The Huntsville Islamic Academy Computer and Intercom System

August 19, 2008 – 10:05 am

Overview

This post outlines the system requirements, design and implementation of a robust Local Area Network and VOIP intercom system at the Huntsville Islamic Academy, in Huntsville AL.   Smart Homes was asked to install an intercom system for the elementary school so that they could achieve state accredidation.  Being a school that relies totally on intentionally affordable tuition and donations, they didn’t have much money either.  The challenge therefore was to design and install a low cost intercom system and a computer network for the schools many un-networked PCs.   Unfortunately to wire and install a traditional intercom system with it banks of amplifiers and miles of wire in the school would have required significant costs for infrastructure and labor.  Furthermore a traditional intercom system can not inter-operate with a computer data network.  They would each require separate wiring and separate controller hardware.  Thus to install a computer network and a intercom system would be two separate projects, that would take up twice as much space, use more power, necessitate the need to install two separate wired networks, and it would require a significant investment into an old analog technology that is outdated will be obsolete in just a few years.

Smart Homes’ novel solution to the problem of investing in older technology and extensive infrastructure costs is to combine the two networks, intercom and computer, into one using VOIP and standard networking hardware.  Voice over Internet Protocol, VOIP, is a term used to describe various implementations of transmitting voice traffic over a data network.  The popularity of VOIP is growing steadily due to the inherent cost savings of combining traditionally separate voice and data networks.  VOIP systems carry voice traffic as packetized and compressed digital audio.  The challenge of voice traffic has always been delay sensitivity.  Packets of must arrive in a controlled pattern and in close sucession to one another to enable real time conversations.  Modern networking hardware and compression technologies can handle these tasks eaisly and cheaply.  There are also a small but growing number of vendors producing VOIP based intercom systems that mimic all the capabilities of traditional intercom system but in a digital environment.  Since the Huntsville Islamic Academy needed both a robust computer network and an intercom system, it seemed logical to leverage VOIP technology and implement both systems with one network.

Requirements

• Intercom system with 10 call boxes, mounted in walls or on the desk
• 1 external, weather resistant and vandal proof call station, with the added ability to unlock a magnetic door lock.
• Extend the current wireless computer network to the upstairs classrooms.
• The intercom system must utilize the computer network infrastructure for transmitting voice data.
• The IP intercoms must be multicast capable to facilitate the broadcasting of announcements school wide.
• The intercom system must be able to support additional loudspeakers and call boxes for future expansion.
• The costs must be minimized.

Design

The network layout consists of two major sub-networks, a wired LAN downstairs and a wired LAN upstairs.  The two networks will be bridged together by means of a wireless link across which data and voice traffic will flow.  The purpose of the bridge is to eliminate the need to span the distance between the floors with several runs of wire.

In the downstairs sub-network, the new network hardware will connect into the existing basic infrastructure consisting of the existing cable modem and the existing router.

A FS116P 16 port switch with 8 ports of “Power Over Ethernet”, PoE, will be connected into the router and installed in the computer lab. It will provide enough local Ethernet ports to connect all of the downstairs intercoms, the PCs in the computer lab, a wireless access point and the front door intercom.  This switch will be mounted on a shelf in the computer lab to place it in close proximity to the PCs in the room.  This makes it possible to easily connect the computer lab PCs directly into the high speed LAN through the switch.

The integrated IEEE 802.3af-based Power over Ethernet (PoE) in the switch eliminates the need for extra power cables and the need to locate connected devices near a power outlet as the devices are powered and receive data over a single Cate5e network cable.

A Netgear Prosafe WG302 PoE wireless access point will be installed at the far end of the hall nearest the gym above the dropped ceiling and it will be powered through PoE from the switch.  This access point will extend the wireless LAN coverage provided by the wireless router in the main office, and it will also act as a bridge moving traffic to and from a wireless access point to be located on the second floor.

Ii3-EDW desktop IP intercoms from Digital Acoustics will then be installed in 5 rooms downstairs.  They will be powered by PoE through the switch located in the computer lab.  Special controller software, the Talk-Master LE software, will be installed on one computer in the school’s office.  This computer will act as the master station for all the intercoms in the building.  The office computer, by means of the Talkmaster LE software, can talk to any one intercom in the building or make announcements to all intercoms at one time.  It can also receive individual calls from classrooms.  The Talk Master LE software uses the PCs speakers, microphone and the attached data network to enable 2-way communication with the intercoms.

 

An optional 2-port switch can be added to each EDW intercom box.  This simplifies the wiring of an adjacent PC or other Ethernet enabled device such as a networked camera, printer, or additional intercom equipment in close proximity to the Intercom box.  This option might be especially useful in the classrooms upstairs.  With this option a teacher can have an intercom on her desk, with a single wire running to the wall connecting the intercom to the switch.  The computer can plug its Ethernet card directly into the intercom box.  This effectively hard wires both the intercom and the Desktop PC into the FS116P PoE switch with a single run of wire.  It saves a port on the FS116P switch, and it also eliminates the need to purchase and install a wireless Ethernet card for the desktop computer.

