Re: found some good deals ......

[JoeRaisin <joeraisin2001@xxxxxxxxx>]

On 3/6/2011 11:13 PM, James B wrote:
> On Mar 6, 7:26 am, JoeRaisin<joeraisin2...@xxxxxxxxx>  wrote:
>> On 3/5/2011 9:29 PM, Chuck wrote:
>>
>>
>>
>>
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>>> I found a few good deals and they are in the mail:
>>
>>> 1) Speco HT650PT10X High Resolution Motorized Dome Camera
>>
>>> 2) Speco DVR4TL250 4 Channel DVR
>>
>>> Now a few questions please -- the DVR has BNC camera inputs but the
>>> instructions for the camera are a little more complex:
>>
>>> ------------
>>
>>> Connect the camera using the supplied terminal block:
>>
>>> A) Connect the control unit via the twisted, 2-conductor line (max length
>>> length 1200 meters) to the pin array 5 (RS485A) and 6 (RS485B).  Connect all
>>> cameras in parallel to this 2 conductor control line.
>>
>>> B) Feed the video signal at contact 3 via a shielded cable to the video
>>> input of the following unit (eg, monitor, camera switcher, video splitter)
>>
>>> Connect the shield to contact 4.
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>>> C) 12V + to pin 1 and ground to pin 2.
>>
>>> -----------
>>
>>> Ok now ..... RS485 control signals interface at a terminal block on both the
>>> camera and DVR.  What is the best twisted wire pair to use for this?  Would
>>> one twisted pair of a Cat 5 cable work ok for 100 yards?
>>
>>> If Cat 5 cable is used for the RS485 control signals, can I transmit the
>>> video and "shield" down a second twisted pair in the same Cat 5 cable?
>>
>> I suggest you do a little research on what a "shield" is.
>>
>>
>>
>>> Could I ship 12 volts and ground down a third twisted pair in the same
>>> cable?  If so, how far?
>>
>>> Last problem, the DVR has BNC connectors for video in.  Would I just soldier
>>> a BNC connector on the video cable for connection at the DVR?  What about
>>> impedance matching?  Any problems to watch for?  What am I missing?
>>
>>> Thanks.- Hide quoted text -
>>
>> - Show quoted text -- Hide quoted text -
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>> - Show quoted text -
>
> Sorry, I did not think to mention what is meant by shield wire.  The
> shield is the overall foil covering that would be around the cat 5
> pairs.  It is used to help keep out interferance.  Along with the foil
> covering will be a wire with no insulation on it.  This is the wire
> that is refered to when shield is mentioned.
>
> James

Right.  My post was aimed at the OP who asked about using a second
twisted pair to transmit the video and "shield".