Most FM broadcasting transmission chains have at least a basic degree of audio processing included, in order to improve the audio loudness. The reason for this is related to the radio listeners’ typical environment: driving in the car, cooking in the kitchen, working in a factory, etc. These environments can be loud and radio audio needs to help to cut through this!
While this is the main reason for audio processing, it is also used for:
- Consistent levels – so listeners don’t have to adjust the volume constantly
- Consistent sonic signature/EQ – so a radio station can have a unique sound that is appropriate for their format of music
- Optimization of the signal to noise ratio of the channel
- Controlling the interference of neighboring radio stations through peak and bandwidth limiting
What is audio processing?
Audio processing uses a combination of compression and limiting to lower the dynamic range, reducing the peak to average the ratio of the audio at each subsequent stage.
1. Compression stage
Compression reduces the dynamic range of the audio slowly, in a manner similar to an operator riding the gain. Compression is usually performed on the RMS level of the audio waveform and is usually gated to prevent ‘suck-up’ of noise during silence or quiet periods. In addition, compression is usually multi-band.
2. Limiting stage
Limiting has faster action and higher ratios than compression. Audio is split into several frequency bands (often 4 or more) so that bass sounds, mids, and highs are processed separately. This prevents most of the problems you get with basic single-band limiters. Each band is compressed in dynamic range – the quiet parts are boosted and the loud parts reduced. It creates a denser, louder sound but can create intermodulation distortion if overdone.
3. The clipping stage – FM & AM
Removes all audio above a certain clipping threshold. Reduces the peak to average ratio of the audio dramatically. It will produce harmonic distortion, and if overused it can also produce intermodulation distortion. The clipping stage has zero time constants, so it has no effect on surrounding audio.
Why do I need audio processing at my radio station?
Most radio stations, big and small, use audio processing in order to stand out from the crowd and get more listeners. The main benefits of audio processing are listed below:
- Increase overall audio level ‘loudness’ and improve the signal to noise: makes you sound louder than other stations and jump out at listeners. Maximize the headroom in the transmission channel, moving audio as far away from the noise floor as possible, which improves the signal to noise. It also aids listener ability in vehicles by having a consistently loud sound to combat engine and road noise
- Ensure audio level consistency to aid listener experience: listeners don’t have to constantly adjust the volume of the radio.
- Over-modulation, distortion, and interference: too high audio level results in distortion in receivers and interference to neighboring FM or AM stations. Digital radio will sound terrible when 0dBFS is hit in the codec, with large amounts of distortion generated. However, too low audio level results in background noise being heard. Changing levels can result in noise, distortion, and listener adjustment
- Create a sonic signature to sound how you want to sound. A unique signature sound sets you apart from other radio stations and is something that listeners will recognize instantly
Audio processing solutions from BW Broadcast
For listeners, good radio sound is everything. It only takes them a few seconds to decide whether they want to keep listening to your station or switch to another. With the right audio processor, you can ensure a high-quality signature sound for your station and attract more listeners.
The BW Broadcast audio processors are popular among many radio stations around the world – from bigger networks such as BBC, to small community stations in Africa. These cost-effective, yet high-quality processors make sure that your audio is loud and clear. Available in different multi-band configurations for FM, AM, digital radio and web streaming.
The original DSPXmini and DSPXtra audio processors have spent the last 12 years dominating the low-cost, high-value audio processing market, offering FM, AM, and HD versions to broadcasters who need to sound the best on a budget.
The Encore versions of this industry favorite now puts all models into a single box, along with platform-wide features such as intelligent PlanB audio backup and remote control monitoring.
BW Broadcast will be exhibiting at IBC, between 15 – 19 September 2017, at RAI Amsterdam, Netherlands.
Don’t miss this event!
Our team will demonstrate how our brand new Encore range of products will improve your radio station – improving its sound, increasing listenership and taking the stress out of managing your station.
IBC sits at the global crossroads of the electronic media and entertainment industry and provides a full and vibrant experience, whether you are a student or CEO, an innovative start-up or media superpower. Held at the world-class venue, the Amsterdam RAI every September, it is always at the forefront of industry innovation and provides unrivaled networking opportunities. Join 55,000 attendees from more than 170 countries and find us on our stand!
At the IBC Exhibition, you will be able to meet us and get a hands-on experience to test out a range of our award-winning products:
- FM transmitters, including a variety of different models from the new V3 range
- FM translators
- Power amplifiers
- FM receivers, including the new RBRX Encore re-broadcast receiver
- Audio processors
- RDS Encoders
Besides trying out all of our products yourself, we will also provide you with a personal advice and recommendations for your radio station using years of knowledge in the FM broadcasting industry.
