Instruments_Q&A_Sudip.pdf

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@सुदिप पौडेल

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• एउटा scientific instrument हो जुन horizontal and vertical planes मा
angles (directions) नप्न प्रयोग हुन्छ।
• Theodolite को Principle Axis (plumb axis, axis of spirit bubble, sight
axis, horizontal (trunnion) vertical axis) हरुको को सम्बन्ध र graduated
circles सहायताले horizontal and vertical plane मा horizontal and
Vertical/Zenithal angles नाप्नु हो।
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• Theodolite को parts/assembly हरु,
• Theodolite मा हुने AXES हरु,
• Theodolite प्रकार हरु,
• Theodolite मा आउने error हरु र त्येसमा लगाइने Adjustment हरु।
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A. Alidade assembly:
• Telescope, vertical circle, index or altitude bubble लगायतका parts
हुन्छ।
• Telescope लाई two stand ले support गरेको हुन्छ।
• Altitude bubble stand मा attached हुन्छ।
• Magnification = 15-30 diopter हुन्छ।
• Theodolite ले व्यावहाररक रूपमा observed गनन सदकने maximum vertical
angle लगभग 68 दडग्री हो।
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B. Horizontal circle assembly:
• Horizontal circle measure गनन सहयोग गछन।
• िुई वटा plate हरु हुन्छन।
a. Lower (main scale) attached to outer spindle.
b. Upper (Vernier scale) Vernier scale attached to inner spindle.
• Maximum reading from main scale is 20' & Vernier scale is 20“
• Lower graduation circle 8 cm to 25cm( 20cm ) सम्म हुन्छ।
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C. Plate level(levelling head) assembly:
• Bottom-must assembly
• Upper and lower tribrach, three/four foot screw सङ्ग circular bubble
पनन हुन्छ।
• Upper part लाइ Supports गछन,
• Theodolite र TriPort लाई जोड्ने काम गछन।
• Bubble used to put the horizontal circle into horizontal plane.
• Instrument setting गिान leg must be separate within 60 degree.
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A. Vertical axis: vertical line जसको referenceमा theodolite लाई horizontal
plane मा घुमाइन्छ(swing गररन्छ)। swing maybe right swing or left swing.
B. Horizontal axis/ transit axis/ trunnion axis: line जसको reference मा
telescopeलाई vertical plane मा घुमाइन्छ(transitगररन्छ)।
C. Plate level axis: Level tube centralमा हुिा सोसँगको tangent हुने axis.
Bubble center भएको बेला Horizontal हुन्छ ।
D. Line of collimation or line of sight: Objective को optical center, eye-
pieceको optical center र cross-wire को center जोड्ने imaginary(काल्पननक) line.
E. Axis of telescope: eye-piece को optical center र objective को optical center
जोड्ने imaginary line.
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AXES
• Vertical axis truly vertical when leveled
• Transit axis र vertical axis(plumb line) perpendicular हुन्छ।
• Line of sight, transit axis सँग perpendicular हुन्छ।
• Truly level theodolite मा Line of sight र axis of telescope coincide
हुन्छ।
• Plate level axis vertical axis सँग perpendicular हुन्छ।
• Horizontal circle को plane सँग vertical axis perpendicular हुन्छ।
• Vertical circle को axis सँग transit axis perpendicular हुन्छ।
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• Truly level theodolite मा vertical axis plumb line संग conside हुनु पछन ।
• Plate level is perpendicular to vertical axis.
• Line of collimation, turning axis संग perpendicular हुनुपछन नत्र incline
plane generate हुन्छ ।
• Altitude level को axis line of collimation संग parallel हुनुपछन नत्र index
error आउछ ।
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• On the basic of Transiting Facilities
A. Transit theodolite :-
• Horizontal/Turnion axis को about ma 180 degree घुमाउन सदकने
theodolite.
• Left & Right face change गनन सदकन्छ । ( transiting)
B. Non Transit theodolite
• transit हुिैन।
• Absolute now days.
• e.g Y-theodolite, Everest theodolite.
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• On the basic of Vernier scale reading.
