E911 mapping

The infrastructure to locate landline calls has been in place for many years now and is commonly referred to as Enhanced 911 (E911). Fundamentally E911 works because a large database of customer addresses called the Master Street Address Guide (MSAG) can be queried whenever an emergency call is made. The 911 dispatchers have at their disposal an address that can be located on a digital map.

Current FCC regulations dictate that all cellular providers support the location of emergency calls from their subscribers. The problem lies in that there is no address assigned to a cellular phone number. A cellular call can originate from nearly anywhere. In many dispatch centers around the county, more than 40% of emergency calls come from cellular phones. Unless the person making the call can give an explicit location to the dispatcher, it is very difficult to know where to send the public safety responders. Enter Phase II Wireless.

There are 2 fundamental methods for locating a cellular phone: handset and network based solutions. In addition, a hybrid solution using both handset and network based location can be employed.

A handset location can be derived by integrating a sophisticated GPS receiver in the phone and installing the infrastructure to route the latitude and longitude to the appropriate dispatch center. This method can be very reliable and accurate.

The problem is that cellular carriers are at the mercy of handset manufacturers to implement this location technology. Cellular carriers could wait for years before any significant rollout of these new location based cellular products occurs.

As an alternative, cellular carriers can opt for a network based solution. The primary advantage of this type of technology is its independence of the handset. In a sense, network based location technology allows the carrier to control their own destiny.

Network based location solutions work by triangulating a cellular phone's RF origin. The principal is very similar to locating the epicenter of an earthquake. If three listening sites pick up the disturbance, the location of its origin can be computed.

One of the critical variables in a triangulation solution is the X, Y, Z coordinates of the listening sites. Any errors in those coordinates will translate into errors in the position of the event. A cellular network solution is no different: the precise location of the antenna arrays must be known.

The location of landline and wireless E911 calls requires better mapping (GIS ) accuracy to meet FCC requirements and improve the response of local First Responders. CompassData has worked with several customers on E911 projects to ehance the GIS data, integrate the MSAG database and produce a Public Safety quality GIS that improves response times and saves lives.

Services provided include:
• Road centerline determination
• Structure level mapping and addressing projects
• GIS and MSAG integration
• Provide imagery and vector data sets
• QA/QC of existing GIS
• Field checking of addresses
• Consulting for address policy definition
• Program Management