We look forward to seeing you at the exhibition, and as a complimentary gift, all our stand visitors can get a FREE visitor pass to the IBC tradeshow. Simply use the unique code 11752 on IBC website and complete a registration form to receive your free pass. Click here to register now.
Here’s a quick overview of our stand at the last year’s exhibition:
Can’t make it? Why not contact your local dealer and arrange a free, no-obligation demo now to see if our products could rock your station. Click here to contact your local dealer.
Come and join us at the Amitra in Acapulco, Mexico from 24 to 27 August 2017.
We are excited to celebrate the 40th anniversary of International Broadcasting Congress this August at Amitra!
Among others, BW Broadcast will be exhibiting at the exhibition on all days so come and see us for new products and presentation.
Explore our award-winning product range, find out how we can help your radio station and test out the remote control solutions that come with all our products. Among others, you can test out the following products:
- Brand new Encore range, which has already revolutionized the radio broadcasting world
- FM transmitters, including products from our brand new V3 range
- Affordable ‘single box’ FM translators for smaller radio stations
- Power amplifiers that can help you boost your signal strength
- Re-broadcast receivers, including our new RBRX Encore rebroadcast receiver
- Audio processors to help you achieve your station’s signature sound
- RDS Encoders that improve your station’s listenership and brand awareness
We will also be there to answer any questions you may have or provide you with a personalized advice to help you and your radio station. So why not register now for the Amitra 2017! We look forward to seeing you in Acapulco.
Not in Latin America? Contact one of our dealers in your region and book a no-obligation demo with them now to find out how our products can make it easier to manage your radio station.
BW Broadcast is excited to announce our return to Asia’s must-attend event for the pro-audio and broadcasting industry. The 22nd International Digital Multimedia & Entertainment Technology Exhibition and Conference will take place from 23 – 25 May 2017 at Suntec, Singapore.
This year, we will bring our best selection of professional radio broadcasting equipment with us to our exhibition stand at the Broadcast Asia. Coupled with our knowledge and years of experience in the industry, our engineers look forward to seeing you at the show to give you the best advice for your radio station and introduce our award-winning products. You can find us from stand 4J2-01.
Our team will be showcasing and demonstrating various award-winning products including:
- DSPXmini Encore audio processor
- DSPmpX Encore stereo encoder & decoder
- ModMon Encore modulation monitor
- RBRX Encore rebroadcast receiver
- FM transmitters
We look forward to seeing you at Broadcast Asia! Click here for the visitor pre-registration. Here’s a video from the last year’s event:
Following the Federal Communications Commission‘s (FCC) newly modified rules, FM translators can now be located anywhere within the AM’s daytime service contour or a 25-mile radius of the transmitter, even if the contour is farther than 25 miles out. Previously, the rule said an AM station could place a rebroadcasting FM translator within the smaller of its daytime service contour or the 25-mile radius of its transmitter.
This means that the 2,000 or so US AM radio stations that rebroadcast on FM translators now have more flexibility in locating those FM signals. A search of the FCC’s database by engineering consulting firm du Treil, Lundin & Rackley, shows 157 commercial band FM translator service applications being accepted by the commission last week compared to approximately 24 the week prior.
BW Broadcast has been a popular manufacturer for transmitter equipment over recent years. Our FM transmitters have been the industry’s chosen units across LPFM stations and community stations in the US and continue to receive positive feedback as truly reliable transmitters or exciters. Offering unprecedented performance and quality, these FM transmitters are feature-packed and sound great right out of the box.
If you are interested in placing a new FM translator following the rules update from FCC, then make sure you choose a high-quality product without blowing your budget.
TX300 – market leading audio performance
The most popular 300W FM transmitter in the world, the TX300 V2 can be found in LPFM stations, community stations, emergency broadcast kits, military applications and as a truly reliable backup transmitter or exciter for national broadcasters. Whatever the application, the TX300 V2 will take it in its stride. Now with built-in 4-band DSPX audio processing, Ethernet control and FSK IDer.
- Integrated multi-band DSPX audio processing makes your station sound great, right out of the box
- Comes with one of the cleanest exciters and an ultra-low distortion modulator, which make it a highly stable FM transmission system
- Slide-in power supplies make the maintenance a breeze, which means that in case of major problems the supplies can be fixed in minutes
- Configurable Status and Alarm ports control and signal to external equipment
- Flexible and extensive Web Mail, SNMP, Telnet and Serial Remote Control that keeps you aware and in control of your station’s transmission
- 2-year international warranty
- 24/7 technical support
Don’t take our word for it. Hear what our customers say
“Easy to install, super natural audio, reliability you can really depend on. No competition in the marketplace, professional natural audio, reliable and excellent value” – David Kennedy, WPBJ
“Really like that BW Broadcast V2 exciter. Easy menu adjustment of frequency and power. Quick bootup, smooth power adjustment using one knob, and easy to read front panel LCD. ”Nice job ole boy!”.” – Jeff Parker, Chief Engineer at Clear Channel Media and Entertainment
A COMPLETE RANGE OF PRODUCTS to SOLVE EVERY BROADCAST NEED
The word Encore is iconic. The French use it as the word to mean ‘again’. In the theatre, it is shouted to the rafters as a demand for the players to return again with the performance or act. The word Encore is synonymous with passion, and a demand from the crowd for more of the same emotions, experience and feelings.
