Oscilloscopes Episode 14 pdf

Thus the density of charge deposited at different points of the trace is not constant, leading to the possibility of 'blooming' speading of the trace to adjacent areas, a perennial probl

248 Oscilloscopes

Writng Gun, j

J / - , '

High Frequency Deflector

Rxding Gun

(a)

' ~ o

m - ~ ' l q g U W m ~ T I [

(b)

Figure 11.18 (a) The scan converter tube used in the SCD 1000 (b) The diode matrix storage target used in the SCD 1000's scan converter tube The SCD 1000 is discontinued, but many are still in use (courtesy Tektronix UK Ltd)

l o w - s p e e d r e a d i n g b e a m f r o m t o p to b o t t o m , left to right by t h e

r e a d i n g g u n , w h i c h o p e r a t e s as a h i g h - s p e e d v i d e o c a m e r a B u t

t h e s y s t e m i n v o l v e s n o p h o s p h o r , n o c o n v e r s i o n of t h e s t o r e d

t r a c e to light a n d t h e n back to a n electrical signal w i t h t h e

a t t e n d a n t losses f o u n d in e a r l y scan c o n v e r s i o n systems W h i l s t

t h e scan rate of t h e w r i t i n g b e a m in t h e X d i r e c t i o n is c o n s t a n t ,

t h e c h a r g e d e p o s i t e d o n t h e s t o r a g e d i o d e s at a n y p o i n t will be

i n v e r s e l y p r o p o r t i o n a l to t h e s p e e d of spot m o v e m e n t , w h i c h is

o b v i o u s l y m u c h g r e a t e r w h e n t h e r e are h i g h - f r e q u e n c y signal

components of high amplitude present Thus the density of charge deposited at different points of the trace is not constant, leading to the possibility of 'blooming' (speading of the trace to adjacent areas, a perennial problem also with direct-view storage tubes) on the one hand, or inadequate storage of the trace on the other Circuits within the i n s t r u m e n t help in controlling this aspect of operation

On readout, the digitized charge data is stored in an array, after correction for an}, variations in sensitivity across the target (stored in a reference 'background' array) It is then processed to find the centre of the stored charge pattern at each point, resulting in a unique vertical value associated with each horizontal location The resultant data is available over the GPIB, and can be displayed if required on the optional display screen of the instrument The system provided an effective single shot writing rate of up to 200Gs/second in the Tektronix SCD1000 Waveform digitizer, n o w discontinued (see Figure 8.21)

The LA354 analogue storage oscilloscope from LeCroy uses an indirect image converter tube This i n s t r u m e n t is illustrated in Figure 10.14

Reference

Schmid, J Principles of Storage Tubes and Oscilloscopes, third edn, Tektronix UK Ltd,

1977

Appendix 1

data

Human eye response

An important factor in selecting a phosphor is the corour or radiant energy distribution of the light output The human eye responds in varying degrees to light wavelength from deep red to violet The human eye is most sensitive to the yellow-green region; however, its responsiveness diminishes on either side in the orange-yellow area and the blue-violet region The eye is not very receptive to deep blue o r red

If the quantity or light falling on the eye is doubied, the brightness ‘seen‘ by the eye does not double The brightness of a colour tone as sccn is approximately proportional to the log of energy of the stimulus

The t ~ r i n /umifzum> is 1 he photometric cqu iva Icn t of b ri gh mess

11 is based on measurcmcnts made with a wnsor having a spectral sensitivity curve rurrecied lo that of the average huimri cyc The

S1 (inlernalional metric standard) units for lrirninance are

candelas per squarc mctrc, bur footlamberts arc still used extensively in thy US; 1 footlambert = 0.2919 candelaim’ The term luminance implies that data has been measured o r corrected

to incorporate the CIE standard eye response curve for the human eye CIE is an abbreviation for Commission Inter- nationale de L‘Eclairage (Internal Commission o n Illumination) The luminance graphs and tables are therefore useful only when the phosphor is being viewed

