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Model 820 Technical Reference Manual

B-27

RMS Exceedance count in record 12.

Example: 

RMS Exceedance count in record 22

I9, 5 (current record is 17)

I 1

Date and Time of Occurrence

ddmmmyy hh:mm:ss 

I 2

Duration

hh:mm:ss / mm:ss.ss 

I 3

Lint

nnn.n dB 

I 4

SEL

        

nnn.n dB 

I 5

Lmin

        

nnn.n dB 

I 6

Lmax

        

nnn.n dB 

I 7

Lpeak

        

nnn.n dB 

I 8

UnWeighted Peak        

nnn.n dB 

I 9

RMS Exceedance Count

nnn 

I 10

Peak Exceedance Count

nnn 

I 11

UnWeighted Peak Excd Count

nnn 

I 12

Overload Counts

nnn 

I 13

nn 1

   

Lnn 

I 14

Ln 1

   

nnn.n dB 

I 15

nn 2

   

Lnn 

I 16

Ln 2

   

nnn.n dB 

I 17

nn 3

   

Lnn 

I 18

Ln 3

   

nnn.n dB 

I 19

nn 4

   

Lnn 

I 20

Ln 4

   

nnn.n dB 

I 21

nn 5

   

Lnn 

I 22

Ln 5

   

nnn.n dB 

I 23

nn 6

   

Lnn 

I 24

Ln 6

   

nnn.n dB 

I 101

Intv Variables 1-24

Macro

Summary of Contents for 820

Page 1: ...Sound Level Meter Technical Reference Manual Model 820...

Page 2: ...20 Technical Reference Manual Larson Davis a division of PCB Piezotronics Inc 1681 West 820 North Provo UT 84601 1341 24 Hour Hotline 716 926 8243 Toll Free US 888 258 3222 www larsondavis com I820 01...

Page 3: ...uld not be construed as a commitment or representation by PCB Piezotronics Inc This publication may contain inaccuracies or typographical errors PCB Piezotronics Inc will periodically update the mater...

Page 4: ...f life please recycle the product through a local recycling center or return the product to Larson Davis Inc Attn Recycling Coordinator 1681 West 820 North Provo Utah USA 84601 where it will be accept...

Page 5: ...r 2 Overview to Model 820 2 1 Understanding the Model 820 Keypad 2 1 Getting to Know Screen Symbols 2 8 Understanding the Model 820 Screen 2 9 Turning On the Model 820 2 9 Checking the Battery Voltage...

Page 6: ...g 7 4 Interval History 7 5 Exceedance 7 8 Setting PassBy Functions 7 12 Overload 7 14 Setting the Daily History Parameter 7 14 Chapter 8 Parameters 8 1 Parameter Key Access Review 8 1 Entering and Exi...

Page 7: ...Reports 10 3 Real time Printing 10 4 Appendix A Specifications A 1 Type A 2 Reference Direction A 2 Measurement Ranges A 3 RMS Detector A 3 Other Detectors A 4 Reference Level A 4 Frequency Weightings...

Page 8: ...2 Commands B 3 History Oriented Commands Mode Commands B 4 Read Variables B 5 Other Read Commands B 11 Group Read Programming B 11 Setting Parameters B 12 Numeric Parameters B 12 Indexed Parameters B...

Page 9: ...iables B 29 Histogram Table Variables B 30 Print Commands B 31 Error Messages and Warnings B 32 Modem Control Mode B 34 Modem Mode 154 B 34 Dial Out Mode 155 B 34 Monitor Number B 34 820 Phone Dialing...

Page 10: ...n combined in a rugged lightweight yet extremely versatile unit Many sound level meters in the market can create significant measurement errors because of their limited dynamic range pulse range and c...

Page 11: ...or unat tended readings setting additional parameters and using the password lock Chapter 7 History Functions Setting parameters for exceedance levels history interval time history and daily history C...

Page 12: ...rted Instructions for unpacking a listing of accessories and optional equipment and initial setup Formatting Conventions This manual uses the following formatting conventions Functions accessed by pre...

Page 13: ...y will appear The flashing f the Keyboard Sta tus Indicator displays which key functions are active This indicates that the function keys are used for different purpose in current func tion Step 2 Sho...

Page 14: ...one range Optional micro phones allow measurements as low as 20 dB or as high as 190 dB A Mic bias is user selectable 0 28 and 200 V Selectable A and C frequency weightings for hearing pro tector app...

Page 15: ...from front panel using an appropriate calibra tion source Easy one step reset of measurement Battery level indication Standard 9V internal alkaline battery life of more than 16 hours or external powe...

Page 16: ...simple user interface TIME TIMER LDL CAL UWPK BATT LOCK MEM LOG STR RCL RESET SHIFT MIN DN L L LARSON DAVIS 820 SLM LEQ SEL T A DOSE EXCD INTV HIST PRINT SETUP R S SLM LMAX PEAK LN TYPE 1 INTEGRATING...

Page 17: ...e rugged and reliable but should be kept in their protective case when not in use Avoid unnec essary shock Although an Larson Davis microphone can usually survive being dropped it is a delicate precis...

Page 18: ...windscreen An AC DC mini phone connector with pinout shown on page 4 8 A 5 pin cable connector with the pinout shown in figure Figure 1 2 Note that this connector is used to access external power Usin...

Page 19: ...can be printed or transmitted at up to 19 2 K baud via RS 232 for further manipulation or archiving Despite its numerous functions the Model 820 is easy to use Annotated displays indicate units and me...