For us at BW Broadcast, it’s all of the above. A demand for more of the same great products. We wanted to continue our legacy of designing and manufacturing award winning broadcast technology products, but unite them all into one easy to use concept that would be worthy of the products that had come before them. Most importantly Encore would offer more great value, more ease of use, higher performance and more reliability than anything that had come before, both from BW Broadcast and from any other broadcast technology equipment manufacturer.
ENCORE IS OUR MOST SOPHISTICATED, FULLY FEATURED PRODUCT RANGE YET
Every single product within the Encore range comes with a standardized hardware and software platform. This has two benefits for broadcasters. The simplicity of servicing, which comes through using a common hardware platform, and secondly, ease of setup and use. Once you’ve set up and used your first Encore product, you’ll know how to use them all. The front panel control system and the web browser based remote control have a familiar feel across the range, making installs and operation a breeze.
Packed with features – ALL AS STANDArD
- Versatile IO, analog, digital and composite
- Plan B audio backup
- Action, events, telemetry and emails
- HTML5 Mobile ready remote control.
- Audio streaming for remote listening
- Unmatched build quality
- Ten-year warranty
Join the Encore family
We are excited to announce that hundreds of BW Broadcast Encore products are now in use at various radio stations around the world and we have received fantastic feedback from our customers. The Encore range is here to revolutionize the radio industry with several industry-first features and a whopping 10-year international warranty.
You are now able to order RBRX Encore, DSPXmini Encore, Ariane Encore, DSPmpX Encore and ModMon Encore products from your local dealer. Each one is guaranteed to transform your radio station with its top-of-the-league features without spending a fortune. Find out more about each product or get in touch with your dealer now to book a demo.
LEGENDARY LEVEL CONTROL
The ‘Ariane’ name is steeped in broadcast heritage. This highly regarded RMS Audio Leveler achieved cult status. Originally in analog form, decades on – those same iconic algorithms have been incorporated into our most sophisticated and feature rich platform ever. This is Ariane Encore.
ONE BOX, MANY TALENTS
Its predecessor, the original DSPXmini has spent the last 8 years dominating the low-cost, high-value audio processing market, offering FM, AM, and HD versions to broadcasters who need to sound the best on a budget.
The Encore version of this industry favourite now puts all models into a single box, along with platform-wide features such as intelligent PlanB audio backup and remote control monitoring.
THE MPX / COMPOSITE SWISS ARMY KNIFE
Its predecessor, the original DSPXmpX has spent the last 10 years dominating the stand alone stereo generator market. The new Encore version goes 1, 2, 3 steps beyond the original.
- It has always visible large front panel LED metering, so you can see your audio and MPX levels easily from across the rack room
- It has an RDS encoder – at no extra cost
- It can decode MPX signals in DSP, with lab grade performance and have the decoded levels shown on the front panel LED metering.
Fitted with two time-aligned and highly sensitive DSP tuners, ModMon Encore has an unfair advantage over its competition: it’s the only modulation monitor that can DSP crossfade between two radio stations without re-tuning, or compare two MPX inputs such as audio processors or stereo generators at the touch of a button – all instantaneously and inaudibly. It’s a tool that helps you make decisions based on research, not just research yourself.
THE PERFECT ENCORE TO AN INCREDIBLE PRODUCT
Our first incarnation of the RBRX went on to solve thousands of weak signal issues at crowded transmission sites around the globe setting a new standard for rebroadcast receiver technology. During the last 8 years, whilst the industry’s been playing catch up, we’ve been busy improving on this legendary product – and RBRX Encore is the result.
Housing two of the world’s most selective and highly sensitive tuners, coupled with the most advanced signal processing capabilities, RBRX Encore is the new pinnacle of rebroadcasting performance.
BW Broadcast is excited to announce our return to the NAB exhibition in Las Vegas on 24 – 27 April 2017. Taking place at the Las Vegas Convention Center, NAB is one of the biggest the largest media, entertainment, and technology convention in the world. You can find out stand from the North Hall, booth number N8631.
Following our last year’s success at NAB, this year we will be showcasing products that have been in development and testing throughout this year that will help you optimize your radio station. Besides our bestselling V2 transmitter range, you will also have a chance to get a hands-on experience of our Encore range as well as get personal advice for your radio station.