An IP7-ST IP intercom controller will be installed in the main office.  It will be powered from the PoE switch located in the computer lab.  The IP7-ST enables control of analog devices through a data network.  In this instance it will be used to control two sets of analog wires as directed by the data network. One set will go to an exterior, vandal proof, stainless steel, call box mounted outside the front door and another will go to control the front door’s magnetic lock.  Once installed an operator at the office computer will be able to talk with people through the exterior callbox and their computer and they will also be able to unlock the front door.

Upstairs another FS116p 16 port switch with 8 ports POE will be installed in an unused room, closet or classroom.  It will provide enough PoE ports to power 5 intercoms and an access point. There will also be a few additional ports open for future expansion.

A WG302 access point will then be installed upstairs in the dropped ceiling nearest the location of the downstairs access point.  The upstairs switch will power the access point via PoE.  The access point function will be to simultaneously supply wireless internet and LAN access to anyone needing it on the second floor and also act as a bridge, bridging all the traffic from the wired intercoms and PCs connected to the switch to the wireless access point located downstairs.

This layout should provide exceptional wireless coverage over a large portion of the school.  It will also provide several high speed wired connections through which hardwired PCs can access the internet.  In addition to creating a high speed network available throughout most of the building, this system also incorporates a digital intercom system, controlled centrally by a PC on the network located in the front office.

In this solution wiring and infrastructure costs are minimal compared to the overall cost of the project.  Only %16 of the costs is in wiring and infrastructure.  Most of the money is spent on the hardware and installation.  Therefore, if the school should move to another building, all of hardware associated with the intercom system and data network can be easily taken to the new school and installed in a new location.  Thus the school will not loose such a large proportion of the associated as would be the case in a traditional intercom system investment.

In a traditional intercom system, over 50% of the installed cost would have been invested in wiring and infrastructure costs alone.  The wiring alone on a comparable 10 room system from a traditional intercom system vendor would cost nearly $4000.

This system has the added benefit of creating a multipurpose and high speed data network which is essential in this day and age for any school.   Overall this is a great solution for the school to help it achieve its goals of implementing a school wide intercom system and a computer network.

 

Equipment Descriptions

Digital Acoustics ii3-EDW-110 VOIP Intercom: The Digital Acoustics ii3-EDW IP Intercom / Paging Module transmits and receives voice quality audio over Ethernet, wireless (802.11b/g) or fiber, in local area networks with Digital Acoustics TalkMaster-LE or TalkMaster Enterprise Edition software (Control Software). It requires a CAT5 connection to a TCP/IP network. Integrated IEEE 802.3af-based Power over Ethernet (POE) support eliminates extra cables and the need to locate near a power outlet, as the intercom is powered over the Ethernet cable.

Digital Acoustics IP7-ST Intercom: The IP7 series powers implements voice-quality audio over Ethernet/IP local area networks (LANs).  The IP7-ST converts analog signals from traditional intercom call stations into digital signals that can be transmitted over an IP network.  It can also be used to drive analog speakers, and control door relays. Integrated IEEE 802.3af-based Power over Ethernet (POE) support eliminates extra cables and the need to locate near a power outlet, as the intercom is powered over the Ethernet cable.

NetGear ProSafe FS116P: The ProSafe FS108P is a 16 port switch with 8 ports capable of providing power and data from a single point, using Power over Ethernet (POE) over a single Cat-5 cable. The eight Fast Ethernet ports can be used for any 10/100 Mbps link and four of these ports can supply industry-standard IEEE 802.3af power. Advanced auto-sensing algorithm gives power only to 802.3af end devices, so no need to worry about damaging proprietary POE or non-POE equipment. In addition, it discontinues the power when POE devices are disconnected. Easy and reliable, the ProSafe FS108P automatically determines POE requirements, speed, duplex, and cable type using AutoUplink^TM. All Netgear Prosafe^TM equipment carries a limited lifetime warranty. http://www.netgear.com/warranty

NetGear Prosafe WP302 Access Point & Bridge: The WP302 is an 802.11b/g Wireless Access Point, Bridge, and Repeater capable of operating simultaneously in bridge and access point modes to create a wireless distribution system (WDS).  It is cost effective, simple to install and use. It is also plenum rated which means it is appropriate for placement above drop-down ceilings and under raised floors. Integrated IEEE 802.3af-based Power over Ethernet (PoE) support eliminates extra cables and the need to locate near a power outlet, as the access point is powered over the Ethernet cable. All Netgear Prosafe^TM equipment carries a limited lifetime warranty. http://www.netgear.com/warranty

(Optional) NetGear Prosafe WP102 Access Point or Bridge: The WP102 is an 802.11b/g Wireless Access Point, Repeater and Bridge which is capable of operating as a bridge, access point, or a wireless repeater to create a WDS. It is cost effective, simple to install and use. It is also plenum rated which means it is appropriate for placement above drop-down ceilings and under raised floors. Integrated IEEE 802.3af-based Power over Ethernet (PoE) support eliminates extra cables and the need to locate near a power outlet, as the access point is powered over the Ethernet cable. The WG102 access point can be used to extend the wireless signal through the school hallways, down to the furthest reaches of the facility. All Netgear Prosafe^TM equipment carries a limited lifetime warranty. http://www.netgear.com/warranty