Delta OHM HD 2020 User manual

HD2020
[ GB ]
Acoustic
calibrator

[ GB ]
[ GB ] Introduction
The HD 2020 sound level calibrator is a portable, battery operated sound source, suitable
for sound level meters (portable and laboratory) and acoustic stations. It allows calibrating
1/2” microphones with mechanical dimensions compliant with IEC 61094-1 (“Measurement
microphones. Part 1: Specications for laboratory standard microphones”) and IEC 61094-4
(“Measurement microphones. Part 4: Specications for working standard microphones”). The
calibration pressure levels of 94dB and 114dB can be selected by the keypad. The 1000 Hz
frequency cannot be changed. If the displayed value doesn't stop blinking within a few sec-
onds, this means that the microphone is not inserted correctly.
To conserve battery life, the instrument is provided with an automatic power off function: if
you leave the instrument on with open cavity, it switches off automatically after 30 seconds.
If the cavity is closed and the microphone is inserted, the instrument switches off 5 minutes
after turning on, provided that you don’t press any key.
The calibrator display shows calibration pressure level, battery life, current date and time.
Acoustic calibrator
1. ON-OFF key: turns on and off the instrument. When you turn the instrument on, the display
will switch on about three seconds later.
2. SETUP key: allows you to enter and scroll menu. To exit, press it repeatedly until you go
back to the standard screen.
3. Display. When you turn the instrument on, it shows all segments on, then the sound pres-
sure level (94 or 114dB) will appear in standard view.
4. Calibrator cavity for conventional 1/2 inch microphones.
5.▼key: in standard mode, it selects 94dB and 114dB pressure levels alternately. In menu
mode, it decreases the current value.
6. ▲key : in standard mode, it selects 94dB and 114dB pressure levels alternately. In menu
mode, it increases the current value.
7. Battery lid.
The HD 2020 calibrator advantages are:
•The1000Hzfrequencyallowscalibratingsoundlevelmeterswithanyweighting(LIN,A,B,
...), without applying any correction factor.
•Thecalibrationsoundpressurelevelisindipendentofatmosfericpressure:youdon’tneed
to adjust the value according to static pressure over a wide range of values.
•TheHD2020calibratorcanbeconvenientlyusedbothinlaboratoryandintheeld.The
114 dB sound level allows performing calibrations even in high background noise environ-
ments.
•Itssimplicityofuseallowsevenunqualiedstafftoemployit.
DISPLAY AND KEYPAD DESCRIPTION
The instrument keypad is composed of 4 keys.
Listedbelowaretheirmainfunctions.
ON
OFF
ON-OFF key
PresstheON/OFFkeytoturnonandofftheinstrument.
When you turn the instrument on, all the display segments are shown, for a few seconds ...
HD 2020
... an automatic test including battery power is performed and the instrument switches to
standard mode.
HD 2020
94
Note: the display turns on 3 seconds after you press the ON/OFF key: meanwhile, the
initial automatic test is performed.
AutoPowerOff function
The instrument is provided with an automatic power off function which switches off the instru-
ment after about 5 minutes if the microphone is inserted in the cavity and you don’t press
any key.
If the cavity is open, the sound level blinks on the display: in this case the instrument switches
off automatically after 30 seconds.
You cannot disable the AutoPowerOff function.
SETUP
SETUP Key
The SETUP key allows entering and viewing the menu. To exit, press the SETUP key until you
go back to the standard screen, or keep it pressed for more than 2 seconds.
The menu shows:
•Currentdateandtimeintheformatyear,month,day,hour,minute,second.
•Currentdateandtimeintheformatyear,month,dayofthelastcalibration.
•Theintervalbetweenthecalibrationdateandtheexpirydateinyearsandmonths.
You can set all these items: press SETUP to select it and use the arrow keys to
change it. Press the SETUP key to conrm.
