A New Space Age Challenge-Standards and Electronic Measurements-EJB

8/8/2019 A New Space Age Challenge-Standards and Electronic Measurements-EJB

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1960 IRE TRANSACTIONS ON INSTRUMENTATION 73A New Space Age Challenge Standards andElectronic Measurements*

LLOYD B. WILSONt, MEMBER, IREANYONE involved in some way in the design, pro- which we can use to measure accuracy-i.e., a meterduction, calibration or use of instruments should which has a scale marked off in accuracy values so thathave a sense of personal pride in the fact that we can look at it and see if we have 5, 1, or 0.0001 perhe is participating in a critical field of work at the time cent accuracy.of our entry into the space age. Mankind's greatest ad- If we cannot measure accuracy by some simple proc-venture planetary escape is about to take place. Man ess such as with a meter, how do we go about determin-himself has not yet achieved planetary escape, but his ing it? As with almost everything we do, there are rightinstruments have already done so in the various rockets and wrong ways of determining accuracy. At the top ofand satellites which have been launched to date. This is the list of the wrong ways is the matter of just having

al l very glamorous and fascinating to contemplate. blind faith3 in the readings of instruments. An exampleHowever, we know that behind these spectacular efforts of this is the tendency to take a manufacturer's specifica-are a grueling and exhaustive series of measurements tion of accuracy at face value, even when the accuracyand tests of materials, components, assemblies and quoted is better than the National Bureau of Standardssystems. The tests are complicated, but at the same can supply. A similar example is the high degree of confi-time interesting, because of the variety and ranges of dence often placed in a manufacturer's specified accu-environmental conditions which will be encountered in racy, even after the instrument in question has beenspace cosmic radiation, temperature extremes, etc.' used for several years without having been calibratedIn our adventure into space, we are depending upon since it was received from the manufacturer. In otherinstruments to give us accurate information. This ap- cases it is not unusual for people to assume that accuracyplies not only to instruments in rockets, satellites and is equal to the readability of the instrument being used,space craft, but also to those used in laboratories and or that accuracy is equal to th e precision or degree of re -shops to develop and produce space age hardware. The peatability obtained when a measurement is repeatedaccuracy of these instruments is very important because several times.it has a direct effect on the amount of information which None of these methods is th e way to determine orcan be communicated to others or which we gain for our even to estimate the accuracy of a measurement. Theyown use. do have some effect on accuracy but other importantfactors must also be considered. For example, in thisACCURACY day and age we depend principally upon a hierarchicalHere we come face to face with the challenige of system for determining the accuracy of the instrumentsstandards and electronic measurements namely, how we use. In other words, in practically all cases today thereliable are th e accuracy figures we use and quote? If we accuracy of an instrument or a standard must be deter-assume that the accuracy of a measurement is better mined by comparison with a standard which is higher inthan it really is, we may be in for a hard time in analyz- the over-all hierarchy of standards. In the United Statesin g and explaining the results of our measurements. this higher level standard is either one which has beenA logical question is , how do we determine accuracy? calibrated at the National Bureau of Standards or atCan we measure it directly, or if not, can we determine least one whose calibration can be traced to NBS. Theit by some other method? First, consider the matter of figures we quote for the accuracy of a measurement or awhether or not we can measure accuracy.2 Note that we calibration tell the limits of probable deviation of the re-said "measure accuracy," not "accuracy of measure- sults from the NBS national standard for this particularment." Unfortunately, it is difficult, if not impossible, to measurement quantity.mneasure accuracy directly. We do not have a meter Eventually we may have a better system wherebyeach of us can determine accuracy in our own labora-*Received by th e PGJ, June 22, 1960. Presented at th e 1960 Con- tory by comparison with independently determinableference on Standards and Electronic Measurements as paper 1-1. standards, without going through a hierarchy of stanld-t Sperry Gyroscope Co., Great Neck, N. Y.1 H. A. Manoogian, "The challenge of space," Electronics, vol. 32,pp . 65-80; April 24, 1959. See especially pp . 67-68. 3"What has the missile age meant to the Bureau of Standards?"

