Quest Engineering Q300 User manual

Q300
Noise Dosimeter
instructions for
Note: Due to the new ATEX Directive in Europe, all references in this document to "Ex" or
"EEx" for intrinsic safety approvals should be disregarded effective 7/1/03 within the
member countries of the European Union (EU). At this time, this product is not approved
in accordance with the new ATEX Directive and is not sold for use in hazardous
atmospheres or explosive zones by customers within the EU. Outside of the EU, all
references to intrinsic safety continue without change.
56-447
Rev. F
8/97
TABLE OF CONTENTS
Q-300 NOISE DOSIMETER
1. INTRODUCTION TO THE Q-300 ..................................................................... 2
1.1AssemblingtheMeter ....................................................................... 2
1.2 Initial Turn On and Check .................................................................... 3
1.3 Calibration................................................................................ 4
StoringtheCalibrationValue .............................................................. 5
1.4 Battery Installation and Removal ............................................................... 6
2. ABOUT THE METER .............................................................................. 7
2.1 TheDisplay............................................................................... 7
2.2 Keypad Functions .......................................................................... 8
2.3 AcousticEventOptions..................................................................... 11
2.4 Memory Capacity ......................................................................... 12
2.5 RESET - Erasing Stored Data ............................................................... 12
2.6 Overload Detection ........................................................................ 12
2.7 Security................................................................................. 13
3. SETUP MENU ................................................................................... 16
CAL................................................................................. 16
EVENT .............................................................................. 16
RANGE ............................................................................. 17
UL.................................................................................. 17
CL.................................................................................. 17
ER ................................................................................. 17
TL .................................................................................. 17
FAST/SLOW.......................................................................... 17
A/C ................................................................................. 17
AO ................................................................................. 18
RT.................................................................................. 18
BAUD ............................................................................... 19
EOL ................................................................................ 19
FLOW ............................................................................... 19
TIME................................................................................ 20
PDOSE.............................................................................. 20
LH-0 ................................................................................ 20
SE20................................................................................ 21
SE10................................................................................ 21
InXX ................................................................................ 21
PrnX ................................................................................ 22
4. COMMUNICATIONS .............................................................................. 23
4.1 PrintingData............................................................................. 23
4.2 ParallelPrinterInterface .................................................................... 25
4.3 RS-232 Serial Interface .................................................................... 30
4.4 Downloading Data ........................................................................ 31
4.5 ASCII Commands ......................................................................... 33
5. GENERAL SOUND MEASUREMENT PRACTICES ...................................................... 35
5.1 Microphone Positioning ..................................................................... 35
5.2 Accuracy of Readings ...................................................................... 36
5.3 Microphone Windscreen .................................................................... 36
5.4 Background Noise ........................................................................ 37
6. TECHNICAL INFORMATION ....................................................................... 38

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6.1 PrinciplesofOperation ..................................................................... 38
6.2 Microphone Characteristics ................................................................. 38
6.3 WeightingCharacteristics ................................................................... 40
6.4 Tone Burst Response ...................................................................... 41
7. SPECIFICATIONS ................................................................................ 42
8. ACCESSORIES .................................................................................. 43
8.1 Using The Microphone Boom ................................................................ 44
8.2 AC/DC Adapter Installation .................................................................. 45
9.0 TROUBLESHOOTING ........................................................................... 46
APPENDIX ........................................................................................ 47
Definitions .................................................................................. 47
TypicalSetups ............................................................................... 50
AcousticalFormulas .......................................................................... 51
QUEST SERVICE AND WARRANTY POLICY ............................................................ 53
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Figure 1. Q-300 Noise Dosimeter.
1. INTRODUCTION TO THE Q-300
The Quest Model Q-300 noise dosimeter performs a wide variety of acoustical measurements. Both exponential
averaged and time integrated measurements may be made, and the results logged in internal memory. The output of an
unweighted peak detector may also be displayed or logged. Applications include industrial, and general acoustical
measurement and analysis. The Q-300 delivers Type 2 accuracy for general field survey work.

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The Q-300 performs the calculations for three dosimeters operating simultaneously in one instrument. A numerical
readout of measurements for any of the three dosimeters may be displayed. The results of individual sound studies may be
stored in internal memory for future reference. Meter operation is controlled from the keypad. Data may be sent to a parallel or
serial printer, or to a computer by using an appropriate interface cable.
The Q-300 may be clipped on a belt or worn in a shirt pocket. The small microphone is simply clipped to the shirt near
the ear. The meters are housed in a tough diecast aluminum case to protect against physical abuse as well as external
electrical interference, such as that from motors or portable radios.
When used with a Personal Computer, the Quest Noise Manager software package allows the user to analyze and print
out pre-recorded data in detail. When used with a printer, the dosimeter can print detailed reports of noise events. It connects
to a printer by using a Quest "Parallel Printer Interface" or "Serial Computer Interface".
1.1 Assembling the Meter
The microphone must be connected to the dosimeter prior to making any measurements. The connector on the top of
the Q-300 is used for both the microphone and the communications interfaces.
To remove the cable connector from the dosimeter, gently grasp and pull the knurled ring of the cable connector.
To attach the cable connector to the dosimeter:
1.) Grasp the black rubber boot of the cable connector.
2.) Gently press the cable connector against the dosimeter connector while slowly rotating it. When it is properly
lined up, it will stop rotating and slide into the dosimeter's connector.
3.) Insert the cable connector until a "click" is heard.
The cable connector is now attached.
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Figure 2. Q-300 Cable Connection.
1.2 Initial Turn On and Check
Before taking measurements with the Q-300, there is a series of quick checks that should be performed. Turn the unit
on by pressing the ON/OFF key. The display will indicate that a brief warmup is taking place. Check for the LOBAT indicator in
the display. If it indicates a low battery condition, replace the battery.
" on " will appear in the display after warmup. Pressing a FUNCTION key (LEVELS, DOSE, AVG or TIMES) will select
a different display. Press the LEVELS key once, followed by the ªand «keys to review the possible measurements. Pressing
LEVELS again will display data for another dosimeter. Do this for each of the other FUNCTION keys. When you have done
this, press LEVELS and ªor «to set the display to read SPL. The meter is now displaying current Sound Pressure Level,
updating the reading every second.
To perform an Acoustic Study, press RUN/PAUSE. Allow the meter to run for a while and press RUN/PAUSE again to
end the study. The FUNCTION keys may now be used to review the results.