The products on display at our this year’s booth will include:
- RBRX Encore
- ModMon Encore
- Ariane Encore
- DSPXmini Encore
- plus a selection of our other award-winning FM broadcasting equipment!
Come and visit us in Las Vegas using our exclusive FREE NAB pass using the unique code LV6365! Click here to claim your free pass.
Here’s a glimpse of our booth at the last year’s show:
Come and meet our team at CABSAT 2017 at the Dubai World Trade Centre between 21-23 March 2017. CABSAT is the largest trade show in the Middle East and North Africa region for broadcasting and digital media.
Our team will be showcasing our latest FM broadcasting equipment at the show, including the award-winning RBRX Encore which has taken over the radio world with its first-in-the-industry features and excellent quality hardware. Come and meet our team at the UK pavilion at hall 2, where you can find our stand and get a hands-on experience of our professional radio broadcasting products.
Besides RBRX Encore, you will also have a chance to explore the rest of the Encore range, as well as our bestsellers from the V2 transmitters range:
- Rebroadcast receivers
- Modulation monitor
- Audio backup
- Audio processing
- Audio over IP
- Stereo encoders & decoders
- RDS encoders
- FM transmission products
Here’s a little overview of the last year’s show at the Dubai World Trade Centre:
Find out how the Radio Christmas helps children in Latin America every Christmas using BW Broadcast transmitters.
Radio Christmas is a small charity radio in the UK, which is run by volunteers to support projects in Latin America. Both the charity behind the radio, Street Kids Direct, and the radio was founded by Duncan Dyason, a youth worker who has a passion for reaching children and young people on the margins of the society.
The radio has been run every Christmas since 2008, and the charity guarantees that 100% of all its donations go directly to the projects they are supporting in Latin America. The Radio Christmas is using our FM transmitters, and Duncan has said they couldn’t be happier with our products and service:
“We took your advice when we had an issue with it, all because we had not connected it properly. Your tech team were available in minutes to resolve the problem.
We really appreciate your support through a crucial time, we would recommend BW Broadcast to anyone for not just great products but also for superb support, which is invaluable.”
Radio World publication have recently gathered around a group of industry professionals to discuss recent trends in FM transmitter technology.
Including our Managing Director Scott Incz, the group provided their views on the current trends in the FM broadcasting technology. Find out more below:
The transmitter is the final leg of the radio broadcast chain. No matter how good the chain is up to that point, failure at the transmitter will render the whole effort for naught.
But changes are coming, disrupting big iron. Radio World talked to some of the leading transmitter manufacturers about what is on their radar these days.
Joining Radio World in a Q&As discussing Transmitter Technologies were our Managing Direct, Scott Incz, along with Rich Redmond, Chief Product Officer at GatesAir’ Chuck Kelly, Director of Sales at Nautel, Thorsten Becher, Vice Director Sales at Transradio and Eric Pere, Broadcast Project Manager at WorldCast.
What is the hottest thing in transmitters these days?
Chuck Kelly: I’d propose that there are two themes driving innovation in our industry today, intelligence and integration; and they are interrelated. By intelligence I mean harnessing IP, local remote data gathering, processing power and connectivity. Mixing these elements has created new options for automatic audio backup and local playout, unprecedented control and opportunities for a true digital path right through to the exciter for optimum loudness and sound. Integration, as a byproduct of harnessing the intelligence in sensible ways, helps engineers reduce the component count in their facilities and do more with less in a positive way. When fewer boxes or components are needed, fewer things can fail and there can be less cost by integrating features in the transmitter. Examples of these two themes working together include integrated audio processing, remote control, codecs, fail-safe systems, etc.
Scott Incz: The advancement in transistor technology, which enables transmitters to be more compact, run cooler and have longer lifespans, especially with the introduction of LDMOS devices. Additionally, one of the hottest things is IP connectivity — not only for remote control monitoring but also for the delivery of audio to the transmitter via the network protocol, such as AES67 and others.
Rich Redmond: Transmitters are going in two directions. They either seem to be built for higher and higher power capabilities, often liquid-cooled in design, to deliver HD Radio and other digital formats, or they are getting simpler and simpler for lower power. If you think of translators, certain Class A stations at very high elevations, educational FMs, and single-frequency boosters, there is a lot of activity in relatively low-power levels under 1 kW. Over time, those transmitters have had more capabilities added, but they get much simpler to operate. And both low- and high-power transmitters have also grown far more compact.
Thorsten Becher: We like to talk about long- and medium-wave broadcast transmitters, which we feel are transmitters offering a DRM power equal to typically 80 percent (or even more) of the AM carrier power with MER >30 dB.