2 C. W. Churchman, "Why measure?" in "Measurement Defini- Product Engrg., vol. 31 , p. 24, 25; May 23, 1960. (Interview with NBStions and Theories," C. W. Churchman and P. Ratoosh, Eds., John Director Dr. Allen V. Astin by Product Engineering's \VashingtonWRiley and Sons, Inc., New York, N. Y. p. 92 ; 1959. editor.)

AlultICLDoJ0a1UfIX Ra


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76 IRE TRANSACTIONS ON INSTRUMENTATION Septemberards to NBS. One of the few examples of such an inde- know that these are areas where NBS offers no calibra-pendently determinable standard which is practical and tion service, except to a limited extent for X-band bo-in use today is the atomic beam type of frequency lometer mounts. However, there are many other meas-standard. Independently determinable standards would urement categories almost as deficient. The answers tobe acceptable substitutes fo r the NBS national stand- th e above questions would probably have to be that weards becatuse they would represent the true or abso- calibrate these items or these quantities indirectly. Forlute value of each of the quantities being standard- example, we may calibrate a water flow type of micro-ized. The only use for the hierarchical system in such wave calorimeter by a derived technique which dependsa utopian age of the future would be fo r the academic upon flow rate and temperature rise of the water. In thesatisfaction to be gained from using it as a cross check. case of power measurements with bolometer mountsHowever, today such independently determinable we may not worry about the efficiencies of the mountsstandards are th e exception rather than the general rule, we use, but instead, rely on a frequency conversionand until such standards are developed fo r a large num- technique wherein dc or low-frequency audio power isber of measurement quantities we must resort to the substituted via a bridge circuit in an amount equal tohierarchical approach to determine the accuracy of our th e microwave power being measured.measurermenlts and calibrations.eAcurenacyt and caliberaetiolns.led byblndfathin LOCAL COMPATIBILITY vs NATIONAI COMPATIBILITYAccuracy cannot be determined by blind faith ininstrumenit readings, by readability, resolution or sensi- We hope the preceding sections have proved that ittivity of instruments, nor by repeatability of instrument is not too hard to find examples where companies arereadings. Instead, accuracy must be determined in establishing many of their own standards indirectly byterms of the accuracy of a standard against which a means of derived calibration techniques or frequencycalibrationi is made, coupled with a proper analysis and conversion techniques. We are now faced with the ques-evaluation of the various sources of error which may tion of whether this in itself is anything to worry about.have arisen in the course of making th e calibration. After all, some people may even prefer this approach toAccuracy implies compatibility or agreement of re - calibrations-particularly the derived type of calibra-sults in an organized system of measurements. An in- tion which sometimes is claimed to be a "primary cali-teresting light is shed on this matter of compatibility by bration" in the sense that it is made in terms of quan-the calibration and standards surveys made within the tities other than the quantity being standardized. Thispast several years-surveys such as that made by the might be well and good if there were reasonable assur-Aerospace Industries Association (AIA),4 or surveys ance that all companies making, e.g., a derived calibra-made by the military services. Many of us have prob- tion of a water flow microwave calorinmeter in terms ofably helped answer questionnaires or at least have seen flow rate and temperature rise of the water, were using-reports of one or more of these surveys. The most the same procedure and the same types of equipment.startling conclusion from these surveys is that the needs Yet, many differences can arise here. One companyof industry for calibration services are, in many cases, might measure the temperature rise by the use of ther-so far beyond the capabilities of NBS that individual mometers, another company might use a calibratedcompanies are establishing their own standards. The thermopile, while a third company might measure theaccuracy and therefore the compatibility of these stand- 60-cps ac power substituted into a heater coil in seriesards with standards of other companies and of the mili- with the water load of the calorimeter. And no mentiontary services is very questionable! has even been made yet of the additional possibilities oferror arising from mismatch of the calorimeter waterload or the inefficiency of the water load. About the bestWe do not have to look far to see that companies are that can be hoped for under these circumstances is thatestablishing many of their own standards in this way. In there will be a certain degree of local compatibility offact, most of us can probably cite examples from the calibrations and measurements within a given group, de-calibration laboratories or engineering departments of partment, or perhaps even an entire company. Theour own companies. For example, how does your com- amount of this local compatibility would be primarily apany make calibrations of microwave power in any fre- function of the use of identical calibration proceduresquency bands except X band? How are calibrations and equipment throughout the particular group, depart-obtained fo r your microwave calorimeters, your bolom- ment, or company.eter mounts? Or, how do you calibrate microwave When we consider the hundreds of companies whichpeak power? How do you calibrate pulse voltage? These make derived and frequency conversion calibrations, itexamples have been chosen intentionally because we is hard to see how there can be any reasonable degree ofnational compatibility with a system such as this. How-4F . McGinnis, H. Martin, J. Novotny, and L. Wilson, "Aero- ever, national compatibility of measurements is par-space Industries Association Industry Calibration Survey," AIA ticularly important these days in view of the complexQuality Control Committee report published by the project sponsor,Sperry Gyroscope Co., Great Neck, N. Y.; 1959. nature of military weapons systems which ar e being de -