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Figure 3. Calibrating the Q-300 Microphone Sensitivity.
1.3 Calibration
Although the Q-300 will maintain accurate calibration over a long period of time, the calibration should be checked
before each use. To check the calibration of the Q-300, perform the following procedure using a Quest calibrator.
1. Check that the LOBAT indicator is not on, indicating a weak battery.
2. Turn the calibrator ON. If optional, set the frequency to 1 kHz. Note the SPL of the calibrator. Make sure that
the calibrator output is within the measuring range to which the Q-300 is currently set.
3. Insert the microphone fully into the calibrator adapter ring, if required for the size microphone in use.
4. Slowly place the calibrator onto the adapter/microphone.
5. Press LEVELS. Use the ªor «keys to set the Q-300 to read SPL. The display should read the proper level
within 0.5dB.
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NOTE: Most calibrators are affected by changes in altitude and barometric pressure. The rated SPL is set at standard
barometric pressure at sea level (760 mm Hg). Consult your calibrator manual for correction factors.
Storing the Calibration Value
The Q-300 can store the time, date and SPL of a calibration, which will be included in the printout and in downloaded
data for each study. If there is data in memory the unit must be RESET prior to performing a calibration (see page 12). To
perform a calibration, enter the following key sequence:
The CAL annunciator in the display will light, and the number in the display should match the output level of the calibrator. (To
change this value, refer to section 3, Setup Menu.) Connect the microphone to the calibrator as directed in steps 2,3 and 4 of
the previous section. Press RUN to begin the calibration routine. The display will read " CAL " and, after a few seconds, return
to the previous CAL display. The calibration SPL, time and date are now stored. If the calibration fails, " FAIL " will appear in
the display.
NOTE: When RUN is pressed to store the calibration value, A weighted SPL and C weighted SPL are measured and set equal
to each other. The unweighted logging peak detector is also calibrated, setting its output at 3dB above the RMS level
shown in the display. The Q300 must be calibrated at a frequency of 1kHz, as this condition is only true at 1kHz (and
6.2kHz).
As the peak detector is most accurate over the upper portion of the range, the calibration value should be in the
upper 40dB of the range used for calibration. It is important to not disturb the microphone during the calibration
routine, as this may cause a high peak reading and result in bad peak data.
The dosimeter will maintain its accuracy for many months of use. However, it is recommended that the dosimeter be
returned annually to a Quest Authorized service station for a recalibration.
Calibration standards, traceable to the National Institute of Standards and Technology (NIST) are maintained and used by
Quest.

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Figure 4. Battery Installation and Removal.
1.4 Battery Installation and Removal
The battery must be a 9 Volt alkaline type.
(Examples are: NEDA 1604A, IEC 6LF22, or IEC 6LR61)
Replace the battery as follows (see Figure 4):
1.) Remove the battery cover.
2.) Lift the non-terminal end of the battery out of the battery compartment.
3.) Remove the battery.
4.) Notice the battery orientation drawing on the battery cover. Be sure that the battery is properly oriented with
respect to the battery compartment terminals.
5.) Angle the non-terminal end of the battery into the battery compartment, and press it down into the holder.
6.) Install the battery cover.
An internal battery powers the clock and memory. When this battery's voltage gets low, data memory and setup will not be
retained when a 9V battery is not in the dosimeter. The memory only draws current from this battery when a 9V battery is not in
the unit. Contact the factory or a Quest service center for replacement.
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Figure 5 Q-300 Display
2. ABOUT THE METER
2.1 The Display
The LCD display provides the user with the selected measurement and the measurement parameters (A or C weighting,
FAST or SLOW response). Instrument status such as low battery ( LOBAT ), RUN , PAUSE , and Overload ( OL ) is also
displayed.
OL - Overload indicator lights when the sound level exceeds the measurement range of the instrument. While in RUN, this
indicator stays lit until the dosimeter is RESET.
SLOW or FAST - indicates the time response of the measurement being viewed.
C, or A - indicates the frequency weighting of the measurement being viewed.
RUN or PAUSE - indicates the operating status of the instrument.
LOBAT - when not lit, indicates at least 8 hours of battery life remaining.

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2.2 Keypad Functions
Pressing this key turns the meter on. After a warmup period of several seconds, the display will read " on " and the
dosimeter is ready to use. Pressing and holding this key will cause the display to read " OFF5 "and count down for
five seconds until " OFF " is displayed. After this the display will blank and you may release the key. Releasing the
key will turn the meter off. Briefly pressing and releasing this key will toggle the display between " on " and " rES5 "
(Reset), except while in RUN mode when the display will read " run ".
Pressing this key begins a study and lights the RUN indicator. Pressing again ends the study and lights the PAUSE
indicator. If the Q-300 is in the setup menu at either CAL or Prn, pressing this key will begin a calibration or start
printing, respectively.
The ENTER key is used in the setup menu to begin and end a change of a menu item's value or state. After using
the arrow keys to select a menu item, press ENTER to light the SET indicator, allowing the value to be changed with
the arrow keys. After changing, press ENTER to store the value.
The up or down arrows are used to select specific measurements within each of the function displays. For example,
after pressing LEVELS, the arrow keys may be used to select SPL, MAX, MIN or PEAK for display. The arrow keys
are also used to select items in the setup menu, or to set the values for a particular item in the setup menu.
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The LEVELS function key selects the group of items SPL, MAX, MIN or PEAK for display. The ªand «keys are
used to select the specific item. Pressing LEVELS again selects the next dosimeter's (I, II or III) levels for display. If
two or more dosimeters have identical measurement parameters, the higher number dosimeter will not be displayed.
The levels between dosimeters will only differ if the time constant selected for one dosimeter differs from that of the
other two.
SPL - Sound Pressure Level (SPL) will be displayed, with the selected weighting and response characteristics. The
value displayed is the maximum SPL during the previous second.
MAX - The Maximum SPL while in the RUN mode is displayed.
MIN - The Minimum SPL while in the RUN mode is displayed.
PEAK - The Peak Level. The output of the peak detector may be viewed as PEAK or logged. Peak values are the
maximum measured while in RUN mode, except when no RUN time has been accumulated.
The DOSE function key selects the group of items DOSE, PDOSE or EXP for display. The ªand «keys are used to
select the specific item. Pressing DOSE again selects the next dosimeter's (I, II or III) dose group to be displayed. If
two or more dosimeters have identical measurement parameters, the higher number dosimeter will not be displayed.
DOSE - Percentage of allowable sound energy that a person may be exposed to during a work day based on
the criterion level, threshold level and exchange rate selected for the particular dosimeter.
PDOSE - Projected dose, calculated by assuming the average sound level measured during the run time and
extrapolating to the number of hours selected in the setup menu.
EXP - Sound Exposure in Pascal-squared hours. The display will show " ---- " if the exchange rate is not 3dB.

