Fiber runs

[griffonsystems 0]

i have 9 cameras with one a ptz - spectra iii running from a second control/monitor area to the main head end room

 

we just found out that the client has 2-3pair of fiber available for this communication - and i believe it is multimode but checking with client

 

i was goign to run the 8 fixed on one fiber line and then the ptz on its own with a video/control trans/rec

 

my dist is checking into mfgs but does anyonw have any warnings, advice, etc?

 

thx

[SeanMort 0]

You need to find out three things;

 

1. Multi-Mode / Single-Mode ?

2. Distance

3. Cable condition (fiber joins, kinks, bends, physical condition)

 

Ideally if you get the existing spare fibers (4 - 6 of) checked with an OTDR (Optical Time Domain Reflectometer) this will indicate most or all of the above. It usually costs to get this test done so be aware of this. Maybe the local Telco guys can help you on this. The important thing is knowing if the "road" you plan to use is OK. You will also need to know about the cable hardware stuff. PM me and I can mail this to you.

 

Now for the gear (and this largely depends on the info above);

 

Putting 8 cams onto one fiber is normally no problem, but these multiplexer end-boxes cost a bit. Obviously single channel gear is way cheaper. For your purpose I would look at using two 4 channel units using two fibers, as this is cheaper than an 8 channel type. As for the PTZ, normally sending the video and data seperately is cheaper if you have the spare fibers to do it, otherwise a single fiber end-box will do, no problem.

 

Just be aware of one thing though; transporting video/data signals over fiber is expensive, but you can be smart and economise if the situation/design allows for it. What I mean here is that if there is an opportunity to site the head-end gear (Mux / DVR / Matrix) on the other side of the fiber from the control end then all you need to transport down the fiber is the keyboard data & monitor/s video (less fiber gear needed). The operation wil be totally transparent.

 

As for manufacturers my preference, in order, would be;

 

1. GE - Fiber Options (they have a great free CD that'll show you the ropes)

2. IFS (also now under the GE belt)

3. American Fibertek

4. COE (UK based)

[griffonsystems 0]

its multimode

distance is about 200ft

cable condition is unknown but its not old so i would assume its good if there telco/it guy tells me it is

 

my distro suggested aft - 8 channel fm video system 880c series and the m1600 series bi directional for the ptz video and data isolating that on its own piece of fiber and putting the other 8 on one

 

commetns?

[Cooperman 0]

If it's 200 feet of resonably new multimode, an OTDR test may be a bit of an expensive luxury (the optical equivalent of testing 20 metres of RG 59B/U!).

 

I agree with SeanMort that it would be better and cheaper to spread your risk, so use fewer video channels per fibre. As suggested, 2 x 4 channel would be preferable to 1 x 8.

 

Depending on the application and possible recording requirements, you could perhaps consider using a multiplexed display down a single fibre, and then use additional fibres (all using single channel TX:RX modules) to select individual images for display / control. With 4 > 6 fibres to play with, you have a number of options, any one of which may fit the budget / clients requirements better than another.

 

Personally, if someone tells me their fibre is fine, I'd want that in writing just to cover my .....

[SeanMort 0]

I agree with Cooperman on the test for the distance. 200' is peanuts. But as he said, get it in writing. Another thing here, and it's really for larger fiber jobs but still applies; when it comes to getting someone to do the splicing/jointing, inform the person/co doing this, upfront, that you will not pay for any splices that exceed a set loss factor, and also insist on an OTDR trace printout for each fiber run processed.We use a minimum factor of 0.3Db per splice @ 850Nm on a 50/125 cable. Anything above this is a re-splice at their cost. It happens sometimes that the person doing the splicing has red-eye from the night before, does a bad splice, and kills the optical budget in one or two splices !!

 

I'm not totally familiar with the gear you want to use but, because it's going to be so close, you need to be aware that the receiver end-box might be overwhelmed by the incoming light source and may need to be attenuated. Most well-known brands can compensate for this with AGC, but I have seen others that cannot, even with AGC. Attenuation is no big deal though, just a couple of attenuation washers on the fiber connector.

Are the units analog mux units or digital ? On this distance the cheaper analog stuff should do well.

 

Try get the GE Fiber Options CD as it is a wealth of information on the subject and doesn't only pertain to their products.