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24

Compression:

This list box selects specific compression formats for re-
cording, and displays the compressed format of the file
currently playing.  

Note that the Sample Rate and Com-

pression for recording can only be changed when the card
is in “Stop” mode.  If the card is in “Paused Record”, or is
recording, the Sample Rate or Compression will not actu-
ally change, even though the dialog box allows you to
change them.

If “MPEG” is double-clicked, the following dialog box will
open which allows you to select different bitrates of MPEG,
which trade off sound quality versus disk space used.

Figure 6.  MPEG Bitrates

Содержание SX-34

Страница 1: ...Digital Audio Adapter User s Manual September 17 1999 Rev E ANTEX ELECTRONICS CORPORATION 1125 W 190 th STREET GARDENA CALIFORNIA 90248 info antex com www antex com Toll Free 1 800 338 4231 Fax 310 5...

Страница 2: ...FCC Rules In order to maintain compliance with FCC regulations shielded cables must be used with this equipment Operation with non approved equipment or unshielded cables is likely to result in interf...

Страница 3: ...BALANCED SIGNALS 13 IMPEDANCE AND SIGNAL LEVELS 14 PLAYBACK AND RECORD DEVICES 15 COMPRESSION DATA RATES AND NETWORKS 16 ISO MPEG 1 BITRATES 17 DRIVER INSTALLATION 19 WINDOWS 95 19 Setup Tips Upgrade...

Страница 4: ...34 SX 6 MIXER AND BLOCK DIAGRAM 36 SX 5e MIXER AND BLOCK DIAGRAM 39 ANTEX METER 42 TROUBLESHOOTING 46 TECHNICAL ORDERING INFORMATION 49 APPENDIX 50 Connectors for Male Headers 50 Terms 50 Specificati...

Страница 5: ...File Open Dialog Box 25 Figure 8 Auto Repeat 26 Figure 9 SX 36 Mixer 32 Figure 10 SX 36 Block Diagram 33 Figure 11 SX 34 Mixer 34 Figure 12 SX 34 Block Diagram 35 Figure 13 SX 6 Mixer 37 Figure 14 SX...

Страница 6: ...s the driver the Antex Demo application Antex Mixer ap plication and Antex VU Meter application Contact Antex Techni cal Support or visit the Antex website www antex com for infor mation about DOS or...

Страница 7: ...del Antex Cards use the same jumper arrangement to set the board number JUMPER SETTINGS CONNECTIONS Top View Board 1 Board 2 Board 3 Board 4 Covered by jumper J1 SX 5e 6 34 35 36 2 1 4 3 2 1 4 3 2 1 4...

Страница 8: ...using connectors on the card s bracket Other connectors for auxiliary functions are single or dual row male headers on the card itself The pins on these connectors are numbered as follows Dual row hea...

Страница 9: ...4 balanced connections and shielded coax cable for unbalanced connections See the section Balanced and Unbalanced Sig nals...

Страница 10: ...ut DB 9 Female Balanced Analog I O Connector 1 2 3 4 5 6 7 8 9 SX 35 36 Balanced I O to XLR 1 2 3 4 5 6 7 8 9 Balanced In XLR male shell female pins Left Right 1 2 3 GND Right Balanced Out XLR female...

Страница 11: ...t Line Output Pin 11 Right Line Output Pin 13 Left Line Output Pin 15 Left Line Output Pin 2 4 6 8 10 12 14 16 Ground This connector duplicates the function of the DB9 connector It might be used with...

Страница 12: ...way as a record source or analog feed through to the Line Out MIC JP7 Pin 1 Microphone input 2 5 VDC phantom power Pin 2 Ground The microphone input will supply phantom power required by an Electret...

Страница 13: ...der the provides connections for an SPx module 2 Output Header JP5 JP5 is a 5 pin 0 100 spaced header that provides connec tions for the left and right output signals These are the same signals provid...

Страница 14: ...0 100 spaced header that provides a microphone input connection This is the same connection provided by the MIC jack on the bracket A signal present at JP7 is switched in only when there is no plug in...

Страница 15: ...10 5 Mono Header JP4 JP4 is a 2 pin 0 100 spaced header that provides a mono in put connection This input is not currently supported 1 Ground Mono Input 2...