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The AVG function key selects the group of items LAVG, TWA or SEL for display. The ªand «keys are used to
select the specific item. Pressing AVG again selects the next dosimeter's (I, II or III) averages to be displayed. If two
or more dosimeters have identical measurement parameters, the higher number dosimeter will not be displayed.
LAVG - The average level over the study. This measurement takes into account the threshold and exchange rate
entered in the setup menu.
TWA - Time Weighted Average. The average level accumulated during a study, but calculated with an eight hour
integration time.
SEL - The Sound Exposure Level is the constant sound level which, if lasting for one second, would deliver the same
amount of acoustical energy as that accumulated over the entire study.
The TIMES function key selects the group of items RT, PT or UL (Run Time, Pause Time or Upper Limit Time) for
display. The ªand «keys are used to select the specific item, with a minutes:seconds display and an hours display
available for each item. Pressing TIMES again selects the next dosimeter's (I, II or III) times to be displayed, where
UL time may differ. If two or more dosimeters have identical measurement parameters, the higher number dosimeter
will not be displayed.
RT - The total RUN time will be displayed. Time may be displayed in MIN:SEC and xx:HRS. The MIN:SEC display
for a study that lasts over one hour will wrap around to 00:00. The xx:HRS display will count to 99:Hr and then
wrap around to 00:00 but the actual time will be stored in memory.
PT - Total PAUSE time since the last time the unit was reset. Pause time is displayed in the same manner as Run
time.
UL - Upper Limit Time, or the time that the SPL exceeded the Upper Limit Level set for that dosimeter in the setup
menu.
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2.3 Acoustic Event Options
The Q-300 presents measurement data as follows. Each time that the unit is Run and Paused creates an Event, which
is a set of measurements performed over a user defined period of time, referred to as the Run Time. The event begins at the
Start Time and ends at the Stop Time. Each event is stored in internal memory, with its own data referred to as the Event
Summary. The Overall Summary is the result of all measurements taken since the last RESET. The time between events is
recorded as Pause Time. The Current Event is indicated in the Setup Menu display as " Cxxx " where xxx is the event number.
This is the event initiated the last time the Q300 was placed in RUN.
An event may be initiated and ended in the following ways:
Manual Event - Press RUN/PAUSE to begin an event, causing the RUN indicator to light. Press RUN/PAUSE again to end the
event, causing the PAUSE indicator to light.
Manual Timed Event - Press RUN/PAUSE to begin an event. If a
Programmed Run Time duration has been set, the event will run for this time duration and
automatically stop. The event may be interrupted by pressing the PAUSE key.
Auto Timed Event - An Auto ON time and date must be set and
enabled in the setup menu and the Q-300 must be turned OFF. When the internal clock/calendar
reaches this time and date, the meter will turn on, warm up for 10 seconds and begin an event. The
duration of the event will be that of the Programmed Run Time stored via the setup menu. At the end
of the event, the unit will PAUSE and turn itself OFF. The event may be interrupted by depressing the
PAUSE key.
Data viewed on the display is normally the Overall Summary Data. SPL is active only while viewing the current event.
In the EVENT portion of the Setup Menu, it is possible to view the data from the current event as it happens, or from previous
events while still in RUN mode. The RUN/PAUSE key may be used to start and stop events while in the EVENT portion of the
Setup Menu. Each time an event is started, the number of that event will briefly appear in the display. Refer to Section 3, Setup
Menu.

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2.4 Memory Capacity
The number of events possible is limited by the available memory. Data stored during events also fills memory, so the
length of each event is a factor in determining the total number possible, with longer events using more memory. Data is logged
at a set rate of once every minute. Run time without logging data is limited to 145 hours and 38 minutes. The Q300 will
automatically PAUSE and display " AOL " if this limit is reached. Without logging, a maximum of 300 events is possible.
Maximum logging time is 52 hours.
The dosimeter will log the following items:
3 LAVGs, 2 LMAXs, 1 Unweighted PEAK
In addition the total amount of energy accumulated during a study is limited. If this limit is reached the Q300 will
PAUSE and display " AOL ". This is dependent upon the range setting and how high the SPLs are during the study. This can
be determined from the value of SEL at various exchange rates as follows:
Exchange Rate Maximum SEL Without Overflow
3 dB 129 dB + Range
4 dB 172 dB + Range
5 dB 215 dB + Range
6 dB 258 dB + Range
For example, with an exchange rate of 3dB on the 70 - 140 dB range, the maximum SEL without overflow would be 129 dB + 70
dB = 199dB.
2.5 RESET - Erasing Stored Data
To erase the data in memory, the Q-300 must be in the PAUSE mode. Press the MENU/ON/OFF key until " rES5 " is
displayed. Press and hold the ENTER key for five seconds. The display will count down from " rES5 " to " rES1 ". After five
seconds the data memory will be cleared, the display will briefly show " ---- ", and " on " will be displayed.
2.6 Overload Detection
While viewing SPL the overload indicator (OL) is displayed whenever the incoming signal saturates (overloads) the
circuitry. If an OL condition occurs while in the RUN mode, the OL indicator will light and remain on for the duration of the study.
If an overload ocurred, it will be indicated on the hard copy printout. While reviewing an event in memory, the OL
indicator will remain on if an overload occurred during that study.
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2.7 Security
The Security feature allows you to lock out another person's access to certain dosimeter functions. There are two
security modes, which appear in the Setup Menu as SE1x and SE2x.
SE1 enabled (SE11 in the setup menu display) secures the units controls while it is in the RUN mode. To
unlock the dosimeter, a four digit security code must be entered.
SE2 enabled (SE21 in the setup menu display) prevents changing any Setup Menu items (except SE1). To
unlock the setup a four digit security code must be entered.
SE10 or SE20 in the display indicates that either security function is disabled. To enable either security feature, press
the following keys:
" On " shown in display
Down Arrow 2 (or 3) times
to SE10 (or SE20) in display
SET indicator ON
Up or Down Arrow to change
SE10 to SE11 in display
"0---" in display
4x; ª«to set, and ENTER
to enter four digits
Returns to SE11 (or SE21) display

