Casella CEL CEL-414 User Manual

SOUND LEVEL METERS

CEL-266/3, CEL-275/3, CEL-414/3

CEL-493/3 - Type 1

CEL-328/3, & CEL-383/3 - Type 2

Operator’s Handbook

Document 060174

Issue: 1C

February 1996

Compliance

The CEL-266/3A, CEL-328/3A, CEL-383/3A & /3B, CEL-275/3A & /3B and CEL-414/3 Sound Level Meters comply with the EMC Directive 89/336/EEC of the European Union. They have been tested according to the standard delivery schedule and comply with the fol- lowing standards.

EN 50081-1 : 1992 EN 50081-2 : 1993Generic emission standards for residential, commercial, light

industry and industrial environments. EN 50082-1 : 1992 EN 50082-2 : 1993Generic immunity standards (for both RF fields and electrostatic

discharge) for residential, commercial, light industry and industrial

environments.

PTB Type Approval

The following instruments have been verified by the German PTB Organisation, which has granted them the relevant Type Approvals:

21.21

CEL-266/3A. ...............................

The instrument consists of the following items: CEL-266/3A Sound Level Meter, CEL-225/3 Preamplifier and CEL-192/2F Microphone.

CEL-328/3A ...............................

The instrument consists of the following items: CEL-328/3A Sound Level Meter and CEL-230 Microphone/Preamplifier Unit.

CEL-275/3A and CEL-275/3B ......................

The instrument consists of the following items: CEL-275/3A or CEL-275/3B Sound Level Meter, CEL-225/3 Preamplifier and CEL-192/2F Microphone.

CEL-383/3A and CEL-383/3B ......................

The instrument consists of the following items: CEL-383/3A or CEL-383/3B Sound Level Meter and CEL-230 Microphone/ Preamplifier Unit.

CEL-414/3 ................................

The instrument consists of the following items: CEL-414/3 Sound Level Meter, CEL-225/3 Preamplifier and CEL-192/2F Microphone.

