: Airspy HF Discovery, Airspy HF+ (Dual Port). (Note: Airspy Mini and R2 are NOT supported.)

SDRplay family: SDRPlay RSP1A, SDRPlay RSPdx, SDRPlay RSPduo, SDRPlay RSP1, SDRPlay RSP2, SDRPlay RSP2pro, MSI.SDR Panadapter (Note: SDRPlay family support on Android is currently limited to the 32-bit version of this app.)

RTL-SDR family: The experimental support for RTL-SDR based RF dongles requires that you manually start the following separate tool before opening this app (on standard port ‘14423’): The app ‘SDR driver’ can be installed from the Google Play Store and other Android app stores.

Analysis... While DRM (Digital Radio Mondiale) has been around as a digital radio standard since 2003, it has proved difficult to get accepted by broadcasters and the general public. Broadcasters were unwilling to use DRM due to a lack of suitable receivers and the public weren't interested because there were a lack of DRM transmissions.

That has changed of late with the introduction of DRM transmissions in the medium wave band in India. Considering its population, it is assumed that this will kick off the development of cheaper DRM receivers.

While SDR receivers are probably used more by those interested in technology and radio rather than the general public, this new app does open up DRM transmissions to a whole new audience.

The app costs in the region of €5/$5 which is very modest for most SDR users.

It is my understanding that a Windows version is being developed by the company and this should be of interest to an even wider audience.

Links...

1) StarWave news release - 13th April 2021

2) Google Play Store

3) Official DRM website

Successful DRM tests on the FM band (88-108 MHz) in Russia

 

DRM (Digital Radio Mondiale) has long been touted as a possible replacement for the analogue AM and FM modes on the radio broadcast bands. The transition to digital has proved problematic as broadcasters and listeners are happy to continue with the status quo, especially on the 88-108 MHz FM band.

While many countries have opted for DAB and DAB+ transmissions on the VHF Band 3 (175-225 MHz), some countries are looking at the option of using DRM transmissions in the spaces between the FM signals on the 88 to 108 MHz band.

From June to December 2019, a sixth month trial DRM transmission was carried out in the Russian city of St.Petersburg. The 800-watt DRM transmitter was on 95.7 MHz between the FM radio stations Studio 21 at 95.5 MHz and Comedy Radio at 95.9 MHz. 

The main audio source for the trial was the Comedy Radio, which was broadcasted simultaneously as an analogue FM service (3KW) and a DRM service (0.8KW). This allowed a direct comparison to be made between the analogue FM and DRM coverage.

The results of the trial were publish in December 2020 in a paper titled..."RESULTS OF THE DRM SIMULCAST FIELD TRIAL IN FM BAND IN THE RUSSIAN FEDERATION... June to December 2019"

Some of the main conclusions were as follows...

The trial has shown that for DRM Simulcast with frequency offset of 150 kHz, DRM digital signal does not interfere with the analog FM signal at a power difference up to -10 dB.

For a frequency offset of 200 kHz, the digital DRM signal does not interfere with the analog FM signal at any power values that the transmitter could provide.

Because DRM Simulcast allows to keep FM broadcasting and launch terrestrial digital radio broadcasting in the same frequency range. DRM multiplexes can be launched between existing FM radio stations without interfering with them. To do this, it can use one transmitter and existing combiner and antenna system.

20:1 Digital Power Advantage... In separate tests done in Indonesia, it was claimed that six test points covered by the 1 kW transmitter (FM) could be served with only 50 watts of DRM power. “In testing a simulcast broadcast using 1 kW and 800 Watt with spacing distance 150 kHz between the middle frequency FM and DRM, the measurement showed no interference between FM and DRM. The DRM quality was at least equally good to FM, but the sound quality of DRM was even better than FM.”

In an article titled "Use DRM on India’s FM Band", the chair of the of the India chapter of the DRM Consortium Yogendra Pal stated..."Using DRM, in the allocated 200 kHz bandwidth, a broadcaster can transmit up to six high-quality audio services along with a host of value-added services and Emergency Warning Functionality (EWF). All digital services work without disturbing the existing analog FM services."

He also claimed that mobile phones that used for listening to analogue FM transmissions can also be used for listening to DRM transmissions as long as manufacturers allow the DRM app to access the baseband digital output.

"DRM standard can be supported natively on all mobile phones based on the already available tuners for analog FM reception. No additional hardware and, therefore, no additional design or component cost is required to enable DRM digital FM support on these phones.

The DRM App for mobile phones has already been developed and demonstrated by a number of organizations. Only the mobile phone manufacturers need to provide access of the baseband digital output. "

In summary... A lot of the information shown above is from the DRM industry who obviously want to push the new digital standard. However, the tests of using DRM on Band 2 (88-108 MHz) do suggest that there are more options than just setting up a new digital broadcast band elsewhere on the VHF spectrum. There are spaces in the FM band (88-108) and DRM can utilise those gaps.

Band 2 also tends to have mush better mobile coverage than the higher VHF bands around 200 MHz which are used for DAB transmissions and many listeners already have dedicated aerials for the 88-108 MHz band.

Transmitting DRM on Band 2 is also an attractive option for broadcasters in that they can use the same antennas and infrastructure. It provides them with an obvious path to gradually migrate to digital only services in the future.

Cambridge Consultants announce low cost DRM receiver design

DRM or Digital Radio Mondiale has long been touted as the digital solution for Medium Wave and Short Wave broadcast radio with higher efficiencies and less noise. There have been tests for well over a decade but very few adopters until now.

India now has 35 DRM transmitters covering the sub-continent with a potential audience of about a billion people. There is however still a serious issue regarding the high cost of receivers.

A company called Cambridge Consultants have now announced a prototype of a DRM design which will cost $10 or less. If they are successful, it could be a game changer for digital radio.

This is from their press release... "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. "

More info HERE