Страница 16: ...ft Out 6 nc 7 nc 8 Right Out 9 Left Out DB 9 Female Balanced Analog I O Connector 1 2 3 4 5 6 7 8 9 SX 6 Balanced I O to XLR 1 2 3 4 5 6 7 8 9 Right Balanced Out XLR female shell male pins 1 1 Left 2...

Страница 17: ...tes the function of the DB9 connector It might be used with a custom Industrial Rack Mount PC with a special cable harness that brought the connections out to the front panel MICROPHONE INPUT JP3 Pin...

Страница 18: ...eceiving only the voltage difference between the 2 wires of the twisted pair Hum and noise picked up by the cable will be picked up equally by both wires of the twisted pair and rejected by the balanc...

Страница 19: ...nus grounded 8 dBu Not recommended Output Minus floating 2 dBu 14 dBu IMPEDANCE AND SIGNAL LEVELS The concept of matching impedances when connecting equip ment is important for radio frequency devices...

Страница 20: ...degrading the signal to noise ratio accordingly The trim controls on the SX 6 and SX 36 operate in the analog domain and preserve the signal to noise ratio It is always better to choose the lower tri...

Страница 21: ...48 KHz would use 48 000 x 2 x 2 1 192 000 bytes second or 11 5 megabytes minute MPEG and ADPCM are examples of file formats which utilize data compression MPEG is the highest quality compressed forma...

Страница 22: ...d a conversation for archive pur poses the sound quality may be adequate ADPCM is also easier to edit In a network environment where all sound files are stored on a server and sent to the individual c...

Страница 23: ...0 96 5 3 96 7 4 96 8 0 128 5 5 128 6 0 160 4 8 Layer II 32 KHz 44 1 KHz 48 KHz Bitrate kbits s Compression ratio Bitrate kbits s Compression ratio Bitrate kbits s Compression ratio 32 16 32 22 1 32 2...

Страница 24: ...diskette into the A drive or point to di rectory containing the installation files Click OK 8 Select SX 36 or other card as appropriate Press OK Press Next 9 Press Finish 10 Select Yes to reboot and...

Страница 25: ...At the prompt for the driver installation disk point to location of driver files Click OK 13 Click OK to exit the System Properties dialog 14 Reboot to enable the driver Setup Tips Upgrade Driver WIN...

Страница 26: ...setup Insert the DRIVER disk into the A drive Click OK 3 The software will install itself on your hard drive 4 The Antex Audio Driver Setup window will pop up Select the correct adapter type SX 36 SX...

Страница 27: ...on a separate floppy disk The same disk is used for Windows 95 98 and NT The software installs in the usual manner 1 Insert the disk into the floppy drive 2 From the Start menu select Run 3 On the com...

Страница 28: ...available on the Antex audio board you have installed in your system Sample Rate This list box selects specific sample rates for recording and displays the sample rate of the file that is currently pl...

Страница 29: ...g can only be changed when the card is in Stop mode If the card is in Paused Record or is recording the Sample Rate or Compression will not actu ally change even though the dialog box allows you to ch...

Страница 30: ...level of the current file that is being recorded or played Wave Device If your driver is configured for dual devices or your com puter has more than one Antex audio board this drop down list box will...

Страница 31: ...nt of time if desired Figure 8 Auto Repeat Play Stop Once a file has been selected pressing the play button will start the playback During playback this button changes to Stop If a file has not been s...

Страница 32: ...ected and that there is a different Address and Interrupt for each card Each device on each card is accessible in the Antex Demo by using the pull down menu Open as many instances of the Antex Demo as...

Страница 33: ...44 1 KHz 32 KHz 48 KHz SX 35 44 1 KHz 32 KHz 48 KHz SX 36 48 KHz 44 1 KHz 48 KHz MIXER AND BLOCK DIAGRAMS The purpose of these two diagrams is to give the user an under standing of the signal flow thr...

Страница 34: ...maximum signal which can be input is 8 dBu without being clipped by the A D converter This applies to having the record source set to G or I If the record source is set to J Line Out a hotter signal...

Страница 35: ...on the Line Out may sound fine To monitor the actual recording it is necessary to select the record source using buttons G H or I and set the record level with an external device before the signal ge...

Страница 36: ...ends on the particular situation The VOX control is used to start the recording of a file automati cally when the audio source level goes above the threshold set by the slider If this control is used...

Страница 37: ...32 L K A A B C D E G H I J Figure 9 SX 36 Mixer...