A. Vernier theodolite:
• Vernier scale reading हुन्छ ।
B. Micrometer theodolite:
• Vernier scale read गनन micro meter attach हुन्छ ।
• Drum set गनुनपने हुन्छ ।
C. Digital theodolite:
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• Repetition clamp भएको र नभएको आधारमा ।
A. Repeating
• Repetition clamp हुन्छ ।
• एउटा angle any time repeatedly पढन नमल्छ ।
B. Non- Repeating
• Repetition clamp हुिैन ।
• Direct theodolite पनन भननन्छ।
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A. Personal error:
• Error due to surveyor
• e.g. cannot estimate fractional parts exactly,
• Reporting and calculation error,
• Vision error etc.
B. Natural error:
• Error due to natural phenomenon.
• E.g. temperature, wind, humidity, refraction etc.
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ERROR CAUSE EFFECT ELIMINATION
Collimation
error
Line of sight transit
axis सँग
perpendicular
नहुनाले।
Face left र face right
reading को difference 200
ग्रेड वा 180 दडग्री हुिैन र
नतनीहरुको फरक collimation
error को िोव्बर हुन्छ।
Face left र face
right िुवै face मा
reading गरर
हटाइन्छ।
Index error Line of sight
horizontal हुिा
index bubble
central नहुनाले।
Zenithal angle को face left
र face right reading को
sum 400g हनु पनेमा हुिैन
Face left र face
reading गरर
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C. Instrumental error:

Defective
level tube
(non
verticality of
instrument
axis)
Level tube
defective हुनाले
level tube बीचमा
हुिा पनन vertical
axis vertical हुिैन।
Vertical axis truly
vertical
हुिैन।
राम्रोसँग level गरेर
मात्र हटाउन
सदकन्छ।
both face reading
गरेर हट्िैन।
Transit axis
error
Transit axis
vertical axis सँग
perpendicular
नभएर।
Horizontal angle
horizontal
plane मा नभई inclined
plane मा नापपन जान्छ।
Face left र face
reading गरर
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Graduation
error of
circle
Circle graduation
गिान division
हरुबीचको gap
समान नभएर।
Error भएको स्थानमा
reading
नलिा नापपएको कोणमा
त्रुदट हुन््।
Multiple set
reading नलयर
Eccentricity
of Vernier
Vernier Theodolite
मा vernier को
centre र main
scale को centre
एक
ै स्थानमा
नपनानले।
िुईवटा Vernier मा
नलइएको
Vernier reading को
मान एउटै
हनुपनेमा हुिैन।
िुवै vernier मा
vernier
reading नलई
average गरर
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A. Temporary Adjustment:
• दफल्डमा हुिा नै लगाउन सदकने Adjustment हरु लाइ Temporary
Adjustment भननन्छ। जस्तै:
• Centering: Instrument को vertical axis लाई ground को स्टेसनबाट जाने
गराउने।
• Levelling: यन्त्रको vertical axis लाई plumb line सँग parallel बनाउनु।
• Elimination of parallax: parallax हटाउनु अथानत imageलाई diaphragm मा
पानुन।
• Focusing the eyepiece and objective.
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B. Permanent Adjustment:
• दफल्डमा जानु भन्िा पदहले नै लगाउनु पने Adjustment(दफल्डमा हुिा नै
लगाउन नसदकने Adjustment) हरु लाइ Permanent Adjustment भननन्छ।
जस्तै:
• e.g. Adjustment of cross hair,
• Graduation error correction,
• Axis relation etc.
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LEVEL(लेवल)
• Horizontal line of sight को माध्यमबाट क
ु नै िुई पवन्िुबाट जाने िुई अलग-
अलग level line वरुबीचको उचाईको नभन्नता पत्ता लगाउनु हो।
• The principle of level is to determine the difference between level
surfaces through two points with the help of horizontal line of sight.
