Verizon is quite open about the extent to which they test their network and their devices to ensure the highest level of reliability. Two years ago we got an exclusive look at Verizon’s national phone test facility in Trevose, PA, which let us see the degree to which Verizon evaluates phones before putting them on store shelves.

Today we got a chance to take a ride with in one of Verizon’s network test trucks, of which about 100 exist in the nation. The trucks sweep through roads and compare data speeds, voice quality, and signal strength, not only on Verizon’s network, but also on the other three major cellular providers in the US. We thank Randy Madden and Verizon Wireless for the opportunity to learn more about their network infrastructure.

Off-camera, we got answers to some of our most pressing questions relating to cell phone towers.

Why are cell towers designed the way they are?

Cell sites are designed based on a variety of factors. Antenna height is determined by the local terrain, the size of the area to be covered and the physical obstructions within the immediate vicinity. The required height is the main factor. Normally VZW will attempt to place antennas on an existing structure (building, bridge, church steeple, etc.). If no existing structure is available, we will construct a tower or a monopole.

What is inside the base station?

Radio equipment, amplifiers, controllers, batteries, a generator, air conditioning equipment and a variety of other electronic gear.

What are the flat “bars” that are attached to a tower towards the top?

I believe these “bars” are the antennas. Multiple carriers can share space on a tower. Each carrier occupies a single platform which generally has three sides. Attached to each side of the platform is generally three or four antennas. These transmit and receive antennas are what provides the radio frequency communication between the wireless network and the handsets/smartphones/laptops that seek voice and internet access.

What kind of wired data connection connects cell phone towers to other parts of the infrastructure?

If it were feeding a home, what would the equivalent speed be? Communications between the cell sites and the public switched and IP networks are provided by a variety of means. Microwave, copper, and fiber make up the majority of those connections. VZW cell sites are connected by multiple (6 to 20 DS1) circuits in some cases and in other cases by 50 or 100Mbps Ethernet backhaul facilities.

Do the cell towers have backup power systems?

VZW cell sites are designed to have a minimum battery back-up reserve of four hours if there is a generator at the site. If there is no generator, there is generally eight hours of battery back up. Beyond that, the site will provide uninterrupted service as long as we can get fuel to the generator.

When it’s time to change wireless standards (CDMA to LTE), how does a tower get upgraded, or must it be replaced?

This depends on the technology. Sometimes hardware is required and sometimes the upgrade requires only a software update. In the case of the CDMA to LTE upgrade, a hardware overlay was required.