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1960 Wilson: Standards and Electronic Measurements 77veloped. The materials and components which comprise each and every one of us in the taxes we pay to the fed-such a systemii are rarely the exclusive product of one eral government every year. In addition, even with thismanufacturer alone. The prime contractor for a typical huge expenditure of money, we are barely able to main-weapon system uses products from a large number of tain our pace as we run neck and neck in th e missile andsubcontractors anid vendors. In addition, once the prod- satellite race with Russia.6uct has been delivered to the military service which has So much for the results obtained to date. Perhaps in-contracted for it, the product is likely to be used by vari- stead of worrying about them we should take a quickous military groups at widely different geographical lo- look to se e if the prospects for the future are any better.cations throughout th e world. For this reason, we can no The only thing to do here is to try to evaluate the ef-longer afford to regard local compatibility as being suffi- forts being expended to improve these situations. In do-cient to assure accuracy of measurement. Dr. Allen V. ing this, we feel competent only to evaluate the calibra-Astin, th e director of th e National Bureau of Standards, tion and measurement efforts. There are other effortssaid in an l interview reported recently in a national mag- of various types which will also contribute to the finalazine,3 "It is important to develop increased apprecia- results we may expect in th e future, but the measure-tion of the necessity of relating measuring instruments ment and calibration efforts should not be overlooked.to national standards whenever measurement data For example, one of the conclusions which was quitetaken at one spot must be compatible with measure- obvious from th e first AIA Calibration and Standardsments in other locations." Survey was that many companies could not show trace-