91.51

21.22

91.52

21.21

92.53

21.22

92.54

21.11

94.78

Page ii - General CEL Sound Level Meters Handbook

Contents Page

1. INTRODUCTION ..........................1

2. SCHEDULE OF PARTS ......................3

3. DESCRIPTION ...........................4

3.1 Technical Description ....................4

3.2 Control Facilities ......................9

3.3 General Reset ......................11

3.4 Display ..........................12

3.5 Auxiliary Outputs .....................13

3.6 Auxiliary Inputs ......................14

3.7 Octave Filters .......................14

3.8 Batteries & Auxiliary Power Supplies ..........15

4. PREPARATION FOR USE ....................16

4.1 Battery Installation ....................16

4.2 Fitting Microphones & Preamplifiers ...........17

5. FIELD ACCURACY CHECK (ACOUSTIC CALIBRATION) ....18

6. OPERATION ...........................20

6.1 General Procedures ...................21

6.2 Measurement of Sound Pressure Level - SPL ......22

6.3 Measurement of One Second Mode - 1SM

(not CEL-266/3, CEL-328/3 or CEL-414/3) ........22

6.4 Duration of Measurement Period - DUR .........23

6.5 Measurement of Maximum Value - L

6.6 Measurement of Equivalent Continuous Level - L

(not CEL-414/3 or CEL-328/3C) ..............23

6.7 Measurement of Sound Exposure Level - SEL

(not CEL-266/3, CEL-328/3 or CEL-414/3) ........24

6.7.1 Event Times Determined by Threshold Level

(only CEL-493/3) .....................24

6.7.2 Events Timed Manually

(not CEL-266/3, CEL-328/3 or CEL-414/3) ........25

6.8 Measurement of 3 & 5s Cumulative Average - L L

(A, B and CEL-493/3) ................26

Tm5

6.9 Measurement of L

OSHA&LDOD

(C & D versions) ....26

6.9.1 Setting the Threshold Level ...............26

6.9.2 L

OSHA&LDOD

Measurement ...............27

6.10 Frequency Analysis Using Built-in Octave Filters

(only CEL-266/3 & CEL-328/3) ..............27

........23

max

Tm3

General CEL Sound Level Meters Handbook - Page iii

Contents Page

7. USE WITH OTHER EQUIPMENT ................ 28

7.1 Frequency Analysis With External Filter Sets

(not CEL-266/3 or CEL-328/3) .............. 28

7.2 Use With CEL-3025 Vibration Attachment Kit ..... 28

7.3 Recording With CEL-238A, CEL-338, & CEL-438 Digital Recorders & Analysers (B, D & CEL-493/3) . . . 29

7.4 Use With Tape Recorders ................ 30

7.4.1 Recording With a Tape Recorder ............ 31

7.4.2 Replay From a Tape Recorder .............. 33

7.5 Graphic Level Recorders ................ 34

8. DIGITAL INTERFACE (B & D, and CEL-493/3 only) ...... 35

9. EXPLANATION OF TERMS USED ............... 38

9.1 Sound Pressure Level (SPL) ............... 38

9.2 Duration of Measurement Period (DUR) ........ 39

9.3 Equivalent Continuous Noise Levels (L

9.4 Sound Exposure Level (SEL or L

9.5 Maximum Value (

)

.................. 41

max

9.6 PeakMaximumValue.................. 41

9.7 3 & 5s Cumulative Average Values

9.8 L

Tm3&LTm5

OSHA&LDOD

- A, B Versions & CEL-493/3) ...... 41

(C & D Versions) ............. 42

)........ 39

)........... 40

10. POST PRODUCTION DEVELOPMENTS ............ 42

10.1 Digital Interface for A & C Versions ........... 42

10.2 1SM Measurement Link ................. 42

11. SPECIFICATION ........................ 43

12. ERROR MESSAGES ...................... 48

13. MANUFACTURERS SERVICING & WARRANTY ....... 49

14. PTB TYPE APPROVAL ..................... 50

Page iv - General CEL Sound Level Meters Handbook

1. INTRODUCTION

These instruments are a re-interpretation of the classic full specification sound level meter.

The CEL-266/3, CEL-275/3, CEL-414/3 and CEL-493/3 satisfy the requirements of IEC 651: 1971 Type 1Ifor precision impulse sound level meters (and ANSI: S1.4-1983, Type S1 when used with an R type random incidence microphone). The CEL-266/3, CEL-275/3 and CEL- 493/3 also satisfy the requirements of IEC 804 Type 1 for integrating sound level meters.

The CEL-328/3 and CEL-383/3 satisfy the requirements of IEC 651: 1971 Type 2

for impulse sound level meters, ANSI: S1.4-1983, Type S2 for sound level me- ters and (except for CEL-328/3E) also IEC 804 Type 2 for integrating sound level meters.

All of these instruments and versions can measure sound pressure levels in the range from 20 dB(A) to 140 dB(A) at fre- quencies between 3.5 Hz and 20 kHz with the microphone supplied, and up to 70 kHz with a suitable microphone.

When used with the CEL-4391 Attenu- ator Pad (supplied) the CEL-493/3 is able to measure sound levels up to 150 dB(A).

The instruments use modern microproc- essor and component integration to pro- viding all the traditional measurement facilities in a compact and easily handled unit.

Well proven concepts and methods have been employed in their design and con- struction so that the most commonly used acoustic measurements can be per- formed. They provide a continuous indica-

tion of the instantaneous sound pressure level SPL in both analog and digital for- mats on a liquid crystal display. Displays showing the measurement duration and maximum value may also be selected.

The CEL-266/3 and CEL-328/3 contain 10 built-in octave filters with centre frequen- cies between 31.5 Hz and 16 kHz. These filters satisfy the requirements of IEC 225 and ANSI S1.11-R1975 Class 2.

With the exception of the CEL-414/3 and the CEL-328/3E, all versions also calcu- late the equivalent continuous level L (plus L

Tm3

and L

Tm5

,orL

OSHA

and L

DOD

) and the sound exposure level SEL at the same time. The CEL-328/3E calculates only the octave filtered L

values.

This Operators Handbook covers all of the instrument types and versions shown below.

CEL

Type

328/3

Type 2

383/3

Type 2

266/3

Type 1

275/3

Type 1

414/3

Type 1

493/3

Type 1

European

Versions

Oct.

Filter

XX X X

XX X

One single version, with European

software plus a built-in interface

I/face

XXXX

American

Versions

I/face

The CEL-493/3 plus B and D instrument versions have a built-in CEL low power interface, which allows them to be con- nected to one of the data logger/printers

General CEL Sound Level Meters Handbook - Page 1

in the CEL-438, CEL-338 and CEL-238A series, or to some other digital device for data logging or processing, and for con- trol purposes.