Phosphor protection

When a phosphor is excited by an electron beam with an excessively high current density, a perrnancnl loss of phosphor efficiency m a y occur The light output of the damagcd phosphor

will be reduced, and in cxircmc cases cornplere desrruction of thc

phosphor may rcsulr Darkening o r burning occurs whcn the

Phosphor ~ Fluorescence Relative Relative

and Relative photographic burn WTDS JEDC phosphorescence luminance x writing speed 3 Decay resistance Comments

GJ P1 Y e l l o w i s h - g r e e n 5 0 % 2 0 % M e d i u m M e d i u m R e p l a c e d b y GH (P3 l) in

m o s t a p p l i c a t i o n s

W W P4 W h i t e 5 0 % 4 0 % M e d i u m - s h o r t M e d i u m - h i g h Television displays

G M P7 Blue 5 35 % 75 % L o n g M e d i u m L o n g decay, d o u b l e - l a y e r

s c r e e n

BE P11 Blue 15 % 1 0 0 % M e d i u m - s h o r t M e d i u m For p h o t o g r a p h i c

a p p l i c a t i o n s

GH P31 G r e e n 1 0 0 % 5 0 % M e d i u m - s h o r t High G e n e r a l p u r p o s e s ,

b r i g h t e s t a v a i l a b l e

p h o s p h o r

GR P39 Y e l l o w i s h - g r e e n 2 7 % NA 4 L o n g M e d i u m L o w refresh rate displays

GY P43 Y e l l o w i s h - g r e e n 4 0 % NA 4 M e d i u m Very h i g h High c u r r e n t d e n s i t y

p h o s p h o r

GX P44 Y e l l o w i s h - g r e e n 6 8 % NA 4 M e d i u m High Bistable s t o r a g e

WB P45 W h i t e 3 2 % NA 4 M e d i u m Very h i g h M o n o c h r o m e TV displays

i Tektronix is adopting the Worldwide Phosphor Type Designation System (WTDS) as a replacement for the older JEDEC 'P' number system reference The chart lists the comparable WTDS designations for the most common 'P' numbers

2 Measured with Tektronix J16 Photometer and J6523 Luminance Probe which incorporates a CIE standard eye filter Representative of 10 kV aluminized screens GH (P31) as reference

3 BE (P11) as reference with Polaroid 612 or 106 film Representative of 10kV aluminized screens

4 Not available

5 Yellowish-green phosphorescence

BE (P11) phosphor has a different spectral output from GH (P31) phosphor standard and more closely matches the sensitivity spectrum of silver halide film types While photographic writing speed is approximately two times the GH (P31) rate, the visual output luminance is approximately 15% of GH (P31)

252 Oscilloscopes

heat developed by electron b o m b a r d m e n t cannot be dissipated rapidly e n o u g h by the phosphor

The two most i m p o r t a n t and controllable factors affecting the occurrence of b u r n i n g are b e a m - c u r r e n t density (controllable with the intensity, focus and astigmatism controls) and the length

of time the b e a m excites a given section of the p h o s p h o r (controllable with the time/div control) Of the total energy from the beam, 90 per cent is converted to heat and 10 per cent to light A p h o s p h o r must radiate the light and dissipate the heat, or like a n y other substance it will burn Remember, burning is a function of intensity and time Keeping the intensity d o w n or the time short will save the screen

Photographic writing rate

Photographic writing rate is a m e a s u r e of the scope/camera/film's capability to record high-speed signals

Recording high-speed signals on film is d e p e n d e n t on at least three factors: the oscilloscope used, film characteristics, and the camera For m a x i m u m writing rate capability, the objective is to get as m u c h light energy to the film surface as possible Since each c o m p o n e n t affects p h o t o g r a p h i c writing rate, the selection for top performance is important The p h o s p h o r offering the highest photographic writing rate is BE (P11) A c.r.t, with this

p h o s p h o r is therefore usually specified for an oscilloscope which

is required to record photographically very fast single events, which leave too faint a trace to be observed visually However, a

m i c r o c h a n n e l plate c.r.t (Figure 9.11) enables one to see clearly single shot events at the full b a n d w i d t h of the oscilloscope For this reason, GH (P31) p h o s p h o r is standard on MCP c.r.t.s

