Sencore DA795 This guide gets you started using the Sencore DA795 Digital Audio Analyzer. Unfortunately, simplified guides cannot cover everything. For detailed information on each test see the DA795 Operator s Manual. 1. DA795 Panel Familiarization Note: Top panel shown upside down to best denote connector placement. 1 http://www.sencore.com email:sales@sencore.com 800.736.2673 or 605.336.0100
2. To get started: To get started, turn the DA795 on and adjust the contrast control for best LCD display viewing contrast. Rotate the Control Knob to highlight the desired field or tests. Briefly push in the Control Knob click to select. 3. Menu Navigation Field/Function Selection 2 http://www.sencore.com email:sales@sencore.com 800.736.2673 or 605.336.0100
4. Digital Signal Inputs Input Selection The DA795 requires selecting an input digital audio signal. Digital audio signals may be interfaced to the DA795 using several interface signal formats and connectors. The Input Select Field selects the input signal to be used for the DA795 test function.. To select an input: 1. Rotate the Control Knob to highlight the Input Select Field. 2. Click the Control Knob to lock into the field. (Field Underlined) 3. Rotate the Control Knob to increment through the input selections: (Spdif/tos, AES/EBU, ADAT1+2, ADAT 3+4, ADAT 5+6, ADAT 7+8) 4. Click Control Knob to release the field selecting the highlighted selection. 3 http://www.sencore.com email:sales@sencore.com 800.736.2673 or 605.336.0100
5. Top Tool Bar Introduction The Top Tool Bar is the top line of icons common to most DA795 test screens. Function Control and Information (Left Side) Return or Exit Arrow. Returns you to the previous menu or screen. (Select & click) Power Indicator. Shows battery or AC power symbol. Shows battery level. Function Name. Shows function currently running. Screen Title. Indicates test title. Some test screens have more than one function available. Highlight & click this field to select added functions when available. Input Control and Information (Right Side) Input Lock. A locked or unlocked padlock. Indicates when the DA795 is locked to an incoming digital audio signal. Open padlock indicates no input or degraded digital audio input. Input Select. Selects an input signal, typically from Input 1. The Digital Lock Test, Jitter Meter, and the Digital Cable Tester functions select from Digital Input 2. Input Sample Rate. Displays the measured sample rate of the digital input signal, with a resolution of 0.1 khz. If no valid digital input signal is detected, this field indicates n/a. Input Level Meter. Displays the audio digital level of the input signal, with a 7-segment bar graph. The bar graph consists of two vertical lines, for the left and right channel levels. 4 http://www.sencore.com email:sales@sencore.com 800.736.2673 or 605.336.0100
6. Bottom Tool Bar Introduction The Bottom Tool Bar is the bottom line of icons common to most DA795 test screens. The bottom tool bar is divided into two sections, left and right. Analog Output Control - Headphone/Speaker Monitor (Left) This section controls the analog audio output to the headphone (hdpn jack), unbal output and built-in speaker. The section provides headphone and speaker monitoring of either an input signal (M=Monitor) or an internal generated signal (G=Generator). Memory Control: This section saves test screens to internal memory 0 39.. S=Save R=Recall Digital Output & Generator Control (Right) The section controls the digital generator and digital outputs of the DA795. Some fields control only the digital generator, while other fields control aspects of the digital output. Generator Jump. The icon jumps to the Generator function screen and back for more output control options, such as frequency and waveform selection. Digital On/Off. This icon switches the digital audio outputs on or off. Line in middle is ON. No line is OFF. Digital Output Level. This level gauge controls the digital generator output level. Every rotating click of the Control Knob changes the output level by exactly 1 db. Word Length. This number field controls the word length (bit depth) of the digital output. You can select any word length from 8 to 24 bits. Output Lock Source. Selects the lock source (master clock) used for the digital output. Internal crystals (32 khz to 96 khz), Word Clock input, AES or S/PDIF input, ADAT input, or Super clock input. Lightpipe Format. The A/T icon selects the output format for the optical output connector. A selects ADAT format; T selects Toslink. Note that in ADAT format, the digital stereo output signal is copied to all four sets of ADAT stereo pairs. Note: Operation of the Analog Output Control section and Digital Output and Generator Control sections are covered in the following sections of this guide. 5 http://www.sencore.com email:sales@sencore.com 800.736.2673 or 605.336.0100