D Standard American version (as C)

that contains a CEL low power serial interface,

E (CEL-328/3 only) Non-integrating

version based on the CEL-328/3C,

With the exception of the CEL-414/3C which has no integration functions, these instruments have the following features:

without L L

All instruments and versions have a simi-

OSHA,LDOD

lar appearance, with minor differences

A Standard European version of the

instrument measuring SPL, L L

Tm3,LTm5Lmax

, SEL, (and 1SM),

with A-weighted and Linear frequency response,

B Standard European version (as A)

that contains a CEL low power serial interface,

C Standard American version of the

instrument measuring SPL, L L

OSHA,LDOD,Lmax

SEL, (and 1SM),

with A- and C-weighted frequency response,

only in the legends on the frequency weighting switch and on the bezel sur- rounding the main display. The best way to identify an instrument version is to re- fer to the suffix letter in the instrument serial number on the rear cover, or to note the version letter (A, C or E in upper case, b or d in lower case) displayed to- gether with the type number during the instruments start up sequence.

All versions will accept the CEL-3025 Vi- bration Attachment connected via the

Table 1: Functions available with various time weighting selections

Version Time Weighting A, B & C & D E 414/3 Fast Slow ImpulsePeak 493/3

, or broadband

Sound Pressure Level (SPL) X X X X X X X Broad band Energy Equivalent Level (L Octave band Energy Equivalent Level (L Maximum Value (L Measurement Duration (DUR) X X X X X X X X Sound Exposure Level (SEL Taktmaximalpegel 3s (L Taktmaximalpegel 5s (L L

OSHA

DOD

1SM

Note1: Slow Leqdoes not fully satisfy the requirements of IEC 804.

: Impulse time weighted Leqis used only when complying with VDI 2058.

Note

: Not available with Types CEL-266/3, CEL-328/3 and CEL-414/3.

Note

: 1SM is a special application required by IEC 651 para 7.8 which calls for a one

Note

second maximum profile to be adopted for the SPL function. Measurements in this mode can be made when the link is connected according to Section 6.3.

)XX XX1X

) XXX XX

) XXXXXXXX

max

)X X X X

)X X X

Tm3

)X X X

Tm5

XX XX

XX XX X

Page 2 - General CEL Sound Level Meters Handbook

CEL-225/3* (supplied only with Type 1 instruments) or the earlier CEL-225 Pre- amplifier so that vibration levels can be measured.

The built-in octave filters of the CEL- 266/3 and CEL-328/3 can be used for fre- quency analysis of both noise and vibration. Frequency analysis can also be performed by the CEL-275/3, CEL-383/3, CEL-414/3 and CEL-493/3 when they are

2. SCHEDULE OF PARTS

connected to one of the CEL-278/3 or /2 Octave, CEL-296/3 or /2 Octave/Third Oc- tave Filter Sets.

Note*: For noise measurements, Type 1

instruments must use the CEL- 225/3 Preamplifier supplied, (identified by a black key line). However, for vibration measure- ment, both Type 1 and Type 2 instruments may use either a CEL-225/3 or a CEL-225.

A complete CEL Impulse Sound Level Meter Type 1 consists of:

CEL-XXX/X Sound Level Meter, CEL-192

⁄2 Precision Micro-

phone for Type 1 Instruments,

CEL-225/3 Preamplifier for Type 1

Instruments.

A complete CEL Impulse Sound Level Meter Type 2 consists of:

CEL-XXX/X Sound Level Meter, CEL-230

⁄4 Microphone and

Preamplifier Unit for Type 2 Instruments.

The following additional items are also in- cluded with the instrument:

CEL-4391 Attenuator Pad (with

CEL-493/3 only), 040004 Protective Wallet, LR6 Battery (4 off), 038054 Calibration Trimtool, 060174 Handbook.

When the instrument is delivered, check that all of these items have been supplied.

Special transit packing is provided for both instrument and microphone which

must be retained for use when the instru- ment is transported or will be consigned by general carriers. (Current or pending legislation on recycling states that this packaging must be retained for re-use or be recycled in the locally approved man- ner). Any instrument returned inade- quately packed to the manufacturers for calibration, service, or repair will be re- packaged and charged accordingly.

The following accessories may be or- dered separately to increase the range of tasks that can be performed by the instru- ment.