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If SE1 is enabled, after the unit is put into the RUN mode only the arrow and ENTER keys will operate. The display will
read
"0---". Press the arrow keys to set the first digit between 0 and 9. Pressing ENTER moves on to the next digit. After all four
digits have been entered, the unit is no longer secured. If the Q-300 remains in RUN mode, data may be reviewed per normal
operation and the unit resecured by going to the SE10 display in the Setup Menu and pressing ENTER, ª, ENTER. This will
immediately change "SE10" to "SE11" and retain the same security code.
Pausing the dosimeter disables SE1. SE1 must be enabled prior to placing the unit in RUN by going to the SE10
display in the Setup Menu and pressing ENTER, ªand ENTER four more times to keep the same code.
NOTE: SE1 may be disabled with either the SE1 or SE2 code.
Security feature SE1 can be used with Auto-On. An Auto-On time and date may be programmed and SE1 enabled. By
turning the unit off, the Q-300 will turn itself on and RUN at the specified time and date. The unit will be secured during that
RUN period.
If SE2 is enabled the Setup Menus may be reviewed, but not altered, except for enabling or disabling SE1. To disable
SE2, go to the "SE21" display in the Setup Menu and press ENTER. "0---" will be displayed. Enter the four digit code as
instructed above. After successfully entering the last digit the display will return to "SE20" and the setup will no longer be
secured.
Once you have entered the security code, be sure that you don't forget it! If you do, once the unit is placed into the
Secure Mode, you will not be able to disable it unless you know the exact code.
Memorize your codes and, if you wish, record the codes here.
SE1 SECURITY CODE ____ ____ ____ ____
SE2 SECURITY CODE ____ ____ ____ ____
If the code is forgotten, you must do one of the following:
Call Quest at 1-800-245-0779. Quest will provide you with a security code that will allow you to gain access to the Q-
300.
FAX Quest at 1-262-567-4047. Quest will FAX you a security code that will allow you to gain access to the Security
Function.
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Figure 6. Q-300 Flow Diagram

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3. SETUP MENU
The Setup Menu allows the user to customize the operation of the Q-300. Such parameters as printout content, RS-
232 communications options, measurement parameters, security options and automatic operation can be selected. These
parameters may only be changed while in PAUSE mode, and measurement parameters may only be changed after the memory
has been cleared (RESET), but contents of the Setup Menu may be reviewed at any time.
To enter the Setup Menu, press MENU/ON/OFF and either the ªor «key to get to either the CAL or PRINT display.
From either display, the ªor «key will step around the Setup Menu. The menu items are discussed below in the order that
they are encountered using the ªkey. (Refer to figure 6).
CAL (Refer to section 1.3 for procedure)
The calibration display has the CAL indicator turned on and the expected calibration value shown in the display.
If the value in the display is not that of the calibrator being used, this number must be corrected by the following key sequence:
SET indicator on Set desired value SET indicator off
EVENT
The event display will light the EVENT indicator and CXXX will show the current event (the event initiated the last time
the Q300 was placed in RUN), with XXX being the event number. To view the current event, press the following key sequence:
Desired Data Group Desired Measurement Return to Menu
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To select a different event for review, press the following:
SET indicator on Select event number Return to Menu
'C' changes to 'r' SET turns off
Pressing any of the four FUNCTION keys, followed by the arrow keys, will select the desired measurement for display.
Press ENTER to return to the menu. Event data may be reviewed at any time, whether in RUN or PAUSE.
Measurement Parameters
The following group of menu items determines how the measurements are performed for each dosimeter. Each item
may be set differently for each of the three dosimeters, except for RANGE and A/C (frequency weighting) which are set once for
all three dosimeters.
RANGE Set to LO (40 - 110dB) or HI (70 - 140dB)
UL Upper Limit Level; Set level in decibels, 40 to 140
CL Criterion Level; Set level in decibels, 40 to 140
ER Exchange Rate; Set to 3, 4, 5 or 6 decibels
TL Threshold Level; Set level in decibels, 40 - 140
FAST/SLOW Response Time; Set to FAST or SLOW
A/C Frequency Weighting; Set to A or C for all dosimeters
These items are all set in the same manner. When the desired item is displayed, its indicator will be turned on, its value
will be displayed and the dosimeter (I, II or III) will be shown at the bottom of the display.
To select which dosimeter's parameter is displayed, press:
When the desired dosimeter's value is displayed, press:
SET indicator on Set desired value SET indicator off

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Auto Run Options
AO Auto-On Time and Date. Set time and date that the Q-300 will turn on and go into Rmode (after a 10
second warmup). The AO indicator will be
on while viewing or setting this item. Time is
set in 24 hour format, or military time.
RT Run Time Duration. Set length of time in hours:minutes to a maximum of 50 hours and zero minutes
that the Q-300 will run following a RUN
command. The RT indicator will be on while
viewing or setting this item. Setting to 00:00
disables this function.
Auto-On time and date has 3 displays to set: XX:XX (time)
dY:XX (day)
o :XX (month)
Run Time duration has 1 display to set: XX:XX (time).
To enable, disable or set a value press:
SET indicator on Selects value or OFF If OFF, SET off.
If the value was left in the display, pressing enter will blank the minutes. Hours must now be set. Setting one value and
pressing ENTER stores that value and advances to the next value to be set. To set a value press:
Set desired value Store and go to
next value
After setting the last value, the SET indicator will turn off. To review the settings, repeatedly press ENTER without
pressing the arrow keys to advance through the screens.
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Communications Parameters
BAUD Baud rate, or data rate for RS-232 communications. Set
to the same rate as the computer or printer being used. Choices are 300 through 19200 baud or PRLL for
parallel printer operation. These are displayed as follows:
b.300 300 baud
b.600 600 baud
b. 1.2 1200 baud
b. 2.4 2400 baud
b. 4.8 4800 baud
b. 9.6 9600 baud
b.19.2 19200 baud
PrLL Parallel
EOL End of Line character for data transmission. The choices are displayed as follows:
LF Line Feed
LFCr Line Feed + Carriage Return
Cr Carriage Return
CrLF Carriage Return + Line Feed
FLOW Flow control (handshaking) option for data communications. This is important for error free transmission of
large amounts of data. The flow control used is XON / XOFF , or software control and should be set the same
on the computer or printer being used. The options are displayed as follows:
FLo1 Software control (XON / XOFF)
FLo0 No flow control
To set a value press:
SET indicator on Set desired value SET indicator off