Eric Pere: It makes me smile to hear of “hot topics” in the FM transmitter market given that it has been around (at least in stereo form) since the 1960s. It is truly amazing to think that it is still so prevalent and has not undergone any major technological changes in that time — just adapting modern technologies to work with old and existing FM systems is in itself a major task. Not that there have not been any changes but, when it comes to transmitters, engineers are notoriously conservative. Most people would never contemplate buying a CRT TV over a flat screen just because it’s “proven technology” but the critical role of the transmitter coupled with the expense involved means that change will come much slower than in other areas. Personally, I think that the time has come to make the definitive switch to digital audio and perhaps even digital MPX. Digitizing an analog MPX signal may not be ideal but we can multiplex various signals in a digital stream in a much more efficient way.
Is liquid cooling the answer for harsh environments?
Liquid cooling would appear to be a winner for closed-loop cooling systems and climates with sites that need almost constant AC like desert or tropical regions. Energy savings should pay for the transmitter in a few years. Few offer this option so far. Is the market just not big enough or what are the reasons it has not gained more traction?
Rich Redmond: GatesAir has been in the liquid-cooled transmitter business for nearly 50 years, including high-power AM and TV transmitters. While liquid-cooling is relatively new to FM, the technology, and its benefits are not new to GatesAir.
It does require a certain skill set to operate that not all engineers possess. These systems are a little more complex and will require some training to learn if the customer does not have prior experience. GatesAir provides that training for customers both new to and experienced with, liquid-cooled transmitters. In some places, the climate doesn’t necessarily call for liquid-cooling. In warmer climates, where irrespective of the temperature you want to run a closed-loop system with air conditioning, there are distinct operating advantages with liquid cooling. But they require more attention than an air-cooled transmitter, where you are simply dumping air into a room for cooling. Each station needs to decide what is most appropriate for their situation, and where they feel comfortable. But we are fans of liquid-cooling, and it offers a very attractive ROI for sites that have significant cooling needs and costs. It is a technology that we are comfortable with, and we have led the industry on the liquid-cooling innovation front for many years.
Thorsten Becher: Both techniques, air-cooling and liquid-cooling, have their particular pros and cons. From our point of view, the major drawback of liquid-cooling is potential leakage, either during normal operation or, particularly, in the course of maintenance work. There is no means for hermetically sealing a liquid-cooling system, thus there remains some risk of water drops affecting sensitive transmitter electronics, or even worse, provoking injury to people due to water contacting mains wires.
Eric Pere: Generally, FM transmitters operate far more efficiently than DTV or DAB transmitters so, the advantages of water cooling aren’t as significant in the FM sphere.
If a manufacturer does wish to produce a water-cooled FM system, they can opt for one of two approaches. The first option requires a significant initial investment by the customer but delivers a highly-efficient and effective performance. This is the route which we at WorldCast Systems chose when, in 2004, we developed a liquid-cooled FM transmitter under our Ecreso brand. For us at that time, it was less about operating at high ambient temperatures and more about improving the reliability of the system. We utilized technologies initially created for the railway industry to reduce the temperature of the power-related components such as the power supplies, RF, coupler etc. We also deployed DC/DC conversion techniques used in distributed computer architectures for greater overall efficiency. The result was a reduction in the total cost of ownership and to the carbon footprint of the system but customers have to be prepared to make a significant capex spend to acquire it. Another approach that manufacturers can adopt is much more affordable for the customer but, in general, offers little or no advantage compared to an air-cooled system. In order to get any appreciable benefit, you need to have a large number of FM transmitters using a single water-cooling system.
Many also tout the maintenance advantages of a water-cooled system as no air cleaning is required. However, when maintenance is required on the water-cooling system, it requires a complete shutdown of all transmitters — a point often forgotten. Given these reasons, we can see why the market is limited for these systems.
Chuck Kelly: Let me start by taking a look at TV broadcasting, where liquid-cooling has been more commonplace. Liquid-cooling as an alternate to a pure air system has historically been very attractive to larger TV sites where high amounts of waste heat are generated by powerful, 20–40 percent low-efficiency TV transmitters. It is hard to beat the thermal properties of a fluid to move large amounts of thermal energy. If there is a negative related to liquid-cooling in these large installations, it is typically related to the additional effort need for plumbing, approvals and exterior air exchange units. Typically the advantages aren’t compelling enough at low- to mid-power and so in the TV industry, liquid-cooling is largely reserved for higher power transmitters.