7. Digital Generator and Output Control Bottom Right Tool Bar The Digital Output and Generator Control section of the bottom right tool bar controls the internal generator and what is output to the Digital Audio Output jacks. Follow the steps shown to configure the internal digital audio generator for a 24 bit 48 khz sample rate digital audio output signal. 6 http://www.sencore.com email:sales@sencore.com 800.736.2673 or 605.336.0100
8. Headphone/Speaker Monitor or Analog Output Control Bottom Left Tool Bar The Analog Output section of the bottom tool bar controls the analog audio to the Hdpn Output, Unbal Output and built-in speaker. Analog audio is sourced from the digital audio inputs or internal DA795 generator. Follow the instructions to configure the DA795 to output audio from an incoming digital audio signal to the stereo headphones. 7 http://www.sencore.com email:sales@sencore.com 800.736.2673 or 605.336.0100
9. Analyzing Digital Audio - Bit Stream Analyzer Introduction The commonly used Bit Stream Analyzer function Status screen provides analysis of an input digital audio signal. It can be divided into 7 sections, each providing useful information regarding the digital audio signal. A brief description follows. 1. Key Channel Status Bit Information: Provides a decoded read out of the key information encoded in the channel status bits of the digital audio signal. 2. Transmission Line Input VPP Level: Indicates the VPP level of the digital signal on the input cable. An AES/EBU line ranges from 2V to 7V while an S/PDIF line is a nominal 0.5VPP. An AES3 signal input to the S/PDIF input should be approx. 1 VPP. 3. Digital Audio Receiver Confidence Indicators: These checks look for proper or improper digital audio signal conditions. Proper conditions are indicated with a check mark while an X indicates abnormal conditions. Confidence Indicators include: Vpp (Volts peak-to-peak check) Eye (Eye Pattern check) Bits L (Bits Left Channel Check) BitsR (Bits Right Channel Check) BIP (Bi-phase Mark Coding Check) CRC (Cyclic Redundancy Check) SR (Sample Rate Check) Par (Parity Check) 4. Digital Audio Sample Rate Frequency Counter: Counts and displays the precise running sample rate of the incoming digital audio. 5. Digital Audio Levels (Left & Right) dbfs: This field indicates the left and right audio level of the digital audio contained in the values of the audio digital word. 6. Digital Word Bit Activity: The Digital Word Bit Activity field visually shows or indicates if the bits in the digital audio word are changing values or are stuck at logic 0 or 1. 7. Active Digital Word Length: Indicates the detected word length of the digital audio. 8 http://www.sencore.com email:sales@sencore.com 800.736.2673 or 605.336.0100
Analyzing a digital audio signal using the Bit Stream Analyzer: BitStream Analyzer Status function Padlock - Locked to incoming digital audio Input Signal Select Field Sencore Bits M Status AES/EBU 48.0 Pro 48.0 khz 24 bit 2ch NoEmp PCM 0 2 Vpp 7 10 Vpp B I P Eye CRC Actual 48000.3 Hz BitsL SR BitsR Par - 50 dbfs -10 0 + + + + + + + + + + + + + + + + + + + + + +Left 24 0 + + + + + + + + + + + + + + + + + + + + + Right24 2 S R x G 24 Int 48k T DA795 DigiPro Digital Audio Analyzer Channel Status Bit Indications Confidence Indicators Left & Right Digital Audio Level meter Left & Right Digital Word Bit Activity Word Length Indicator Sample Rate Frequency Counter Vpp Digital Interface Line Level Sample Rate Of Input Digital Audio To analyze the digital audio output by the DA795 with the Bit Stream Analzyer status function: 1. Connect an XLR cable from the DA795 AES/EBU Digital Output to the AES/EBU Input 1 as shown. 