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TIME Time of day, date, month and year are set one item at a time. Setting and storing one value
advances to the next until all items have
been stored. The displays are shown as
follows:
XX:XX Time (24 hour military time)
dY:XX Day of the month
o :XX Month
199X Year
To set a value press:
SET indicator on Set desired value Store and go to
next value
After setting the last value, the SET indicator will turn off.
PDOSE Projected dose time. Set to desired number of hours for projected dose calculation, from 1 to 18
hours, displayed as XXHr.
To set a value press:
SET indicator on Set desired value SET indicator off
LH-0 Data Logging History turned on or off. LH-0 indicates
logging disabled, LH-1 indicates logging enabled. Disabling data logging saves memory while in RUN, allowing
more Events.
To set LH-0 or LH-1 press:
SET indicator on Set desired value SET indicator off
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Security Features
SE20 Security mode for locking all setup parameters.
SE10 Security mode to lock unit operation while in RUN mode:
The last digit of either display can be a 1 or a 0. 1 indicates that security is enabled, and 0 indicates that security is
disabled. To enable or disable security, change the 0 to a 1, and enter a four digit code using the arrow and ENTER keys. After
correctly entering the last digit, the display will return to the SE11 or SE21 display. See section 2.7, Security, for details. To
enable either security feature, press the following keys: (example shows SE1)
SET indicator ON
Up or Down Arrow to change
SE10 to SE11 in display
"0---" in display
4x; ª«to set, and ENTER
to enter four digits
Returns to SE11 display
To disable security, press ENTER at the SE11 or SE21 display. Then enter the code which returns to the SE10 or
SE20 display.
InXX Printout Interval for shortening the printout when printing logged data, where XX is the number
of minutes of data combined into one data
point. Data is logged at one minute intervals.
Printout Interval may be set to 1, 5, 10, 15,
30 or 60 minutes. To set this value press:
SET indicator on Set desired value SET indicator off

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PrnX Printout mode display, also used to determine the printout contents. Choices include turning
logged data and statistics on or off and
whether or not to print event summaries.
The choices are displayed as follows:
Logged Data Statistics Events
Prn0 Off Off Off
Prn1 On Off Off
Prn2 Off On Off
Prn3 On On Off
Prn4 Off Off On
Prn5 On Off On
Prn6 Off On On
Prn7 On On On
If Events is turned on, logged data is presented for each event rather than for the overall study. To set this value press:
SET indicator on Set desired value SET indicator off
Press RUN to print.
24
4. COMMUNICATIONS
DEFINITIONS
PARALLEL MODE: Data is passed along multiple wires simultaneously. This is used for sending information to parallel
printers.
SERIAL MODE: All of the data is passed along a single wire in a sequential stream. This mode is used when sending
information to a computer or serial printers. RS-232 is a type of serial mode communication.
BAUD RATE: Baud rate is the speed at which serial communications take place, measured in bits per second. The baud rate
options for the Q-300 are 300, 600, 1200, 2400, 4800, 9600, and 19,200. The higher the baud rate, the faster the
communication. When trying to pass information from an instrument to a computer or serial printer, both must be set for
the same baud rate. (Baud rate settings have no affect on parallel printing.)
COM PORT: Abbreviated name for a serial communications port on a computer (also called RS232 port). Most PCs have
between 1 and 4 serial ports referred to as COM1, COM2, etc... This is where the cable from the meter connects to the
PC. The COM ports generally will take the form of either a 25 pin male (has pins instead of holes) connector or a 9 pin
male connector.
4.1 Printing Data
The Q-300 may be connected to either a parallel or serial (RS-232) printer by using the proper cable and adapter. Data
may also be printed directly to a PC by using a communications package such as Procomm or Windows Terminal. The printout
contains the Overall Summary information and individual Events, if desired, including:
1. All measurement parameters (Range, Weighting, etc.)
2. Data Summary of all measured parameters (LEQ, LMAX, etc.)
3. Start, Stop and Run Times and OL
The information printed will be that selected in the Print portion of the Setup Menu (PRNX - Refer to section 3). See the
end of this section for a sample printout. The printout sections selected in the setup menu are labeled on the sample printout for
clarity.
To connect the Q-300 to a parallel printer, the 056-957 Parallel Interface is required. The 10 pin circular connector
plugs into the jack on the top of the meter. The 36 pin flat cable connector plugs into the printer. The meter must be set for
parallel operation (PRLL option for Baud Rate, located in the Setup Menu - Refer to section 3).
The Q-300 and the printer should all have their power switches turned ON. The meter must be in PAUSE mode. The
display must be set to the PRNX portion of the setup menu. Pressing the RUN/PAUSE key will start the printout.
To interrupt a printout, press RUN/PAUSE again. Disconnect the interface from the printer before turning the Q-300 off.
The Q-300 can be connected to a serial (RS-232) printer or a PC by using the Serial Communications Interface (056-
956). A 25-pin male to male gender changer will be required for connection to the printer. The printer's communications
parameters must match that of the Q-300. Refer to the following section.
Some printers can work either in serial or parallel mode. The printer must be set up for one or the other. Simply
plugging into the correct connector is not sufficient. Refer to the printer's manual. THE Q-300 HAS A SEPARATE CABLE FOR
CONNECTING TO A PARALLEL PRINTER. THE SERIAL CABLE CANNOT BE ADAPTED TO WORK WITH A PARALLEL
PRINTER.

25
Figure 7. Parallel Printer Interface.
4.2 Parallel Printer Interface
The Parallel Printer Interface is compatible with most Centronics compatible printers. The 056-957 contains electronics which
converts data from the Q-300 into parallel information. The electronics are powered from the Q-300. (An older version of this
cable required its own 9 volt battery.)
The Output Format of the Parallel Printer Interface is as follows:
The dosimeter sets up 8 data lines.
If the Busy line is not high, the dosimeter sends a Strobe pulse.
If the Busy line is high, the dosimeter will wait.
26
General Printer Configuration (Parallel and Serial)
Each line of print must end with the following two EOL (End of Line) characters:
LF (Line Feed)
CR (Carriage Return)
The EOL (End of Line) characters can be:
Both set within the printer configuration.
Both set within the dosimeter configuration.
One setting within the printer configuration and one setting within the dosimeter configuration.
The dosimeter can be programmed to one of the following four settings:
LF/Cr (Line Feed followed by Carriage Return)
Cr/LF (Carriage Return followed by Line Feed)
LF (Line Feed only)
Cr (Carriage Return only)
To try a few lines of print, depress RUN/PAUSE twice. If the printer does not work properly, change the
dosimeter setting until it works.
If the system still does not print properly, you may need to change the printer setup. Refer to the printer
manual to aid in the printer configuration. After changing the printer setup, it is usually necessary to reset the
printer as follows:
Turn the printer off for a few seconds and then back on. Most printers only read these switches during
the turn on.
Parallel Printer Configuration
The printer must be Centronics compatible.
The dosimeter baud rate does not matter.
If the printer operates in either the Serial or Parallel mode, be sure that it is set to Parallel.
Serial Printer Configuration
Refer to section 4.3, RS-232 Serial Interface.