Page 20: ...ated Measurement modes are selected and shown in informative screens on the 32 character liquid crystal diode LCD display The custom keypad provides direct access to the needed data or setup item An a...

Page 21: ...of this manual see the copyright page your instrument s serial number located on the label on the back of the Model 820 the microphone serial number located inside the microphone the preamp serial num...

Page 22: ...ectly to sound level meter Optional Equipment The following optional equipment is also available ADP005 BNC to preamp thread adapter to input direct signal through preamp Includes equivalent capacitan...

Page 23: ...case 13 1 2 X 12 7 8 X 6 in EPS012 CCS002 weatherproof fiberglass case with cus tom cut foam interior and desiccant Sealed signal cable feed through Features lock hasp and may be chained through hand...

Page 24: ...r use with INT002 PSA002 AC DC power adapter 220 Vac to 9Vdc 50 60 Hz for use with INT002 820 OPT01 Modification of the Model 820 for use in out door noise monitoring system using the Model PRM2101 Ou...

Page 25: ...Computer Serial Printer Modem Larson Davis WEB Page Software SWW SLM UTIL SWW SLM LINK SWW ENV SWW REM SWW NMS SWW ACS EPS012 Environmental Case EPS013 Environmental Case w Battery CCS009 Soft Case T...

Page 26: ...left side of the instrument by sliding it out as shown in Figure 1 5 Figure 1 5 Remove Battery With the battery door removed drop the battery into the opening in the case as shown in Figure 1 6 making...

Page 27: ...le time to adjust to abrupt temperature changes Condensation may form inside a cold Model 820 if it is brought into a warm room or vehicle and may persist long after the outside case has adjusted to t...

Page 28: ...u can turn it on and take simple measurements In this chapter we discuss the following Understanding the Model 820 Keypad Understanding the Model 820 Screen Getting to Know Screen Symbols Turning on t...

Page 29: ...anual Figure 2 1 Model 820 Keypad TIME TIMER LDL CAL UWPK BATT LOCK MEM LOG STR RCL RESET SHIFT MIN DN L L LARSON DAVIS 820 SLM LEQ SEL T A DOSE EXCD INTV HIST PRINT SETUP R S SLM LMAX PEAK LN TYPE 1...

Page 30: ...r Cancel the present function OFF SHIFT OFF turns off the Model 820 after it has been stopped s PRINT Access to a list of reports scrolled through the display a key name is indicated for each one If t...

Page 31: ...t instrument data and configuration The level of security is configured in Setup M INTV The Interval History provides a history of a number of measurement values for a moderate size time interval 1 mi...

Page 32: ...e ment period displayed with the date and time of its occurrence Two additional screens accessed by pressing the left or right arrows show the number of times the SPL exceeded two fixed levels LMIN Th...

Page 33: ...true energy measure with no thresh old Time The date and time of last reset or mea surement start are available from the Time a display The current date and time are shown with the Time b display t SE...

Page 34: ...shown LDN b Shows the average levels of the exceedances and the average levels Bk Gnd of energy not contained in exceedances E DOSE The Dose and Projected Dose sound exposure percentages are displayed...

Page 35: ...ctions are active The lower four modes are possible and appear in the lower right corner or the display Symbol Functionality SsS flashing upper case to lower case Model 820 is stabilizing upon warm up...

Page 36: ...ty of pos sible screens Turning On the Model 820 Step 1 Press O to power the Model 820 and initiate a self test Three successive displays will appear while the meter stabilizes for 10 45 seconds The f...

Page 37: ...begin taking actual measurements When the system initiation is com plete a stick figure in the upper right corner of the display will appear seated indicating the Model 820 is in STOP mode Checking th...

Page 38: ...r a key is pressed in order to interpret the keyboard event Therefore where possible do not press the B key during a valid event you wish to measure The first screen a displays the percentage of power...

Page 39: ...uld make it a regular practice to perform an instrument calibration before and after you take actual measurements in the field However you do not have to recalibrate the Model 820 when you change the...

Page 40: ...the value 200 appears and then press e If you are using a pre polarized microphone this parameter should be set to 0 In this screen the value 200 is selected from three options 200 28 0 Step 3 Press c...

Page 41: ...e Step 7 Seat the microphone fully in the calibrator cavity If possible both units should be at the same tempera ture and stationary so that hand vibrations are not transmitted to the SLM Refer to th...

Page 42: ...ment is cali brating The Model 820 will wait until the reading is stable indicator is SsSsSs then adjust the offset for the proper reading CcCcCc An improper calibration offset for instance something...

Page 43: ...d other characters Setting Time Date and Day parameters Setting Parameters Using Function Keys The Parameter fields can be accessed in several ways By entering numbers assigned to each parameter the n...

Page 44: ...eplaced by a flashing n indicating the numeric key access The flashing parenthesis indicate this field is ready to receive numeric input Step 3 To access the Current Time press 0 and then 6 The number...

Page 45: ...enter all of the capital letters from A to Z the digits 0 to 9 and some punctuation charac ters There are three levels of U functions when in the Alpha Parameter Modify Mode The charts below Figures 4...

Page 46: ...ift Level 1 Alpha Numeric Keyboard This panel is accessed by pressing the shift key two times The number 2 appears in the lower right cor ner of the display indicating this panel is accessed Figure 4...