2. Select the BitStream Analyzer function from the Analysis Function menu. 3. Setup the bottom right tool bar section to output a digital audio signal (500 Hz sine-wave) a. Set the Sample Rate generator field to Int 48 k (Sample Rate = 48 khz) b. Set the Digital Audio Word Length field to 24. (24 bit audio) c. Turn the Digital Audio Signal On/Off field to ON (Line in middle of icon). d. Click on Generator Shortcut field - clicking jumps you to a full generator screen. Set for sine-wave 500 Hz. Click < to return to BitStream Analyzer function. 4. Highlight the Input Select field, click and select AES/EBU. A Locked indicator icon should appear along with a 48k sample rate indicator in the top tool bar. (Top center) 5. Read 2 nd Row - Channel Status Bits: Pro 48.0kHz 24bit 2ch Noemp PCM (These are encoded by the internal DA795 digital audio generator) 6. Note the VPP Level, Sample Rate Frequency readout, dbfs level, bit activity, word bit depth and confidence indicators. All should be normal. * You may change the generator bit depth, sample rate and digital audio levels (bottom left icons) and note the changes to the status. 9 http://www.sencore.com email:sales@sencore.com 800.736.2673 or 605.336.0100
10. Analyzing Digital Audio - Bit Stream Analyzer (Channel Status Bit Decoding) Each sub-frame contains a C bit or channel status bit. C bits can be encoded with information regarding the digital audio signal. Digital equipment may decode and take action based upon the information. Channel status bits are decoded from the 192 audio sub-frames into 24 bytes, each with 8 bit words. Once arranged into bytes, the individual bits are decoded providing information regarding the digital audio signal. The illustration shows how coding is performed and interpreted based upon the 24 arranged bytes. 10 http://www.sencore.com email:sales@sencore.com 800.736.2673 or 605.336.0100
Consumer digital audio signals are encoded differently in regard to channel status bits. The first channel status bit (Byte 1, Bit 0) indicates if the digital audio is a professional or consumer type. The DA795 Bit Stream Analyzer function decodes and displays channel status bit information including format (pro or con), sample frequency, word length, channel mode, emphasis, PCM audio status, and copy write or frequency scaling as illustrated. 11 http://www.sencore.com email:sales@sencore.com 800.736.2673 or 605.336.0100
11. Analyzing Digital Audio - Bit Stream Analyzer (Level VPP Indicator) Bits Level VPP AES/EBU = 2-7VPP Status AES/EBU 48.0 Con 48 khz -- bit 0 NoEmp PCM 0 2 Vpp 7 10 Bits Level VPP S/PDIF Norm =.2-.7VPP AES3id: 1VPP Status Spdif/tos 48.0 Con 48 khz -- bit 0 NoEmp PCM 0.2 Vpp.7 1.0 G 2 S R x G 24 Int 48k T 2 S R x G G 24 Int 48k T AES/ EBU XLR Connector Balanced Line 2-7 Vpp 110 ohm S/PDIF Unbalanced.5VPP RCA Phono Connector 75 ohm AES3id BNC Connector Unbalanced 1VPP 75 ohm Note: To analyze AES3id professional digital audio use a BNC to RCA and input to the S/PDIF input. Level should range from.2 to 1 VPP. Ignore the VPP confidence indicator as it may show X if the VPP is over.7vpp. The VPP meter is not used with Toslink or ADAT optical inputs. 12. Analyzing Digital Audio - Bit Stream Analyzer (Sample Rate Frequency Counter) The digital audio sample rate frequency is measured and displayed by the Bit Stream Analyzer. The sample rate counter indicates if your digital audio is at the proper sample rate. * A few seconds are required for the precision freq. counter to obtain a stable reading after the Bit Stream Analyzer lock to the incoming digital audio. Note: The SR (Sample Rate) Confidence indicator shows an X when the measured sample rate does not agree with the decoded channel status bit sample rate. * A more precision digital audio sample rate frequency, clock frequency and accuracy in PPM (parts-per-million) may be determined using the Clock/Sample Counter function. 12 http://www.sencore.com email:sales@sencore.com 800.736.2673 or 605.336.0100
13. Analyzing Digital Audio - Bit Stream Analyzer (Digital Audio Level dbfs) The levels of the left and right audio within the digital signal are metered with a dbfs unit of measurement. The scale of digital audio levels may vary from 0 dbfs (clipping) to 140 dbfs (24 bit). The Bit Stream Analyzer includes a level meter section. The Bit Stream Analyzer provides left and right audio channel level metering using a dbfs scale from -60dBFS to 0dBFS. * For a more precise level measurement use the Level Meter function selectable within the System Tools menu. (See Section 16) The Level Meter also provides a VU Meter for digital level measurement of audio program material. (See Section 17) 13 http://www.sencore.com email:sales@sencore.com 800.736.2673 or 605.336.0100