27
SAMPLE PRINTOUT
(HEADER and OVERALL SUMMARY)
QUEST TECHNOLOGIES
Q300 NOISE LOGGING DOSIMETER
Unit Version Number: 1.00 Serial Number: QC50100005
Name _____________________________________________________________________
Work Area ________________________________________________________________
Comments _________________________________________________________________
__________________________________________________________________________
Meter Calibration: 114.0dB 10-MAR-95 @ 13:06:18
Calibrator:
Serial Number ___________________ Calibration Date ___________________
Measuring Parameters: ( Range 70-140 Weighting A )
DOSIMETER 1 DOSIMETER 2 DOSIMETER 3
Time Constant SLOW Time Constant SLOW Time Constant SLOW
Exchange Rate 5dB Exchange Rate 5dB Exchange Rate 3dB
Threshold 80dB Threshold 90dB Threshold 80dB
Criterion 90dB Criterion 90dB Criterion 85dB
Upper Limit 115dB Upper Limit 115dB Upper Limit 115dB
Session Started Session Stopped Run Time
18-MAR-95 @ 13:32:45 18-MAR-95 @ 14:53:21 1:21:36 O.L. Occurred
DOSIMETER 1
Peak Level 124.5dB 18-MAR-95 @ 13:32:45
Slow Max Level 114.4dB 18-MAR-95 @ 13:32:45 UL TIME 0:00:00
Slow Min Level 99.8dB 18-MAR-95 @ 13:33:18
LAVG 108.5dB TWA 79.6dB DOSE 1.6% DOSE(12) 1500%
SEL(5) 126.2dB Pa2Hr 0.2
DOSIMETER 2
Peak Level 124.5dB 18-MAR-95 @ 13:32:45
Slow Max Level 114.4dB 18-MAR-95 @ 13:32:45 UL TIME 0:00:00
Slow Min Level 99.8dB 18-MAR-95 @ 13:33:18
LAVG 109.5dB TWA 80.6dB DOSE 2.6% DOSE(12) 1556%
SEL(5) 126.2dB Pa2Hr 0.2
DOSIMETER 3
Peak Level 124.5dB 18-MAR-95 @ 13:32:45
Slow Max Level 114.4dB 18-MAR-95 @ 13:32:45 UL TIME 0:00:08
Slow Min Level 99.8dB 18-MAR-95 @ 13:33:18
LAVG 110.5dB TWA 81.6dB DOSE 4.2% DOSE(12) 3076%
SEL(3) 118.2dB Pa2Hr 0.2
Page 1
28
(EVENT SUMMARY)
EVENT (1)
Notes ____________________________________________________________________
__________________________________________________________________________
Session Started Session Stopped Run Time
18-MAR-95 @ 13:32:45 18-MAR-95 @ 14:53:21 1:21:36
DOSIMETER 1
Peak Level 124.5dB 18-MAR-95 @ 13:32:45
Slow Max Level 114.4dB 18-MAR-95 @ 13:32:45 UL TIME 0:00:00
Slow Min Level 99.8dB 18-MAR-95 @ 13:33:18
LAVG 108.5dB TWA 79.6dB DOSE 1.6% DOSE(12) 1500%
SEL(5) 126.2dB Pa2Hr 0.2
DOSIMETER 2
Peak Level 124.5dB 18-MAR-95 @ 13:32:45
Slow Max Level 114.4dB 18-MAR-95 @ 13:32:45 UL TIME 0:00:00
Slow Min Level 99.8dB 18-MAR-95 @ 13:33:18
LAVG 109.5dB TWA 80.6dB DOSE 2.6% DOSE(12) 1556%
SEL(5) 126.2dB Pa2Hr 0.2
DOSIMETER 3
Peak Level 124.5dB 18-MAR-95 @ 13:32:45
Slow Max Level 114.4dB 18-MAR-95 @ 13:32:45 UL TIME 0:00:00
Slow Min Level 99.8dB 18-MAR-95 @ 13:33:18
LAVG 110.5dB TWA 81.6dB DOSE 4.2% DOSE(12) 3076%
SEL(3) 118.2dB Pa2Hr 0.2
(LOGGED DATA)
EVENT (1) LOGGING
LAVG 1 (5 MINUTE TIME HISTORY)
13:37 112 114 117 114 113dB +----+----+----+----+-- 115dB
14:02 106 104 110 105 109dB +----+----+----+--- 108dB
14:27 124 116 119 106 117dB +----+----+----+----+---- 119dB
14:52 106# # # # #dB +----+- 83dB#
LAVG 2 (5 MINUTE TIME HISTORY)
13:37 112 114 117 114 113dB +----+----+----+----+-- 115dB
14:02 106 104 110 105 109dB +----+----+----+--- 108dB
14:27 124 116 119 106 117dB +----+----+----+----+---- 119dB
14:52 106# # # # #dB +----+- 83dB#
LAVG 3 (5 MINUTE TIME HISTORY)
13:37 112 114 117 114 113dB +----+----+----+----+-- 115dB
14:02 106 104 110 105 109dB +----+----+----+--- 108dB
14:27 124 116 119 106 117dB +----+----+----+----+---- 119dB
14:52 106# # # # #dB +----+- 83dB#