Page 47: ...n Step 2 Press m Notice the parentheses begin to flash and the f changes to n and the L is underscored Larson Davis You may now enter the appropriate letters here by using the Alpha Character Keyboard...

Page 48: ...ear for five seconds The letters from the 3 panel are available for entry The display in Step 1 above will appear If you change your mind about clearing the field hit c to return to the original title...

Page 49: ...as fol lows Step 1 With the Model 820 on press R UT The current time is displayed If it is incorrect enter the correct time Step 2 Press the mkey and use the numeric keys to enter correct time and th...

Page 50: ...figure 4 5 The DC output provides a voltage from the RMS detector that is proportional to the sound level The scale is 20 3 mV dB The output voltage is 0 3 volts with an output impedance of 600 The AC...

Page 51: ...y requires pressing the S or RUN STOP key In this chapter we will Take a measurement Examine and briefly explain the function keys associated with the measurement i e CVKBT DtE and M Stopping the meas...

Page 52: ...play Press the d key to access the first a Parameter 61 RMS Exceedance b Parameter 62 RMS Exceedance 2 c Parameter 63 Peak Exceedance d Parameter 64 UWPK Exceedance e Parameter 112 Overload current f...

Page 53: ...o be 85 5 dB C weighted the mea surement ran for nearly four min utes Should one of four letters OVLD flash intermittently with the stick figure an Overload has occurred in this measurement see Chapte...

Page 54: ...hese parameters turn the Model 820 on by pressing c Next press R m 3 9 e Or press R C and the following screen will appear Slow exponential avg 1 second constant Fast exponential avg 1 8 second consta...

Page 55: ...or the microphone Choose 28 or 200 V typically 200 V is cho sen for condenser type micro phones and 0 V for pre polarized microphones electret Step 8 Press c to exit setup mode Lmax Lmin We have alrea...

Page 56: ...rd screen The display shows that parameter 62 was set to 65 dB and is C weighted This measurement topped this level 6 times The same key V finds the Lmin values in conjunction with the U key Step 1 Ex...

Page 57: ...urred at the time and date shown on the screen Parameter 63 sets the level above which the readings must go to be recorded by the Model 820 Step 2 The second display available from this function is ac...

Page 58: ...urrent measurement Step 1 Access Ln by pressing the B key and a screen similar to the following will appear Parameters 55 56 in this example were set to 5 and 10 respectively This screen shows their v...

Page 59: ...erall Parameters 45 54 are used with the calculation to arrive at the current dose from the current data and sets the exchange rate threshold level and criteria level for the current measurement These...

Page 60: ...t The Current Exchange Rate parameter item 45 is quickly accessed by following the following steps Step 1 Press O R m 4 and 5 then e The choices here are listed below 3dB 4dB 5dB 6dB The appropriate v...

Page 61: ...nges can be made in any dis play by pressing m entering desired values and pressing e Full Dose Hours item 51 has a range of 0 to 99 hours but is normally set to an 8 hour workday Step 5 To access Ful...

Page 62: ...ment ran for nearly four hours and the dose was 0 28 The Projected Dose extrapolates the eight hour dose from dose A which is the current measured dose LDL readings are displayed on four screens We wi...

Page 63: ...Ldn by pressing U andD Two screens are available using the r key Ldn is the noise descriptor that applies a 10 dB weighting factor between the hours of 10 00 PM and 7 00 AM when calculating the Time W...

Page 64: ...ey and a screen similar to the follow ing will appear Eight additional screens are avail able from this function Warning or Error messages encountered dur ing normal operation will be dis played here...

Page 65: ...y to examine this screen This display indicates there are 8 Histories in memory 3 Logs and 0 Calibrations Hs is the number of time history samples Lg is the number of RUN STOPs made and CL is the numb...

Page 66: ...ne or two measurements a day between two dates or a single block measurement from a start date and time to a stop date and time In this chapter we will discuss Using the Timer for Unattended Readings...

Page 67: ...op Time 2 each day from Run Date to Stop Date Example Suppose we want to measure a given area near a large machine in a factory for 5 days 2 periods each day Step 3 To do this choose 2 Day and press e...

Page 68: ...l appear The five day block is now set Next we will set the time periods each day within the block Step 8 Press thed to Run Time 1 and press m Our start up time is 8 30 A M so press 08 30 and e and th...

Page 69: ...e turned off by pressing UOand placed in the test area Make sure to check the battery Chapter 2 or connect to external power Also con sider the safety of the instrument during the test period Finally...

Page 70: ...e second screen The second display shows the cur rent date day and time Step 3 Press c to return to the main screen Setting the Password Lock to Protect Settings The Model 820 SLM can insure that your...

Page 71: ...For example if Yes is entered for Lock Setup then the R S and other func tion can be used when Setup Lock function is implemented Press d to see other functions that can be locked See chapter 8 param...

Page 72: ...nd Viewing Advanced Functions Time History Time History Data Log and Data Interval History Interval History Data Exceedance Setting PassBy functions Dealing with OVERLOAD Setting the Daily History Par...

Page 73: ...the d to item 81 History Resolution 1 0 d B 0 1 dB Normally all data is taken with 0 1 dB resolution 2 bytes level To save memory this option allows storage of history in 1 0 dB resolu tion Step 4 To...

Page 74: ...stored data which the preceding base level operates For example if this was set to Peak and the base level set to 100 dB only peaks 100 dB and above would be displayed Step 13 To change the field pre...