14. Analyzing Digital Audio - Bit Stream Analyzer (Digital Word Bit Activity) This section analyzes the activity of the digital bits within the digital audio. Each of twenty four possible positions (24 bit word) are shown for each audio channel and are arranged from left MSB to the right LSB. Active Bits: Changes from + to -. Stuck Bits: Show a 1 or 0. Common Bit Activity & Likely Causes: All Bits 0 (Inactive): You have no audio in digital stream. Audio turned off or missing? All but MSB bit Active: Normal, seldom does last MSB bit become active. Note: Use active audio program material, sine-wave or pink noise test signals when analyzing bit activity. These test signals result in active bits. Square wave test signals result in bits stuck at 1 or 0. 14 http://www.sencore.com email:sales@sencore.com 800.736.2673 or 605.336.0100
15. Analyzing Digital Audio - Bit Stream Analyzer (Digital Word Length/Bit Activity) The Active Digital Word section within the Bit Stream Analyzer shows how many active bits are in the digital audio words. This can be compared with channel status bit indications of word length or source equipment indicators to determine if they are working properly. Active Digital Word bits Note: The BitsL and BitsR Confidence indicators will show X if the detected active word length does not agree with the word length indicted by the channel status bits. The illustration shows how the Active Word Length and Digital Word Bit Activity sections of the Bit Stream Analyzer change when digital audio word lengths are 24, 20, or 16 bits 15 http://www.sencore.com email:sales@sencore.com 800.736.2673 or 605.336.0100
16. Measuring Digital Audio Levels dbfs Level Meter A digital left and right audio level meter provides level calibration. Units of measurement include: db rms in reference to 0dBFS, % rms of full digital scale, and % peak of full digital scale. LEVEL METER Left Channel Measurement db Meter function Level or VU Input Lock Input Select Field Right Channel Measurement db Sencore Level Level AES/EBU 48.0 THD Left Right - 20.3 db rms -21.3 G G DA795 24 Int 48k T DigiPro Digital Audio Analyzer Unit of Measurement db rms, % rms, To measure the audio levels on an incoming digital audio signal: 1. Connect a digital audio cable from the digital audio source to the proper input on the DA795. 2. Select the Level Meter function from within the System Tools Menu. 3. Select the LEVEL meter from the main function field. Selections are LEVEL or VU. 4. Highlight the Input Select field and choose the input in which the digital signal is applied. Upon receiver lock, a lock indicator padlock should be shown along with the sample rate frequency. (If not, check to be sure you have a good digital audio signal input) 5. Read the left and right digital audio level. 0dBFS or full scale digital is the reference. (rms is the normal unit of measurement referencing full scale) * A reference chart on dbfs levels is included in section 13. LAeq Dialog Level: This function is provided in the System Tools menu. It measures the combined A weighted long-term average audio level. This measurement is used by broadcasters in meeting the AC-3 spec of -27 db FS for program material. 16 http://www.sencore.com email:sales@sencore.com 800.736.2673 or 605.336.0100
17. Measuring Digital Audio - VU Meter The VU/PPM meter provides a standard left and right VU meter of audio program content. The meter shows a bar graph VU level of both channels and a single bar above the main bar indicating the peak or instantaneous program peaks. A max or peak and hold digital indicator shows the left and right max level captured by the meter. 17 http://www.sencore.com email:sales@sencore.com 800.736.2673 or 605.336.0100
