7/28/2019 Cctv Tips Art

1/3

CCTV VIDEO TROUBLESHOOTING TIPS

by: Don McCl atchi eFM SYSTEMS, I NC.Sant a Ana, CA.

TEL: 800- 235-6960

Someone once sai d, "Knowl edge i s t he key to success" . Thi s r ul e al soappl i es t o the i nst al l at i on and mai nt enance of CCTV camera equi pment .Have you ever i nst al l ed a CCTV camera syst em and then had to go back t osol ve a pr obl em t hat was over l ooked. A basi c under st andi ng of CCTV vi deosi gnal s, can save you hundr eds of man hour s, i mpr ove cust omer r el at i onsand i ncrease j ob pr of i t abi l i t y al l at t he same t i me. Thi s ar t i cl e wi l ldi scuss probl ems and sol ut i ons f or CCTV camer a i nst al l at i ons.

To di scuss vi deo l et ' s st ar t wi t h t he uni t of measure, t he I . R. E.uni t . I . R. E. st ands f or I nst i t ut e of Radi o Engi neer s, t hi s regul at i ngbody set t he standar ds of measur e f or t he vi deo i ndust r y. Thi s st andar dhas been adopt ed by al l i ndust r i es i n t he Uni t ed St at es and ot her par t sof t he wor l d. 140 I . R. E. uni t s i s equal t o 1 Vol t Peak to Peak. I . R. E.

uni t s ar e easi er t o use because t hey di vi de i nt o a vi deo si gnal evenl y.

For exampl e pr oper Sync on a camer a i s 40 I . R. E. uni t s, t he Vol t ageequi val ent woul d be 0. 2857143 Vol t s. Unf ort unat el y t hi s vol t age cannotbe measur ed on t he Vol t Ohm Mi l l i amp Meter t hat you use f or checki ngcont act s. An osci l l oscope has been used by some peopl e f or t hi s pur pose,but i t i s bul ky and does not r ead i n I . R. E. Most peopl e woul d r at her uset he si mpl e 40 I . R. E. uni t s of measure. For t unatel y some equi pmentmanuf actur ers sel l hand- hel d bat t er y oper ated meter s t o measur e t hevi deo si gnal i n I . R. E. uni t s. Thi s equi pment i s compact , ext r emel yaccur at e and si mpl e t o use. Some uni t s l i ke t he "CAMERA MASTER" can evenhel p t o set t he f ocus of a camer a more accur atel y.

SYNC PULSE AMPLI TUDE, HOW I T EFFECTS CCTV I NSTALLATI ONS.

A CCTV vi deo camer a creat es synchr oni zat i on pul ses t o l ock t hevi ewi ng moni t or on t he pi ct ur e. These pul ses occur at a r at e of 15, 750t i mes a second. Ther e i s one synchr oni zat i on pul se or ( sync pul se) f oreach l i ne i n t he pi ct ur e f r ame. The sync pul se t el l s t he vi deo moni t ort o st ar t dr awi ng a vi deo l i ne across t he pi ct ur e screen. When i t get s t ot he end of t he scr een another sync pul se begi ns t he next l i ne, and sof or t h unt i l t he screen has been f i l l ed wi t h l i nes. I t t akes 262 and ahal f l i nes t o f or m a f r ame, and t wo f r ames t o f or m t he vi deo pi ct ur e wesee on t he moni t or .

The proper l evel f or sync i s 40 I . R. E. uni t s. I f t he sync si gnalf r om t he camer a i s t oo smal l i n ampl i t ude t he pi ct ur e wi l l br eak up orr ol l . I f t he sync pul se i s t oo bi g, any bl ack por t i on of t he pi ctur ewi l l be more gr ay and t he dynami c r ange of t he pi ct ur e wi l l be degr aded.Peak whi t e l evel wi l l al so be compr essed causi ng a bl oomi ng ef f ect ( l ossof pi ct ure def i ni t i on) .

cct vt i ps. ar t page 1 of 3

7/28/2019 Cctv Tips Art

2/3

WHI TE LEVEL I RI S SETTI NG, HOW MUCH I S ENOUGH?

There i s a st andar d f or I r i s set t i ng, or whi t e l evel and i t i s 100I . R. E. uni t s. When set t i ng a manual i r i s, or an aut omat i c i r i s t he l evelshoul d be t he same, 100 I . R. E. uni t s. I f you set t he i r i s bel ow 100I . R. E. uni t s, t he pi ctur e wi l l be di m wi t h l ess t han desi r ed dynami cr ange and t he whi t e pi ct ur e el ement s wi l l not be pur e whi t e. I f you sett he i r i s f or mor e t han 100 I . R. E. uni t s, t he pi ct ur e can be washed out

causi ng l oss of pi ct ur e def i ni t i on. Some camer as can be set t o 120I . R. E. uni t s, but i t shoul d be not ed t hat t he st andar d i s 100 I . R. E.uni t s and i n any case al l camer as i n t he syst em shoul d be set t o t hesame l evel of whi t e. Thi s wi l l ensur e t hat t he whi t e por t i on of t hepi ct ur e wi l l be t he same br i ght ness when a moni t or i s swi t ched betweent hem.