Page 75: ...by a key stroke Step 2 Press the d key to sequence through the stored his tory data Press the d key to view other readings Log The Log key function is a Run Stop log It indicates how many times the me...

Page 76: ...and times Interval History The Interval History Parameters allow you to select and define the interval size and determine what data are to be saved Each interval gives you Leq SEL Min Max Peak UWPK E...

Page 77: ...val report with the Daily History Report If Yes is entered the Interval Report will be started or restarted if already run ning at the start of each hour For this to work properly the Interval Time sh...

Page 78: ...the Time and Date of a given Interval Duration Leq Lmin and Lmax Peak and UWPK and the level setting measurements Step 9 Examine the data available in each INTV Press r and scroll to each The l will...

Page 79: ...e other hand is obtained whenever the level goes above RMS EXCD LVL 1 RMS EXCD LVL 2 PEAK EXCD LVEL and UWPK EXCD LEVEL and are indi cated on the printout respectively This count has nothing to do wit...

Page 80: ...1 Press R and L to access item 66 from the pre vious field or press R m 66 and e Here is a brief explanation of each parameter 66 Excd Enable Yes No Yes would insure the exceedance report will be stor...

Page 81: ...to satisfy additional needs found in the field These will now be explained 161 Timed EXCD Per mm ss Exceedance Time history is recorded from 10 samples before exceedance to 10 samples after this peri...

Page 82: ...eriod to 0 5 or 1 second by entering a 16 or 32 for parameter 70 since the exceedance time history buf fer is used to create this function The max duration of a passby event is 128 samples which is 64...

Page 83: ...assby or other event noises such as blasts or gas getting noise In addition to the levels measured the date and time of the Lmax and the dura tion of the event are recorded The maximum duration of pas...

Page 84: ...S level and Symmetry of PassBy record e EXCD e Peak PassBy level and UWPK of PassBy record If PSBY appears in the screen it means you are in the Max PassBy data screen Hit U l to get into the Exceedan...

Page 85: ...nternal circuitry limits such as dropping or jarring the instrument Should an OVERLOAD occur during a measurement the data accumulated during the occurrence will not be accurate The Model 820 register...

Page 86: ...ng the Daily History Parameter 7 15 Step 1 To access item 88 Daily Enable press R U and D Yes No Choose Yes if you wish this option enables Daily Noise History can only be viewed in the Daily Noise Hi...

Page 87: ...o store up to 11 other set ups in memory for later recall Along with downloadable set ups from software this truly makes the Model 820 a myriad of instruments in one In this chapter we will review the...

Page 88: ...tup menu press d to move down the list of parameters one at a time All items in the list of parameters can be accessed by using the u and d Step 2 When the arrow keys are used in conjunction with the...

Page 89: ...ded brackets that mean this is an entry parameter Type the number or character desired see Chapter 4 If there is an angle bracket then the entry field is too big to fit the screen and will scroll with...

Page 90: ...selection Step 1 Press m and then the l and r keys Step 2 Confirm change with e Step 3 Cancel change by pressing c before e Error Messages Entry errors will be noted by a warning message For example...

Page 91: ...OM Parameters in the EEPROM regis ter are secure even if the batteries are disconnected since the EEPROM does not require bias voltage to maintain its state A minimum of 5 000 STORE operations are pos...

Page 92: ...accomplished Step 1 In the stop mode press U S e to reset memory Then press U R Step 2 The EEPROM is again the default Use d to scroll through the ten RAM registers or the pro grammed ROM setups RAM...

Page 93: ...l 0 for selection Some reserved parameters or selections are not available Many of these are active in the Model 870 the Model 820 s big brother System 1 20 R U S The following parameters define measu...

Page 94: ...r computer rate should be the same 10 RS 232 Address 0 127 Enables addressed communication mode for a network of Larson Davis SLMs Each must have a unique address Normally only one Model 820 is used t...

Page 95: ...ssumed to be a mini mum time and the output will be asserted for a minimum of the time selected If the time is programmed to be greater than 5 sec then the time is considered to be the maximum dura ti...

Page 96: ...and enter the password No Prompt Entry Comment 21 Timer Mode Off Block 1 day 2 day Block Run Time 1 on Run Date to Stop Time 1 on Stop Date 1 day Run Time 1 to Stop Time 1 each day from Run Date to S...

Page 97: ...Lock mode change 30 Lock Setup No Yes 31 Lock Function No Yes 32 Lock Reset No RES ALL Cur All 33 Lock ON Key No Yes 34 Lock I O No Yes No Prompt Entry Comment 35 CAL Level 114 00 0 255 dB Enter the...

Page 98: ...0 V for pre polarized microphones electret 44 Reference Level 0 to 255 dB measured level reference level rel ative level used in some functions 45 Currant Exchange Rate 1 3dB 4dB 5dB 6dB Exchange rate...

Page 99: ...evel histogram see item 77 The measured and displayed Lnn may be changed during the mea surement The six nn are automatically listed in increasing order No Prompt Entry Comment 51 Full Dose Hours 0 99...

Page 100: ...d Lvl 1 0 255 dB First rms detector exceedance level 62 RMS Excd Lvl 2 0 255 dB Set above Level 1 63 Peak Excd Level 0 255 dB Weighted peak exceedance level 64 Uwpk Excd Level 0 255 dB Unweighted peak...