When we look at the radio broadcast industry we find dramatically more efficient transmitters, typically in the 60–75 percent range, so radio engineers normally find heat extraction much easier to manage. While there may be some broadcasters with very high power needs and liquid-cooling-friendly sites, the majority can manage waste heat extraction quite effectively using an all-air cooling system. So, this becomes a “your mileage may vary” situation depending on many factors including TPO power, transmitter efficiency, existing air investment versus greenfield site, floor space costs, site readiness for liquid-cooling and local power rates. For new installations, where the cooling infrastructure is not already in place, and where high-power and warm climates incentivize its consideration, a case can be made for the total cost of ownership of a liquid-cooled system. However, the station must be aware that initial cost and installation costs will be higher and the time required for installation will be days instead of hours. Further, only about two-thirds (but not all) heat is transferred to the heat exchangers, so nominal conventional cooling is still required for power supply dissipation. Factory training on the technology is essential, and it may not lend itself to being maintained by non regular contract engineers making only occasional visits. Similar to the TV broadcast situation, for transmitters with lower waste heat generation, air-cooling will continue to be the de facto standard. The vast majority of broadcasters have air-cooling-compatible sites today, so it will be interesting to watch the ongoing trend in preference for air-cooling versus liquid for radio broadcasters as radio transmitters become more efficient and waste heat requirements decrease.
Scott Incz: With efficiencies of modern devices sometimes exceeding 90 percent, the requirement for liquid-cooling is less necessary in FM transmitters, than say, TV transmitters. TV transmitters’ digital waveforms mean lower efficiencies are obtained from power amplifiers, creating heat issues. Liquid-cooling should really be unnecessary and would only increase the complexity of design and build for the manufacturer, and maintenance cost for the customer. We would rather spend time increasing our transmitters efficiency and thus alleviating the need for complex cooling systems. Less maintenance, increased reliability and reduced operating costs. It’s a win-win for manufacturers and customers alike.
Has the LDMOSFET technology maxed out?
LDMOSFET has been the winning SS RF device technology choice for a number of years. Has that technology been maxed out for efficiency and performance? If not, what other improvements are in the pipeline and if so, are there any new technologies being developed to replace LDMOSFET?
Eric Pere: Today the performance of MOSFET amplifiers is close to the theoretical limit. Those final few percentage points will be the most difficult to obtain, but development continues. As a comparison, 90 percent efficiency was a good performance for switching power supplies a few years ago. Now, with some fine tuning on the DSP, we can obtain upwards of 95 percent. LDMOSFET’s most likely successor waiting in the wings is GaN or gallium nitride. GaN offers low intrinsic losses to achieve high efficiency as well as very large bandwidth with a flat gain over frequency. It is currently more expensive compared to LDMOS and will likely only become an affordable option for FM transmitters following larger scale deployment in the TV market.
Scott Incz: The latest technology of LDMOSFET devices has certainly not “maxxed” out. Our own design engineers are starting to see efficiency close to 90 percent and we believe we can obtain even higher with some of the design concepts we are working on at the moment. This is still work in progress but we hope to reveal more soon.
Rich Redmond: LDMOS is the standard today, and the most beneficial innovations in recent years was the development of 50 V LDMOS. This really ushered in the convergence of robust, cost-effective power supplies from the IT and telecom industry; along with very robust and high-power RF devices. The transmitters can now take advantage of some of the innovations in very-high-efficiency power supplies that come from these other industries. What we continue to see is increased power density in the device. A few years ago, a 500 W device was a fairly large device to have. Today, there are 1500–1600 W LDMOS devices. The technology to cool and handle that amount of wattage in a small footprint continues to evolve. The advances continue, and we’ll continue to see the evolution of LDMOS both in power handling capability, the ability to cool it and energy efficiency. Some of these innovations come from mobile base station market developments, so in broadcast the convergence of 50 V LDMOS really introduces a lot of technologies that broadcasters can take advantage of for very reliable, highly efficient and cost-effective transmitter solutions.
Thorsten Becher: The latest versions of LDMOSFETs seem to have reached some maximum of efficiency and performance limits. Nevertheless, innovation in the semiconductor market never comes to a stop. Remember the microprocessors used in PCs of the 1980s, and compare to today’s high-speed multicore chips used in any cheap smartphone. We are confident that ongoing development in new material compounds, further minimization of the active element size and application of new structural designs will without doubt lead to further improvement until reaching the limits given by physics.
Chuck Kelly: While LDMOS and alternative chip technologies still hold potential for performance gains, unfortunately most chip manufacturers are directing their investment towards the high-frequency or pulse-power devices needed in lucrative, high-growth sectors such as LED lighting, high-power ISM, “big science,” cellular, satellite, military and space. The result is that broadcast transmitter designers today are faced with the prospect of squeezing out incremental performance gains. That being said, our industry is populated with many creative engineers who have proven their ability to leverage chips optimized for other technology sectors and create performance advancements in our own industry.
What is a modern transmitters expected life span?
Radio World: Transmitters used to last 20 and even 30 years before short life cycles for chip versions and computer control entered this space. The same is true for consoles and studio gear. Manufacturers are now telling us 10 years is about the most we can expect. Replacing large capital items like transmitters at that cycle is not something most station owners can easily budget for and accommodate. What are transmitter manufacturers doing to alleviate that pain?