CEL-250

⁄2 Precision (Type 1)

Electret Microphone - robust construction suitable for long term monitoring (USE ONLY with C6601/10 Preamplifier Extension Cable that has 200 V polarization supply disabled),

MK-301

⁄4 Microphone - allows

Type 1 instruments to measure up to about 160 dB,

CEL-216 Line Input Adaptor for

Type 1 Instruments,

General CEL Sound Level Meters Handbook - Page 3

CEL-316 Line Input Adaptor for

Type 2 Instruments,

CEL-282 Acoustic Calibrator for

Type 2 Instruments,

CEL-284/2 Precision Acoustic

Calibrator for Type 1 and 2 Instruments,

CEL-278/3 Octave Filter Set (not

for CEL-266/3 or CEL-328/3),

CEL-296/3 Octave/Third Octave

Autoscan Filter Set (not for CEL-266/3 or CEL-328/3),

CEL-2962 Windshield for

⁄2

Microphones,

CEL-4672/2 Windshield for

⁄4

Microphones, CEL-4627 Tripod, CEL-3025 Vibration Attachment, CEL-3732/3 Mains Power Supply

(needs C4461/2 Cable), CEL-338 Graphics Printer and Logger, CEL-438 Noise Level Analyser, CEL-433 Serial Interface, C4493/10 Preamplifier Extension

Cable (10 m), C6602/0.3 0.3 m Flat Ribbon Cable

Extension for C4493

Cable, C4425/2 Signal Cable - Uher

4000 series analog

tape recorders, C3526/2 Replay Cable - Uher

4000 series recorder to

BNC plug,

C4520 AC Output Cable - BNC

plug,

C4530A/1.5 Digital Output and

Control Cable for B, D & CEL-493/3,

C6620/2 Output Cable for

CEL-493/3 - BNC plug to Sony TCD D10 and PRO II DAT Recorders (needs CEL-6616 Adaptor),

SC174 Control Cable for

CEL-493/3 - 14-way LEMO plug to specially converted Sony TCD D10 or PRO II DAT Recorder Handset (needs CEL-6616 Adaptor),

SC167 Signal and Control

Cable for CEL-493/3 - 14-way LEMO plug to specially converted Sony TCD D10 DAT Recorder Handset,

SC161 Signal and Control

Cable for CEL-493/3 - 14-way LEMO plug to specially converted Sony TCD PRO II DAT Recorder Handset.

These instruments are also available as components of measurement kits.

Please contact your CEL representative for details.

3. DESCRIPTION

3.1Technical Description

Type 1 Microphone

The standard Type 1 192 Precision Air Condenser Microphone

Page 4 - General CEL Sound Level Meters Handbook

⁄2 diameter CEL-

is available in free field (suffix F) versions to meet IEC measurement standards and random incidence (R) versions to meet ANSI standards. The microphone capsule is screwed on to a low noise CEL-225/3 Preamplifier which plugs into the tapered end of the sound level meter.

The preamplifier supplies the 200 V polari- zation voltage required by the micro- phone, provides 30 dB or unity gain, and conditions the output.

The CEL-225/3 Preamplifier can be identi- fied by the black key line that should align with a similar line on the sound level me- ter. The CEL-225/3 Preamplifier is a devel- opment of the CEL-225 used with earlier sound level meters such as the CEL-275 and CEL-275/2 (which have no key line).

measurement requirements for both ran- dom incidence (ANSI standards) and free field (IEC standards).

For vibration measurement and analysis with a Type 2 instrument, the CEL-230 Microphone/Preamplifier Unit must be re- placed by a CEL-225/3 (or CEL-225) Pre- amplifier which accommodates a CEL-3025 Vibration Attachment screwed on in place of a microphone to accept in- put signals from an accelerometer.

The preamplifiers have a similar appear- ance, but function in a different way, so that although no damage would occur, they should not be substituted for each other when measuring sound levels.

When an earlier preamplifier is used with a later sound level meter, the noise floor for linear noise measurement will be raised to about 70 dB. If an older series of Type 1 sound level meter is used with a CEL-225/3 Preamplifier for sound level measurement, the instrument stabilisa- tion time will be increased to at least three minutes. Therefore, it is not recom- mended to mix old and new versions.

When vibration measurement and analy- sis is to be undertaken by a Type 1 instru- ment, both types of preamplifier may be used to accommodate a CEL-3025 Vibra- tion Attachment. This is screwed on in place of the microphone to accept input signals from an accelerometer.

Type 2 Microphone

The standard Type 2

⁄4 diameter prepo-

larised electret microphone capsule is permanently attached to a low noise am- plifier to form a CEL-230 Microphone/Pre- amplifier Unit that plugs into the tapered end of the sound level meter. The charac- teristics of the microphone satisfy the

Both types of microphone can be used re- mote from the instrument when the pre- amplifier is connected to the Sound Level Meter via an extension cable. C4493/5 (5 m), C4493/10 (10 m), and C4493/20 (20 m) are standard cables, and a maxi- mum length of 100 m can be delivered. The C6602/0.3 (3 m) Flat Ribbon Cable can be used to carry microphone signals through door or window closures.