18. Viewing Digital Audio BitScope Seeing the audio signal on a scope screen shows the signals shape and amplitude. The BitScope feature of the DA795 provides a display of the decoded digital audio signal in the time domain. Bitstream Analyzer AES Status Analyzing (BitScope Familiarization) Run/Hold Sencore Function Select (Scope Mode or x/y mode) BitScope s/d AES/EBU 48.0 Lin 0 dbfs 12.5 S/div M G 24 Int 48k T DA795 DigiPro Digital Audio Analyzer Channel Select Gain Vert. Range Sample/Division (Scope -Time scale) 1. Connect a cable from the DA795's AES/EBU output to the AES/EBU input 1. 2. Select the BitScope function within the Analysis Functions menu. 3. Generator Setup: Setup the bottom right tool bar section to output a digital audio signal (500 Hz sine-wave) a. Set the Sample Rate generator field to Int 48 k (Sample Rate = 48 khz) b. Set the Digital Audio Word Length field to 24. (24 bit audio) c. Turn the Digital Audio Signal On/Off field to ON (Line in middle of icon). d. Click on Generator Shortcut field - clicking jumps you to a full generator screen. Set for sine-wave 500 Hz. e. Click < to return to BitScope function. 4. Highlight the Input Select field, click and select AES/EBU. A Locked indicator icon should appear along with a 48k sample rate indicator in the top tool bar. (Top center) 5. BitScope Setup: a. Select Function Select field: Set Mode to s/d (scope mode), b. Set Vert. Gain Field to 0 dbfs, c. Set Sample/Division field to 5.0 S/div. (To view 500 Hz sinewave) 18 http://www.sencore.com email:sales@sencore.com 800.736.2673 or 605.336.0100
19. Monitoring Digital Audio WatchDog The WatchDog function monitors a digital audio signal over a specified time up to 24 hours logging 8 different types of errors. Errors detected during the test period are indicated by vertical bars placed within the test screen. When the cursor is positioned over the error bars, the error code is displayed in the 2 nd row of the Watchdog screen. Eight Digital Audio Error Codes include: QR: Cycle Redundancy Check Error (Channel Status) CR: Cycle Redundancy Check error(s) (Data) Lk: Lock Error lost digital audio lock V: Validity flag Ey: Eye Error Bp: Biphase Error incorrect coding Pr: Parity Error Ov: Digital signal level over Level Threshold Setting. (The Ov error indicator indicates the audio program material peaked over the reference level. The reference level is adjustable in the 2 nd row, 2 nd field from the left.) Errors 1. Input a digital audio signal to the DA795. Select Digital WatchDog function from Analysis Function menu. 2. Select the proper input in the Input Select field and achieve signal lock. 3. Select the time period for logging in the Run Time field. 4. Click on the Run/Pause field to start the time period. (A progress bar moves left to right at top of graph) * Upon completion of the time period, highlight and click on the Measurement Cursor field. Rotate the control knob to place the cursor on a vertical error bar on the graph. Error codes (2 nd row) indicate the error type. 19 http://www.sencore.com email:sales@sencore.com 800.736.2673 or 605.336.0100
20. Testing Digital Audio Distortion (THD + Noise) Total harmonic distortion (THD), occurs when a sine-wave is modified from its original perfect shape. A perfect sine-wave has no harmonic content but when distorted contains harmonic content. THD is a measurement ratio between the voltage level of the test sine-wave and voltage level of the harmonic voltages. It is expressed as a percentage or as a db difference. Visual Scale THD+N % THD+N Measurement db Test Frequency: 63, 125, 250, 500, 1k, 2k, or 4k Channel Select THD+N Measurement % Sencore Distortion THD AES/EBU48.0 Frequency: 1000 THDHz Left in - 108.0 db THD+N.0003% 100 10 1.1.01.0001 G G DA795 24 Int 48k T DigiPro Digital Audio Analyzer Digital Audio with sinewave data on both channels Digital Audio Equipment 1. Connect a cable from the AES/EBU output to the input of the digital audio equipment. Connect a cable from the digital audio equipment output to Input 1 of the DA795. 2. Setup the bottom right tool bar section to output a digital audio signal (1000 Hz sine-wave) a. Set the Sample Rate generator field to Int 48 k (Sample Rate = 48 khz) b. Set the Digital Audio Word Length field to 24. (24 bit audio) c. Turn the Digital Audio Signal On/Off field to ON (Line in middle of icon). d. Click on Generator Shortcut field - clicking jumps you to a full generator screen. Set for sine wave 1000 Hz. Click < to return to BitStream Analyzer function. 3. Select DA795 Distortion Meter from the Analysis Functions 4. Select AES/EBU (Input Field at top right) - Lock symbol should appear (top center) and a 48kHz lock frequency should appear (upper right corner). 5. Select the distortion test frequency to 1000 Hz (2nd line of DA795 test screen). This must agree with the incoming digital audio test signal frequency. Allow several seconds for distortion test to range down to minimum distortion 6. Record the distortion THD + NOISE indicated by the DA795. % (The lower the value or farthest movement to the right side of display the better.) THD of less than.001 % is desirable. 20 http://www.sencore.com email:sales@sencore.com 800.736.2673 or 605.336.0100
