BW Broadcast DSPXtra-FM Скачать руководство пользователя

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Source Quality And Pre-emphasis

OUrCE

atErIaL

UaLIty

The DSPXtra-FM has the ability to substantially improve the quality of your ON-AIR broadcast. However the

DSPXtra-FM can only work with what you provide it. The best performance will be obtained when the DSPXtra-

FM is fed with very clean source material. After dynamic multi-band re-equalisation is performed poor quality

source material will sound poorer when processed with the DSPXtra-FM.

We strongly advise against the use of MP3's and other compressed audio formats for audio storage. If you must

use compressed audio we advise rates of 256 Kbps and higher. Linear formats are always to be preferred.

Compressed audio formats employ frequency masking data reduction techniques to reduce the bit-rate. Through

re-equalisation the DSPXtra-FM can violate the frequency masking characteristics of the bit reduction process,

creating distortion that was inaudible prior to the DSPXtra-FM processing.

EMPhaSIS

If you are using the DSPXtra-FM to process for FM broadcast you will need to enable the pre-emphasis filter in

the DSPXtra-FM. Even though your STL or transmitter may contain pre-emphasis we recommend disabling it,

letting the DSPXtra-FM handle the pre-emphasis for the transmission system. The DSPXtra-FM uses sophis-

ticated processing methods to limit the high frequency energy of the pre-emphasis curve while maintaining a

'bright' sound. Using de-emphasis and then pre-emphasising again will only degrade performance and possibly

casue overshoots, resulting in lower average deviation.

The exception to the rule is when the DSPXtra-FM is feeding discrete left and right outs to a compressed audio

STL. Bit rate reduction codec's do not cope with pre-emphasis very gracefully and artifacts will be generated.

The best option in this case is to de-emphasise the output of the DSPXtra-FM prior to the STL system. At the

transmitter site the pre-emphasis can be enabled in the transmitter to restore the processed signal back to nor-

mal prior to transmission.

The best solution is always to locate the processor at the transmission site. This way overshoots are minimised
and quality is maintained.

Содержание DSPXtra-FM

Страница 1: ...DSPXtra incorporating the Broadcast Audio Processor Operational Manual Version 2 30 www bwbroadcast com RMS Leveller...

Страница 2: ...16 The DSPXtra FM and its processing structure 17 The processing path 17 Processing block diagram 19 User levels 20 The DSPXtra FM menu system overview 21 The menu structure 22 Processing parameters...

Страница 3: ...maintenance repair work are expressly excluded from this warranty in particular if caused by improper handling of the product by the user This also applies to defects caused by normal wear and tear in...

Страница 4: ...rs stoves or other appliance including amplifiers that produce heat Power Source The appliance should be connected to a power supply only of the type described in the operating instructions or as mark...

Страница 5: ...ive 2004 108 EC electromagnetic compatibility Conformity is declared to those standards EN50081 1 EN50082 1 WARNING This equipment generates uses and can radiate radio frequency energy If not installe...

Страница 6: ...or was the DSPX Why DSPX Like most products the concept is conceived nameless The name DSPX came about for several reasons Firstly the BW team couldn t decide on a name we liked so the concept became...

Страница 7: ...eadphone jack and memory devices to hold the software and firmware The Processing Architecture After input selection the 24 bit digital audio signal is passed through conditioning circuitry before bei...

Страница 8: ...70 60 50 40 30 20 10 PILOT 0 0 3 6 9 12 15 18 21 24 27 30 33 36 39 42 1 2 3 4 5 6 7 8 9 10 11 12 15 18 6 4 2 0 2 4 6 8 10 12 14 16 18 GATE CLIP GATE 18 16 14 12 10 8 6 4 2 0 2 4 6 HOLD 2 4 6 8 10 12 1...

Страница 9: ...column of each band 1 through 4 represents the Right plus Left component aka the SUM signal while the right hand column of each band represents the Left minus Right component of the audio aka the DIF...

Страница 10: ...EBU Indicates the presence of a valid AES EBU signal connected to the digital audio input of the DSPXtra FM EDIT Indicates that you are currently editing a parameter LOW HIGH MIDH MIDL LOW HIGH MIDH M...

Страница 11: ...6 Connect the audio outputs as required and set the de emphasis for the analogue and digital outputs to OFF MODE to DR and set the output levels for the analogue and digital outputs to match the equip...

Страница 12: ...med on the RMS level of the audio waveform and the ratio of compression is usually adjustable Compression is usually gated to prevent gain riding and suck up of noise during silence or quiet periods L...

Страница 13: ...RMS Average One very useful way to determine average level is called Root Mean Squared or RMS for short This is a math ematical process where the audio s absolute value is squared then an average of t...

Страница 14: ...When one instrument that is confined to a limited portion of the spectrum such as a bass drum is higher in energy level than the rest of the spectrum combined the level intensity and rhythmic variatio...