PEAK TO PEAK MEASUREMENT OF THE CCTV SI GNAL.

A qui ck measur ement of t he peak t o peak vi deo si gnal wi l l r e- assur eyou t hat t he CCTV camer a i s put t i ng out t he r i ght l evel . The standar dl evel i s 140 I . R. E. uni t s.

COLOR CAMERA' S AND WHAT I S COLOR BURST ANYWAY?

More col or camer as ar e bei ng used i n CCTV i nst al l at i ons. The col orcamera adds a chr omanance component ( col or i nf ormat i on) t o t he si gnal ,al so known as Chroma. Thi s Chroma si gnal operates at 3. 58 Mega- Hert z.The st andar d l evel f or t he Chroma i s 40 I . R. E. uni t s. When t he chromal evel i s l ow, t he col or s wi l l be dul l . I f t hi s l evel i s too l ow, t hecol or moni t or wi l l t ur n i t s col or r ecei ver of f causi ng a Bl ack and Whi t eonl y pi ctur e. Thi s condi t i on al so i ndi cat es a l oss of pi ctur e det ai l .You can see t hi s ef f ect on l ong cabl e r uns. The sol ut i on i s t o i nst al l avi deo equal i zer i n t he l i ne and adj ust t he col or bur st back t o 40 I . R. E.uni t s. I f t he Chr oma si gnal i s t oo hi gh t he pi ctur e wi l l di spl ay col or

f l ar i ng and r educt i on of det ai l at t he edge of t he col or f l ar e.VERTI CAL I NTERVAL, I TS MANY USES

The Ver t i cal I nterval ( V. I . ) i s t he par t of t he vi deo si gnal t hatt el l s t he moni t or t o st ar t dr awi ng a new scr een. I t i s made up ofspeci al SYNC pul ses wi t h no pi ct ur e el ement s. The st andar d l evel f ort hese SYNC pul ses ar e 40 I . R. E. uni t s. Al l vi deo SYNC pul ses shoul d be40 I . R. E. uni t s. The Ver t i cal I nt er val i s a ver y usef ul pl ace t o putal arm and cont r ol si gnal s. Some manuf actur ers make equi pment f or pan andt i l t camer a cont r ol , al ar m cont act i nf or mat i on, and dat a t r ansmi ssi ont hat i s i nser t ed i nt o t he V. I . si gnal and sent up or down t he cabl e.

TERMI NATI ON, THE END OF THE LI NE.

A t er mi nat i on f or vi deo i s a 75 Ohm r esi st or pl aced at t he end ofany vi deo cabl e t o pr event si gnal r ef l ect i ons t hat cause ghost i ng ormul t i pl e i mages on the moni t or . Some CCTV equi pment have bui l t - i nt er mi nat i ons some of whi ch ar e swi t ch abl e. I f you ar e usi ng t hi sequi pment i n seri es, you must swi t ch of f al l Ter mi nat i ons except t het er mi nat i on at t he l ast pi ece of equi pment i n t he cabl e r un.

cct vt i ps. ar t page 2 of 3

7/28/2019 Cctv Tips Art

3/3

Proper t ermi nat i on can be checked by measur i ng t he SYNC pul seampl i t ude anywher e i n t he vi deo cabl e. I t shoul d r ead 40 I . R. E. wi t h t het er mi nat i on ON, and 80 I . R. E. wi t h t he t er mi nat i on OFF. I f t he SYNCl evel does not change when you remove t he t ermi nat i on, t he camera orvi deo sour ce i s not st andard 75 Ohms and shoul d be servi ced or r epl aced.Pr obl ems wi t h V. I . cont r ol syst ems can r esul t i f t he l evel does notdoubl e when you remove the t ermi nat i on.

THE BASI C THREE

To check per f ormance of any CCTV camera i nst al l at i on makesur e t he SYNC l evel i s 40 I . R. E. uni t s +/ - 5 I . R. E. . WHI TE l evelshoul d be 100 I . R. E. uni t s +/ - 5 I . R. E. . Remember i f you want t or un hi gh whi t e l evel say 120 I . R. E. , be sur e t hat al l camer a' s i nt he syst em have t he same l evel of I . R. E +/ - 5 I . R. E. Col or bur stl evel shoul d be 40 I . R. E. uni t s +/ - 5 I . R. E. . SYNC, WHI TE, andCOLOR BURST ar e t he t hree basi c measur ement s t o make t o i nsur eproper operat i on of your CCTV syst em.

THI S METER WI LL MEASURE I . R. E. UNI TS AND ALOT MORE!

cct vt i ps. ar t page 3 of 3