21. Digital Audio Jitter Testing Digital audio signals contain timing variations or jitter. The DA795 analyzes digital audio signals and equipment for digital audio jitter degradation. Jitter measures small timing errors expressed in nano or pico seconds. Errors are expressed as an average RMS value to reduce the measurement effects of randomly occurring peak jitter errors. The AES/EBU standard specifies that jitter be less than +/- 20 ns. However, it is desirable to minimize jitter to much lower levels to optimize digital sound reproduction 21 http://www.sencore.com email:sales@sencore.com 800.736.2673 or 605.336.0100
22. Digital Audio Latency Testing Latency is the delay in time that a digital signal experiences as it passes through digital equipment. All digital equipment has some inherent delay. However, it is important to match the delay time of multiple audio signals to maintain proper phase. Latency Self Test: 1. Connect a cable from the DA795 s digital Output to its AES/EBU Input 1. 2. Select AES/EBU in the input select field (upper right). 3. Set the generator for Int 48k and the output for Output Digital at bottom left. 4. Start Test by clicking the Start Test Icon. ( II is shown) Delay should show 0 samples & 0 seconds. To measure the latency of digital audio equipment, continue with steps 5-6. 5. Move/Connect the AES/EBU output (DA795) to the input of the digital audio equipment. Connect the digital audio output from the equipment to Input 1 of the DA795. * Select the correct input in the Input Select field if changed from AES/EBU. 6. Record the latency result: L = Samples ms R = Samples ms 22 http://www.sencore.com email:sales@sencore.com 800.736.2673 or 605.336.0100
23. Pass Mode Analyzing Digital Sample Rate Conversion/Jitter Correction The Pass Mode function provides digital audio sample rate conversion (SRC). The converter is able to take any digital audio input sample rate and convert it to 32, 44.1, 48, 88.2, or 96 khz or lock it to an incoming clock. The converted digital audio is output to the DA795 s digital outputs. The stable internal clock insures an accurate conversion and jitter correction. You may also SRC to a Word Clock or Super Clock input to the DA795. * The Pass Mode function is unique in that it passes the digital audio input selected in the Input Select field to the Digital Outputs of the DA795. The digital audio signal passes through. To Sample Rate Convert an incoming digital audio signal to a different audio sample rate: 1. Select the PASS MODE function from the DA795 s SYSTEM TOOLS menu. 2. Input a digital audio signal to Input 1 of the DA795. 3. Select the proper input in the Input Select field (Upper Right). Lock symbol appears. 4. Set the internal generator to Int 48k, Int 44.1k, Int 88.2k, Int.96k, Word Clk, or Super Clk. (Bottom Left field). This turns the sample rate converter (SRC) ON and locks it to the selected signal. * If you select Word Clk, Super Clk or other input you must have a signal applied. The field selection blinks if no signal is available for lock. 23 http://www.sencore.com email:sales@sencore.com 800.736.2673 or 605.336.0100
24. Pass Mode Analyzing Modifying Channel Status Information The Pass Mode function passes an input digital audio signal through to the digital audio outputs of the DA795. While passing, the DA795 can modify the channel status bits of the digital audio for testing downstream digital audio equipment. The Pass Mode function includes a description of the key channel status information on the incoming and output digital audio signal. Each of the output channel status bit fields in the Pass Mode function may be selected and changed by modifying the output channel status bit information. Note: The DA795 needs to show a locked indicator to be sure the proper input is selected and locked for decoding and proper channel status bit display. Channel Status Bit Information Digital Audio IN Pass Mode Sencore Pass Mode AES/EBU SRC 88.2 khz INPUT CHANNEL STATUS Con 48kHz -- bit 0 NoEmp PCM RESET OUTPUT CHANNEL STATUS Pro 96kHz 20bit 2ch NoEmp PCM DIGITAL GAIN: 0.0 db SRC ON G G 24 Int 88.2k T DA795 DigiPro Digital Audio Analyzer Digital Audio OUT Channel Status Bit Information To change channel status bit information within the passing digital audio signal: 1. Select the PASS MODE function from the DA795 s SYSTEM TOOLS menu. 2. Input a digital audio signal to Input 1. 