ORBAN 8200_Section_3 电路图.pdf

《ORBAN 8200_Section_3 电路图.pdf》由会员分享，可在线阅读，更多相关《ORBAN 8200_Section_3 电路图.pdf（78页珍藏版）》请在收音机爱好者资料库上搜索。

1、Section 3 Operation pagecontents 3-38200 Controls and Meters 3-5Introduction to Processing 3-7Customizing the 8200s Sound 3-9About the Processing Structures 3-9Factory Programming Presets 3-15The Protection Limiter Structure 3-21The Two-Band Structures 3-31The Multi-Band Structure 3-418200 Screen Di

2、splays 3-45RECALL PRESET Screen 3-49MODIFY Screens 3-59AUTOMATION Screens 3-63SYSTEM SETUP Screens Caution The installation and servicing instructions in this manual are for use by qualified personnel only. To avoid electric shock do not perform any servicing other than that contained in the Operati

3、ng Instructions unless you are qualified to do so. Refer all servicing to qualified service personnel. OPTIMOD-FM 8200OPERATION 3-1 RadioFans.CN 收音机爱 好者资料库 CONTROL KNOB ARROW KEYS SCREEN CONTRAST CONTROL SOFT KEY BUTTONS ESC BUTTON HELP BUTTON TEST SWITCH POWER LED STEREO ENCODER CONTROLS 3-2 OPERAT

4、ION OPTIMOD-FM 8200 RadioFans.CN 收音机爱 好者资料库 pagecontents 8200 Controls and Meters Arrow Keys (, , , ) are used for moving around screen to select a function to be changed. Control Knob is used for changing the setting that is selected by the arrow keys. Screen Display provides all metering informati

5、on, labels the five soft-key buttons, provides control setting information. Screen CONTRAST adjusts the optimum viewing angle of the screen display. Five Soft Key Buttons provide access to all 8200 functions and controls. The functions of the buttons change with each screen, according to the labels

6、at the bottom of each screen ESC Button provides an escape from current screen, returns user to the next previous screen, and repeated ESC commands will always return you to the IDLE G/R screen. HELP Button provides HELP information for the current screen and provides detailed help for all of the bu

7、ttons on that screen (by pushing HELP button, then the screen button). POWER LED lights when the unit is powered. (It monitors the unregulated +12V DC bus.) Stereo Encoder Screwdriver-Adjustable Controls Orban supplies a special green-handled flat-blade screwdriver (Xcelite R3323) to adjust the ster

8、eo encoder controls. Note that the Orban tweaker tool supplied with the analog OPTIMODs cannot be used with the 8200. Test Switch (OPERATE SUB TO MAIN MAIN TO SUB) sets the stereo encoder to operate normally, or to produce pure LR or L+R signals for system testing. COMPOSITE LEVEL 1 sets the output

9、level of Composite Output 1. COMPOSITE LEVEL 2 sets the output level of Composite Output 2. SEPARATION adjusts the level of the L+R signal, enabling you to optimize the separation through the entire transmission system. (See step 4 on page 4-11.) PILOT LEVEL adjusts the level of the 19kHz stereo pil

10、ot tone. See the note on page 4-14 about accessing and using the pilot meter. OPTIMOD-FM 8200OPERATION 3-3 RadioFans.CN 收音机爱 好者资料库 This Page Intentionally Left Blank. 3-4 OPERATION OPTIMOD-FM 8200 Introduction to Processing Some Audio Processing Concepts Loudness is increased by reducing the peak-to

11、-average ratio of the audio. If peaks are reduced, the average level can be increased within the permitted modulation limits. The effectiveness with which this can be accomplished without introducing objectionable side effects (such as clipping distortion) is the single best measure of audio process

12、ing effective- ness. Compression reduces the difference in level between the soft and loud sounds to make more efficient use of permitted peak level limits, resulting in a subjective increase in the loudness of soft sounds. It cannot make loud sounds seem louder. Compression reduces dynamic range re

13、latively slowly in a manner similar to riding the gain: limiting and clipping, on the other hand, reduce the short-term peak-to-average ratio of the audio. Limiting increases audio density. Increasing density can make loud sounds seem louder, but can also result in an unattractive busier, flatter, o

14、r denser sound. It is important to be aware of the many negative subjective side effects of excessive density when setting controls that affect the density of the processed sound. Clipping sharp peaks does not produce any audible side effects when done moderately. Excessive clipping will be perceive