29
SLOW MAX (5 MINUTE TIME HISTORY)
13:37 114 114 109 114 113dB +====+====+==== 114dB
14:02 106 104 110 105 109dB +====+==== 109dB
14:27 114 116 119 106 117dB +====+====+==== 114dB
14:52 106# # # # #dB +====+= 106dB#
FAST MAX (5 MINUTE TIME HISTORY)
13:37 118 114 117 114 113dB +====+====+====+=== 118dB
14:02 106 104 110 105 109dB +====+==== 109dB
14:27 114 116 119 106 117dB +====+====+==== 114dB
14:52 106# # # # #dB +====+= 106dB#
PEAK (5 MINUTE TIME HISTORY)
13:37 124 114 117 114 113dB +====+====+====+====+==== 124dB
14:02 106 104 110 105 109dB +====+====+==== 109dB
14:27 120 116 119 106 117dB +====+====+====+====+ 120dB
14:52 106# # # # #dB +====+= 106dB#
Page 2
(STATISTICS)
% TIME STATISTICAL DISTRIBUTION
Weighting A Time Constant Slow
Total Samples 156672
Total Run 1:21:36
0 20 40 60 80 100
dB Samples % Time +----+----+----+----+----+----+----+----+----+----+
99 212 0.13% *
100 2012 1.28% *
101 4025 2.57% **
102 25009 15.96% ********
103 27113 17.30% *********
104 24666 15.74% ********
105 8602 5.49% ***
106 2804 1.78% *
107 50811 32.43% *****************
108 6298 4.01% ***
109 3111 1.98% *
110 1087 0.69% *
111 460 0.29% *
112 201 0.12% *
113 166 0.10% *
114 37 0.02% *
dB Samples % Time +----+----+----+----+----+----+----+----+----+----+
0 20 40 60 80 100
When printing time history, the last row of data may be incomplete due to the study ending prior to the last interval
printed. This will be indicated by #. In the example printout, the data was logged at 1 minute intervals, but combined into five
minute intervals for the printout. Each row contains five five minute intervals and the average for the entire 25 minutes. The #
in the last row indicates that the first value was combined from less than five logging intervals, and the average for the row , for
25 minutes, was from less than 25 minutes of complete data.
30
Figure 8. Serial Communications Interface.
4.3 RS-232 Serial Interface
The jack on the top of the Q-300 provides direct connection to a computer's COM port with the serial communications
cable (#056-707) provided. To connect to a serial printer or similar device, a 25-pin male to male gender changer is required.
Serial Communications Interface
The Serial Communications Interface is compatible with most Computer COM Ports and most Serial Printers. It converts data
from the Q-300 into RS-232 compatible information.
The communications parameters for the ASCII data byte are the following:
1 start bit
8 data bits
1 stop bit
No parity (disabled)

31
Baud rate and flow control must be set the same for both the Q-300 and the RS-232 device connected to it (BAUD and FLOW
as set in the Setup Menu). Refer to section 3 COMM Setup Menu.
There are three common problems when using COM ports.
1. The ports are often not labelled, making it difficult to determine which port is connected.
2. The printer output port on the computer is a 25 pin female. Adding an extra 'converter' cable to the
serial cable and plugging it into the printer port will not work.
3. Often some other device, such as a mouse, is plugged into the COM port. If that is the only COM port
then the mouse must be disconnected and the PC possibly must be reconfigured.
4.4 Downloading Data
Data stored in the Q-300 may be downloaded to a personal computer. Several methods are available.
The Quest Noise Manager software package provides an easy method of receiving data from the Q-300. Data
presentation options include tabular or graphical form. In addition, remote control and access to all operating parameters is
possible via an easy to use menu driven interface.
By using the RS-232 port on a PC and a communications package such as Procomm or Windows Terminal, the printout
from the meter may be received and stored as a file. The Q-300 must be set for serial operation and the settings (baud rate,
etc.) must match that of the PC. The serial communications cable must be connected between the meter and the PC. Pressing
the PRINT key will cause the meter to print to the PC.
32
Downloading Using WindowsTM TERMINAL
Microsoft®WindowsTM has a communications program under the ACCESSORIES icon called TERMINAL. Instructions
on how to use TERMINAL are located in the Windows'TM manuals.
Open TERMINAL. For TERMINAL, the communications settings are found by first selecting SETTINGS, then
COMMUNICATIONS. Select the desired COM (serial) port and the baud rate. The baud rate must match the BAUD selected in
the Q-300's Setup Menu. TERMINAL also needs the following information in its setup:
data bits = 8 stop bits = 1
parity = none flow control = must match the Q-300
To save the downloaded data to a file, use the following procedure. After the communication settings are made:
1. Select TRANSFERS, then select RECEIVE TEXT FILE.
2. Enter a file name with the ending .TXT .
3. Press MENU and «on the Q-300. Prnx will appear in the Q-300's display. Press RUN/PAUSE to print.
4. When complete, Prnx will disappear from the Q-300's display. Select TRANSFERS, then STOP in the
TERMINAL program.
5. Exit TERMINAL.
6. The file has been saved and can be opened with a word processor or editor such as Windows'TM NOTEPAD.
(Remember which directory the file was saved in. The default for Terminal is the WINDOWS directory.)

