Talk:Infrared Leds, Cameras, DC-DC converters etc

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Request for comment: I will discuss various ways of using DSLAMS, Video baluns , copper, Telephone poles and fiber to setup a neighbourhood surveillance system.

Slice the street up into multiple camera zones

Three cameras should be trained down the length of the street. One to monitor only the tar road and the other two to monitor the pavements. Motion detection works best the narrower the zone is to be monitored. Multiple cameras can be spanned adjacent to each other, thus slicing up the road into as many sections as desired. Plant to poles on the pavement and suspend the camers at a certain height across the road. It is critical that nobody's privacy is invaded with such a setup, with each resident able to see each camera output this will be ensured.

DSLAM and video baluns

A DSLAM is a Point-to-Multipoint device. It can be thought of as a massive SwiTch. It strength lies in it's ability to download/upload high bandwidth content to each ADSL modem, connected to it's ports, over twisted pair copper. DSLAM sizes vary between eight and 200 ports. The eight port uses RJ-45 telephone jack connectors. The larger port sizes use a Telco-50 connector cable. Each port connects to only one ADSL modem.

Functioning as a switch, it receives the ADSL modem data (connected to it via twisted pair copper wire) on a port and streams this data via the Ethernet gigabit link that physically plugs into the DSLAM itself unto the Internet or local network.

The DSLAM can multicast a video stream to all the ADSL modems at the same time. An eight-port DSLAM can stream eight different movies and at the same time the ADSL modems can upload data unto the DSLAM to be routed unto the Internet or local network via the DSLAM's Gigabit Ethernet port. This allows for See The DSLAM has QOS and bandwidth control in increments of 32k, allowing bandwidth management to each ADSL modem.

It overcomes the distance limitation of 100m over copper wire that limits Ethernet usage. Via the ATM protocol a DSLAM downloads/uploads it's data to the ADSL modem connected to one of it's ports at a distance of over 5km. The ATM protocol uses fixed packet widths. The Ethernet protocol uses variable data rates. As the distance of a wire increases, its resitance increases hence the the need for the ATM protocol.

Upload speed from an ADSL modem to it's DSLAM port: 1meg ~ 1.6km

Download speeds from a single DSLAM port to it's ADSL modem

  • 25meg at 1000 feet
  • 24meg at 2000 feet
  • 23meg at 3000 feet
  • 22meg at 4000 feet
  • 21meg at 5000 feet
  • 19meg at 6000 feet
  • 16meg at 7000 feet

As the distance of the ADSL modem from the DSLAM increases the throughput will drop. At any distance where the speed becomes unacceptable , connect an Fiber/Ethernet module to the ADSL modem's ethernet port. The ADSL could be seen as an ATM to Ethernet protocol converter. All switches, hubs, routers and bridges uses the Ethernet protocol.

A DSLAM is a viable alternative to many Fiber deployments, it allows people to build their own private telephone exchanges via telephone poles and underground cabling in the exact same manner that a Telco builds their exchanges.

Connect an analogue camera to a VideoBalun. The balun transmitter converts the analogue signal to digital and transmits the video data a distance of 1km over twisted pair copper to the receiver balun which converts it back to analogue. These analogue signals are connected to cards installed inside Zoneminder boxes. The Zoneminder box connects to the DsLam besides it via it's Ethernet port. The DsLam streams the captured video to the ADSL2+ modems.

See *DsLam