Note The information in this appendix is reproduced by courtesy

of Tektronix UK Ltd

Appendix 2

Oscilloscope manufacturers

and agents

The following list gives the names, addresses and sales office

t e l e p h o n e / f a x n u m b e r s of most of the m a n u f a c t u r e r s of oscillo- scopes and PC-oscilloscope adapters w h o s e products are readily available The i n f o r m a t i o n is believed to be correct at the date of publication but no responsibility can be t a k e n for errors or omissions For overseas manufacturers, the address of the p a r e n t

c o m p a n y is given, as also is the address of the UK subsidiary, UK sales office or agent as appropriate, w h e r e k n o w n W h e r e an agent is given, this is n o t necessarily the distributor or m a i n agent M a n u f a c t u r e r s of some related i n s t r u m e n t s (e.g pan- oramic receivers, spectrum- and network-analysers, logic ana- lysers, recorder/oscilloscopes) are also listed

Tel: = t e l e p h o n e Fax: = facsimile

A g i l e n t Technologies UK L i m i t e d (formerly Hewlett-Packard), Cain Road, Bracknell, Berks RG12 1HN UK Tel: 01344 366666 Fax: 01344 362852

A g i l e n t Technologies Inc., 9780 S Meridian Boulevard, Engle- wood, CO 80112 Tel 00 1 800 8 2 9 4 4 4 4

A m p l i c o n Liveline Ltd, C e n t e n a r y Industrial Estate, Hollingdean Road, Brighton, East Sussex BN2 4AW UK Tel: 01273 570220 Fax: 01273 570215 M a n u f a c t u r e r of PC plug-in DSO modules

Anritsu Corporation, 5 - 1 0 - 2 7 Minamiazabu, Minato-ku, Tokyo

1 0 6 - 8 5 7 0 , Japan Tel: 8 1 - 3 - 3 4 4 6 - 1 1 1 1 Fax:

8 1 - 3 - 3 4 4 2 - 0 2 3 5 M a n u f a c t u r e r of s p e c t r u m a n d n e t w o r k analysers

Anritsu Ltd, Capability Green, Luton, Beds LU1 3LU, UK Tel:

+ 4 4 - 1 5 8 2 - 4 1 8 8 5 3 Fax: + 4 4 - 1 5 8 2 - 3 1 3 0 3

A S M A u t o m a t i o n S e n s o r s M e a s u r e m e n t Ltd, Imperial House,

St Nicholas Circle, Leicester LE1 4LF UK Agent for Hioki

254 Oscilloscopes

A s t r o - M e d , Inc., Astro-Med House, 11 Whittle Parkway, Slough SL1 6DQ, UK Tel: 01628 668836 Fax: 01628 664994

A s t r o - M e d , Inc., Astro-Med Industrial Park, West Warwick, Rhode Island, 02893 USA Tel: (401 ) 828-4000 Fax: (401 ) 822-2430 Cell SA., 12 a v e n u e des PrOs, F-78059 St-Quentin-Yv Cedex France Tel: 33 (0) 144 O1 22 Fax: 33 (0) 144 01 33 M a n u - facturer of PC DSO modules

C h a u v i n A r n o u x UK Ltd, Waldeck House, Waldeck Road,

M a i d e n h e a d SL6 8BR Tel: 01628 788888 Fax: 01628 628099

F e e d b a c k I n s t r u m e n t s Ltd, Test and M e a s u r e m e n t Division, Park Road, C r o w b o r o u g h , Sussex TN6 2QR UK Tel: 01892 653322 Fax: 01892 663719 Agent for Hameg, Hitachi, ITT Metrix,