Page 101: ...ples 161 Timed EXCD Per mm ss Exceedance Time history is recorded from 10 samples before exceedance to 10 samples after this period 162 Excd Trigger Level Bypass Bypass Enables a variable threshold 16...

Page 102: ...eady run ning at the start of each hour or min ute depending on Intv duration 77 Intv Save Ln s No Yes Selects whether interval Ln s are stored The Ln s stored are those in effect items 55 60 at end o...

Page 103: ...samples are averaged into an integrated sound level Leq stored every time history period 85 Hist Base 0 255 dB This is for editing purposes only All history is stored regardless of this base level Ho...

Page 104: ...tup parameters 92 RMS Histogram No Yes Prints histogram of overall rms levels 93 Lowest Level 0 255 RMS Histogram lowest printed level 94 Highest Level 0 255 RMS Histogram highest printed level 95 His...

Page 105: ...XCD Report No Short Long Prints exceedance report 105 Lowest Rec 0 65535 Starting exceedance record number of printout 106 Highest Rec 0 65535 Ending exceedance record number of printout 107 INTV Repo...

Page 106: ...159 Power Mode Normal Ext CO Normal meter uses internal battery unless greater external voltage is also applied Ext CO external cutoff when exter nal power falls below 10 5 V meter turns off to preven...

Page 107: ...l Reference Manual 8 21 171 Rt RUN LOG No Yes Print run log history 172 Rt Daily Report No Yes Print daily report 173 Rt CAL Report No Yes Print cal report 206 Daily Save Ln s Yes No Enables Ln table...

Page 108: ...idering the given options Estimate memory usage by giving an example of a test reading and an associated chart to determine the memory needed to complete the reading Determine Storable Data The follow...

Page 109: ...shown if enabled Bytes Basic Daily Record 175 Save Daily Ln s Yes Prm 206 18 Daily Ln Table Aux Cntl Reg Bit Value 1 Prm 210 440 Time History Records Time History Enable Yes Prm 80 Options Bytes Hist...

Page 110: ...820 can gather data As an example let s assume a job requires monitoring the noise made by trucks coming and going from a factory near a residential area From an initial site survey it is discovered t...

Page 111: ...val Memory Estimation Bytes 4Used Bytes needed 6 Basic Interval Record 34 4 34 7 Intv Save Ln s Yes Prm 77 18 4 18 8 Intv Save Ln Table 384 0 9 TOTAL Bytes Intv sum lines 6 8 52 10 Anticipated Intv Da...

Page 112: ...23 Exceedance History bytes day from line 5 16520 24 Interval History bytes day from line 11 1248 25 Daily History bytes day from line 15 193 26 Time History bytes day from line 22 2880 27 Run Log by...

Page 113: ...g with printing baud rate needs to be deter mined and entered Set parameter 9 to proper baud rate deter mined by type of printer used If after starting printing bad information is printed baud rate or...

Page 114: ...here as item 177 the beginning of the param eters that manage printouts Items 89 113 allow you to select the reports which are to be printed and how the output data are to be configured Items 89 113 a...

Page 115: ...screens You will notice that the scroll is quite rapid To slow it down so you can study the options use the u or d keys and the display will remain for five seconds before returning to automatic scro...

Page 116: ...t period Real time Printing Another feature of the Model 820 is the ability to print out reports in real time These are called the real time printer parameters or Rt print parameters These parameters...

Page 117: ...g to those parameters settings in the Time History 80 87 Interval His tory 72 79 and the Exceedance History 61 65 For instance if the history period parameter 83 is set to 6 seconds the printer will p...

Page 118: ...nce Direction Measurement Ranges Reference Level Frequency Weighting Detector Time Weightings Effects of Temperature Effects of Humidity Limits of Temperature and Humidity Microphone Extension Cables...

Page 119: ...data logger The Model 820 can also be used with any of the Larson Davis 1 2 condenser microphones They may also be used with any Larson Davis 1 4 or 1 microphones provided they are used with an ADP011...

Page 120: ...ry Indicator Range 105 0 dB The instrument will have a different Noise Floor Lower Limit and Overload Level depending on the sensitivity of the micro phone used Some typical values for 2 different Lar...

Page 121: ...Unweighted Peak Detector 38 0 dB AC Output 88 0 dB DC Output 105 0 dB Reference Level The reference level is 114 0 dB SPL Frequency Weightings The available frequency weightings for the Models 820 ar...

Page 122: ...eighting dB Nominal Fre quency Hz Unweighted Peak FLAT Weighting dB Nominal Frequency Hz Unweighted Peak FLAT Weighting dB 10 3 4 160 0 0 2500 0 0 12 5 2 5 200 0 0 3150 0 1 16 1 7 250 0 0 4000 0 2 20...

Page 123: ...A 6 Frequency Weightings Model 820 Technical Reference Manual 125 0 2 2000 0 0 AC Output FLAT Frequency Response...

Page 124: ...he refer ence reading for this test is taken at 20 C and 36 relative humidity RH the input signal is at 1000 Hz Effects of Humidly The SPL level varies 0 5 dB when the complete instrument is tested ov...

Page 125: ...l 820 placed on a tripod AC and DC Outputs The output impedance is 600 for both the AC and DC out puts of the Model 820 For minimal error use instruments with 100 k input impedance when making AC or D...

Page 126: ...settings Weighting Detector etc are changed Microphone Electrical Impedance The Larson Davis ADP005 should be substituted for the 1 2 microphone when performing electrical tests on the Model 820 The...