SPACE AGE NEEDS FOR IMPROVED STANDARDS, ability of their calibrations to NBS. The situation iscomplicated by the fact that NBS does not provideCALIBRATIONS AND MEASUREMENTS many needed calibration services and as a result manyEarlier we used the word startling to describe the con- companies have been forced to establish their ownclusion that individual companies are establishing their standards on a local compatibility basis.own standards although their compatibility withstandards of other companies and of the militarv serv- EFFORTS BY THE NATIONAL BUREAU OF STANDARDSices is questionable. Perhaps th e word shocking or even AND BY THE \4LITARY SERVICESth e word frightening would have been more appropriate. In evaluating th e efforts being expended to improveAt this time in the history of mankind, when we are these situations, we should also take into account whatrelying upon new and dramatic scientific achievements NBS is doing and has been doing while these problemsto uniock the doors of the space age, it is frightening to were developing. The people at NBS were aware of thesethink that we are building our new space age technolo- problems, in a general way, even before the rash of sur-gies on such unsubstantial foundations. This is parti- veys made during the past two years, and they havecularly true in th e electrical, radio frequency and micro- been doing the best they can with the facilities andwave measurement categories in which so many of to - within the financial limitations under which they oper-day's calibration problems exist and which we are dis- ate. An example of these limitations is that this yearcussing at this Conference. It is doubly significant for they have essentially the same staffing level as they hadthese measurement categories because it is by electrical, in t950.3 However, the indications are that NBS needsradio frequency and microwave devices that we will three to five times the facilities it now has, with a pro-control, acquire and analyze much of the data which portionate increase in its staff to work with these fa-will supply basic information about our experiments in cilities.7 About all we can conclude here is that NBS isth e exploration of space.5 forging ahead slowly over a broad front, doing it s bestAt this point we might logically ask: If calibrations against overwhelming odds. Unless drastic changes oc-and stanidards are that important in supporting our new cur, it cannot hope to catch up with all the requirementsspace age technologies, why are we so far behind? Why for increased accuracies, increased ranges of measure-isn't more being done right now? Do we really have ment, and new categories of measurement.calibration and measurement problems, or are we mak- The military services have been increasingly con-in g mountains out of molehills? An analysis of the re- cerned with the need for improvements in calibrationssults of our progress into the space age to date shows and standards. The effort here is evident in the form ofthat we still have reliability problems, we still have rather elaborate standards and calibration programs setschedule delays because many problems ar e solved on a up within their own organizations. The Navy has itscrisis b)asis, and we still have constantly increasing costs. calibration program affecting contractors on certainAl l of these things are directly reflected in our huge major NTavy projects, as described in two papers givennational budget of approximately $40 billion a year forthe military services. This, in turn, is directly affecting 6L. V. Berkner, "IRE enters space,"' PROC. IRE, VOl. 47 , PP.1048-1052; June, 1959. See p. 1052.7"Proceedings of the Forum, 15th Annual Meeting, Standards5C. H. Hoeppner, "Space electronics," PROC. IRE, vol. 48 , pp. an d Metrology Division, American Ordnance Association," Redstone435-437; April, 1960. See p. 436. Arsenal, Huntsville, Ala., p. 5; January 22 , 1960.