3. Select the proper input in the Input Select field (Upper Right). Lock symbol appears. 4. Select any of the channel status bit fields below the OUTPUT CHANNEL STATUS header. (Click to lock onto field, rotate knob to view selections, click to select & release field) Note: Channel status bit changes can be made if the SRC is either on or off. To isolate problems caused by improperly coded channel status bits, run the digital audio signal in question through the DA795 in the PASS MODE. Change output channel status bit field to properly reflect the digital audio signal parameters as determined by the Bitstream Analyzer function of the DA795. Test for normal operation. Change pre-emphasis or copy-write fields and test for normal operation. 24 http://www.sencore.com email:sales@sencore.com 800.736.2673 or 605.336.0100
25. Transparency Testing A Transparency Test determines if a digital system or digital audio device is altering digital values from its input to its output. For synchronous testing the DA795 digital output feeds the system or device input. The output of the system or device is input to the DA795 and analyzed for errors. You may select bit patterns, sample rates and word lengths for the test generator. For asynchronous testing a transparency test bit sequences is output from the DA795 and recorded by a DAT, multi-track recorder or other digital audio storage medium. The recorded digital audio bit pattern is sourced by the recorder through the system or device to be tested and input to the DA795 for Transparency Test error analysis. * You must set the DA795 for the same test bit pattern or waveform that is recorded. You must set the generator icon ON to begin the test. 25 http://www.sencore.com email:sales@sencore.com 800.736.2673 or 605.336.0100
26. Cable Testing Jitter Analysis The DA795 outputs a special digital signal sequence (Julian Dunn J-test waveform) into a cable to test it for digital audio interface jitter. The cable is connected from the DA795 output to the jitter meter input (Input 2). The analyzer quantifies the amount of jitter produced by the cable. 26 http://www.sencore.com email:sales@sencore.com 800.736.2673 or 605.336.0100
Sample Rate: Clock 256Fs Data Rate Frame Time Sub-Frame Time 44.1 khz 11,289,600 2,822,400 4.35374 ms 11.337 us 48 khz 12,288.000 3,072,000 4.0 ms 10.4165 us 88.2 khz 22,579,200 5,644,800 2.17687 ms 5.668 us 96 khz 24,576,000 6,144,000 2 ms 5.208 us 27 http://www.sencore.com email:sales@sencore.com 800.736.2673 or 605.336.0100
APPENDIX 1. DA795 Panel Familiarization... Page 1 2. To Get Started... Page 2 3. Menu Navigation Field/Function Selection... Page 2 4. Digital Signal Inputs Input Selection... Page 3 5. Top Tool Bar Introduction... Page 4 6. Bottom Tool Bar Introduction... Page 5 7. Digital Generator and Output Control Bottom Right Tool Bar... Page 6 8. Headphone/Speaker Monitor or Analog Output Control... Page 7 9. Analyzing Digital Audio Bit Stream Analyzer Introduction... Page 8 10. Analyzing Digital Audio-Bit Stream Analyzer (Channel Status Bits)... Page 10 11. Analyzing Digital Audio-Bit Stream Analyzer (Level VPP Indicator)... Page 12 12. Analyzing Digital Audio-Bit Stream Analyzer (Sample Rate Freq. Counter)... Page 12 13. Analyzing Digital Audio-Bit Stream Analyzer (Digital Audio Level dbfs)... Page 13 14. Analyzing Digital Audio-Bit Stream Analyzer (Digital Word Bit Activity)... Page 14 15. Analyzing Digital Audio-Bit Stream Analyzer (Word Length/bit Activity)... Page 15 16. Measuring Digital Audio Levels dbfs Level Meter... Page 16 17. Measuring Digital Audio VU Meter... Page 17 18. Viewing Digital Audio BitScope... Page 18 19. Monitoring Digital Audio WatchDog... Page 19 20. Testing Digital Audio Distortion (THD + Noise)... Page 20 21. Digital Audio Jitter Testing... Page21. 22. Digital Audio Latency Testing... Page 22 23. Pass Mode Analyzing Digital Sample Rate Conversion/Jitter Correction... Page 23 24. Pass Mode Analzying Modifying Channel Status Information... Page 24 25. Transparency Testing... Page 25 26. Cable Testing Jitter Analysis... Page 26 Digital Audio Theory/Information... Page 27 Appendix... Page 28 28 http://www.sencore.com email:sales@sencore.com 800.736.2673 or 605.336.0100