Input signals can be accepted from other sources. For example when a CEL-216 Line Adaptor is used with a Type 1 instru- ment or a CEL-316 Line Adaptor with a Type 2 instrument, AC input signals with a maximum level of 22.5V in from a tape recorder, (and 21V

pk-pk

can be fed

pk-pk

signals can be applied via the auxiliary socket).

As can be seen from the block diagram in Figure 1, the input from the preamplifier can be switched to pass to the wide range RMS detector through a variable gain amplification stage with linear re- sponse on A & B versions and the CEL- 493/3, and C-weighted on C, D & E versions), or it may be passed through an A-weighted filter that meets the require- ments of IEC 651 Type 1. Linear, A- or C- weighted signals are passed via a CAL control, and may also be passed either to the internal filter sets of a CEL-266/3 or a

General CEL Sound Level Meters Handbook - Page 5

CEL-192 Microphone

Type 1

30 dB

Gain

30 dB

Gain

Type 2

920001

10 dB AttenuatorPad (493/3 only)

CEL-225/3 Preamplifier

200 VPolarisation Voltage

A-Wtg

C-Wtg

Freq Weighting

Lin. or C-Wtg

CEL-230 Microphon/ Preamplifier Unit

External Power Supply

Low Voltages

To Ext Filter: AC Out From Ext Filter

(not 266/328)

50 20

Range

Amplifier

Cal

Lin, A-,or C-Wtd AC Out

Log DC Out

Address Bus

Figure 1: Block diagram

Power Supply

10 Octave

Filters

(only 266/328)

RMS

Detector

Batteries

Battery Condition

A / D

Converter

Data Bus

Interface

(only B, D &

493/3)

Display

Micro-

processor

RAM (not

414 or

328/3C)

EPROM

Internal

Controls

CEL-328/3, or to an optional external filter set connected to the sound level meter via the auxiliary socket, so that frequency analysis can be performed.

Integrated RMS detectors are employed that provide a full 120 dB measurement range in three overlapping 60 dB dy- anamic ranges (100 dB ranges on the CEL-493/3). The standard Fast, Slow, Impulse, and Peak time weightings can be selected. The RMS output signal passes through an analog to digital con- verter to the built in low power microproc- essor which drives a custom designed liquid crystal display with both analog and digital indication.

The digital display can be switched to show the sound pressure level, or any of the calculated parameters with a resolu- tion of 0.1 dB. The analog display is a bar graph that always gives an indication of the instantaneous sound pressure level

Page 6 - General CEL Sound Level Meters Handbook

with 1 dB resolution. In order to display the whole 60 dB (or 100 dB) dynamic range of the instrument on a 26 segment bar, the analog display is auto-ranged in 20 dB steps with a reference datum.

Control of the display and calculation func- tions is undertaken by the microproces- sor. Not only is a continuous display of the sound pressure level provided at all times, but the detector output is also sampled 320 times per second, and the samples integrated by the microproces- sor (not CEL-328/3E or CEL-414/3).

Simultaneous calculations are made to de- termine each of the parameters available from the instrument. The results are stored in registers, and may be shown on the digital display.

Special control sequences are avoided by using simple push button controls to se- lect any required parameter by stepping

the digital display through the registers. The following parameters may be se- lected (and identified) on the digital dis- play:

SPL Sound Pressure Level, L

Equivalent Continuous Level (not CEL-414/3, only octave band L

on CEL-328/3E),

Tm3

Maximum A-weighted Average taken over 3 second periods (A, B & CEL-493/3),

Tm5

Maximum A-weighted Average taken over 5 second periods (A, B & CEL-493/3),

OSHA

Averaged level with preset threshold and q = 5 (C, D versions but not CEL-414/3),

DOD

Averaged level with preset threshold and q = 4 (C, D versions but not CEL-414/3),

max

Maximum Level

DUR Duration over which

measurements taken,

SEL Sound Exposure Level

(not CEL-266/3, CEL- 328/3 or CEL-414/3),

31-16k Octave bands centered

on indicated frequency (only CEL-266/3 & CEL-328/3).

Each parameter may be reset inde- pendently from the other parameters, while an internal clock with an accuracy better than five seconds in 24 hours measures the time elapsed from the start of the measurement in hours and min- utes.