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78 IRE TRANSACTIONS ON INSTRUMENTATION Septemberat the last Conference on Electronic Standards and associated with them. Therefore, in April, 1960, the AIAMeasurements held at the NBS Boulder Laboratories again questioned its Quality Control Committee mem-in August, 1958.8,9 In addition, all of the military serv- ber companies in a survey of priorities of industry cali-ices have requested their resident inspectors to check bration needs. The results of this are shown in the barmore carefully on contractor efforts in providing ade- graphs of Fig. 1. These bar graphs cover only the electri-quate calibration of instruments used in connectioi with cal, radio frequency, microwave and time portions ofmilitry contracts. this survey. Actually, the survey covered all majormeasurement categories, including categories such asTHE CALIBRATION SURVEYS OF 1959 AND 1960 dimensional, infrared, temperature, humidity, pressure,None of the above reasons really tell why we are so optics, etc. As we can see from Fig. 1, there are a largelacking in support of our new space age technologies, nor number of companies which have problems in thedo they tell how much we are suffering from lack of electrical, radio frequency, microwave and time cate-proper calibrations and standards in this work. It was gories of measurements.to try to probe deeper and to answer these questions The next step in obtaining additional informationthat the AIA surveys and other similar surveys were about the exact nature of certain indicated problemmade. The years 1959 and 1960 may well go down in the areas and the degree of urgency associated with themhistory of metrology as the years of the calibration sur- was the planning of a series of meetings between NBSveys; not that there were no surveys ever made before and industry personnel to discuss these problem areas.this to determine calibration and standards needs, but The official title given to these meetings is the Measure-during these two years a number of surveys were made. ments Research Conference series, and the first twoThis paper refers to the AIA calibration and standards meetings have already been held on the subjects ofsurveys a number of times because these are the ones microwave power and microwave attenuation measure-with which the author has been most intimately asso- ments. These meetings were held at the NBS Boulder-ciated, having helped to formulate a number of the Laboratories on May 24 and 25, 1960, and were at -questions, to prepare the reply of the Sperry Gyroscope tended by twenty industry representatives and by aCompany to the questionnaires, and to analyze and pre- number of NBS personnel. The objectives of thesepare the AIA reports on the results from the question- meetings were as follows:naires. However, similar surveys were made by the 1) To present and discuss with NBS personnel theElectronic Industries Association and by the National needs of defense industries for new types of micro-Security Industrial Association. In addition to the sur- wave power and attenuation calibration servicesveys made by these associations, teams of Air Force and where NBS provides no services.NBS personnel visited many companies working on 2) To present and discuss with NBS persoiinel thedefense contracts to gain first-hand information of cali- needs of defense industries for microwave powerbration problems and needs. and attenuation calibration services of increasedA major step forward in initiating these surveys was accuracy and/or increased magnitude and fre-taken in November, 1958, when Colonel J. G. Schneider quency ranges where NBS now provides onlyand Colonel Richard Stolle of the Air Force Head- limited services.quarters Air Materiel Command Quality Control group 3) To recommend courses of action for NBS, industryat Wright Field requested the AIA Quality Control and others which will result in long-range as wellCommittee to question its member companies regard- as interim solutions to meet these needs.in g their needs for improved calibrations and standards.In December, 1958, and February, 1959, two question- Several interesting results came out of these meetings.naires were sent out by ALA, and the resulting informa- The first is that there definitely are urgent needs fortion was made public at a press conference held at the better calibrations in the microwave power and micro-Sperry Gyroscope Company in Great Neck, N. Y. on wave attenuation categories. For example, one of theAugust 25, 1959. The AIA report on these surveys, as speakers at th e first Measurements Research Conferencewell as the individual replies, were studied carefully by meeting on microwave power pointed out that a savingNBS. The information was found to be extremely help- of several months of schedule time and several hundredful and, as a result, work was started in some of the thousand dollars could have been achieved in the de-problem areas. velopment of a high-power klystron tube if proper NBSHowever, NBS felt that it was important to obtain power calibration services had been available. At theadditional information about the exact nature of cer- second M4icrowave Research Conference meeting ontamn indicated problem areas and the degree of urgency microwave attenuation another speaker said that almosta million dollars might have been saved if attenuationTRANS. ON' INSTRUJMENTATION, VOl. 1-7, PP. 357-360; December,clbainsrie a enaalbei ubn oa1958. accuracy of a few tenths of a db fo r a range of 60 to 80patM.nL. Stcroggls, "InstBrument cfalibrratiaontpCrsogram wilthintThe De- db. If such calibrations had been possible, a computerON INSTRUMENTATION, VOl. 1-7, PP. 360-363; December, 1958. could have been used to calculate the design of anl an-



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1960 Wilson: Standards and Electronic Measurements 79

ELECTRICAL CATEGORYDC RESISTANCE 4DC VOLTAGE - DIGITAL 2 1_ 0VOLTMETERSA C VOLTAGE 6 9DC VOLTAGE RATIOPULSE VOLTAGECAPACITANCE

RADIO FREQUENCY CATEGORYPOWERFREQUENCY 7ATTENUATIONIMPEDANCEPHASEVOLTAGECURRENTFIELD STRENGTH 6

MICROWAVE CATEGORYUNMODULATED AND AVERAGPULSED POWERPULSED POWER, PEAKFREQUENCYATTENUATIONVSWRPHASENOISECALIBRATION OF FIELDINTENSITY DEVICES..PROPERTIES OF MATERIALS |_

TIME CATEGORYTIME INTERVAL _FREQUENCY

LEGEND:HIGH MEDIUM LOW Q NuMBER OF REPLIES

Fig. 1-Results of AIA survey of priorities of industry calibration needs.