Page 127: ...nications Data Rate 19 200 bits per second Digital Display 2 line 32 digit 7 segment LCD Full ASCII character set Fully annotated date displays parameter with units Digital Display Resolution dB leve...

Page 128: ...EC 651 Type 1 IEC 804 Type 1 Directive 86 188 EEC Directive IEC TC 29 CE Information The Model 820 SLM complies with the European Community EMC Directive 2004 108 EC and also the Low Voltage Safety Di...

Page 129: ...scientific and medical ISM radio frequency equipment Elec tromagnetic disturbance characteristics Limits and methods of measuremen t Class B IEC61010 1 2001 Safety requirements for electrical equipme...

Page 130: ...nstruments can be formed all controlled by one computer by using the address ability mode This chapter will describe the Serial Port interfacing of the Model 820 and the various interface commands wit...

Page 131: ...dshaking protocol are selected using parameters 9 10 and 12 Unless using addressing set the address to 0 Signal 5 Pin configurations for the INT002 follow Daisy Chain Addressing A network of instrumen...

Page 132: ...be spelled out though only the first character is significant i e READ 123 may be abbreviated to R123 Every command has a response to acknowledge that it was received correctly and to provide data re...

Page 133: ...m variable_value I nterval variable_number relative_rec variable_value D aily variable_number hour_num variable_value L og variable_number relative_rec0 variable_value C alibration variable_number var...

Page 134: ...is possible by using the M9 1 command All sound levels are then sent with an additional fractional character nnn nn giving 1 100th dB resolution The Model 820 acquires noise data with 1 32 dB resoluti...

Page 135: ...t Lmin Date and Time ddmmmyy hh mm ss R 19 _O LMAX OverAll Maximum Level nnn n dB R 20 _O TMAX OverAll Lmax Date and Time ddmmmyy hh mm ss R 21 _C LMAX Current Maximum Level nnn n dB R 22 _C TMAX Curr...

Page 136: ...LDL Projected Dose nnnnn n R 50 _LDLLINT LDL Lint nnn n dB R 51 _LDLSEL LDL SEL nnn n dB R 52 _LDLXR LDL Exchange Rate Text ccccc R 53 _LDLVALID LDL Valid display see note below cccccc R 54 _RELLVL La...

Page 137: ...kground Leq nnn n dB R 71 85 _unused unused variable R 86 _BATT Battery Level nnn R 87 _BATTSRC Battery Source INT EXT ccc R 88 _TEMP Temperature nnn n R 89 _SERNUM Serial Number ccccc R 90 _REVNUM So...

Page 138: ...16 131 _unused unused variable R 132 _DYMIN Today s Minimum Level nnn n dB R 133 _DYMAX Today s Maximum Level nnn n dB R 134 _DYPEAK Today s Peak Level nnn n dB R 135 _DYUWPK Today s UWPk Level nnn n...

Page 139: ...rrupt W Watchdog Reset R 152 _INRMS Internal RMS detector level nnn nn dB R 153 _INPEAK Internal PEAK detector level nnn nn dB R 154 _INUWPK Internal UwPk detector level nnn nn dB R 155 _KEYCNT Free B...

Page 140: ...G0 and the O ther 3 command return the values of a list of up to 8 read variables previously defined by the programmer In order to define the variables read by group read commands use the following co...

Page 141: ...with S See Chapter 8 for a list of all the parameters and their settings Note that the parameter numbers are for both Set S and Query Q commands There are four types of parameters Numeric Indexed Char...

Page 142: ...mand may be used with flag 2 of the query command which automatically encloses the parameter and required spaces in brackets Examples S62 120 sets RMS Excd Level 2 to 120 Syntax Response S et item_num...

Page 143: ...d by The display shows day month abbreviated and year in that order Example _Time The hour minutes and seconds are entered in that order and are separated by Military 24 hour clock time is used i e ad...

Page 144: ...No or n if numerical Syntax Response Q uery item_number flag Depends on flag Flag Response none Current parameter 1 Parameter name and current setting 2 Current parameter setting including spaces in b...

Page 145: ...Q HALT HALT LINE MODE Halt Line Mode Q18 has a None state available This allows systems with intrusion alarm hardware to be disabled during servicing The choices are None Pause Toggle Level Alarm The...

Page 146: ...PASS FILTER unused Q 42 Q LPASS LOW PASS FILTER unused Q 43 Q MICV MIC POLARIZATION unused Q 44 Q REFLVL RELATIVE LEVEL REFERANCE Q 45 Q CXRATE CURRENT EXCHANGE RATE Q 46 Q CTHOLD CURRENT THRESHOLD Q...

Page 147: ...SAVE A D ENABLE unused Q 72 Q IVENB ENABLE INTV HISTORY Q 73 Q IVXRT INTV EXCHANGE RATE Q 74 Q IVTHOLD INTV THRESHOLD Q 75 Q IVPER INTV PERIOD Q 76 Q IVSYNC INTV TIME SYNC Q 77 Q IVLN INTV SAVE Ln S Q...

Page 148: ...HISTOGRAM TABLE HI VALUE n Q 95 Q PRN RMS HISTOGRAM TABLE RESOLUTION x Q 96 Q PRN PEAK HISTOGRAM TABLE x Q 97 Q PRN PEAK HISTOGRAM TABLE LOW VALUE n Q 98 Q PRN PEAK HISTOGRAM TABLE HI VALUE n Q 99 Q...