Fromthestandardscreen,presstheSETUPkeytoviewthecurrentyear:
HD 2020
94
>>
SETUP
>>
HD 2020
Use the arrow keys to increase/decrease the value. Press the SETUP key to conrm and go
to the current month:
SETUP
>>
HD 2020
Use the arrow keys to increase/decrease the value. Press the SETUP key to conrm and go
to the current day:
SETUP
>>
HD 2020
Use the arrow keys to increase/decrease the value. Press the SETUP key to conrm and go
to the current time:
SETUP
>>
HD 2020
h06
Use the arrow keys to increase/decrease the value. Press the SETUP key to conrm and go
to the current minute:
SETUP
>>
HD 2020
'30
Use the arrow keys to increase/decrease the value. Press the SETUP key to conrm and go
to the current second:
SETUP
>>
HD 2020
Whenever you press the arrow keys, seconds will be reduced to zero. Press the SETUP key
to conrm and go to the calibration menu, the triangle in the lower left corner appears and the
1 7
2 6
3 5
4

calibration year is displayed. (This parameter can’t be modied by the user).
HD 2020
(calibration year – rst triangle)
Press the SETUP key to go to the calibration month (this parameter can’t be modied by the
user).
HD 2020
(calibration month – rst triangle)
Press the SETUP key to go to the calibration day (this parameter can’t be modied by the
user).
HD 2020
(calibration day – rst triangle)
Press the SETUP key to conrm and to go to menu to set up the calibration expiration date.
The second triangle will appear and the number of years between the calibration date which
is entered by the calibration laboratory and the expiry date can be entered. When the time
interval expires, the triangle will blink to remind you that the calibrator needs adjusting.
HD 2020
(validity years – second triangle)
Use the arrow keys to increase or decrease the value. Press the SETUP key to conrm and go
to the number of validity months.
HD 2020
(validity months – second triangle)
Use the arrow keys to increase or decrease the value. Press the SETUP key to conrm and
go back to standard mode.
▲Arrow key
In standard mode, it selects 94dB and 114dB sound pressure levels alternately. In menu
mode, it increases the current value.
▼Arrow key
In standard mode, it selects 94dB and 114dB sound pressure levels alternately. In menu
mode, it decreases the current value.
CALIBRATION PROCEDURE
The HD 2020 can calibrate standard 1/2” microphones compliant with IEC 61094-1 and
IEC61094-2.
To calibrate the microphone, insert it deep into the cavity. The O-ring will offer some resis-
tance.
The calibration can be effected by holding the HD2020 upright as well as by leaning the instru-
ments on a worktable.
While measuring, you should move neither the microphone nor the calibrator; make sure that
the worktable doesn’t transmit vibrations.
A small misalignment of the microphone and calibrator axes is allowed.
•Beforebeginningtocalibrate,youshouldmakesurethattheambientnoiseleveldoesn’t
affect the calibration. After inserting the microphone into the cavity, with the sound level
meter and the calibrator off, switch on the sound level meter and detect the unweighted
ambient sound pressure level. If the measured level is below 78 dB, you can use both cali-
bration sound levels (94 dB and 114 dB); if the level is between 78 dB and 98 dB you can
use the 114 dB level only, while a sound level above 98 dB means that calibration is not
possible.
•PresstheON/OFFkeytoswitchontheinstrument.
•Usethearrowkeystoselectthesoundlevel:94dBor114dB.
•Makesurethatthemeasurementvalueisnotblinkingonthedisplay:thismeansthatthe
microphone is not inserted correctly.
•Calibratethesoundlevelmeteraspertheprocedureshownintheinstrumentmanual.
•Applythecorrectiontothepressureleveldependingonthemicrophone(seethefollowing
chapter).
•Oncecalibrationiscomplete,switchoffthesoundlevelmeterandthecalibratorandremove
the microphone from the cavity.
The HD 2020 calibrator allows calibrating any sound level meter provided that it is equipped
with a laboratory or working standard 1/2” microphone compliant with IEC 61094-01 and IEC
61094-4 standards.
Corrections depending on the microphone
The HD2020 calibrator generates a 94 dB (or 114 dB) sound pressure level referred to 20μPa.
