The NAB convention dust has settled, leaving many with the feeling that the DTV transition may be getting back on track—more or less—in 2004. But at the same time that exhibitors are feeling optimistic about the second half of the year, new product developments are reflecting a perhaps not-so-surprising trend: Analog seems to be making a comeback.
After the flurry of tube and transmitter developments that helped breathe life into the DTV transition, stations were relieved to see that both transmitter and tube manufacturers haven’t totally given up on analog designs.
Analog is still bringing in the lion’s share of every station’s income, despite the fact that many transmitters operating NTSC today are in need of either major surgery or their last rites.
What the DTV derailment has meant to RF manufacturers is that they’ve had time to rethink analog and answer the question: “If the industry research shows stations want an analog transmitter, what can we offer that we haven’t offered before?”
Back to the drawing boards (or their CAD/CAM programs) they went, and this NAB became an analog renaissance. Transmitter manufacturers delivered analog rigs that station engineers could have only dreamed about five years ago. And tube manufacturers were right on their heels, making certain their newest, super-efficient designs could also handle analog.
The result was a surprising number of truly new VHF and UHF analog transmitter introductions. In fact, the sheer number of transmitter introductions this year surely represents an all-time record for the NAB convention.
Down The Aisles
Axcera unveiled their new Innovator HX high-power VHF transmitter, designed with the understanding that broadcasters need to upgrade their analog VHF plant with a rig built completely new from the ground up. The Innovator HX is not only built with the latest available technology, it can be easily converted to digital. It has an in-circuit programmable control system based on common microprocessor technology, a concession that helps the user avoid future obsolescence due to proprietary microprocessor designs and components.
The transmitter uses the latest MOSFET transistors in identical high-gain power amplifiers for visual, aural, and digital operation. Since the PAs are high-gain, the complete transmitter high-power rig can be driven directly by its frequency agile exciter/driver, making for a simplistic design and minimizing spare parts stock.
Axcera can deliver the HX transmitter with either linear or more modern switching power supplies. The linear supply is redundant, but the switching supply uses four modular, hot-pluggable, power factor-corrected supplies per cabinet.
The HX is available in both digital and internally diplexed or externally diplexed analog setups. The choice comes down to externally diplexing, which is more ideal for analog performance and efficiency, or internal diplexing, coupled with a digital mask filter that is tuned for analog rejection. In that case, digital conversion requires just the addition of a digital modulator. Those anticipating a return to their legacy VHF channel will appreciate this option.
New Transmitter, New President
The secrecy surrounding Harris’ new PowerCD UHF transmitter had more to do with completely testing the transmitter before delivery to the NAB exhibit than any revolutionary technology it might employ. As Harris promised, the PowerCD drew the attention of attendees because it truly is new, from the ground up.
With the PowerCD, the most obvious departure from the norm is its two GUI monitors. Instead of being built into the cabinet, the monitors are on pivot arms that allow the engineer to physically rotate the monitors up, down, and side to side, or fold them flat against the transmitter. In other words, there is no poor viewing angle.
The PowerCD includes Harris’ APEX exciter, with proprietary linear and nonlinear Real-Time Adaptive Correction (RTAC) and simple keylocks for quick, safe access to high-voltage components. Thyratron crowbars, a long-time maintenance headache, have been eliminated. The company insists this is the smallest MSDC IOT footprint at the transmitter site.
The PowerCD relies on Harris’ Cool Fuel System, which uses sharp-tuned filtering techniques to maintain spectral performance at higher transmitter output levels and reduces interference in adjacent channel-combining systems.
The PowerCD also takes advantage of Harris’ eCDI network monitoring and control system, which gives the user complete transmitter control locally or remotely via a web browser. Along with “drill down” capabilities, its SNMP connections enable the transmitter to be linked to a network management system.
A hoist in the PA cabinet means the depressed collector IOT can be removed without pulling out the trolley assembly.
Shortly after NAB, Harris announced that Jeremy Wensinger has been named the new president of the company’s broadcast communications business, replacing the recently retired Bruce Allen. Wensinger had been serving as the vice president and general manager of Harris Technical Services Corporation, which is part of the Harris government communications systems division.
The Eclipse Is Here!
LARCAN dubbed their newest transmitter the Eclipse. According to the company, their goal in developing the Eclipse was to create a unique, uncompromised, universal analog UHF solid-state design. That meant keeping it functional and intuitive, with no-nonsense bells and whistles. They also wanted the outcome to be bulletproof, in a range from 5-20kW.
Based mainly on the design of the Magnum Series of digital transmitters, Eclipse now takes its innovations to new levels for analog as well. Its exciter relies on a patent-pending RF amplifier design that features LDMOS technology, multiple regulated power supplies, and is uniquely modular, hot-pluggable, and fully redundant.