Eric Pere: Granted, new transmitters nowadays may not last 20 or 30 years but, in general, they are more affordable than they have ever been. This is especially true when you consider the fact that they have (or at least should have!) a built-in digital exciter and a much-improved total cost of ownership as well as being more compact than previously.
And of course, computer control also brings some great advantages such as the ability to monitor every single part of your transmitter in great detail. We are very fortunate at WorldCast to have great experience in monitoring and control through our Audemat branded products and we apply this expertise and technology throughout our Ecreso transmitter range. This has resulted in features such as Expert Maintenance Reporting (EMR), which sends the user regular reports on the status of key parameters as well as information on the performance and lifespan of components. We also have a new SNMP management software suite called WorldCast Manager which provides performance and alarm information on not just the transmitter but all devices across a network.
Chuck Kelly: At Nautel we talk a lot about the long view. We know our customers buy equipment for the long haul and we do our best to design our whole offering: transmitters, reliability, serviceability and support in a way that supports that long vendor relationship. In fact, even the ownership structure of our company is supportive of the long view approach. Our experience is that we are still seeing many customers maintaining our systems for multiple decades, but we also do see the impact of an increasing pace of technological innovation that causes some customers to replace systems earlier to gain new capabilities or efficiencies. For instance, our higher efficiency transmitters sometimes justify an earlier technology upgrade to attain lower operating costs. Another example would be a customer who can change the way they monitor their facilities thanks to modern sophisticated control capabilities afforded by Nautel’s Advanced User Interface. Digital radio components also tend to have a shorter replacement cycle given the pace of change in the digital broadcasting space. So while we still see and believe in the long term view, there are situations where customers are choosing to change out equipment at a faster pace than may actually be required through the lifecycle of the product.
Thorsten Becher: A good work rule in the early design phase is to select and use well-proven components known for their long-lasting availability in the market. More complex devices such as embedded computers or touchscreens should be, both electronically and mechanically, of an easily replaced design. What really counts is energy costs, reliability, ease of maintenance and availability of spares for a long period of time. Following this rule, Transradio manufactures transmitters with minimum maintenance requirements, and can provide spare parts for typically 15 years or more.
Scott Incz: The advances made in transmitter technologies have actually led to an increase in reliability, cost and lifespan of transmitters. The reason many stations may look to upgrade transmitters after 10 years is to take advantage of features that the newer transmitters will offer them. Each generation of transmitters is more efficient, more reliable and offer stations flexibility, sometimes integrating other products to create a “one box” solution. Stations may actually find it more cost-effective to upgrade to a greener, more reliable, less maintenance heavy transmitter, than continue with their existing one. The cost of transmitters is actually far less than it was 20 years ago, so even smaller stations can take advantage of upgrading to keep up with the larger networks.
Rich Redmond: There was a period of time when computers lasted for a very long cycle. Transmitter designs, like computers, have changed over time. Part of it is the sophistication: Transmitters that lasted 20-to-30 years had relay-type control and/or very large transistor logic. They had a single tube and a blower inside to cool them. They also weren’t incredibly efficient like today’s transmitters, which have the benefits of soft failure, solid-state and high-efficiency advances. Often, the replacement cycle is not because the product wears out; it’s that certain devices within that transmitter cease to be available.
If you look at the price of transmitters now compared to then, they are much more cost-effective than they were a number of years ago. In the early 1990s, a 1 kW FM transmitter might cost you $16K. Today, a 1 kW is generally under $8K. The prices have dropped, and they are easier to repair and maintain over time. Engineering resources are also more efficiently put to use; weekly trips to the site, and consistent tube cleanings, are eliminated. Lighter weights from today’s more compact transmitter footprints often allow single-engineer maintenance. So overall, the capital investment of buying, installing and maintaining a transmitter is substantially less expensive, even when considering the quicker replacement cycle.
What are the most common failures?
Radio World: In general, what are the most common failure modes of modern designed transmitters manufacturers are seeing in the field? Lack of cleaning and maintenance plus improper grounding and lightning protection are certainly the major ones, but what are the others?
Chuck Kelly: The vast majority of failures can be traced to lack of maintenance, improper grounding or poor lightning protection (ties to grounding). It’s hard to say there’s another common failure mode beyond those — short of the ones that result due to customers not keeping up with software updates. It’s important to remember that we frequently use software updates to perform hardware changes (adjusting amplifier bias levels, power supply output voltages, etc.). Therefore, what we used to do by sending out a bag of parts and an instruction sheet we now do with a software update and not implementing these updates can have a direct effect on equipment reliability.