The display will give an automatic indica- tion of the following conditions:

Signal overload,

SEL Event in Progress (CEL-493/3 only),

Use of linear or A-weighted signals (A & B versions and CEL-493/3),

Use of A- or C-weighted signals (C&Dversions),

Use of an external filter set (not CEL-266/3 or CEL-328/3),

Use of pause button (not CEL-414/3),

Low battery.

Battery level can also be indicated by us- ing the Battery position on the power switch.

Both AC and DC analog output signals proportional to the indicated value are available from an auxiliary socket in the base of the instrument. The conditioned RMS AC output has a full scale deflection value of 7.75 V, (8.0 V on the CEL-493/3) while the DC output is a logarithmic sig- nal nominally 48 mV/dB with a typical maximum value not exceeding 5 V on all instruments.

In addition to the analog outputs, the B and D versions plus the CEL-493/3 are equipped with a CEL low power digital in- terface that allows them to feed all digital data to a CEL-438 Noise Level Analyser, CEL-338 Graphics Printer and Logger, and CEL-238A Secondary Processor. Alternatively, data on the selected pa- rameter can be fed via a CEL-433 Serial Interface to a suitably equipped com- puter. This arrangement is very useful in data logging applications, as two samples per second of the SPL display are trans- mitted in this way.

External control of digital functions is ex- ercised via the interface, so that parame- ter selection, and operation of pause and reset functions can be performed re- motely, or under program control.

General CEL Sound Level Meters Handbook - Page 7

Black Key Line

Version

C, D & E

BAT PSE OSH DOD

Version

A, B &

CEL-493/3

Pause Reset

CAL

Range

A C

FA FL

SEL__EVENT 1SM

BAT PSE LT3

LT5

DATUM 5 10 15 20 25

Function

P I F S

ON80 BAT OFF

LEQ

SPL MAX DUR

CEL- 192 Microphone (Type 1)

CEL-225/3 Preamplifier (Type 1)

CEL-230 Microphone/ Preamplifier Unit (Type 2)

Pause (not CEL-414/3)

Parameter Reset

Calibration Potentiometer

Function Step (Counter-clockwise)

Function Step (Clockwise) (not CEL-414/3)

On-Bat-Off (Power Switch) Sets SEL Threshold Level & Onset Time on CEL-493/3 Sets Threshold Level for L L on C & D versions

OSHA DOD

P-I-F-S (Time Weighting Switch)

A-C-FA-FL (C, D & E versions) A-L-FA-FL (A & B versions) (Frequency Weighting Switch)

80-50-20 (Range Switch) (Hi-Med-Lo on CEL-493/3)

SEL__EVENT 1SM (Octave Centre Frequencies on CEL-266/3 & CEL-328/3)

Digital Display

Analog Display

Auxiliary Socket

Filter Attachment Insert (not CEL266/3 or CEL-328/3)

Battery Compartment

920002

Page 8 - General CEL Sound Level Meters Handbook

Figure 2: Front panel & instrument

controls

The interface uses four lines, two of which are used for data transmission, while the other two are for the hand- shake request to send and clear to send signals. Each digital output con- sists of five bytes which describe the fre- quency weighting, time weighting, parameter selected, and its numeric value. Use of the pause and reset func- tions will also be indicated. More detailed information on the output and input facili- ties will be found in Sections 3.5 and 3.6.

3.2Control Facilities

The functions of the various controls are identified by the legends marked along- side them on the instrument front panel as follows, (see Figure 2).

ON-BAT-OFF

This three position slide switch is the main on/off control for the instrument. It provides the following settings:

OFF No power is drawn from

the supply, nor any function performed,

ON All instrument functions

are available as described below,

BAT* The on-load battery

voltage is displayed, while all normal functions continue to be performed.

Note*: On CEL-493/3, BAT position is also used

while setting the SEL event threshold level and onset time. Similarly, on C and D versions, the BAT position is used while setting the threshold for OSHA and DOD measurements.

When the instrument is first switched ON, the start up messages CEL to-

gether with the software issue number appear on the digital display, changing af- ter about five seconds to the instrument type number (for example 275) with the instrument version letter (A, b, C, d or E).

The analog bar graph steps along its seg- ments to indicate that the microproces- sor self checking procedures are being operated. When this test has been com- pleted satisfactorily, all measurement and calculation functions become available. Should the instrument fail the self test, an error message will be displayed as de- tailed in Chapter 12.

P-I-F-S (Time Weighting Switch)

A four position slide switch that selects the time weighting required in the RMS detector. It provides the following stand- ardized settings:

P Peak: <100µs, I Impulse: 35 ms rise time

and 1500 ms decay

time, F Fast: 125 ms, S Slow: 1 second.

