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Содержание 2607

Страница 1: ...vels with averaging times from 0 1 to 300 sec and positive peak negative peak or maximum peak levels with a rise time of 20 p sec With a B K microphone and preamplifier it conforms to precision sound...

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Страница 3: ...MEASURING AMPLIFIER TYPE 2607 November 1970...

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Страница 5: ...Measurements 17 Using Accelerometer Calibrator 4291 17 Using Internal Reference Voltage 18 3 5 Measurement of Vibration 19 3 6 Calibration for Voltage Measurements 19 3 7 Voltage Measurements 20 Input...

Страница 6: ...all Characteristics 41 Dynamic Range 41 Frequency and Phase Characteristics 44 5 FREQUENCY ANALYSIS AND RECORDING 47 5 1 General 47 5 2 RMS Measurements and Statistical Accuracy 47 5 3 Practical Notes...

Страница 7: ...ich the range setting is automatic ally indicated facilitates the direct calibration of the 2607 for sound pressure level acceleration and voltage measurements Amongst other features are mains or batt...

Страница 8: ...on Attenuator METER SCALE Fig 2 1 Front Panel of 2607 Tilt the glass panel forward to slide the scale out Immediately below the meter are two rows of push buttons Their funct ions are as follows POWER...

Страница 9: ...of audio frequency range For selection of one of the weighting net works D A B or C When none are selected the amplifier has a linear frequency response from 2 Hz to 200 kHz The remaining controls an...

Страница 10: ...he gain of the input amplifier to com pensate for different transducer sensitivities They work independently of each other and each has a range of approx 14 dB Stepped attenuator 10 dB steps for atten...

Страница 11: ...s according to Dl N and IEC standards Discharges the RMS and Peak Rectifier Circuits of the 2607 to reset the meter for RMS Peak and Impulse measurements Output socket for AC or DC recording With AC t...

Страница 12: ...on voltage Socket for measurement of polarization volt age with an external DC voltmeter having a rating of at least 20 kOJVolt A ground socket is situated to the right of this socket NOTE Only signal...

Страница 13: ...lection of correct mains supply voltage To turn the selector unscrew central AC fuse with small coin or wide blade screwdriver For connection of AC mains supply with pro vision for connecting one of t...

Страница 14: ...o 06 Fig 2 4 BATTERY socket These sockets are for connection to an external filter and fit the standard B K coaxial plugs The input impedance of the External Filter Output is 146 kD 1 00 pF while the...

Страница 15: ...sary It should be noted that with DC operation the scale lamps are not lit saving 2 Watts The range indicator lights still operate and show when the instrument is on The above adjustments are part of...

Страница 16: ...1 Carry out the preliminary adjustments if necessary 2 Fit the meter scale appropriate to the sensitivity of the microphone being used See Table 3 1 3 Fit the microphone and associated preamplifier 4...

Страница 17: ...spectively If it does not adjust the SENS potentiometer beside the input socket that is being used until the correct deflection is obtained 3 2 2 Using Internal Reference Voltage 1 Carry out the preli...

Страница 18: ...t 1 m away from the body or set it up on a tripod or other support that will not interfere with the sound field 3 Select the weighting network to be used 4 Keeping the OUTPUT SECTION ATTENUATOR in the...

Страница 19: ...ccelerometer and associated preamplifier 4 Set knobs GAIN CONTROL Cal OUTPUT SECTION ATTENUATOR x 1 METER FUNCTION Max Peak AVERAGING TIME Fast REMOTE MANUAL Manual 5 Set the INPUT SECTION ATTENUATOR...

Страница 20: ...of the accelerometer being used 3 Fit the accelerometer and appropriate preamplifier 4 Switch on the instruments and allow 30 sec for the 2607 to warm up before proceeding with calibration 5 From the...

