Iconyx White Paper 电路图.pdf

DSP-Driven Vertical Arrays Acoustical, Electronic and architectural styles that are in conflict with typical systems. Design Criteria: Meeting Application Challenges Full range output The diagrams above make it clear that any line source, even with very sophisticated DSP, can con- trol only a limited range of frequencies. However, we decided early in the design process to use full range co- axial drivers as the line source elements. Providing full range output, we reasoned, could make the overall sound of the system more accu- rate and natural without seriously compromising the benefits of beam- shaping and steering. In typical program material, most of the energy is within the range of controllable frequencies. Earlier designs radiate only slightly above and below the frequen- cies that are controllable. Thus much of the pro- gram source is sacrificed, without a significant increase in intelligibility. Full control with advanced electronics To maximize the effectiveness of a digitally con- trolled line source, it s not enough to start with high- quality transducers. We knew that we also had to enable full control of each element. This was the start of our search for a compact multi- channel amplifier with integral DSP capability. The D2 audio module that we used has the required output, full DSP control and the added advantage of a purely digital signal path option. When PCM data is deliv- ered to the channel via an AES/EBU or CobraNet input, the D2 audio processor/amplifier converts it directly into PWM data that can drive the output stage. First- generation “ digital” amplifiers require that PCM data be converted to analog waveforms and then back to digital PWM data in order to drive their out- put stages. The added D/A and A/D converters add cost, distortion and latency. Flexibility We believe that when accurate, natural reproduc- tion is combined with digital control of the line source, the potential applications are greater than just cathedrals and transportation terminals. Therefore we made flexibility a goal of Iconyx design. We started with a modular concept that allows very tall lines to be built up from smaller modules. Individual modules can be shipped via low- cost carriers such as UPS, then quickly assem- bled on site. Direct control of each line source ele- ment allows multiple lobes to be shaped and aimed from the same array. Acoustic centers of these lobes can be moved independently of the physical location of the array, because inter- driver spacing is constant throughout the full length of the line. Horizontal Directivity Is Determined By The Array Elements Like other vertical arrays, Iconyx systems can be steered only in the vertical plane. Horizontal cover- age is fixed and we knew it would be determined by the choice of array elements. The transducers used in Iconyx modules have a horizontal dispersion that is consistent over a wide operating band, varying only between 140 and 150 degrees from 100 Hz to 16 kHz. Iconyx has much more consistent hori- zontal directivity than similar arrays using 4” full range drivers. Polar response of a full range 4- inch cone: note the progressive narrowing as the frequency increases. DSP- Driven Vertical Arrays 10 The polar response of the Iconyx co- axial 4- inch driver: high frequency dispersion is much wider. The off- axis narrowing observed in many coaxial transducers is absent, thanks to a time- aligning passive crossover net- work. Wider dispersion confers both performance and cost advantages Wider dispersion, particularly of high frequencies, enables Iconyx systems to deliver more consistent performance and intelligibility, particularly on the edges of the coverage area. In many situations, the wider coverage angle means that fewer devices can be used to produce acceptable results, which trans- lates into cost savings. Line Source Performance: Real Driver Interactions Real drivers are not uniformly directional: as with any source that has physical dimensions (as opposed to a theoretical perfect point) they get more directional with increasing frequency. For instance, the 4 inch diameter co- axial driver used in Iconyx vertical arrays is omni- directional to about 300 Hz and half- hemispherical from 300 Hz to about 1kHz. Over the next decade (1 kHz to 10 kHz) the pattern is conical 140 x 140. It should be obvious that an array of these sources will behave differently from a line of point sources with perfectly spherical radiation. Measurements confirm this: the rear lobe is much lower in level than the front lobe; off- axis “ grating” lobes, when they do occur, are lower in level than the main lobe. In particular, grating lobes at 90 to the main axis of the array are greatly reduced in level. Iconyx Arrays (1 wavelength) IC8 400 Hz IC16 200 Hz IC24 125 Hz IC32 100 Hz The lobes are similar in shape, although the IC32, which is 4x higher than the IC8, is narrower. IC32 1.25 kHz At 1.25 kHz, the IC32 radiates a near- perfect 10 vertical beam. Side lobes are present but their level is well (- 9 dB) below that of the main beam. DSP- Driven Vertical Arrays 11 IC32 31 At 3.1 kHz the main lobe is still well focused, but two grating lobes are also present. Because of the wide angle to the main beam, these side lobes do not present practical problems. Iconyx Directivity Remains Consistent With Changing Frequency IC32 5 & 12.5 At 500 Hz (5 ), the IC32 shows a 10 lobe that is very consistent with both the 100 Hz and 1.25 kHz measurements. At 1.25 kHz (12.5 ), the 10 lobe radiated by the IC32 is slightly narrower but still consistent. Steering is SimpleJust Progressively Delay Drivers If we tilt an array, we move the drivers in time as well as in space. Consider a line array of drivers that is hinged at the top and tilted downward. Tilting moves the bottom drivers further away from the lis- tener in time as well as in space. We can produce the same acoustical effect by applying progressively longer delays to each driver as we move from top to bottom of the array. Again, steering is not a new idea. It is different from Mechanical AimingFront and Rear Lobes Steer the Same Direction. Beam- steering produces different acoustical results than mechanical aim- ing because both front and rear lobes are steered in the same direction. For progressive delay to steer the main lobe, the array must be two wavelengths (2 ) tall The different model designations in the IC Series refer to the number of co- axial transducers in the vertical array. The different models can be steered effectively down to the following frequencies: IC8: 800Hz IC16: 400Hz IC24: 250Hz IC32: 200Hz BeamWare: The Software That Controls Iconyx Linear Array Systems The section of this white paper entitled Multi- Channel DSP Can Control Array Height on page 7 discusses how a series of low- pass filters can main- tain constant beamwidth over the widest possible frequency range. The ideas are simple, but for the most basic Iconyx array, the IC16, we must calculate and apply 16 sets of FIR filters, and 16 separate delay times. If we intend to take advantage of constant inter- driver spacing to move the acoustical center of the main lobe above or below the physical center of the array, we must calculate and apply a different set of filters and delays. Complex low- pass filtering produces a 20 lobe for an IC8 array DSP- Driven Vertical Arrays Theoretical models are necessary, but as discussed in the section on Line Source Performance: Real Driver Interactions, the behavior of real transducers is more complex than the model. Each of the com- plex calculations underlying the Iconyx beam- shap- ing filters were simulated, then verified by measur- ing actual arrays in our robotic test and measure- ment facility. Fortunately, the current generation of laptop and desktop CPUs are up to the task. BeamWare takes user input in graphic form (side section of the audi- ence area, location and mounting angle of the physical array) and provides both a simulation of the array output that can be imported into EASE (v4.0 or higher) and a set of FIR filters that can be downloaded to the Iconyx system via RS422 serial control. The result is a graphical user interface that delivers precise, predictable and repeatable results in real- world acoustical environments. Iconyx: a next-generation solution Sound Quality Iconyx sounds like a Renkus- Heinz loudspeaker, because it has been designed from the start for accurate, natural reproduction of both speech and music. Earlier digitally controlled arrays had restrict- ed bandwidth and sounded more like “ tall paging horns.” One of key differences between Iconyx array modules and earlier designs is that Iconyx uses wideband, wide- angle co- axial drivers instead of “ full range” cones or separate dome tweeters. Wider dispersion. The decision to use high performance co- axial driv- ers gives Iconyx wider horizontal dispersion, espe- cially at high frequencies. This means more consis- tent frequency response across the coverage area, and wider dispersion that allows many spaces to be covered properly using fewer devices. Flexibility Iconyx modules are vertical arrays of identical co- axial transducers. Because inter- driver spacing is constant, the acoustical center of the lobe can be positioned anywhere on the array. This can be very useful when the physical location of the array is either too high or too low for optimum coverage with a lobe radiating from the center of the array. Modular design allows each Iconyx array to have multiple elements and lobes. Multiple separate lobes can be produced from a single Iconyx array: each lobe can have a different beamwidth and steering angle. Lower cost Again thanks to the wider dispersion of the co- axial array elements, each Iconyx array can cover a larg- er area. Modular design cuts shipping cost because individual modules can be shipped via UPS and similar low- cost carriers. Main Performance Advantages of the Iconyx Design More efficient vertical pattern control Iconyx arrays with similar directivity indices to previ- ous designs are substantially smaller: arrays of sim- ilar size are more directional, which means they are more intelligible in reverberant spaces. In addition, the modular design of Iconyx gives the designer and installer more flexibility. Full bandwidth Previous designs had restricted bandwidth of 200 Hz 4khz. Iconyx is a full range system with a fre- quency response of 120 Hz 16 kHz. In addition, Iconyx modules are more electrically and acousti- cally efficient: they are 3 4 dB louder than previ- ous designs of similar dimensions. With full range output and greater efficiency, Iconyx sounds like a loudspeaker, not a “ tall paging horn.” Advanced electronics Each Iconyx array element is driven by its own processor/amplifier. If the optional AES/EBU or CobraNet inputs are used, the signal path is “ pure digital.” The DSP amplifier converts the PCM input data directly to PWM data that drives the output stage. First- generation “ digital” amplifiers must con- vert PCM data to analog waveforms and then con- vert again from analog to PWM. These conversion stages introduce distortion and latency into the sig- nal chain. Sophisticated DSP algorithms Developed specifically for Iconyx, the sophisticated DSP algorithms and BeamWare interface make it easy to adapt Iconyx arrays to a wide variety of audience areas. SPL can be made consistent over distances of up to 300 feet. The lobe center can be moved anywhere from the top to the bottom of the array. Multiple lobes with individual beamwidths and steering angles can be produced from a single array. An EASE DLL allows Iconyx arrays to be accurately modeled in EASE 4.0 and higher. 19201 Cook Street, Foothill Ranch, CA 92610, USA . Phone: +1 949 588 9997 . Fax: +1 949 588 9514 . salesrenkus- . www.renkus- RH577 Rev B 17/06