K e n w o o d and Tektronix

F l u k e (UK) Ltd, Colonial Way, Watford, Herts WD2 4TT UK Tel:

01923 240511 Fax: 01923 225067

F l u k e C o r p o r a t i o n , PO Box 9090, Everett, WA 98206 USA Tel:

00 1 800 4 4 3 - 5 8 5 3 Fax: 00 1 425 356-5116

F l u k e E u r o p e BV, PO Box 1186, 5602 BD Eindhoven, The Netherlands Tel: 00 31 (0)40 2 678 200 Fax: 00 31 (0)40 2 678

222

G o u l d Nicolet Technologies, Roebuck Road, Hainault, Essex IG6 3UE UK Tel: 0208 500 1000 Fax: 0208 501 2438

G o u l d I n s t r u m e n t S y s t e m s Inc., 8333 Rockside Road, Valley View, OH 44125-6100 Tel: (216) 328 7000 Fax: (216) 328

7400 Offices in France, Germany, Italy, China etc

H a m e g GmbH, Kelsterbacher Str 15-19 6000 Frankfurt a m Main 71, Germany Tel: (069) 6 7 8 0 5 - 0 Fax: (069) 6780513

H a m e g Ltd, 7 4 - 7 8 Collingdon St, Luton, Beds LU1 1RX UK Tel:

01582 413174 Fax: 01582 456416

H e w l e t t - P a c k a r d - see Agilent Technologies

Hioki E.E C o r p o r a t i o n , Koizumi, Ueda, Nagano, 386-1192, Japan Tel: + 8 1 - 2 6 8 - 2 8 - 0 5 6 2 Fax: +81-268-28-0568

Hitachi D e n s h i (UK) Ltd, 14 Garrick Industrial Centre, Irving Way, H e n d o n NW9 6AQ UK Tel: 0181 202 4311 Fax: 0181

202 2451 See also T h u r l b y - T h a n d a r Ltd

I w a t s u Electronics C o r p o r a t i o n , 1-7-4 Kugayama, Suginami-

Ku, Tokyo 168-8501, Japan Tel: 0081 35370 5111 Fax: 0081

35370 5119

Oscilloscope manufacturers and agents 255

K e n w o o d T M I Corporation, 1-16-2, Hakusan, Midori-Ku, Yoko-

h a m a City 226-8525, Japan

K e n w o o d UK Ltd, K e n w o o d House, Dwight Road, Watford, Herts WD1 8EB UK Tel: 01923 816444 Fax: 01923 819131

K i k u s u i Electronics Corporation, 1-1-3 Higashi-Yamata, Tsu- zuki-Ku, Yokohama 224-0023, Japan Tel: 0081 4559 30200 Fax: 0081 4559 37591

Leader Electronics Corporation, 2 - 6 - 3 3 Tsunashiria Highashi,

K o h o k u - k u Yokohama, Japan Tel: 45 541 2123 Fax: 45 544

1280 See also Thurlby-Thandar

LeCroy Corporation, 700 Chestnut Ridge Road, Chestnut Ridge

NY 10977 USA Tel: (+1) 914 578 6020 Fax: (+1) 914 578 5985 LeCroy Corporation, 27 Blacklands Way, Abingdon Business Park, Abingdon, Oxon OX14 1DY UK Tel: 01235 533114 Fax:

01235 528796

M a r t r o n - see Yokogawa

M e t r i x - see Chauvin Arnoux

N a t i o n a l P a n a s o n i c (registered trade m a r k of Matsushita Com-

m u n i c a t i o n s - see Panasonic)

Nicolet I n s t r u m e n t - see Gould Nicolet

P a n a s o n i c - see Farnell I n s t r u m e n t s Ltd

P h i l i p s Test & M e a s u r e m e n t - see Fluke

Pico Technology Ltd 149-151 St Neots Road, Hardwick, Cambridge CB3 7QJ Tel: +44 (0) 1954 211716 Fax: +44 (0)