Страница 15: ...ified design The above waveform chart demonstrates the peak level of a piece of typical music audio in blue superimposed with its RMS energy value the black line Note that the RMS level does not close...

Страница 16: ...using the DSPXtra FM to process for FM broadcast you will need to enable the pre emphasis filter in the DSPXtra FM Even though your STL or transmitter may contain pre emphasis we recommend disabling i...

Страница 17: ...ly with less bits of digital information because it is not wasting bits encoding non audible clipping artifacts Look ahead limiting produces less harmonic distortion but produces IM distortion if over...

Страница 18: ...e analogue output also has one extra path that can be routed to its outputs This is a lower latency delay path that bypasses the final clipper stages and reduces delay by more than 4mS This can be use...

Страница 19: ...N 1 DELAY ATTACK RELEASE LOOKAHEAD DR MODE N 1 DELAY ATTACK RELEASE N 1 DELAY ATTACK RELEASE LPF 15 19 OUTPUT MPX PILOT OUT D A MPX COMP CLIP DIGITAL SRC DE ANALOG D A DE PILOT SYNC SCA IN MPX OUT DSP...

Страница 20: ...le Another reason for doing this is to stop the scenario of setting an advanced control to a certain value and then switching to begin ner mode and having no way of fully controlling the processing be...

Страница 21: ...hat affect input selection level control and signal conditioning PROCESS Contains all the controls that affect the processing OUTPUT Contains all the controls that affect output selection level contro...

Страница 22: ...ner mode selected MENU INPUT INPUT SOURCE STEREO MODE ANALOG INPUT LEVEL RIGHT TRIM INPUT FAIL SWITCH HIGH PASS FILTER PHASE ROTATOR PRE EMPHASIS MENU PROCESS MENU ARIANE MODE Enables one of three Ari...

Страница 23: ...w fre quency energy that could otherwise cause carrier shift AFC LOOP problems in older FM transmitters We suggest you leave the high pass filter off unless you have a reason to turn it on Phase Rotat...

Страница 24: ...prevents suck up of noise during periods of silence or low level audio The level can be adjusted to turn on when the input drops to a level from 15dB to 35dB below the reference level After 10 seconds...

Страница 25: ...smaller numbers indicating faster release times B3 RELEASE Controls the release decay rate of band 3 of the AGC the time the AGC takes to respond to a decrease of input level The DECAY time can be var...

Страница 26: ...Controls the average release decay rate of the limiter the time the limiter takes to respond to a decrease of input level The DECAY time can be varied between 1 and 10 which corre sponds to 200mS to 5...

Страница 27: ...M mode of operation MULTI BAND CLIP DRIVE Controls the drive into the multi band clippers that precede the main clipper Adjustable over a 6dB to 6dB range BASS CLIP LEVEL Controls the clip level of th...

Страница 28: ...ALOG menu contains the controls relevant to the analogue outputs OUTPUT LEVEL Controls the output level of the analogue output Range is 12dBu to 24dBu MODE This parameter sets the output mode of the a...

Страница 29: ...t the daypart will run for The SYSTEM menu contains all the system controls non processing such as remote control and secu rity LCD CONTRAST Sets the contrast of the front panel LCD screen The range i...

Страница 30: ...t from the program material Phase rotator This parameter if enabled will help to reduce vocal distortion in aggressive presets by reducing asymmetry in the voice which would otherwise put more workloa...

Страница 31: ...band When enabled the restriction controls make it impossible for the Low and High bands to ever operate with more than a specified amount of gain beyond that of the adjacent band note they are alway...

Страница 32: ...you will generate higher levels of IM distortion and the sound will take on a busy packed tex ture You may also observe higher levels of high frequency noise when the band 3 and 4 drives are increase...

Страница 33: ...k and average energy in the detector With smaller numbers more energy is transferred into the average circuit and a higher platform level is created so more time will be spent releasing at the slower...

Страница 34: ...but a band output level control where small EQ changes can be made It has been called the mixer as most other processors have a mixer at this position and our VIRTUAL mixer does the same job Bands 1...

Страница 35: ...Higher numbers produce more bright ness but at the expense of greater distortion in the final clipper A balance of multi band clipping and final clipper clipping produces the best results Bass clippi...

Страница 36: ...do what we want to use the clipper for which is gaining loudness You may not notice the effect of this control on all program material When adjusting the clipper finesse control we recommend that you...

Страница 37: ...its look ahead limiter this high frequency energy can modulate the rest of the audio waveform and introduce a pumping type sound If you are using the processor to process for DUAL services FM and dig...

Страница 38: ...s letting each bands energy not be restricted by its neighbour While it is possible to create a strange response in the Ariane it is hard to produce distortion because what ever gets through the AGC i...

Страница 39: ...tortion generated in the multi band clipper Decrease the final clipper drive Increase the clipper finesse control Look ahead limiter DRUSE Decrease the look ahead limiter drive Decrease the attack tim...

Страница 40: ...hich will be removed by the de emphasis curve in the listeners radios The HF CLIPPING band 5 and or 6 PEAK ATTACK and THRESHOLD controls governs the amount of high frequency control distortion control...

Страница 41: ...rol is set at 0dB then full processed spatial energy is demultiplexed with the L R mono signal At the other end of the scale setting the control to OFF will inject zero energy into the demultiplexor l...

Страница 42: ...you press the DONE soft key to save the preset to the DSPXtra FM s memory For speed saving the current settings to the same active preset is as simple as pushing the same button three times as SAVE s...

Страница 43: ...e for lighter formats where loudness is not everything Matrix mode in the Ariane F3 AC ST A nice balance for lighter formats where loudness is not everything Stereo mode in the Ariane F4 AC V LOUD A m...

Страница 44: ...ighs with this preset will make your sound roll Stereo is used in the Ariane F20 ROCK MA Lots of HF and clipping going on here Smash it up baby Matrix is used in the Ariane F21 ROCK ST Lots of HF and...

Страница 45: ...A of this manual This section of the manual will refer to only serial and lan ports as the rear panel serial port and front panel USB port are the same to the DSPXtra FM they are only differentiated...

Страница 46: ...password control elsewhere in this manual NET LAN PORT The DSPXtra FM is equipped with a NET LAN port for ease of remote control setup and monitoring CONTROL OF THE DSPXtra FM BY THE NET LAN PORT If y...

Страница 47: ...pending on what option is selected on the menu tree located to the left of the screen The DSPXtra FM remote control application has three windows The left hand contains the navigation preset window Th...

Страница 48: ...re are two additional identifiers to mark these occurrences DP for Daypart and TR for remote trig ger If a daypart of trigger occurs the TR or DP will appear next to the name and the preset name will...

Страница 49: ...a factory preset Rename preset Rename preset allows the user preset name to be edited You are restricted to 15 characters Saving presets to PC This option will pop up the standard windows save dialog...

Страница 50: ...s Each has three parameters The left hand box contains the name of the preset that you want this daypart to switch to This box also has the ability to turn the daypart OFF by clicking down on the arro...

Страница 51: ...g the default preset and overlaying dayparts we are able switch presets significantly more than you first think you will be able to A B COMPARISON FEATURE The Remote application has two buttons labell...

Страница 52: ...e connected to the earth return pin they will change the currently active preset to the user preset triggered by that pin If more than one pin is pulled low at the same time the pin with the lowest nu...

Страница 53: ...GO soft key can be pressed to confirm entry and proceed If unsuccessful you will be required to try again If successful the DSPXtra FM will allow you to re confirm the code or change it This is where...

Страница 54: ...and with the same control set the preset to switch to when the daypart triggers when the daypart start time matches the system clock You can also set the start time trigger of each daypart and set the...

Страница 55: ...shelf bass enhancement along with composite clipping with pilot protection Dual processing paths make the DSPXtra FM effectively two processors in one feeding both your analogue transmitter and a dig...

Страница 56: ...htclicking on the appropriate connection and selecting Disable from the menu The connection can be re enabled after the installation is complete This is not necessary under Windows XP SP 2 if configur...

Страница 57: ...s in the example below or browse to it by clicking the browse button Once the file path has been entered in the box click next to proceed If Windows XP is configured to warn when unsigned non WHQL cer...

Страница 58: ...XP copies the required driver files Windows should then display a message indicating that the installation was successful Click Finish to complete the installation This has installed the serial conver...

Страница 59: ...rd will continue by installing the COM port emulation driver The procedure is the same as that above for installing the serial converter driver Open the Device Manager located in Control Panel System...

Страница 60: ...TTACK B1 B2 COUPLE dB B3 B4 COUPLE dB L R B1 MUTE L R RESTRICTION dB L R INJECTION dB STEREO MODE IDR dB GATE dB ATTACK B1 RELEASE B2 RELEASE B3 RELEASE B4 RELEASE B1 B2 COUPLE dB B3 B4 COUPLE dB CHAN...

Страница 61: ...P ATTACK COMP DECAY HOLD dB dB dB dB DELAY BAND 5 DRIVE dB dB dB dB THRESHOLD dB dB dB dB LIMIT ATTACK LIMIT DECAY COMP ATTACK COMP DECAY HOLD dB dB dB dB DELAY BAND 6 DRIVE dB dB dB dB THRESHOLD dB d...

Страница 62: ...N CLIP FINESSE OVERSHOOT CTRL ITU LIMITER dBr dBr dBr dBr LOOKAHEAD DRIVE dB dB dB dB SHELF EQ Hz Hz Hz Hz LOW ATTACK LOW DECAY MID ATTACK MID DECAY HIGH ATTACK HIGH DECAY OUTPUT STEREO LEVEL dBu dBu...

Страница 63: ...www bwbroadcast com...

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