33
4.5 ASCII Commands - The following is a list of commands used to setup the Q-300 via RS-232. The display will automatically
switch to the " on " display when commands are being received.
Setup Commands - Duplicates the setup menu functions. Omitting parameters w, x, y, or z will return the
current setting. The dosimeter number should be
included. Refer to Section 3.3 for details on setting
the following parameters.
AOTx enables or disables Auto On feature. x = Y for enabled,
x = N for disabled.
AOTSvv:ww:xx:yy:zz sets the auto on time. vv = month, ww = day, xx = hour (0 to 24), yy = minutes, zz =
seconds.
BAUDxxxxx sets the baud rate for serial communications.
xxxxx = 300, 600, 1200, 2400, 4800, 9600 or 19200.
CALxxxx sets the calibration SPL, where xxxx = the SPL of
the calibrator (no decimal point, 1143 = 114.3dB). Set
range is 900 to 1250.
PRLL sets communications for a parallel printer.
FLOWx enables or disables flow control for RS-232.
x = Y for ON, x = N for OFF or no flow control
EOLxx sets the end of line character for serial
communications, either carriage return, line feed or a combination of the two. xx = C, CL, L or LC
where
C = carriage return and L = line feed.
ERxy sets the exchange rate. x = 1, 2 or 3 for dosimeter 1,
2 or 3. y = 3, 4, 5 or 6.
INxx sets the printout interval, where xx = 1, 5, 10, 15, 30
or 60 (Minutes)
LHx enables or disables data logging. x = Y for enabled,
x = N for logging disabled.
PRNx sets the items to print. x = 0 through 7
Logged Data Statistics Events
Prn0 Off Off Off
Prn1 On Off Off
Prn2 Off On Off
Prn3 On On Off
Prn4 Off Off On
Prn5 On Off On
Prn6 Off On On
Prn7 On On On
34
PRTx enables or disables the programmed run duration.
x = Y for enabled, x = N for disabled.
PRTDxx:yy sets the programmed run duration where xx =
hours, yy = minutes.
THxyyy sets the integration threshold. x = 1, 2 or 3 for
dosimeter 1, 2 or 3. yyy = 40 to 140, 0 for OFF
TIMExx:yy sets the clock where xx = hours (0 to 24),
yy = minutes
DATExx/yy/zzzz sets the calendar. xx = month, yy = day,
zzzz = year.
CLxyyy sets the criterion level. x = 1, 2 or 3 for dosimeter
1, 2 or 3. yyy = 40 - 140.
RESPxy sets the response time. x = 1, 2 or 3 for dosimeter 1,
2 or 3. y = F or S.
ULxyyy sets the upper limit level. x = 1, 2 or 3 for
dosimeter 1, 2 or 3. yyy = 40 - 140.
WGTx sets the weighting. x = A or C.
RNGx sets the measuring range. x = H for high (70-140dB), or
x = L for low (40-110dB) range
PTDx sets the Projected Dose Time. x = 1 - 18 (hours)
Security Commands - Note: Security function SE2 does not affect the ability to change parameters via RS-232.
SEyz enables or disables the SEy security feature, where y = 1 or 2. z = Y for security ON, z = N for
security OFF.
SEyzzzz sets the security code. y = 1 for SE1 or 2 for SE2.
zzzz = equals the security code.
Function Commands
OFF turns the unit off. Caution: unit cannot be turned on via remote control. Auto On must be enabled with a valid
date and time for the unit to turn on automatically.
PRINT will return the printout.
RESET clears the memory.
FACTORY clears the data memory and resets all setup menu
parameters to factory settings.

35
Figure 9. Placement of Microphone When Used as a Personal Monitor.
5. GENERAL SOUND MEASUREMENT PRACTICES
Before taking measurements with the Q-300 there is a series of quick checks that should be performed. After switching
the unit ON, check for the LOBAT indicator in the display. Replace the battery if needed.
Although the Q-300 will maintain accurate calibration over a long period of time, the calibration should be checked and
the calibration routine run, if necessary, before each use.
When performing integrating measurements, press the RUN/PAUSE key, making sure " RUN " is indicated in the
display. It is always a good idea to document all measurement conditions and meter settings for possible future needs. If the
data is printed, the settings will all appear on the printout.
5.1 Microphone Positioning
The dosimeter measures sound most accurately without the presence of sound reflecting or absorbing objects. Any
near-by object or surface (including the operator) will act as a reflector or absorber of sound. To minimize these errors, use the
dosimeter as follows:
When taking Personal Noise Dosimeter Measurements:
Connect the Microphone to the shirt at the shoulder. (See Figure 9) Keep it high on the shoulder and away
from the neck if possible.
If the noise seems to be coming from one location, place the microphone near the ear facing that location.
Install a Windscreen on the microphone. It holds the microphone in an upright position and keeps the microphone from
brushing against clothing, which can produce high noise levels into the microphone.
When taking Stand-Alone measurements:
Mount the dosimeter to the tripod mount (located on the belt clip) with the microphone upward forming
approximately a 70 degree angle with the noise source.
36
5.2 Accuracy of Readings
For maximum accuracy, it is important to use the dosimeter correctly and to understand its limitations. It will correctly
integrate all sound levels within the range of the instrument.
A few items related to accuracy are as follows:
There is a tendency to overestimate the accuracy of digital readings. The values (such as Leq) are computed to a
precision of 0.1 dB. However, the absolute accuracy of the reading is not 0.1 dB, but is accurate to the stated overall accuracy
of the instrument.
The 0.1 dB resolution is useful in determining the minimum sample time required to get an accurate short term
measurement.
If, for example, the Leq is increasing 0.3 dB every second, then a longer sample time is required.
If the Leq is remaining stable from second to second within a few tenths of a dB, then the sample time is long
enough.
5.3 Microphone Windscreen
It is recommended that a windscreen be used at all times. The Q-300 uses the WS-5 Windscreen. Using a windscreen will
improve the accuracy by minimizing the effect of the following:
Wind blowing across the microphone can produce higher than normal sound level readings. The windscreen blocks
wind from direct contact with the microphone, producing less unwanted noise.
Clothing brushing against the microphone can produce higher than normal sound level readings. The windscreen helps
position the microphone so that clothing cannot brush against it as easily.
Dirt entering the microphone, in time, can damage the microphone, possibly changing the microphone's frequency
characteristics. The windscreen catches and collects this dirt before it enters the microphone.
Simply insert the microphone into the windscreen and gently pull it over the Velcro strip.
5.4 Background Noise
Background noise can cause considerable error in measurement when its level is close to that of the noise source of
interest. When it is not possible to eliminate or reduce the background noise, use the curve shown in Figure 10 to correct for
the effect of the background noise on the measurement.

37
Figure 10. Block Diagram of the Q-300
The effect of the "Noise Floor" on low level readings can cause inaccurate data. In a "Perfectly Quiet" room, the
electrical noise produced by the microphone is approximately 35 dB on A weighting or 45 dB on C weighting.
Measurements must always be at least 5 dB above the "Noise Floor". to be valid. Therefore, the lowest possible
measurements of the dosimeter are approximately:
40 dB on "A" Weighting (Lowest Valid Reading).
50 dB on "C" Weighting (Lowest Valid Reading).
6. TECHNICAL INFORMATION
6.1 Principles of Operation
The Q-300 dosimeter uses low power state-of-the-art circuitry. The dosimeter is very stable and reliable over a wide range of
environmental conditions.
The low power circuitry gives the dosimeter a long battery life. When the 9 volt battery is changed, all dosimeter information is
retained due to an internal lithium battery. The lithium battery lasts for many years before needing replacement. (See
SPECIFICATIONS)
A rubber Key Pad is used for all data entry and settings. Menus appear on the display and the keys are used to enter changes.
A block diagram of the Q-300 is shown in Figure 11.
38
Figure 11. Q-300 Microphone Frequency Response.
6.2 Microphone Characteristics
The Q-300 Noise Dosimeter uses an 8 mm omnidirectional ceramic microphone. It is buffered by a high impedance FET input
stage. (See Figure 12.)