1954 211880 M a n u f a c t u r e r of PC DSO modules

P o w e r t e k , Unit 148, B e e c h a m Road, Reading RG30 2RE Agent for CELL

S i e m e n s plc I n s t r u m e n t a t i o n , Sir William Siemens House, Princess Road, M a n c h e s t e r M20 8UR UK Tel: 061 446 5270 Fax: 061 446 5262

Tektronix, Inc PO Box 500, Beaverton, Oregon, 97077-0001 USA Tel: (503) 627 6905 Fax: (503) 627 6611 Offices

t h r o u g h o u t the world

Tektronix UK Ltd, The Arena, Downshire Way, Bracknell, Berks RG12 1PU UK Tel: 01344 392400 Fax: 01344 392403 Telonic I n s t r u m e n t s Ltd, Tootley Industrial Estate, Tootley Road, Wokingham, Berks RG41 1QN UK Tel: 0118 978 6911 Fax:

0118 979 2338 Agent for Kikusui

256 Oscilloscopes

T h u r l b y - T h a n d a r Ltd, Glebe Road, Huntingdon, Cambs PE18 7DX UK Tel: 01480 412451 Fax: 01480 450409 Manu- facturer of PC DSO modules Agent for Hitachi, Leader, Trio- Kenwood

T r i o - K e n w o o d - see Kenwood

Unigraf Oy, Ruukintie 3, Fin-02320, Espoo, Finland Tel: +358 (0)9 859 550 Fax: +358 (0)9 802 6699 Manufacturer of PC DSO Units

Wavetek Ltd, Hurricane Way, Norwich, Norfolk NR6 6JB UK Tel:

44 (0)1603 256600 Fax: 4 4 (0)1603 483670 Manufacturer of oscilloscope calibration equipments

Y o k o g a w a Electric Corporation, T &M Business Division, 155

Takamuro-cho, Kofu-shi, Yamanshi-ken, 400, Japan Tel:

8 1 - 4 2 2 - 5 2 - 6 6 1 4 Fax: 81-422-52-6624 Offices in USA and Europe

Y o k o g a w a M a r t r o n Ltd, Wellington Road, High Wycombe, Bucks HP12 3PR UK Tel: 01494 459200 Fax: 01494 535002

I n d e x

ADC (analogue to digital

converter), 115, 132, 141

flash, 128

resolution, 129

SAR (successive

approximation), 128

Add s e e Vertical modes

Alias, -ing, 104

detect circuit, 136

perceptual, 132, 136

Alternate s e e Vertical mode,

Display, Trace

Aluminising, 177, 187

Arming, 24, 25, 121

Astigmatism, 20, 177

Attenuator (input), 200

Auto brightline s e e Brightline

Averaging, 138

exponential, 140

stable, 141

Axis, 1

Babysitting, I46, 147

Backup, batteries, 20

Balanced, 69, 190

TDR measurements, 161

circuits, 69

measurements, 69

Bandwidth, 18, 73, 82, 140, 193,

197

analogue (of DSO), 128

limit(ing), 22

optical, 169-

real time, 125

resolution, 164 single shot, 125, 128 video, 160, 164 Battery, -ies:

dry, rechargeable, 150 charger, 150

Beam, 176- dual, 65 flood, s e e Cathode ray tube BER (bit error rate), 75 Blanking, 97, 179 Blooming (of storage crt trace),

249 Brightline, 16 Brilliance:

control, 11 modulation s e e Z modulation Burn(ing), 12

Calibration, 28 scope cal output, 22 calibrators, 45 Cameras (scope), 4 2 - 4 5 Cartesian s e e Coordinates Cascode, 191-

Cathode-ray tube (c.r.t.), 8, 117,

176 dual beam, 66, 67 electrostatic deflection, 176 magnetic deflection, 176 long persistence, s e e Phosphor microchannel plate, 186 screen, 176-

single beam, 65