A-L-FA-FL (Frequency Weighting & Filter Switch - A & B versions and CEL-493/3)

This four position slide switch provides selection of the linear (flat) response or the built-in A-weighting network, and the use of external filter sets. The following options are provided:

A Internal A-weighted

network, L Linear response of

instrument (+0.5/-3 dB

typical points),

80 (Hi) Range 3.5 Hz

to 70 kHz,

General CEL Sound Level Meters Handbook - Page 9

50 (Med) & 20 (Lo) Ranges 3.5 Hz to 40 kHz,

FA Either internal

A-weighted network PLUS internal octave filters, or external filter set connected via the auxiliary socket,

FL Either linear response

PLUS internal octave filters, or external filter set connected via the auxiliary socket.

Note: On instruments that have no built in

octave filters, there will an incorrect indication if FA or FL is selected when no filter is connected.

A-C-FA-FL (Frequency Weighting & Filter Switch - C, D & E versions)

This four position slide switch provides selection of the built-in A- or C-weighting network, and the use of external filter sets. The following options are provided:

A Internal A-weighted

network,

C Internal C-weighted

network,

FA Either internal

A-weighted network PLUS internal octave filters, or external filter set connected via the auxiliary socket,

FL Either linear response

PLUS internal octave filters, or external filter set connected via the auxiliary socket.

Note: On instruments that have no built in

octave filters, there will an incorrect indication if FA or FL is selected when no filter is connected.

80-50-20 (Range Switch: not CEL-493/3)

This slide switch sets the gain of the am- plifiers, and hence controls the measure- ment range of the instrument. The three dynamic ranges available are:

80 80-141 dB, 50 50-111 dB, 20 20-81 dB.

When 20 is set, the total dynamic range is limited by the self noise of the pream- plifier, approximately 20 dB(A), or 35 dB(Lin or C).

80-50-20 (Range Switch: CEL-493/3 only)

This slide switch sets the gain of the am- plifiers, and controls the measurement range of the instrument. The three dy- namic ranges available are:

Hi High (50-151 dB), Med Medium (40-141 dB), Lo Low (10-111 dB).

In Lo range, the total dynamic range is limited by the self noise of the preampli- fier, approx. 17 dB(A), or 35 dB(Lin).

FUNCTION

Two push buttons (one button only on CEL-414/3) that are used to select a pa- rameter for display.

The legends around the display bezel shown in Figure 3 identify the different parameters available. In turn, each pa- rameter can be selected for display as shown by an arrow marker on the screen that points to the selected identity. This is accomplished by using the push but- tons (one for each direction) to step from

Page 10 - General CEL Sound Level Meters Handbook

one parameter to the next. Full details are given in Table 1, page 2

during the pause so that the Operator can see when the transient has passed.

Certain combinations of function and time weighting must not be used, and the instrument will not allow them to be selected. For example, when the peak time weighting is selected, ONLY the maximum level can be selected.

PAUSE (not CEL-414/3)

This push button interrupts all calculation procedures and allows unwanted tran- sient signals to be excluded from the measuring period.

The first press prevents all of the calcu- lated values from being updated (includ- ing the duration counter), holds the currently indicated value on the digital dis- play, and causes the pause condition to be indicated. The second press unlatches the pause condition and allows the calcu- lations to proceed again from where they were interrupted.

The analog bar graph continues to show the instantaneous sound pressure level

A, B, and CEL-493/3

31 63 125 250 500 1k 2k 4k 8k 16k

RESET

This push button resets the parameter currently indicated. For example, to reset L

use the FUNCTION buttons to bring

max

the maximum value to the display, then press RESET. The duration and all other calculations continue without interruption.

3.3General Reset

A general reset of all parameters, includ- ing duration, ensures that all registers are synchronised. It is applied only when the setting of one of the following controls is changed.

80-50-20 Range Switch, A-L-FA-FL or

A-C-FA-FL Frequency Weighting &

Filter Switch, P-I-F-S Time Weighting Switch.

Note: The push button RESET operates only

on the parameter being displayed at the time the button is pressed.

Only CEL-266/3 and CEL-328/3

C, D & E Versions

BAT PSE

BAT

OSH

PSE

DOD

1SM

CEL-414/3

920003

BAT PSE

LT3

LT5

SEL EVENT

F A L C

LOW BAT OVERLOAD

DATUM

10 15 20 255

1SM

LEQ SPL MAX DUR

SPL MAX DUR

CEL-414/3

Figure 3: Liquid crystal display showing all parameter identities on all

versions (Note that these legends will appear together only during the start

up sequence)

General CEL Sound Level Meters Handbook - Page 11

3.4Display

Function Indicators

Figure 3 shows the display with the vari- ous parameters that may be indicated as follows.