15、d as audible distortion. Distortion in Processing In a competently-designed processor, distortion occurs only when the processor is clipping peaks to prevent the audio from exceeding the peak modulation limits of the transmission channel. The less clipping that occurs, the less likely that the liste

16、ner will hear distortion. However, to reduce clipping, you must decrease the drive level to the clipper, which causes the average level (and thus, the loudness) to decrease proportionally. The FM pre-emphasis curve introduces further complications. Pre-emphasis boosts the treble at 6dB/octave starti

17、ng at 2.1kHz (for 75s countries) or 3.2kHz (for 50s countries). This reduces the headroom available at high frequencies, and makes it difficult to achieve a bright sound. This is because bright sound requires considerable high frequency power to appear at the output of the receivers de-emphasis filt

18、er, and thus requires a very large amount of high frequency power to be transmitted so that a sufficient amount will survive the de-emphasis process. Without very artful processing, the pre-emphasis will radically increase the level of the peaks and force you to decrease the average level proportion

19、ally. Orbans high frequency limiting and distortion-canceling clipping systems greatly ease this trade-off, but cannot entirely eliminate it. Therefore, you can only increase brightness by reducing average modulation (loudness) unless you accept the increased distortion caused by driving the final c

20、lippers harder. OPTIMOD-FM 8200OPERATION 3-5 Loudness, Brightness and Distortion. In processing, there is a direct trade-off between loudness, brightness, and distortion. You can improve one only at the expense of one or both of the other two. Thanks to Orbans psychoacoustically-optimized designs, t

21、his is less true of Orban processors than of any others. Nevertheless, all intelligent processor designers must acknowledge and work within the laws of physics as they apply to this trade-off. Perhaps the most difficult part of adjusting a processor is determining the best trade-off for a given situ

22、ation. We feel that it is usually wiser to give up ultimate loudness to achieve brightness and low distortion. A listener can compensate for loudness by simply adjusting the volume control. But there is nothing the listener can do to make an excessively-clipped signal sound clean again, or to undo t

23、he effects of excessive high-frequency limiting. If processing for high quality is done carefully, the sound will also be excellent on small radios. Although such a signal might fall slightly short of ultimate loudness, it will tend to compensate with an openness, depth, and punch (even on small rad

24、ios) that cannot be obtained when the signal is excessively squashed. If women form a significant portion of the stations audience, bear in mind that women are more sensitive to distortion and listening fatigue than men. In any format requiring long- term listening to achieve market share, great car

25、e should be taken not to alienate women by excessive stridency, harshness, or distortion. OPTIMOD-FM from Bach to rock. OPTIMOD-FM can be adjusted so that the output sounds as close as possible to the input at all times (using the Protection Limiter Structure), or so that it sounds open but more uni

26、form in frequency balance (and often more dramatic) than the input (using any of the Two-Band Structures or slow Multi-Band Structures), or so that it sounds dense, quite squashed, and very loud (using the fast Multi-Band Structure). The dense, loud setup will make the audio seem to jump out of car

27、and table radios, but may be fatiguing and invite tune-outs on higher quality home receivers. The loudness/brightness/distortion trade-off explained above ap- plies to any of these setups. You will achieve best results if Engineering, Programming, and Management go out of their way to communicate an

28、d cooperate with each other. It is important that Engineering understand the sound that Programming desires, and that Management fully understand the trade-offs involved in optimizing one parameter (such as loudness) at the expense of others (such as brightness, distortion, or excessive density). Ne

29、ver lose sight of the fact that, while the listener can easily control loudness, he or she cannot undo excessive high-frequency limiting or make a distorted signal clean again. If such excessive processing is permitted to audibly degrade the sound of the original program material, the signal is irre

30、vocably contaminated and the original quality can never be recovered. 3-6 OPERATION OPTIMOD-FM 8200 Customizing the 8200s Sound The subjective setup controls on the 8200 give you the flexibility to customize your stations sound. But, as with any audio processing system, proper adjustment of these co

31、ntrols consists of balancing the trade-offs between loudness, density, brightness, and audible distortion. The following pages provide the information you need to adjust the 8200 controls to suit your format, taste, and competitive situation. When you start with one of our factory presets, there are