Working standard ½” microphones for sound level meters are manufactured to achieve at
frequency response in free or diffuse eld, i.e. in a eld of progressive plane waves propagat-
ing in the same direction as the microphone axis and in a eld of sound waves coming from
every direction, respectively. These propagation conditions are different from those in the
calibrator cavity.
In free eld, reections due to the microphone alter the sound level by increasing the high-
frequency cartridge effective sensitivity. Microphones optimized for free eld measurements
exploit this phenomenon to achieve at frequency response even at very high frequencies. In
these microphones, the sound level increase at 1 kHz corresponds to approximately 0.05 dB
÷ 0.20 dB. Therefore, when you calibrate a free eld microphone, you must allow for this dif-
ference when you set a sound level 0.1 dB or 0.2 dB lower than the calibrator nominal one.
Microphones optimized for diffuse eld measurements don’t require corrections when cali-
brated in a closed cavity at 1 kHz instead.
LOW BATTERY INDICATION AND REPLACEMENT
The HD 2020 calibrator is provided with two batteries: a 9V alkaline battery that can be
replaced by the user and a lithium buffer battery. The latter allows the date indicator and
watch to work even without external battery: it must be replaced by a Delta Ohm authorized
service centre.
The 9V battery power is constantly monitored:
•Ifthebatteryisfullycharged,itssymbolisoff;
•Ifthebatteryispartiallycharged,itssymbolblinks:pleasereplacethebatteryassoonas
possible;
•Ifthebatteryisunchargedandtheinstrumentcannotworkproperly,itssymbolisconstantly
on. When the battery is uncharged, the calibrator switches off in about 10 seconds.
To replace 9V batteries, switch off the instrument and open the lid at the bottom of the instru-
ment. Replace the battery. Close the lid.
Date, time and calibration interval are stored if the buffer battery is charged.
The average life of the buffer battery depends on the external battery: if you use it, the average
life of the internal battery is about 5 years.
Battery tips
•Ifthebatteryislow,replaceitassoonaspossible.
•Makesurethatthereisnolossofliquid.
•Usegoodqualitysealedbatteries(alkalineifpossible).
CONSTRUCTION AND FUNCTIONING
Mechanical construction
Fig.3Calibratormechanicalconstruction(section).
Fig.3schematizestheHD2020calibratorstructure(section).Thebatterycompartmentison
the right side of the case. The printed circuits and the electronics are over and under the bat-
tery compartment. The display and the keypad take up the higher part. The electro-acoustic
transduction device is on the left and it consists of a wide cavity with a piezoceramic genera-
tor and a feedback sensor. The device emits the signal through the ½” microphone. An outer
capillary hole balances the chamber static pressure protecting microphones from overpres-
sure due to their insertion.

Control electronics
Fig.4showsthecalibratorblockdiagram.
Micropocessor
Reference
Oscillator
Keypad
AGC
RMS
HD 2020
Fig.4Electronicsblockdiagram.
The electronics consist mainly of an oscillator combining high stability and low distortion, as
well as an RMS converter, the automatic gain control (AGC), the driver for the ceramic resona-
tor and the feedback signal conditioning.
The RMS level of the signal provided by the sensor is compared with the factory set reference
level; the difference adjusts the signal width generated by the oscillator and thus the acoustic
signal generated by the piezoelectric transducer through automatic gain control.
The signal provided by the sensor slightly varies with the ambient temperature and the static
pressure; the frequency of the signal provided by the oscillator is also stable in relation to
ambient parameters.
INSTRUMENT STORAGE
Instrument storage conditions:
•Temperature:-25...+55°C.
•Humidity:below90%RHwithoutcondensation.
•Whenstoringtheinstrument,avoid:
High humidity.
Direct exposure to sunlight.
Exposure to high-temperature source.
Strong vibration.
Steam, salt and/or corrosive gas.
The instrument case is made of ABS: please use only compatible solvents to clean it.
FUNCTIONING AND OPERATING SAFETY
Authorized use
Please read carefully the specications listed in the following chapter. You are allowed to use
the instrument only in compliance with these instructions. Any other use is not authorized.