Страница 21: ...he vibration environment and any other unrequired influences 4 Keeping the OUTPUT SECTION ATTENUATOR in the x 1 posit ion as far as possible adjust the INPUT SECTION ATTENUATOR to obtain a suitable de...

Страница 22: ...eflection is insufficient even when the INPUT ATTENUATOR is in its 3 mV range then adjust the OUTPUT ATTENUATOR 3 7 2 Input Voltages up to 700 Volts Peak Use can be made of the GAIN CONTROL to accommo...

Страница 23: ...ing the open circuit sensitivity of the microphone The open circuit sensitivity of a microphone at a given single frequency is the voltage which appears at its terminals when the microphone is working...

Страница 24: ...he 2617 preamplifier and connect to the Preamp input of the 2607 2 Apply the Sound Level Calibrator 4230 to the microphone and note the voltage produced from the cathode follower Vc F 3 Remove the sou...

Страница 25: ...libration voltage take a lead from the Direct input socket to the INSERT VOLT CAL socket to which the generator is connected The calibrat ion voltage can be read directly from the meter and the microp...

Страница 26: ...g 3 5 averaging times from 0 1 to 300 sec may be selected Switch for remote meter reset time constants Averaging Time Socket Ext view 0 1 sec 0 3 sec 1 0 3 0 sec 10 sec 30 sec 100 StlC 300 sec Switch...

Страница 27: ...t can be used to provide a remote meter reset facility This is particularly useful when measuring impulsive signals with a long decay time constant selected and for Impulse Hold measurements The rear...

Страница 28: ...utput amplifier of the 1612 This could normally be provided by the remote control connection to the Level Recorder connecting pin 6 of the 2305 s REMOTE CONTROL to pin 5 of the 1612 s REMOTE CONTROL i...

Страница 29: ...4 1 Block diagram of 2607 4 1 INPUT CIRCUIT AND INPUT AMPLIFIER elnput External Filters eeOutput DC Output 17 4 77 There are two alternative input sockets One is the standard 8 K coaxial socket The o...

Страница 30: ...o two sections with1 an atten uator section in between Both sections are similar but on the first there is a balanced input stage to regulate the sensitivity of the two input sockets The first amplifi...

Страница 31: ...e basic shape and tolerances set by the proposed amendment to the IEC Recommendation 179 for precision sound level meters see Table 4 1 It should be noted that the tolerances s t by the IEC amend ment...

Страница 32: ...1 0 1 0 2 0 1 5 1 5 1600 1 0 0 1 1 0 1 0 5 5 1 5 1 5 2000 1 2 0 1 0 2 1 0 1 0 8 0 1 5 1 5 2500 1 3 0 2 0 3 1 0 1 0 10 1 5 1 5 3150 1 2 0 4 0 5 1 0 1 0 11 1 5 1 5 4000 1 0 0 7 0 8 1 0 1 0 11 1 5 1 5 5...

Страница 33: ...e Output Section Amplifier is split up into a number of stages The first stage includes a field effect transistor at its input to reduce the loading on the filters and to give the best overall signal...

Страница 34: ...te the amplified signal by up to 50 dB in accurate 10 dB steps The remaining amplifier stage of the Output Section splits the signal into two components one in phase with the input signal which is amp...

Страница 35: ...indication via the AVERAGING TIME socket section 3 9 4 7 RMS DETECTION AND AVERAGING Circuits for extracting the RMS value of an alternating signal consists in principle of squaring averaging and root...

Страница 36: ...instantaneous signal level is increased further the rectifier current will rise linearly to charge the averaging capacitor via the resistor R1 and to raise the voltage levels at the junctions of the...

Страница 37: ...t this corresponds to a root extract ion process as the charging current is now proportional to the input voltage Consequently the RMS circuit s output will be linear even though the RMS Rectifier s i...

Страница 38: ...it These are operated automatic ally via a Switching Circuit which is triggered when the signal level is higher than that corresponding to 20 dB below FSD Full Scale Deflection When triggered the atte...