Bar Graph & Datum Indicator

This gives an analog indication of the instantaneous sound pressure level as soon as the self test sequence has been completed. It continues to show the sound level for as long as the instrument is switched ON and has sufficient battery power.

The indicated level is consistent with the settings of the range, frequency weight- ing, and time weighting switches.

The graph has 26 segments which indi- cate the level in 1 dB steps above the da- tum indicated to the left of the bar. When the level approaches either full scale or minimum deflection, it is auto-ranged in 20 dB steps, and the new datum dis- played. This arrangement allows the bar graph to cover the three full 60 dB dy- namic ranges of the instrument (CEL- 493/3 has 100 dB dynamic range).

Main Display

This four digit display is the instruments primary indicator. It displays the parame- ters measured in dB as hundreds, tens, units, and decimals, and time information as hours and minutes separated by a co- lon (:).

When the instrument is first switched on, the alphanumeric legends CEL and software issue number followed by the instrument type number and version let- ter are displayed for approximately 10 s while the start up sequence is in opera- tion.

These are letters that indicate which filter or weighting network is in use, and a se- ries of arrows that point towards the leg- ends on the bezel. The filter and weighting network indication letters are as follows.

A A-weighted network, L Linear response (A, B

& CEL-493/3),

C C-weighted network

(C, D & E versions),

A, F A-weighted network

PLUS internal or external filter set,

L, F Linear response PLUS

internal or external filter set.

The arrows indicate which parameter is being displayed, normally with only one arrow at a time active as follows.

Equivalent Continuous Level (not CEL-414/3 and only octave band L

with 328/3C),

SPL Sound Pressure Level, L

max

Maximum Level,

DUR Duration over which

measurements taken,

Tm3

Maximum A-weighted Average taken over 3 second periods (A, B & CEL-493/3),

Tm5

Maximum A-weighted Average taken over 5 second periods (A, B & CEL-493/3),

OSHA

Averaged level with a preset threshold and q=5(C&Dversions but not CEL-414/3),

DOD

Averaged level with a preset threshold and

Page 12 - General CEL Sound Level Meters Handbook

q=4(C&Dversions but not CEL-414/3),

SEL Sound Exposure Level

(not CEL-266/3 CEL-328/3 or CEL-414/3),

31-16k Octave bands centered

on indicated frequency.

Certain specialised applications require that the one second maximum (1SM) specified in IEC 651 para 7.8 be adopted for the SPL function. This operating mode may be invoked by adding a link as described in Section 10.2. When the link is included, an automatic indication is given against the 1SM legend instead of SPL, which will not be available.

Overload

The OVERLOAD legend appears be- low the main digital value if any of the overload detectors in pre- and post- weighting, or in the RMS detector are ac- tivated.

When SPL mode is selected, an overload indication is given only during the actual overload period. However, as the dwell

time is approximately two seconds the operator can detect even brief overloads.

In memory modes, the overload indica- tion is a latching function that can be re- leased by performing a general reset of the instrument as described in Section

3.3, or by resetting the relevant parame- ter individually by pressing the RESET but- ton.

Low Battery

When the battery voltage falls below ap- proximately 3.2 V, the LOW BATT mes- sage is displayed. This can be reset only by switching the instrument off, replacing the batteries, and restarting the measure- ment sequence.

3.5Auxiliary Outputs

Two analog output signals are provided via the auxiliary socket in the base of the instrument (or of a CEL filter set when connected). The B and D versions also yield a digital output via this socket as described in Chapter 8. Figure 4 shows the pin connections for the auxil- iary socket.

920004

Batt +

1. Batt - (0V: Instrument ground)

2. Not used

3. Un-filtered AC Out

121314

Figure 4: External view of auxiliary socket

Analog ground

5. AC from Filter (not CEL-266/3 & CEL-328/3)

6. Up function

7. Pause

8. RTS Request to send (B, D & CEL-493/3)

9. TXD Serial data (B, D & CEL-493/3)

10. Remote reset

11. CTS Clear to send (B, D & CEL-493/3)

12. Log. DC out

13. Event in progress (only CEL-493/3)

14.

General CEL Sound Level Meters Handbook - Page 13

+ 39 hidden pages

Casella CEL CEL-414 User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual