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BW Broadcast DSPXtreme-FMHD Operational Manual

Broadcast audio processor
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DSPXtreme-FMHD
Broadcast Audio Processor
Operational Manual
Version 1.30
www.bwbroadcast.com

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Summary of Contents for BW Broadcast DSPXtreme-FMHD

  • Page 1 DSPXtreme-FMHD Broadcast Audio Processor Operational Manual Version 1.30 www.bwbroadcast.com...

  • Page 2: Table Of Contents

    Table Of Contents Warranty Safety Introduction to the DSPX treme DSPXtreme connections DSPXtreme meters Quickstart An introduction to audio processing Source material quality Pre-emphasis Low pass filtering and output levels The DSPXtreme and its processing structure The processing path Processing block diagram The DSPXtreme menu structure Processing paramters Setting up the processing on the DSPXtreme...

  • Page 3: Warranty

    Any repair or opening of the unit carried out by unauthorized personnel (user included) will void the warranty. If an inspection of the product by BW Broadcast shows that the defect in question is not covered by the war- ranty, the inspection costs are payable by the customer.

  • Page 4: Safety

    afety nStructIonS CAUTION: To reduce the risk of electrical shock, do not remove the cover. No user serviceable parts inside. refer servicing to qualified personnel. WARNING: To reduce the risk of fire or electrical shock, do not expose this appliance to rain or moisture. This symbol, wherever it appears, alerts This symbol, wherever it appears, you to important operating and mainte-...
  • Page 5 Object and Liquid Entry: Care should be taken so that objects do not fall and liquids are not spilled into the enclosure through open- ings. Damage Requiring Service: The appliance should be serviced by qualified service personnel when: - The power supply cord or the plug has been damaged; or - Objects have fallen, or liquid has been spilled into the appliance;...

  • Page 6: Introduction To The Dspx Treme

    The BW Broadcast DSPXtreme is a new generation of digital audio signal processor that can be used to process audio ready for FM and digital broadcasting such as HD Radio, DAB or internet radio. Using the latest multi-band DSP technology the DSPXtreme offers a versatile and powerful tool in creating a loud punchy on-air presence.

  • Page 7: Dspxtreme Connections

    Connections...

  • Page 8: Dspxtreme Meters

    dSPX treme eterS The DSPXtreme has a dedicated LCD screen on the left displaying instant IO and processing metering. You can switch from processing metering to IO metering (and back) with the button located on the bottom-right side of the touch-screen. Change from I/O metering and GR metering with this button I/O metering The input meters show the level of the input audio.
  • Page 9 G/R metering - six band limiter The six band limiter displays gain reduction from 0dB to -dB in dB steps. There is only one meter per stereo channel and the value shown is the largest gain reduction of the left and right channels.

  • Page 10: Quickstart

    uIck Start 1. Install the processor into the rack. 2. Connect AC power to the unit, and turn on the power. 3. Connect the analogue and / or digital audio inputs. 4. Select the analogue or digital input as the source of the processing with the 'INPUT SELECTION' parameter which can be found in the 'INPUT' menu.

  • Page 11: An Introduction To Audio Processing

    ntroductIon udIo roceSSInG Most audio processors use a combination of compression, limiting and clipping to 'funnel' the dynamic range down, reducing the peak to average ratio in each stage. A cascaded arrangement of compressor, limiter and clipper produces the best results. The first stage of processing usually operates in a slow manner, the process- ing getting progressively faster and more aggressive as the audio passes through the chain.

  • Page 12: Source Material Quality

    ource aterIal ualIty The DSPXtreme has the ability to substantially improve the quality of your ON-AIR broadcast. However the DSPXtreme can only work with what you provide it. The best performance will be obtained when the DSPXtreme 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 DSPXtreme.

  • Page 13: The Dspxtreme And Its Processing Structure

    dSPX treme roceSSInG tructure The DSPXtreme broadcast audio processor can be used for processing audio prior to broadcast on FM and digital radio services. Digital radio encompasses DAB, HD Radio (IBOC) and other radio based broadcasting as well as internet radio, also known as streaming. The DSPXtreme can also be used effectively for audio post pro- duction and mastering, ideal for giving CD’s that HOT sound.
  • Page 14 Mixer The six bands are 'virtually' mixed together at this stage. In truth, the six bands have become three. The three bands are fed off into the two peak processing paths. Distortion controlled clippers (PEAK CONTROL PATH 1) The DSPXtreme clipping algorithms peak limit (clip) and linear phase filter the audio in three bands for maxi- mum distortion control before being fed to the final clipper stages.

  • Page 15: Processing Block Diagram

    Block Diagram...

  • Page 16: The Dspxtreme Menu Structure

    AES1 OUTPUT LEVEL tructure AES2 OUTPUT LEVEL AES1 RATE MENU: INPUT AES2 RATE INPUT SOURCE AES1 DE-EMPHASIS STEREO MODE AES2 DE-EMPHASIS ANALOG INPUT LEVEL MENU: STEREO RIGHT TRIM LEVEL INPUT FAIL SWITCH PILOT LEVEL HIGH PASS FILTER PILOT PROTECTION PHASE ROTATOR ITU LIMITER PRE-EMPHASIS 19K REFERENCE OUT...

  • Page 17: Processing Paramters

    roceSSInG arameterS User Level: This parameter allows you to select between beginner and advanced modes. Beginner mode restricts access to certain menus and controls. The 'INPUT' menu contains all of the options and parameters relating to the control and conditioning of the audio inputs.
  • Page 18 'GATE THRESHOLD' The gate function 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 -0dB to -0dB. The gate can also be switched off or forced on. The gate when turned on will cause the gain reduction to move towards the level set by the RTR LEVEL control and to move towards that level at the rate set by the RTR speed control.
  • Page 19 in 0.dB steps. 'LIMITER ATTACK' Controls the attack rate of the limiter, the time the limiter takes to respond to an increase of input level. The attack time can be varied between 1 and 10 which corresponds to 1 ms to 00 ms on a semi-exponential scale.
  • Page 20 'MID ATTACK' Controls the average attack rate of the B3 look-ahead limiter. This defines the energy dis- tributed into the secondary time constant circuit. The attack time can be varied between 1 and 10 which corresponds to 10 ms to 000 ms on a semi-exponential scale. 'MID DECAY' Controls the average decay rate of the B3 look-ahead limiter.
  • Page 21 Overdrive the main clipper to hear the effect of this control and then back the drive back down after the finesse control is set to your taste. 'OVERSHOOT CONTROL' Controls how much the main clipper will pass overshoots to the compos- ite clipper.
  • Page 22 limiter will drastically reduce the loudness of your signal and should be used only if the regulations in your country require you to comply with ITU BS.1. Otherwise set this parameter to off. The thresholds are calibrated in dB relative to the ITU BS.1 reference. 'PILOT OUTPUT' This controls the 19KHz pilot output reference signal which is available on the DSPXtra-FM back panel.
  • Page 23 'DELAY COARSE' Adjusts the delay in seconds, from 0 s to 1 s in 0.1 s steps. 'DELAY MEDIUM' Adjusts the delay in miliseconds, from 0 ms to 99 ms in 1 ms steps. 'DELAY FINE' Adjusts the delay in samples, from 0 smps to 7 smps in 1 smps steps. The 'SCHEDULE' menu contains all the controls for the dayparting (REAL TIME CLOCK) preset switch- ing.

  • Page 24: Setting Up The Processing On The Dspxtreme

    dSPX ettInG uP the roceSSInG on the treme This section has more detailed information on setting up the DSPXtreme’s processing. Because the DSPXtreme contains another product in its own right, the Ariane, we have decided to start with discussing that section of the processing and its setup. This also seems logical because it is the first part of the processing chain after the audio has been routed through the high pass and phase rotating filters which we will get out of the way below before moving on to the background, workings and setup of the Ariane.
  • Page 25 The effects of time constant speeds AGC attacking and decaying with faster time AGC attacking and decaying with slower time constants constants which the program material must fall below for the gate to become active, and this can be adjusted over a range of -0dB to -0dB.
  • Page 26 Band-couplings The DSPXtreme band-coupling controls allow us to reduce the effects of the multi-band processing by coupling the bands to a certain extent. This may be desirable if we want to limit the re-equalisation effects of the multi- band AGC and limiters. By carefully selecting the coupling ratios we can also reduce any possible spectral skewing when the processing stages are driven into heavy gain reduction.
  • Page 27 of 6dB is a good compromise and starting point. The peaking bass equalizer is a pseudo parametric style bass equalizer control that allows you to sweet tune the bass. Four frequencies, amplitudes and Q's are provided giving you 6 different bass curves to select from. Frequencies selectable: 60Hz, 76Hz, 9Hz and 10Hz.
  • Page 28 mum setting of a balance of the two. The peak attack time should be set to the desired attack time required from that limiter. The range is 1-10 which corresponds to 1 to 00mS on an exponential scale. The peak decay time should be set to the desired peak decay time required for transients.
  • Page 29 The multi-band limiters have an extra mechanism called HOLD which works in the same way as the GATE con- trol in the AGC stages. Unlike the GATE control the HOLD control has no extra associated controls like return to rest levels and speeds. The hold feature when triggered will HOLD the average platform level at its last value before the hold was triggered.
  • Page 30 Radio stations have a desire to be competitively loud and clipping is the easiest and most effective way in gain- ing loudness in a processor. While clipping is effective there is only so far you can push a clipper before notice- able distortion occurs.
  • Page 31 creating space for the other bands. What mode should I use? If you can live with the delay then try both and see what sound you prefer. Talk radio and softer formats such as easy listening usually sound better with the soft option. Dance and urban formats can benefit from the added punch generated by the controlled distortion with the hard bass-clipper.

  • Page 32: Stereo Generator

    need to be adjusted carefully to prevent pumping when driving the look-ahead limiter more aggressively. Like the dual time constants in the multi-band limiters you can adjust so that the peak time constants have most of the control or the secondary ones have most of the control, or a balance, which works best. To lessen the effect of the secondary time constants set the attack to 10 and the decay to 1.
  • Page 33 The composite clipper in the DSPXtreme's stereo encoder is highly over-sampled and allows you to gain an extra dB or two of modulation loudness when using the multiplex output to drive your FM transmitter. The range of the composite clipper is -0. to dB. If you are using high composite clipping drive (lots of composite clipping), an optional pilot protection notch filter will protect the pilot area from being contaminated by clipping harmonics.

  • Page 34: Getting The Sound That You Want

    ettInG ound While the DSPXtreme can help you obtain the sound that you want we must always take into account the limita- tions presented to us by the transmission channel. The biggest problem we have is the maximum peak level that can be handled by that transmission channel.
  • Page 35 More CLARITY We can obtain extra clarity and quality in several ways. Multi-band AGC: Slow down the release times. Decrease the GATE thresholds allowing the release times to release less often. Increase the band and channel coupling ratios , letting each bands energy be restricted by its neighbour. Multi-band Limiters: Speed up the peak attack times, letting less through to the clippers.
  • Page 36 Bass clipper: (FM USE) Increase the multi-band clipper drive. Increase the bass clip level. Set the bass clip mode and shape to suit the tone of the bass you prefer. Look-ahead limiter: (DR USE) Increase the look-ahead limiter drive. Increase the band 1 look-ahead limiter attack time constant slowing down the attack of the secondary time constant circuit.

  • Page 37: Managing Presets

    anaGInG reSetS front Panel control The DSPXtreme has an assortment of factory presets and provision for 16 user ones. While the factory presets may not suit your tastes you will generally find one that serves as a good starting point in creating your own cus- tom preset.

  • Page 38: Factory Presets

    actory reSetS The factory presets in the DSPXtreme are not supposed to be de facto standards by any means but are start- ing points for you to create your own user presets. It is impossible to create presets that will suit every format and market.

  • Page 39: Remote Control Of The Dspxtreme

    Firmware (new versions of DSPXtreme code) will also need to be uploaded into the DSPXtreme via the serial port system. The BW Broadcast development team have built the serial communications XMODEM protocol. Any standard terminal program will allow you to send an update file into the DSPXtreme via XMODEM protocol.
  • Page 40 Remote application connection screen NET/LAN PORT The DSPXtreme is equipped with a NET/LAN port for ease of remote control, setup and monitoring. CONTROL OF THE DSPXtreme BY THE NET/LAN PORT If you wish to use the NET/LAN port to control the DSPXtreme follow the steps below 1.
  • Page 41 Remote application connected When the DSPXtreme is connected the LED’s will show activity and the main controls window should show processing controls, depending on what option is selected on the menu tree located to the left of the screen. The DSPXtreme remote control application has three windows. The left hand contains the navigation/preset window.
  • Page 42 Preset window shown If you are not using dayparting or the external trigger port the default preset will always be the 'on air' preset and it will be marked in the preset list with a (DEF) which appends to the preset name. If the scheduler (dayparting) or the remote trigger interface has changed the preset the (DEF) marked preset may not be the one that is on the air.
  • Page 43 Loading presets from a PC This option will pop up the standard windows load dialog box. You can browse to and select a preset file to be loaded into the DSPXtreme. The preset location that is loaded is the currently highlighted (in blue) preset, not the one that is currently 'on-air' You can only load into a user preset.
  • Page 44 by clicking down on the arrows until you reach the off option. If off is currently selected you can click up to rotate through the user and factory presets. The middle box contains the time and day that the daypart will start at. To select day, hour or minute click on the appropriate part of the box before using the up and down arrows.

  • Page 45: Remote Trigger Port

    MITERS OUTPUT HO LD DSPXtra REMOTE INPUT LOAD PROCESS AES/EBU OUTPUT SAVE EDIT emote rIGGer The system menu contains the remote trigger port option from where it can be enabled or disabled. If enabled the remote trigger port on the processor allows you to select any of the first 8 user presets by pulling one of 8 pins on the trigger port socket low.

  • Page 46: Clock Based Control

    lock aSed ontrol ayPartInG Your processor contains a battery backed up real time clock that can maintain the current time and date even when the power has been removed. This allows users to switch between presets at specific times of the day or week.

  • Page 47: Specifications

    PecIfIcatIonS Specifications apply for measurements from analog left/right input to stereo composite output and to FM analog left/right output. Measurements apply to FM mode of operation. Frequency Response (Bypass Mode): Follows standard 0µs or 7µs pre-emphasis curve ±0.10 dB, .0 Hz– 1 kHz.
  • Page 48 Filtering: RFI filtered. MPX output 1 Source Impedance: 10 Ohm Single-ended, floating over chassis ground. Load Impedance: 600 Ohm or greater. Maximum Output Level: +1.0 dBu (peak) software-controlled output level control. Minimum Output Level: 0 dBu (peak)Software-controlled output level control. Pilot Level: Adjustable from 6.0% to 1.0% and OFF, software controlled.

  • Page 49: Preset Sheet

    DSPXtreme-FMHD v1 preset sheet Preset 1 Preset 2 Preset 3 Preset 4 INPUT SOURCE MODE ANALOG LEVEL INPUT FAIL HP FILTER PHASE ROTATOR PRE-EMPHASIS µs µs µs µs PROCESS MULTI-BAND AGC WINDOW GATING GATE B1< COUPLE B3> COUPLE CHANNEL COUPLE...
  • Page 50 LIMIT. ATTACK LIMIT. DECAY COMP. ATTACK COMP. DECAY HOLD DELAY BAND  DRIVE THRESHOLD LIMIT. ATTACK LIMIT. DECAY COMP. ATTACK COMP. DECAY HOLD DELAY BAND  DRIVE THRESHOLD LIMIT. ATTACK LIMIT. DECAY COMP. ATTACK COMP. DECAY HOLD DELAY BAND 6 DRIVE THRESHOLD LIMIT.
  • Page 51 STEREO LEVEL PILOT LEVEL PILOT PROTECTION ITU LIMITER 19kHz SYNC Preset Sheet...
  • Page 52 www.bwbroadcast.com...

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