Страница 38: ...33 Figure 10 SX 36 Block Diagram...

Страница 39: ...34 SX 34 MIXER AND BLOCK DIAGRAM The SX 34 diagrams are the same as the SX 36 with the excep tion that the SX 34 does not have the Input or Output Trim Con trols C D E G H I K L Figure 11 SX 34 Mixer...

Страница 40: ...35 Figure 12 SX 34 Block Diagram...

Страница 41: ...because using these controls lowers the signal levels while leaving the noise floor unchanged These controls are intended to mix 2 playback files together or to fade a file up or down at the beginnin...

Страница 42: ...37 M L B K Figure 13 SX 6 Mixer...

Страница 43: ...38 Figure 14 SX 6 Block Diagram...

Страница 44: ...e in the digital domain They amount to multiplication routines in the DSP which take the signal level and multiply it by a scaling factor between 0 and 1 This is important to note because using these...

Страница 45: ...tting both sliders at maximum is when playing 2 files simultaneously In this case it may be necessary to lower the sliders slightly to prevent clipping from occurring when peaks of both files occur at...

Страница 46: ...41 Figure 16 SX 5e Block Diagram...

Страница 47: ...to the meter in the Antex Mixer or Antex Demo but is much more flexi ble It also may be used in conjunction with third party software applications The ability to size the window is very convenient wh...

Страница 48: ...43 If you right click or double click on the meter window the following window will pop up Figure 18 Antex Meter pull down menu...

Страница 49: ...lows you to select whether the meter is peak reading or averaging VU Peak Hold Level will keep the peak level lit for the time indicated Headroom Indicator determines where the 0dB point is The defaul...

Страница 50: ...x Card Note that even if the meter is in peak mode peaks which occur in between the update intervals will be missed To avoid this the update interval should be 5 ms or less Once the meter is set the w...

Страница 51: ...r Input Output Range Make sure you select a valid setting for the Antex card and that the dialog box shows that there are no conflicting devices in your system at the selected Interrupt or I O range I...

Страница 52: ...f cable to 7 feet 3 Make sure signal levels are matched Set the Play sliders in the Antex Demo or Antex Mixer applications at or close to maximum for lowest noise level Set the Trim Control to 8 rathe...

Страница 53: ...and There is a lot of noise or hum even when the Antex Card is idle above There are dropouts or pops and clicks 1 You may be exceeding the maximum sample rate the card is capable of with the number o...

Страница 54: ...will re duce the amount of data required by each card TECHNICAL ORDERING INFORMATION If you have any questions concerning the operation of your board or would like to place an order please contact us...

Страница 55: ...headers is to use insulation displacement ribbon cable connectors This is the type of cable that connects to your hard drive These are lower profile but the ribbon cable wires are fairly delicate The...

Страница 56: ...gital domain Only the specifica tions of the device will tell you whether the control is actually digi tal or analog The digital type of volume control will degrade sig nal to noise performance when u...

Страница 57: ...sponse 20Hz to 20KHz 5dB Mic input level 10mV RMS Mic input impedance 1K ohms Mic phantom power 2 5VDC w 2K limiting resistor SX 36 THD N 02 max Dynamic Range 80 B min Balanced Output level low trim 8...

Страница 58: ...nput impedance 10K ohms DSP TMS320C32 50MHz Note that the Line Out will drive headphones but the low fre quency response will begin rolling off at approximately 90Hz SX 6 THD N 02 max Dynamic Range 85...

Страница 59: ...s to trans mit digital audio signals by wire or radio However this practice has not yet become common due to the extremely wide signal bandwidth required to transmit real time digital audio signals Fo...

Страница 60: ...as linear pulse code modulation or PCM Let s take a brief look at how PCM works Converting an analog signal to digital is a two stage process sampling and quantization This is illustrated in Figure 20...

Страница 61: ...tom of Figure 20 Once for each cycle of the sam pling frequency the sample and hold circuit slices the input sig nal allowing the quantizing circuit to generate a digital number equal to the closest o...

Страница 62: ...iscrete voltage equal to the quantization levels in the analog to digital process The shape of this continuously changing stream of quantization levels approximates the shape of the original wave This...

Страница 63: ...a very brief and of necessity oversimplified ex planation of how digital audio works For the interested reader the book Principles of Digital Audio by Ken C Pohlmann copy right 1985 by Howard W Sams i...

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