Страница 39: ...that of the input signal and with a rise time of approximately 20 p sec The pulse is then rectified by a peak diode detector and passed to an integrating network where its max value is stored in a cap...

Страница 40: ...he largest peak is rectified and stored The Peak Rectifier may also be utilized for the measurement of impulsive sounds to DIN standards for which Impulse and Impulse Hold measurement positions are pr...

Страница 41: ...7 2 2 8 8 2 Table 4 3 Requirements of DIN 45633 for response of an Impulse Sound Level Meter to repeated impulses For Impulse measurements the 2607 meets the measurement characteristics given Althoug...

Страница 42: ...nt accuracy of 0 5 dB at 25 C A schematic diagram of the converter is shown in Fig 4 9 Input from either RMS or Peak Rectifier Fig 4 9 Schematic of Lin Log Converter Here the linear DC output signal f...

Страница 43: ...for the microphone and the high voltage for the output amplifiers are supplied from 150 V and 300 V transformer tappings which are subsequently regulated A 12 V stabilized power supply is used for the...

Страница 44: ...nuator settings c z w I z 0 i u w en 1 a z 3mV 10 mV 30mV 0 1 v 0 3 v 1 v 3 v 10 v 30 v 100 v 300 v X 0 003 120 110 100 90 80 70 60 50 40 30 20 OUTPUT SECTION ATTENUATOR X 0 01 X 0 03 X 0 1 x0 3 X 1 1...

Страница 45: ...7v 3 6v Sv 4 26v 1 I I I I I I I I I I I I I I I I I 20dB 10dB OdB 10d8 20d8 30dB I I I I I I 1 I OdB l lOdB 20dB I I I I I I 1 I I I I I I I Zero Scale log Full Scale log Full Scale lin Fig 4 10 Dyn...

Страница 46: ...f the system since when measuring signals con taining many significant harmonics some harmonic components may be attenuated giving an incorrect measurement The phase response of the 2607 is shown in F...

Страница 47: ...w ever if the signal is complex and does contain phase related frequency components as in the case of a square wave signal the measurement accuracy will be affected Measurements made on a symmetrical...

Страница 48: ...a b c d e 17oit93 Fig 4 13 Typical output waveforms from 2607 for symmetrical square wave input with repitition frequencies of a 5Hz b 50 Hz c 1kHz d 10kHz e 100kHz 46...

Страница 49: ...D STATISTICAL ACCURACY In any true RMS measurement system the accuracy of the data obtained is not only dependent on the system accuracy but also on the inaccuracies arising from the effect of statist...

Страница 50: ...equation 5 2 and its application refer to Measurement and Analysis of Random Data by J S Bendat and A G Piersol John Wiley 1967 and to statistical textbooks on the chi square distribution Equation 5...

Страница 51: ...tween Averaging Time and the Writing Speed of the Level Recorder is given in Table 5 1 The averaging times given in Table 5 1 are approximate values and are valid for measurement bandwidths greater th...

Страница 52: ...Filter Scanning Speed When a 1614 or 1615 is used in the measurement system the filter scanning speed will be another factor influencing the measurement accuracy This is a direct function of the Level...

Страница 53: ...me setting of the 2607 as well as the dynamic range of the measurements and the type of analysis are given in Table 5 2 For AC recording a single relationship serves and this is given by PAPER SPEED X...

Страница 54: ...Figs 5 1 and 5 2 Pilot Lamp A z Paper Drive Mechanical Output Drive Shaft I Preprinted recording paper Cover locking Screw Drive Shaft II Ref Voltage Pushbutton Cover Locking Screw out In Control for...

Страница 55: ...fected in accuracy by this control on the Level Recorder LOWER LIMITING FREQUENCY selection should there fore be on the basis of stable operation of the writing system 4 The INPUT POTENTIOMETER and IN...