Eric Pere: Generally, poor or unstable mains supply is one of the most common causes of failure observed. In many awkward transmitter locations, mains electricity is subject to large variations, short dips and interruptions which means that voltage regulators, inverters or generators are often necessary. However, these can also generate some unexpected variations when switching or adjusting the voltage. Most modern transmitters use switching power supplies which can easily manage voltage changes but several, quick variations generate large current peaks which, in turn, generates a lot of stress for their active parts. This was not an issue for the old linear-style power supplies but their poor efficiency and noisy AC behavior rendered these obsolete.
Scott Incz: Lightning protection is incredibly important and is responsible for some in-field failures, but we see many more power supply failures due to AC main surges or dirty power, this is especially a problem in emerging markets.
Thorsten Becher: From our experience, the predominant cause for failure is an inadequate cleaning of air filters by maintenance staff. In few cases, also high spikes on the mains supply lines have been encountered.
Radio World: How much longer will high-power tube transmitters be relevant in our business? Many engineers worry that if companies that make and rebuild tubes like Econco/Eimac and Richardson decide to stop producing or close their doors, that will mark the end of this era.
Rich Redmond: High-power tubes will remain relevant for the foreseeable future for a certain customer base. This will continue to dwindle as the engineering base shifts to a younger, more IT-savvy generation. Fewer engineers entering the market today do so as RF specialists. More often, RF is a trade they learn, or outsource to firms with experience. However, today’s solid-state transmitters are often sensible for younger engineers that have IT experience, and there is a quicker learning curve when it comes to maintaining the transmitters thanks to design benefits such as hot-swappable PA module and power supply replacement. But the change will continue over time, and there is still a need for vendors that make tube transmitters, and make and/or rebuild the actual tube components.
Chuck Kelly: Tube technology is still the most efficient, cost-effective approach to high-power shortwave transmission where quick frequency changes are made over a wide frequency range. However, in AM and FM systems over all power ranges, solid-state has become the preferred technology as it has evolved to be more cost-effective, more fault-tolerant and offers higher performance than tubes. And yes, the writing seems to be on the wall for tube suppliers/rebuilders. In AM and FM broadcast at least, it’s hard to imagine a scenario where it would be wise to specify a tube in a new design or purchase.
Thorsten Becher: Today, all broadcast bands ranging from longwave up to band IV/V for DVB-T(2) and, literally, each RF power in the respective band can be served with all solid-state transmitters. Thus, we consider tubes no longer relevant for new transmitter investments. But agreed — as soon the few remaining companies in this business such as Eimac or Richardson close down production or refurbishment of power tubes, the tube transmitter era will come to its final end.
Scott Incz: Not so relevant because long-life solid-state amplifier parts, including the latest LDMOS technology, are producing longer lifetime, more compact levels of high-power RF. It is probably accurate to say that the tubes won’t be around for much longer, at least for broadcast applications.
What’s the future for transmitter technology?
Radio World: Put on your science fiction cap. What fantasy yet possibly-doable-someday transmitter technology do you wish you could invent, perfect, bring to the market at an affordable price?
Thorsten Becher: Just my personal fantasy — making a transmitter offering the same RF power in a cabinet of half the size and weight than today, saving production costs and simplifying shipment in the entire world.
Rich Redmond: Imagine a high-power transmitter that is 100 percent efficient and the size of a college dorm fridge. Once we have reached that point — and the day will eventually come — there’s a high chance that there won’t be much more room for innovation. In the meantime, we will continue to work toward that goal.
Scott Incz: A supercool, super-efficient, super-reliable transmitter, in an unbelievably small box! It would need to have superconductivity in the power supplies and RF amplifier stages, an RF amplifier output requiring no cooling and minimal real estate. It would need increased high-power FET devices that need little matching to the antenna stage, as well as a single-chip IP audio to on-channel modulation capabilities. It’s not here yet, but we are getting there.
Eric Pere: I can imagine some kind of high power RF DAC to achieve direct to RF output modulation. On the other hand, it is more likely that, after being around for a century, FM broadcasting will be replaced by a new way of listening to radio. I still dream that it could be possible to achieve highly-effective digital radio with affordable receivers and good coverage but if we continue to pretend that it already exists, it will probably never actually happen.
Chuck Kelly: Well, with ATSC 3.0 we may see a lot of broadcasters implementing SFNs … we should watch that space. As a company we’ve explored some work on making portions of the radio broadcasting spectrum all-digital and yet live comfortably within the existing analog and hybrid digital spectrum allocation. We still see generous amounts of room for dreamers and innovators in radio broadcasting. We’ve been fortunate to be able to hire a lot of fresh designers over the past few years and we look forward to the contributions they will make in the coming years.
Looking even farther out, we envision that all broadcast content will be data, reconstituted at the receiver to be separated out and readied for consumption. Broadcast AM/FM/TV will continue to be relevant as long as the cost to distribute that data is less than other methods. Read the full article on Radio World.