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80 IRE TRANSACTIONS ON INSTRUMENTATION Septembertenna radome instead of having to resort to a trial and use the services of NBS to establish better direct trace-error approach which involved several million dollars of ability of ou r calibrations, i.e., calibrations performed intooling costs. Another speaker pointed out that from a terms of the same units as the quantities being stand-company primary standards laboratory point of view, ardized. In addition, fo r those measurement categoriesit was necessary to have increased accuracy in micro- where NBS cannot yet provide direct calibration serv-wave attenuation measurements because manufacturers ices, we must work hard to achieve an interim solutionof conmmercial instruments are specifying, and in some by establishing a nationally compatible system of in-cases even guaranteeing, accuracies fo r microwave at - directly traceable calibrations. In other words, we musttenuators and directional couplers which are equal to or expand ou r present system of local compatibility tobetter than those NBS will certify. One of the results make it a nationally compatible system for calibrationsof th e first two meetings is that a series of recommenda- which must be obtained by derived techniques or bytions wa s prepared and is Inow beinig reviewed for ac- frequency conversion techniques.tions to be taken by NBS, the military services, and in - Th e third and final part of the challenge is that wedustry to obtain improved calibrations for standards of must close the loop by checking on the end result wemicrowave power and microwave attenuation. seek-accurate measurements to see how well we areachieving that goal. This can be done by a measure-CoNcL.ITSJON ment-agreemenit type of checking operation. Such a sys-By now I think that we can start to se e the over-all tem already has proven practical in company opera-picture the real challenge taking shape. It consists tions; therefore, I see no reason why it should not beof three parts. First, the necessity for action must be practical on a national scale. For example, the Generalbrought out into the open and made known. Here we do Electric Company does this throughout its departmentsnot look to NBS for the needs; they must come from and divisions spread all over the United States by whateach and every one of us in industry and in the military is called an interlaboratory comparison of standardizingservices. One of the things which I feel very strongly facilities.10The Sandia Corporation determines quality ofabout, and which was discussed as one of the recom- work done in Atonmic Energy Commission secondarymendations at the first two Measurements Research calibration laboratories by means of what are calledConference meetiings, is the need for improved com- technical audits." Establishment of a national systemmunications withini industry to pass on the need for of checking similar to these would show whether or notbetter calibrationis to NBS. Few, if any, companies have we are getting accurate and compatible measurementsa central clearinig house for information on calibration and, if not, it would show where effort is needed most.needs. Eveni company standards laboratories which Each of us can help to meet this new space age chal-might normally be expected to have this information lenge the challenge of accurate and compatible stand-readily available do not seem to have it. This is im- ards and measurements. Onily through our efforts canportant not only in providing proper calibration services the need for better standards and measurements bewithin a company, but also in passing appropriate parts brought to light and passed on to the National Bureauof this needs information on to NBS. If the needs ar e of Standards. And only through our cooperaiion canthere but are not passed on to those who can take action there be a measurement-agreement type of checkingto meet thenm, then there is very little chance that any- operation on a national scale to tell how well we arething will be done until a crisis arises. In the case of cali- meeting the challenge. The end results will be improvedbrations aind measurements, the crisis approach is being quality, improved reliability and reduced cost for spacerelied on too frequently to solve problems, and, as we age products.all know, the crisis approach to solving calibration andmeasurement problems involves not only extra money 10 S. C. Richardson, "Reference Level Standards in a Large Elec-costs but also schedule delays. trical Manufacturing Company," presented at t he 14th Annual In-The second part of the challenge is that once these strument-Automation Conf. and Exhibit, Chicago, Ill., p. 9-59-4;September 21-25, 1959. (Instrument Society of America Conf. Pre-needs are made known, action must be taken to meet print No. 9-59.)them. NBS must be the focal point in this effort, but 11 H. C. Biggs, "Physical and electrical standardization programfo r the AEC," IRE TRANS. ON INSTRUMENTATION, VOl. 1-7, pp .this is not a problem for NBS alone. We must learn to 364-370; December, 1958. See p. 365.

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A New Space Age Challenge-Standards and Electronic Measurements-EJB