Page 149: ...AL POWER CUT OFF VOLTAGE Q 161 Q TMEXPR TIMED EXCD PERIOD Special Functions Advanced use only Remaining commands are not available on SETUP menu Q 162 167 Q NI18 23 RESERVED PARAMETER 18 23 Q 168 Q RT...

Page 150: ...Q 190 Q RPT UWPK HISTOGRAM TABLE HI VALUE n Q 191 Q RPT UWPK HISTOGRAM TABLE RESOL x Q 192 Q RPT EXCD REPORT x Q 193 Q RPT EXCD REPORT LOW RECORD n Q 194 Q RPT EXCD REPORT HIGH RECORD n Q 195 Q RPT I...

Page 151: ...Compensate Q208 which will place the Model 820 in an extended Linearity Range Mode The true noise floor of the entire system must be measured and entered in Q207 This will vary with the selected inpu...

Page 152: ...Q 218 225 Q NI42 Q N149 RESERVED PARAMETER 42 49 respectively Q 226 Q OVLDLVL OVERLOAD LEVEL Q 227 Q RMSOS RMS CALIBRATION OFFSET Q 228 Q PKOS PEAK TO RMS CAL OFFSET Q 229 Q UWPKOS UwPk TO RMS CAL OFF...

Page 153: ...ntax indicate optional characters and oper ands cr carriage return lf line feed Types of History Denoted in syntax by history_no 1 Exceedance E 2 Interval I 3 Daily D 4 Run Log L 5 Calibration C 6 Tim...

Page 154: ...ple Generally one uses the Find command to get to the first record F1 2 and the Advance command A to move up through the records History Data Variables Exceedance History Variables Brackets in the syn...

Page 155: ...5 Lmax nnn n dB E 6 Lpeak nnn n dB E 7 UnWeighted Peak nnn n dB E 8 Peak Exceedance Count nnn E 9 Overload Counts nnn E 10 Illegal Indication BEEP ILLEGAL E 17 Excd Time Hist Samples nnn E 18 n Excd...

Page 156: ...EL nnn n dB I 5 Lmin nnn n dB I 6 Lmax nnn n dB I 7 Lpeak nnn n dB I 8 UnWeighted Peak nnn n dB I 9 RMS Exceedance Count nnn I 10 Peak Exceedance Count nnn I 11 UnWeighted Peak Excd Count nnn I 12 Ove...

Page 157: ...tor c D 7 Daily Lmin nnn n dB D 8 Daily Lmax nnn n dB D 9 Daily Lpeak nnn n dB D 10 Daily Luwpk nnn n dB D 11 Daily Run Time hh mm ss mm ss ss D 12 Daily Avg Wind Speed nnn n or nnnnn unused D 13 Dail...

Page 158: ...tax Response L og var_nolog_var Example L1 Run Stop number L 1 Run Stop Number nnnnn L 2 Run Stop Type RUN STOP CONT PAUSE MARK L 3 Cause TIMER KEY A D n HALT INTV BATT L 4 Day Date and Time ddd ddmmm...

Page 159: ...eak level in current record H 1 RMS Level nnn n dB H 2 Peak Level nnn n dB H 3 Run Time of Sample calc hhhhh mm hh mm ss mm ss ss H 4 HISTORY BARGRAPH Syntax Response T able var_no table table_var T1...

Page 160: ...d EXCD report enables short to Yes and 3 begins printing to the computer Syntax Description P 0 Standard Report Formatted from normal setup parameters P 1 Data Report P 2 Data Histograms P 3 Short Ful...

Page 161: ...ode Message 1 COUNT OVERFLOW 2 EXPONENTIAL OVERFLOW 3 RTX TASK SELECT 4 ILLEGAL EXCHANGE RATE 5 UNKNOWN INTERRUPT 6 WATCHDOG RESET 7 OPCODE ERROR Warning Code Message 128 Out of Memory 129 Battery Low...

Page 162: ...Operand Invalid 151 Unable to Calibrate 152 EEPROM Write Error 153 Memory was Lost Data Reset 154 RECALL Not Found 155 Function Not Implemented 156 System Locked 157 A D Stack Full 158 A D Over Run 1...

Page 163: ...Model 820 will not dial a computer for any rea son Excd The Model 820 will dial a computer to report when an illegal exceedance is logged into memory An illegal exceedance is when Excd Lmax RMS Excd...

Page 164: ...2 is a flag 1 Alarm 2 Exceedance 4 Low Memory More than one of these can be set at a time in which case x is the sum of all set flags Step 5 The Model 820 awaits a response code which should be 820 A...

Page 165: ...arm 2 Exceedance 4 Low Memory More than one of these can be set at a time in which case x is the sum of all set flags Step 5 The Model 820 awaits a response code which should be 820A0123 11111111 ente...

Page 166: ...Exchange Rate The equation for it is where Lc is the Criterion Level Tc is the Criterion Duration Q is the Exchange Rate K is the Exchange Rate Factor and Lavg is the Average Sound Level Example If L...

Page 167: ...ll sources of sound that differentiates between daytime evening and nighttime noise exposure The equation for it is The continuous equivalent sound level is generally calculated on an hourly basis and...

Page 168: ...25 Criterion Sound Level Lc It is the sound level which if continually applied for the Criterion Duration will produce a Noise Dose of 100 The current OSHA Criterion Level is 90 dB Standard ANSI S12...