The new design includes highly linear broadband PA modules and intuitive diagnostics to ensure signal quality and maintainability. Its extensive monitoring system is based on simplifying maintenance.
Clearly working on minimizing the real estate it requires, the 20kW version will fit into less than 25 square feet of space.
VHF Gets The OPTIMUM-CA
Thales Broadcast & Multimedia put the spotlight on their new VHF OPTIMUM-CA analog transmitters. CA stands for Common Amplification.
The new rig uses common amplification architecture for its analog visual and aural carriers, making it easier to convert to digital down the road. The series features a range of liquid and air-cooled designs.
The OPTIMUM-CA also offers a cable-less structure, which allows a direct interface between the power amplifier, power supply, and combiner assemblies. This reduces RF signal losses and makes servicing simple, which leads to high reliability.
Thales is using the latest MOSFET technology. Since it uses common amplification, all its amplifiers can be re-used in their original configuration when the time comes to transition to DTV service. Like all Thales solid-state transmitters, there are no driver modules between the exciter and the parallel power amplifier stage. This ensures you’ll stay on the air in the event of a failure.
In terms of redundancy you can select Main/Standby exciters with automatic switchover, Main/Standby pumps and/or heat exchangers, and a passive reserve configuration supervised by a controller.
One of the major benefits of this new system design is that you can reuse the output filter after a conversion to DTV. This is a big cost savings, and it simplifies the conversion process.
Thales also announced it has added the e2v ESCIOT as a DXC Paragon UHF transmitter option.
Rohde On The Move
One of the surprise announcements in the RF sector at NAB2004 was that Rhode & Schwarz has decided to assume direct responsibility for sales and service support of all its products being offered in North America.
Previously, Ai (a.k.a. Acrodyne) had been the exclusive Rohde connection in the U.S. According to Rohde & Schwarz, those connections have not been severed. But one does wonder how that relationship will continue. However, Ai’s Quantum transmitter still uses Rohde’s exciter and some of its amplifier technology.
Rohde also announced that it was beefing up its body count in the U.S. The estimate at NAB time was that they were staffing up to a total of 150 employees to man offices in a number of states. Its customer support and service center is located in Columbia, MD.
Along with its line of television transmitters, the company expanded its SV700 exciter with the addition of the optional NX7000 ADE (Adaptive Digital Equalization) software for digital TV transmitters. This option adds the capability of automatically correcting linear and nonlinear transmitter distortion in just a few minutes. The option is suitable for both DVB-T and ASTC and is available as an integral part of the exciter.
Taking Control
While transmitter developments dominated the RF sector, there were some interesting developments in other product categories.
Dielectric has developed what they’re calling a Real-Time High Power Monitoring System. Basically, it offers TDR-like monitoring at full power, locates faults within your transmission system, allows you to pre-define component and system operation parameters, and is also ideal for single or multi-frequency DTV systems.
TDR is a reference to time domain reflectometry, which allows a TDR user to spot a transmission line problem at a great distance. When VSWR is a problem, how can you track down the problem without going off the air, sweeping the system with a low-power network analyzer, and hoping the problem will reveal itself at that low power? Oh yes, and keep the GM off your back?
Dielectric’s monitoring system utilizes Z-Technology’s DM11010W demodulator, standard directional couplers, and proprietary software to isolate individual components, such as elbows, gas barriers, power dividers, power splitters, individual transmission line sections, and the antenna itself.
Alarm levels can be set for each component to sound alarms, issue foldbacks, or shut down signals to the transmitter. Integrated graphics illustrate in realtime the complete performance of the transmission system and the antenna system.
Meanwhile, at the MYAT booth, the company was showing off their new Dual-Mode Filter. It’s a six-section reflective dual-mode filter specifically designed for efficiency and small space requirements. They use a unique technique to enhance cavity Q where it is needed the most.
Their precision cavity designs minimize tuning screw penetration, resulting in an efficient filter that can accommodate higher average and peak power levels. In other words, it has applications for DTV and analog service.
MYAT also took the wraps off the new High VHF Diplexer and their interesting solid-state UHF digital transmitter and DT*Star Gysel Power Combiner.
Another interesting RF product was available in the RF Central booth. Under the RF Extreme banner, the company was showing its new RFX Messenger. It’s a completely wireless digital microwave system. Aimed at sports, news, and production applications, it operates from 1-6GHz, with a selectable bandwidth of 6, 7, or 8MHz. Its security option, the MDT, can be delivered with either a fixed key scrambling system, or an Advanced Encryption System (AES) for protecting the signal in sensitive applications.
RF Central also showed the new RFX Clip-On. With the same applications, it operates from 1.3-15GHz, with 64QAM, 16QAM, and QPSK demodulation. The tuning range is 600MHz bandwidth.
The transmit output power is 100mW.
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