32、 two levels of subjective adjustment available to you to let you customize the factory preset to your requirements: LESS-MORE The first level is called LESS-MORE. As you go from less to more, the air sound will become louder, but (as with any processor) processing artifacts will increase. The single

33、 LESS-MORE control changes many different subjective setup control settings simultaneously according to a table that we have created in the 8200s permanent ROM (Read-Only Memory). In this table are sets of subjective setup control settings that provide, in our opinion, the most favorable tradeoff be

34、tween loudness, density, brightness, and audible distortion for a given amount of processing. We believe that most 8200 users will never need to go beyond the LESS-MORE level of control, because the combinations of subjective setup control settings produced by this control have been optimized by Orb

35、ans audio processing experts on the basis of years of experience designing audio processing, and upon hundred of hours of listening tests. Please note that the highest LESS-MORE setting is purposely designed to cause unpleasant distortion and processing artifacts! This helps assure you that the sett

36、ing of the LESS-MORE control that you choose is optimum, because turning the control up to this point will cause the sound quality to become obviously unacceptable. FULL-CONTROL If you want to create a signature sound for your station that is out of the ordinary, or if your taste differs from the pe

37、ople who programmed the LESS-MORE tables, FULL-CONTROL is available to you. At this level, you can customize or modify any subjective setup control setting to create a sound exactly to your taste. You can then save the settings in a user preset and recall it whenever you wish. You need not (in fact,

38、 cannot) create a sound entirely from scratch. All user presets are created by modifying factory presets or by further modifying factory presets that have been previously modified with a LESS-MORE adjustment. Because the LESS-MORE control also adjusts certain invisible system parameters that cannot

39、be accessed by the user even at the FULL-CONTROL level, it is wise to set the LESS-MORE control to achieve a sound as close as possible to your desired sound before you make further modifications at the FULL-CONTROL level. OPTIMOD-FM 8200OPERATION 3-7 If you want to create your own user presets, the

40、 following detailed discussion of the processing structures is important to understand. If you only use factory presets, or if you only modify them with LESS-MORE, then you may still find the material interesting, but it is not necessary to understand it to get excellent sound from the 8200. Fundame

41、ntal Requirements: High-Quality Source Material and Accurate Monitoring A major potential cause of distortion is excess clipping. Another cause is poor-quality source material, including the effects of the stations playback machines, electronics, and studio- to-transmitter link. If the source materi

42、al is even slightly distorted, that distortion can be greatly exaggerated by OPTIMOD-FM particularly if a large amount of gain reduction is used. Very clean audio can be processed harder without producing objectionable distor- tion. See Audio Quality in the FM Plant (a separate Orban publication inc

43、luded with each unit) for a discussion of how to improve source quality. A high-quality monitor system is essential. To modify your air sound effectively, you must be able to hear the results of your adjustments. In too many stations, the best monitor is significantly inferior to the receivers found

44、 in many listeners homes! See Audio Quality in the FM Plant for a detailed discussion of how to efficiently create an accurate monitoring environment (and otherwise bring the audio plant up to state-of-the-art quality). 3-8 OPERATION OPTIMOD-FM 8200 About the Processing Structures In the 8200, a pro

45、cessing structure is a program that operates as a complete audio processing system. Only one processing structure can be active at a time. Just as there are many possible ways of configuring a processing system using analog components (like equalizers, com- pressors, limiters, and clippers), there a

46、re many possible processing structures achievable by the 8200. Unlike an analog system, where creating a complete processing system involves physically wiring its various components together, the 8200 realizes all of its processing structures as a series of high-speed mathematical computations made

47、by Digital Signal Processing (DSP) integrated circuit chips. So the 8200 can be changed from one structure to another almost instantly by loading new software from high-speed semiconduc- tor memory within the 8200. Refer to the second page of this manual for the processing structures included in you

48、r version. Factory Programming Presets Factory Programming Presets are our “factory recommended settings” for various program formats or types. Each Factory Programming Preset is simply a Factory Processing Preset set to the LESS-MORE setting that is likely to match that program format in an average

49、 market. The Factory Programming Presets are designed as starting points to help you get on the air quickly without having to understand anything about adjusting the 8200s sound. Each of these presets can be edited with the LESS-MORE control to optimize the tradeoff between loudness, brightness, and distortion according to the needs of the format. Because it is so easy to fine-tune the sound at the LESS-MORE level, we think that most users will quickly want to customize their chosen preset to complement their market and competitive position after they had time to familiarize th