Page 169: ...example Lp represents the sound pressure level The table below shows the actual value of a specific item such as sound pressure for which the level is to be determined First the value is put into exp...

Page 170: ...the signal then averages it in accor dance with the time weighting characteristic and then takes the square root This results in an amplitude described as rms root mean square Eight Hour Time Weighted...

Page 171: ...efinition of Acoustic Near Field for the advantages of in the acoustic far field Geometric Far Field The distance from a source of sound is greater than the largest dimension of the sound source In th...

Page 172: ...ency called an upper cutoff frequency The difference between the two cutoff frequencies is called the bandwidth It is used to discriminate against both lower and higher frequencies so it passes only a...

Page 173: ...age Level dB A descriptor of a measured physical quantity typically used in sound and vibration measurements It is attached to the name of the physical quantity to denote that it is a logarithmic meas...

Page 174: ...n electrical cir cuit and thereby to create a signal The voltage across the dia phragm is caused by the charge embedded in the electret material so no internal source is needed Microphone Uses The fre...

Page 175: ...s applied to the other half the net force is zero and essentially no motion of the diaphragm occurs This occurs at high frequencies and for specific orientations of the microphone Rules 1 Do not use a...

Page 176: ...th an open window As you move your ear to the plane of the window the sound pressure level builds up rap idly wind noise since most of the pressure changes are to move the air and very little of it co...

Page 177: ...ency In this respect it is similar to white light Noise Dose D It is the percentage of time a person is exposed to noise that is potentially damaging to hearing Zero represents no exposure and 100 or...

Page 178: ...itory sensation evoked by the oscillatory changes Difference between sound and noise Sound is the physical phe nomenon associated with acoustic small pressure waves Use of the word sound provides a ne...

Page 179: ...time Sound Pressure The physical characteristic of sound that can be detected by micro phones Not all pressure signals detected by a microphone are sound e g wind noise It is the amplitude of the osc...

Page 180: ...values below Fixed Average The averaging process is over a fixed time period The equation for it is The sound pressure is squared and averaged over a fixed time period Unlike the moving average the s...

Page 181: ...3 dB then the sound pressure is Energy Average Leq The value of a steady sound measured over a fixed time period that has the same sound energy as the actual time varying sound over the same period T...

Page 182: ...measured in meters per second It should not be confused with sound or particle velocity which relates to the physical motion of the medium itself Spectrum Frequency Spectrum The amplitude of sound or...

Page 183: ...mpulse The time constant is 35ms for the rise and 1 5 seconds 1500 ms for the decay The reason for the double constant is to allow the very short signal to be captured and displayed Vibration The osci...

Page 184: ...f is the frequency in Hz and is the radian frequency It has the dimensions of inverse length Yearly Average Sound Level YDNL Lydn The Day Night Average Sound Level for each day is averaged over the en...

Page 185: ...0 1 10 C Calendar real time A 10 Calibration 1 6 8 11 C 1 glossary C 2 key 2 5 Model 820 1 2 3 1 Character Parameters B 14 Clock real time A 10 run time A 11 Commands status B 5 Conventions formatting...

Page 186: ...glossary C 6 F Far Field C 6 acoustic C 6 geometric C 6 Features 1 5 Model 820 1 5 Formatting 1 3 conventions 1 3 Free field C 6 Frequency band pass filter C 7 glossary C 6 Hz rad sec C 7 Frequency W...

Page 187: ...8 10 Lmax 2 5 Lmin 2 5 Lmin Lmax 8 14 Ln 2 6 8 13 LOCK 8 10 Lock 2 4 log 2 4 memory 2 4 5 14 Modify 2 7 numeric 4 3 parameter 4 1 PEAK 2 5 Print 8 18 RCL 8 7 RESET 8 7 Reset 2 4 Run Stop 2 4 R S 8 7 S...

Page 188: ...lines C 9 reference number 1 12 what it measures C 9 Microphone Extension Cables specifications A 7 Microphones capacitor C 9 electrit C 9 uses C 9 Mode commands B 4 Model 2 1 2 9 Model 820 accessorie...

Page 189: ...4 exceedance history 7 9 exceedance level 7 8 indexed B 12 Interval history 7 5 key access 8 1 Model 820 1 2 numeric B 12 printout 10 1 query B 15 setting B 12 setting and viewing 7 1 setting keys 4 1...

Page 190: ...8 SEL key 2 6 Serial number 1 12 Serial Port App C 1 2 Setup enter and exit 8 1 key 2 3 recalling 8 6 storing 8 5 Setup Parameters 8 7 Shift 2 3 key 2 4 SLM 5 1 key 2 5 SLM Sound Level Meter 8 11 Sou...

Page 191: ...d Exposure time Ti C 1 Key 2 6 weighting C 18 Time History 8 15 data 7 3 Time History see History 2 4 Time Weighted Average see T A 2 7 Timed Measurement Chapter 6 6 1 Timer for unattended readings 6...

Page 192: ...Index Wavelength l glossary C 18 Wavenumber glossary C 18 Weighted 8 hour time weighted average sound level C 5 Weighting 8 12 frequency C 7 slow 5 4 time C 18 Weightings A and C 5 4...

Page 193: ...Total Customer Satisfaction Guaranteed 3425 Walden Avenue Depew NY USA 14043 Phone 716 926 8243 Toll Free 888 258 3222 LarsonDavis com FAX 716 926 8215...

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