Страница 56: ...on on the Microphone Open Circuit Sensitivity scale and note the value of the corresponding deflection on the dB scale The pen should be set to this dB value on the paper e g If the microphone has an...

Страница 57: ...SINGLE CHART CONT RECORD push button and release after the chart has travelled 20 mm or more The paper should continue to move but will stop automatically after one chart length or less 6 Once the pap...

Страница 58: ...ECTION ATTENUATORS AVERAGING TIME Adjust to obtain a suitable recorder pen deflection keeping the OUTPUT SECTION ATTENUATOR in the X 1 position if possible As required see Table 5 1 11 Note the new Me...

Страница 59: ...on 5 4 1 3 RECTIFIER RESPONSE of the 2305 should be set to RMS and LOWER UMITING FREQUENCY to a value below the lowest frequency required from the analysis 4 The 2607 output switch must be set to AC 1...

Страница 60: ...and analysis of sound and vibration the use of the 7001 Tape Recorder will be found very con venient especially when employed with the 2607 Measuring Amplifier The 7001 has four tape speeds ranging fr...

Страница 61: ...o noise ratio than the attenuation provided by an increase in 2607 range setting Fig 5 7 Attenuation of 2607 output for tape recording For an analysis of a tape recording the information to be process...

Страница 62: ...in selecting an AVERAGING TIME longer than the time for a complete loop cycle One of the most useful applications of the 2607 with such a tape loop analysis is that of impulse analysis where the Peak...

Страница 63: ...ase KA 0026 makes the B model or alternative ly with the addition of a 19 inch metal rack mounting frame KS 0014 makes the C model Both the mahogany case and the metal rack mount ing frame are availab...

Страница 64: ...Sound level Calibrator El 4230 Normal Protecting Grid 1 Mic Ill 4117 Normal Protecting Grid 1 4 Mic Nose Cone 4135 UA0053 4136 1 8 Mic 1 8 1 2 Adaptor q j 4138 UA 0036 1 5 1 daptor UA 0160 Fig 6 1 17...

Страница 65: ...r 2624 b 1 Vibration Pick up I j E Preamplifier JP 0028 I I 2625 __ 101 Power Supply To Mains 28V 11 2805 Power Supply ZR 0024 r I 1606 0 Integrator 1 1 2 Adoptor Preamplifier L__t l ZR 0020 DB 0375 2...

Страница 66: ...tween two instruments in the 5 Hz to 20kHz range 120 dB 1 Mrl 50 pF In accordance with B K Microphone Pre amplifiers 700 V peak 310 V peak for signal frequencies 60Hz 165 V peak for signal frequencies...

Страница 67: ...s according to IEC 179 1965 60 dB 0 3 dB from 10 dB above to 40 dB below FSD at 25 C 0 5 dB from 40 to 50 dB below FSD at 25 C o o3 dB C Impulse according to DIN 45633 part 2 March 1967 plus Impulse H...

Страница 68: ...mps light for overload pulse longer than 0 2 msec and remain lit for 0 5 sec minimum REFERENCE VOLTAGE Signal Stability Distortion 50 mV at 1 kHz 2 at 5 to 40 C for both amplitude and frequency 2 EXT...

Страница 69: ...V RMS A Weighting B Weighting C Weighting D Weighting Output Section Linear 2 Hz 200 kHz Operating Temperature POWER REQUIREMENTS AC Power Socket Voltage Consumption Battery Socket Voltage Consumption...

Страница 70: ...ltage and dB scale 50 dB 26 80 mV per N m2 microphone scale 2 6 10 mV per N m2 microphone scale 6 17 mV g accelerometer scale dB Lin Log scale Log 50 dB Lin 20 dB 0 100 scale Absorption Coefficient sc...

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Страница 72: ...s Accelerometer Preamplifiers Accelerometer Calibrators Vibration Meters Magnetic Transducers Capacitive Transducers Vibration Exciter Controls Vibration Programmers Vibration Signal Selectors Mini Sh...

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