General safety instructions
ThisinstrumentismanufacturedandtestedincompliancewithEN61010-1safetystandard
on electronic measuring instruments and it leaves the factory in perfect safety conditions.
Normalfunctioningandoperatingsafetyareguaranteedonlyifallusualandspecicsafety
standards described in this manual are observed.
Normal functioning and operating safety are guaranteed only if climatic conditions are the
same as described in the “specications” chapter.
Use and store the instrument avoiding:
•Suddenchangeoftheambienttemperaturethatmaycausecondensation.
•Inammableorcorrosivegases.
•Directvibrationorblows.
•Intenseelectromagneticelds,staticelectricity.
If you carry the instrument from a cold to a hot environment, condensation may affect its
functioning. In this case you should wait for the instrument temperature to reach the ambient
temperature before using it again.
User obligations
The user must comply with the following standards and directives on the use of dangerous
materials:
•EECdirectivesonsafetyintheworkplace
•Nationallegislationonsafetyintheworkplace
•Safeworkingpractices
SPECIFICATIONS
The HD 2020 calibrator complies with IEC 60942-2003 Class 1 and ANSI S1.40-1984.
Coupling cavity: for standard 1/2” microphones (12.7 ±0.03 mm)
according to IEC 61094-1 and IEC 61094-4
Frequency: 1000Hz
Frequencytolerance: 1%intherange-10...+50°Cand10%...90%RH
Sound pressure level: 94.0 dB and 114.0 dB ±0.2 dB at 1kHz
 (referred to 101.3 kPa, 23°C ±3°C and 65%
R.H.)
Referenceconditions: 20°C, 50% RH, 101.3kPa, 10 mm
3
cartridge
volume
Stabilization time: 10s
Totaldistortion: <1%
Ambient condition inuence
-Temperatureandhumidityinuence: < 0.3 dB in the range -10°C...50°C and
10%...90%RH
- Static pressure inuence: < 0.1 dB in the range 65 kPa ... 108 kPa
Stability levels
- Short-term stability: ±0.03 dB
- Stability after 1 year, normal use: ±0.1 dB
Operating conditions
-Workingtemperature: -10…+50°C
-Relativehumidity: ≤90%R.H.
Storagetemperature: -25…+70°C
Microphone equivalent volume: 5 to 250 mm
3
Powersupply: 9ValkalinebatteryIECtype6LR61.9Vrecharge-
able batteries are also allowed.
9V battery autonomy: 48-hour continuous functioning with good quality
alkaline batteries.
Automatic power off: 5 minutes – it cannot be disabled
Watch/date-indicator: internal with 3V lithium buffer battery
Case material: ABS
Dimensions: 53x43x83mm
Weight: 160g.
IP Protection degree IP64
Effects of electromagnetic elds: < 0.3 dB
ORDERING CODE
HD2020: The kit includes: HD2020 calibrator, one 9V alkaline battery, instruction manual and
calibration report.

Delta Ohm srl - Via G. Marconi, 5 - 35030 Caselle di Selvazzano (Pd) - Italy
Tel.00390498977150r.a.Fax0039049635596-E-mail:[email protected]WebSite:www.deltaohm.com
Ro H S
20 0 2/ 9 5/ E C
01
06.08
Manufacture of portable and bench top instruments
Current and voltage loop transmitters
Temperature - Humidity - Pressure
Airspeed-Light-Acoustics
pH - Conductivity - Dissolved Oxygen - Turbidity
Elements for weather stations - Thermal Microclimate
SITCENTREN°124
Temperature - Humidity - Pressure - Air speed
Photometry/Radiometry - Acoustics
CECONFORMITY
• Safety: EN61000-4-2,EN61010-1Level 3
• Electrostatic discharge: EN61000-4-2Level3
• Electric fast transients: EN61000-4-4livello3,EN61000-4-5Level3
• Voltage variations: EN61000-4-11
• Electromagnetic interference sucseptibility: IEC1000-4-3
• Electromagnetic interference emission: EN55020classB