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• Level को parts/assembly हरु,
• Level मा हुने AXES हरु(same as theodolite),
• Level प्रकार हरु,
• Level मा आउने error हरु र त्येसमा लगाइने Adjustment हरु।
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सबै LEVEL(लेवल) हरुमा mainly three parts हुन्छन।
A. Telescope assembly
B. Level tube assembly
C. Levelling head assembly
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• line of sight provide गननको लानग प्रयोग हुन्छ।
• लेभल instrument राखिएको टेनलस्कोपमा क
े को प्रयोग गरी variable
focusing प्राप्त गररन्छ भन्ने आधारमा telescope िुई प्रकारको हुन सक्छ।
A. Internal focusing telescope: Focusing achieve गननका लानग eye-
piece र objective को बीचमा रहेको bi-concave shape को focusing lens
साररन्छ।
B. External focusing telescope: Focusing प्राप्त गननका लानग
objectiveलाई नै साररन्छ। त्यसैले हरेक अवस्थामा telescope को effective
focal length फरक हुन सक्छ।
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• Level tube को कायन भनेको line of sight को horizontality assure गने हो।
• Level tube मा नभत्रपखट्ट उपयक्त
ु दकनसमको liquid राखिएको हुन्छ र क
े दह
भाग बाँकी छोदडन्छ, अथानत दहमीले िेख्ने bubble air को bubble हो।
• Bubble जदहले पनन highest position मा हुन्छ। यदि bubble ‘center of it’s
run’ मा भए line of sight truly horizontal हुन्छ ।
• Bubble tubeमा use गररने liquid(usually a colored spirit or alcohol) less
viscous र temperature ले कम असर गने दकनसमको हुनुपिनछ।
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• यसले क
ु नै level tube ले non-verticality of instrument axis लाई कनत सानो
सम्मको फरक िेिाउन सक्छ भन्ने क
ु रा जनाउँछ।
• Level tube को sensitivity बढी हुनु भनेको सानो मात्र error पनन थाहा हुन्छ भनेको
हो।अथानत level tube more sensitive हुनु भनेको सोले levelling राम्रोसँग गनन
सदकनु हो।
• Sensitivity of level tube is normally expressed in terms of angular unit.
• If sensitivity of a bubble tube is expressed as 1 div= 2’, it means that if the
bubble is out of center by 1 div, the vertical axis of instrument will deviate by
an angle of 2’ from vertical line.
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Sensitivity of level tube can be increased by:
• Increasing the length of vapor bubble
• Increasing the diameter of level tube
• Increasing the radius of curvature of inner surface of bubble tube
• Decreasing the viscosity of liquid
• Decreasing the roughness of inner surface of level tube
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• Level को मानथल्लो भागहरुलाई support प्रिान गनन।
• लेभललाई tripod सँग connect गने।
• Line of sight लाई horizontal बनाउन मद्त गछन।(A levelling head (tribrach
and trivet stage) to bring the bubble in center.)
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• Dumpy levels
• Wye or(Y) level
• Cooke’ s reversible level
• The Cushing's Reversible levels
• Tilting level
• Automatic level
• Digital level
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• Short and stout(छोटो र मोटो हुन्छ )
• Level tube placed longitudinally, parallel to the axis of telescope
• Power of telescope 30D
• Bubble tube sensitivity 2 mm in 20 second.
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• अंग्रेजी अक्षर Y जस्तो frame मा support गररएको हुन्छ।(Called wye level
for being supported on two clips of Y-shaped)
• Y-clips can remove from stages and telescope can be reversed
• Magnification & sensitivity same as dumpy level.
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• It is combination of dumpy level and wye level
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• The objective lens & Eye piece can be change.(Eye-piece र objective
को direction उल्याउन सदकने।)
• टेनलस्कोप ननकालेर उल्ट्यर राख्न सदकने।
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• Vertical plane मा (±4° सम्म) घुमाउन सदकने।
• Telescope can be rotate about horizontal axis.
• line of sight vertical axis सँग लम्ब नहुने।
• The line of collimation and vertical axis should not essentially
perpendicular to each other.
• सबैभन्िा शुद्द लेबल।
• Consider as must precise type of level.
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• levelling गिान vertical axis पूणन रुपमा vertical नभई 15’ सम्म ढखल्कएको
अवस्थामा स्वत: correction गने।
• compensator जदडत गररयको हुन्छ।
• Fast and easy to use
• Consist of two prism arrangement called compensator that adjust the
line of sight when level has been leveled up to 15l off the vertical.
• Low accuracy than other.
• Mostly use for ordinary purpose.
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• बारकोड युक्त staff प्रयोग गने लेभल।
• staff reading यन्त्रले नै गरर रेकड गरर राख्न सक्ने दकनसमको level.
• Self-reading level, that uses special barcoded staff.
• Bar code pattern of staff read electronically and converted to staff
reading by instrument processing mechanism.
• Horizontal distance calculated by instrument itself and reading stored
in its internal memory.
• When sighting after focusing, observer just need to press measure
bottom.
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A. Personal error:
• Error due to surveyor
• e.g. cannot estimate fractional parts exactly, Reporting and calculation error,
Vision error etc.
B. Natural error:
• Error due to natural phenomenon.
• E.g. curvature, refraction temperature, wind, humidity, etc.
• Error due to instruments
• E.g. Collimation error, graduation error, defective staff, defective tripod etc.
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• लेभल यन्त्रको levelling गररसक
े पनछ सोको line of sight horizontal बन्नु
पनेमा त्यसो नभई horizontal plane सँग inclined हुनु collimation error
आउनु हो।
• समान िूरीमा collimation error को कारणले staff reading मा आउने error
पनन समान हुने हुिा level instrument िेखि back sight staff र foresight
staff समान िुरीमा रािेर(balancing of sight द्वारा) हटाइन्छ।
• Collimation error पत्ता लगाउनका लानग two peg test प्रयोग गररन्छ।
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STEPS FOR TWO PEG TEST
1.मानथ figure मा िेिाए जस्तै लेभल मेनसनलाइ िुइवटा staff को पबचमा
राख्ने।(जस्तै d=१०-१० नमटर)
2.Point A र Point B को staff reading नलने ।(RA and RB)
3.िुईवटा staff reading को difference ननकाल्ने।(RA-RB=X(let)
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STEPS FOR TWO PEG TEST
4. लेभल मेनसनलाइ shift गरेर Point A वा point B को नखजक set गने।(जस्तै point A
बाट ५ नमटर को िुररमा र point B बाट १५ नमटरको िुररमा)
5. Point A र Point B को staff reading नलने।(RA0 and RB0 )
6. Step 3 मा जस्तै िुईवटा staff reading को difference ननकाल्ने। RA0 - RB0 =Y(let)
7.यदि X-Y=0 छ भने त्यहा collimation error छैन।यदि 0 छैन भने collimation error
छ।
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• पृथ्वीको सतह curved भएकाले level surface पनन curved नै हुन्छ। तर level
instrument को line of sight horizontal line हो, जसले staff लाई level line ले
भन्िा मानथ काट्छ।
• Curvature का कारणले गिान staff reading बढ्छ, अथानत staff reading मा
positive error आउछ। Object वास्तपबक उचाइभन्िा कममा भएजस्तो लाग्छ
(object appears too low due to curvature)
• Curvature correction always negative or subtractive.
• Formula=-0.0785D^2 or D^2/2R m जहा D is distance in km, R is earth radius
in m.
• Curvature correction is positive when applied to its RL
• Balancing of sight द्वारा(BS र FS distance balance गरेर) curvature का कारणले
आउने error हटाइन्छ ।
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• Refraction को कारणले line of sight तलनतर झुकी staff reading घट्छ।
अथानत,Refraction error –ve हुने हुिा correction positive हुन्छ।
• Refraction correction curvature correction को 1/7 हुन्छ र नचन्ह पवपरीत
हुन्छ।
• Refraction correction always positive or additive.
• Refraction correction = + 0.0112D^2 or D^2/14R m जहा D is distance in
km, R is earth radius in m.
• Combined correction for curvature and refraction = -0.0673 D^2m
or 6/7. D^2/2R m , जहा D is distance in km, R is Earth Radius.
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ZERO ERROR: लामो समयसम्म प्रयोग गिान स्टाफको base खिइएर
graduation zero बाट सरु हुनु पनेमा सो नहुनु : zero error of staff
• Zero error ले गिान staff reading बढ्छ।
• Error is always positive.
• Benchmark िेखि benchmark सम्म even setup बनाएर हटाइन्छ
GRADUATION ERROR: स्टाफको graduationमा हुने error.
• Levelling मा प्रयोग गररने staff को graduation गिान division हरु uniform
नभएमा आउने त्रुटी Field procedure बाट हटाउन सदकिैन।
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NON-VERTICALITY OF STAFF: If the staff deviates out of vertical
towards or away from the observer, staff reading and calculated distance
will increase[because the slant length is greater than the vertical
distance and the intercept will also be greater].
• It is always positive and cumulative[greater for higher reading value].
WARPAGE OF STAFF: Due to bending of staff of loose fitting at the
junction of folding staff.
• Reading increases(i.e. error +ve)
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A. TEMPORARY ADJUSTMENT:
• लेभल यन्त्रलाइ काम गननका लानग तयारी अवस्थामा ल्याउने कायन।
• Levelling: लेभल यन्त्रको vertical axis लाई truly vertical अथानत plumb
line सँग समानान्तर बनाउने कायन। foot screw को सहायताले गररन्छ।
• Elimination of parallax: image diaphragm मा नबनेको कारणले
observerको आँिासँगै cross-hair चल्ने कायन।
• Parallax(relative movement of cross-hair with observer’s eye is called
parallax।
• Parallax हटाउनका लानग eye-piece र objective लाई focusing गरर
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B. Permanent Adjustment:
• Adjustment done before setting up the instruments
• e.g. Adjustment of cross hair,
• Graduation error correction,
• Axis relation,
• Staff graduation error correction etc.
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• EDM = Electromagnetic or Electronic Distance Measurement
• Electronic distance measurement (EDM) is a method of determining
the length between two points using electromagnetic waves.
• EDM indirect linear measurement को पबनध हो जसले electromagnetic
wave को प्रयोग गरर िुरर नाप्छ।
• EDM ले जदहले पनन Slope distance दिन्छ।
• EDM ले नाप्नका लानग प्रयोग गने wave को velocity 3*10^8 m/s हुन्छ।
• सबैभन्िा पदहलो EDM: Geodimeter, 1948 by Eric Bergstrand
(Swedish),जुन optical EDM नथयो।
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• िोस्रो EDM: Tellurometer, 1957 by T.L. Wadley( micrometer EDM नथयो।)
• Normal range of 30–50 km but can extend up to 70 km.
• EDM को accuracy PPM (Part Per Million ).
• यो पपवननधबाट आजकल १०० दक मी सम्मको िूरी 10^5 मा 1 अंशको शुद्दता
सखजलै प्राप्त हुन््।
• Some common EDMs: Distomat, Geodimeter, Tellurometer, Mekonometer
• V.D = Slope distance *SinZ
• H.D = Slope distance*cosZ
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• Electromagnetic wave ले EDM िेखि target मा पुगी पनु : EDM सम्म
आइपुग्न लागेको समय (t) र light को velocity(v) को आधारमा slope
distance calculate गररन्छ ।
Distance = ½ v*t
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EDM instruments can classify according to their operational
range(नाप्नसक्ने अनधकतम िुरी)
• Long Range
• Medium Range
• Short Range
A. Long range(लामो िुरी) EDM: These EDMs are used to measure
distance more than 100km.
• These instruments use microwave or radio waves.
• टापुहरु पवचको िुरी ननकाल्न, marine work etc.
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B. Medium range(मध्यम िुरी) EDM: These EDMs are used to measure
distance between 10-100km.
• These EDMs uses Light, infrared, microwave or laser waves to
measure distance.
• Precise Triangulation को काम वा अन्य geodetic कायनमा आवश्यक पने
आधार िुररको लागी।
C. Short range(छोटो िुरी) EDM: These EDMs are used to measure short
distances up to 5km.
• These EDMs uses light, infrared or Laser waves.
• इखन्जननयररङ्ग सम्बन्धी सबै कामको लागी।
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According to the type & wavelength of electromagnetic energy
generate(प्रयोग गररने Electromagnetic Energy को आधारमा) .
• Microwave system
• Electro-Optical wave system
A. Microwave system: This type of instrument use the EM energy of 3
to 35GHZ wavelength. लामो िुरीको नाप्नको लानग राम्रो हुन्छ।
They are further classified as,
• Visible light range instruments
• Infrared instruments
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B. Electro-Optical wave system: Light wave को प्रयोग गररन्छ।
• Short distance को लानग धेरै प्रचनलत छन।
• नयननहरु साना,हलुका,स्वचानलत(automatic) र धेरै भरपिो हुन्छन।
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A. Personal error:
B. Natural error:
• Scale error: Emitter को temperature change भएको कारणले calibrate
भएको भन्िा फरक wavelength को wave emit गनुन ।
• Zero error: EDM को center ground station को ठीक मानथ नपनुन ।
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• Plane tabling मा line of sight को direction measure गने
यन्त्र(Instrument used to define line of sight and direction in plane
tabling)
• Straight edge ruler having some form of sighting device.
• The alidade is useful for establishing a line of sight.
• Alidade िुई प्रकारका हुन्छन,
( I ) Plain alidade or sight rule
( ii ) Telescopic alidade
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• 60 cm long metal base: िुवै नतर fold गनन नमल्ने एक-एकवटा vanes हुन्छ।
• i.e. Length of plain alidade equal to width of plane table( 60 cm)
• Eye-vane मा simple vertical slit हुन्छ।
• Object vane मा vertical काटेर बीचमा thread राखिएको हुन्छ।
• Both vanes perpendicular to base.
• एकानतर को दकनारा लाइ छड्क
े पारर काटेर drawing गनन नमल्ने बनाइएको हुन्छ
जसलाई fiducial edge भननन्छ।
• Plain alidade े
ल direction र distance नाप्न टेपको प्रयोग गररन्छ ।
• It is not suitable on hilly area since the inclination of the line of sight is
limited.

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• Telescope जदडत alidade लाई telescope alidade भननन्छ।
• यो साधारणतया उकालो ओरालो जग्गामा प्रयोग गररन्छ।
• It consists of a small telescope with a level tube.
• Drawing लानग Movable fiducial edge वा beveled edge,जो जदहले पनन line of
sight सँग समानान्तर हुन्छ
• Fiducial edge को लम्बाई 380mm*65mm हुन्छ।
• Plain alidade भन्िा शुद्द हुन्छ(telescope प्रयोग गररएकाले र magnified image
िेखिने भएकाले)
• Distance दहसाब गननका लानग optical method (staff reading) प्रयोग गररन्छ,
अथानत,telescopic alidade distance र direction िुवै नाप्नका लानग प्रयोग गररन्छ।

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• Line of sight को झुकाव दहसाब गननको लानग micrometer वा vertical circle
हुन्छ।
• It consists of three scale,
a. H-scale ranges +20 upward and downward.
b. V-scale ranges +-40 upward and downward.
c. θ -scale ranges + - 45 degree/50g
• If provided with vertical angle(θ) is zero when line of sight is
horizontal, and increases on both directions, upward sight being
positive and downward sight being negative.

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H-scale V-scale
Horizontal distance ननकाल्नको
लागी
Height difference ननकाल्नको लाग
Always positive Line of sight मानथ नतर भए positive, तल नतर
भए Negative हुन्छ।
Line of sight horizontal हुिा zero,
तल र माथी िुवै नतर वढ्छ।
Line of sight horizontal हुिा zero, तल मानथ
िुवै नतर बढ्छ तर मानथ positive र तल
negative हुन््।
यदि vertical angle θ, Zenithal
angle Z भए: H = 100sin^2θ or
100cos^2Z
यदि vertical angle θ, Zenithal angle Z भए:
V=100*sinθ*cosθ or 100sinZ*cosZ or
50sin2 θ

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• Telescope मा stadia diaphragm(Beamann Stadia Arc) राखिएको हुन्छ जसको
सहायताले horizontal distance र elevation compute गनन सदकन्छ।
• 𝐻𝑜𝑟𝑖𝑧𝑜𝑛𝑡𝑎𝑙 𝑑𝑖𝑠𝑡𝑎𝑛𝑐𝑒(D) =100S𝑐𝑜𝑠^2(𝜃),
• 𝐻𝑜𝑟𝑖𝑧𝑜𝑛𝑡𝑎𝑙 𝑑𝑖𝑠𝑡𝑎𝑛𝑐𝑒(D) = 𝐼 ∗ (100 − 𝐻) 𝑜𝑟 (𝐼 ∗ 100 − 𝐼 ∗ 𝐻),
• H𝑒𝑖𝑔ℎ𝑡 𝑑𝑖𝑓𝑓𝑒𝑟𝑒𝑛𝑐𝑒(Δℎ) = 𝐼 ∗ 𝑉 then
• H𝑒𝑖𝑔ℎ𝑡 𝑑𝑖𝑓𝑓𝑒𝑟𝑒𝑛𝑐𝑒(Δℎ) = 100S𝑐𝑜𝑠𝜃𝑠𝑖𝑛𝜃
• RL= Δℎ + height of instrument(H.I) – middle wire reading(M).
• जहाँ S or I = staff intercept = (top wire − bottom wire),θ = vertical angle
• H=H − scale reading, V = V − scale reading.

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A. Personal error:
B. Natural error:

8/17/2022 86

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