FRS/GMRS Radio Mapping Guide

Radio mapping is the process of creating a visual representation of radio signal strengths and coverage areas across specific geographic locations; in this case, a team's Service Area. A radio map highlights areas with strong, weak, or no signal, helping organizations understand coverage patterns, identify dead zones, and optimize communication infrastructure.

Radio mapping is a useful team response planning activity.

Introduction to Radio Mapping

Scenario

A disaster has struck the Portland metropolitan area. Routine communications methods (e.g. cell phones) are disabled, and NETs are self-deploying to their Staging Areas/Incident Command Posts. After making some initial assessments, Incident Team Leaders begin deploying strike teams to render aid in the surrounding neighborhoods.

After dispatching a strike team to travel a specific route, the Incident Team Leader discovers they cannot establish FRS/GMRS radio communications with them. Time passes and nothing is heard. Is the team in a radio dead zone? Have their radios failed? Is the team in trouble? Should the Incident Team Leader dispatch a runner to their last known location? Does the strike team need the assistance of a follow-up strike team? Where are they?

Meanwhile, the strike team discovers they can no longer communicate with the NET Incident Command Post. How can they reestablish communications? Should they double back to the last point of communication, risking wasted time and physical exertion? Should they continue forward and hope to reestablish communications at a future location? How long will that take? If the team is in serious trouble, should they detour from their route to call for help? If so, in which direction?

The purpose of FRS/GMRS radio mapping is to provide some solutions for addressing these types of questions in an already stressful situation.

Method

FRS/GMRS mapping may be conducted by placing a two-person team, one Radio Operator and one Scribe, at a proposed NET Incident Command Post location. Rover Teams report to the Radio Operator as they stop at specific locations throughout the NET Service Area. The Radio Operator and the Rover Teams record the radio voice quality for the conversation, as they heard it, at each location. The radio voice quality values for each reported location are then used to create color-coded maps for Incident Command staff and Strike Teams for use during large-scale disaster response.

Goals

The primary goal of a Radio Coverage Survey is to measure the radio voice quality of FRS/GMRS radio communications within a prescribed NET Service Area.

The radio voice quality values may be used to:

• Validate prospective primary and backup locations for a NET Incident Command Post;
• Determine radio voice quality at points throughout the NET Service Area;
• Scope out potential locations for an FRS/GMRS repeater or relay sites.

The process of radio mapping with team members will also:

• Improve radio skills;
• Increase familiarity of the NET Service Area;
• Allow practice of elements of the Incident Command System (ICS);
• Build team cohesiveness; and,
• Cultivate an understanding of radio communication coverage patterns to reduce uncertainty and anxiety during a major disaster.

Radio Coverage Survey Sessions

A team working together can accomplish a Radio Coverage Survey Session in a series of one-and-a-half to two-hour periods. These short sessions enable more volunteers to participate and may be scheduled any time or day of the week.

Several documents available here for download and printing can facilitate a Radio Survey. They include:

Document	Download	Last Update
Radio Coverage Survey Action Plan	[PDF]	2024.11.10
Radio Survey - Command/Listening Post Log	[PDF]	2024.09.20
Radio Survey - Rover Team Log	[PDF]	2024.09.19
Survey area maps
NET Form 2A Personnel Check In	[PDF]
NET Form 3 Team Leader Assignment Tracking Log	[PDF]

Radio Coverage Survey Action Plan

The key elements of a Survey Action Plan should include, at the minimum:

• “What we are going to do”: the goals and plan for the survey;
• “Who is responsible for doing it”: participant assignments;
• “How do we communicate with each other”: survey radio protocols; and
• “What is the procedure if someone is injured”: work in pairs, apply first aid, and contact Command Post and/or 911 as need be.

Additional elements of the Survey Action Plan should include instructions for using Survey Log forms and Survey Area Map.

The Radio Coverage Survey Action Plan, including radio protocols, should be reviewed with survey participants in a NET meeting before the first radio mapping session. Additionally, survey participants should review the action plan before each session. A sample Radio Coverage Survey Action Plan is available as a fillable form in the table above or download here, and can be modified for the NET Service Area surveyed.

Command/Listening Post Radio Log

The Command and listening posts use the Command/Listening Post log to record radio voice quality values of rover team communications. This form should include the date, location, survey radio operator and scribe names, radio type (FRS or GMRS), and radio make and model.

The following information is recorded for each survey location:

• Time (use military time)
• Rover team name
• Location (by cross streets, street address, or other place name)
• radio voice quality value

A sample Command/Listening Post Log is located in the table above, or here.

Survey Area Map

The radio mapping exercise organizer can use My Google Maps or a similar application to create survey area maps identifying key locations. Those locations being:

• Survey Command Post
• Any listening post(s)
• Rover team survey locations

Survey area maps should be prepared in advance and distributed to rover teams at the beginning of the mapping session by the Command Post scribe. Rover teams use these maps to identify survey locations and determine the most efficient path of travel between locations.

A guide to using My Google Maps to create survey area maps is located here. A sample survey area map is located HERE.

Rover team survey locations

PBEM recommends that rover team survey locations should be selected to form a uniform grid across the NET Service Area. A uniform grid is most easily constructed in areas where streets are arranged in a uniform rectilinear pattern. In this situation, survey locations may be places at street intersections. Where long blocks break up a uniform pattern of intersections, survey locations may be placed at specific addresses.

In areas where streets follow elevation contour lines, survey locations may also be placed at specific street addresses or other easily identifiable locations. These locations may be where streets change directions, traverse abrupt changes in terrain, or pass by a distinguishing landmark.

The distance between survey locations should be short enough to eliminate ambiguity in the radio voice quality values in a region. In general, in NET Service Areas with relativity flat terrain, survey locations may be spaced further apart than in areas where elevation changes may obstruct radio signals. Some experimentation may be required to determine the best distance between survey locations. The distance between survey locations may differ in different parts of a NET Service Area.

Taking measurements at too many locations is more advisable than skipping locations and introducing uncertainty into the results.

Radio Mapping Roles

Survey Command Post

The Survey Command Post should be located at the Primary Incident Command Post as specified in the NET Operations Plan. However, radio coverage surveys may be used to evaluate the suitability of other locations if the Primary Incident Command Post has not been established or is being evaluated for relocation.

The Command Post should be staffed with at least two participants: one person acts as the Survey Radio Operator (SRO), and the other acts as a Scribe. The SRO and Scribe collaborate to decide on a radio voice quality value and other rover team information being recorded on the Command/Listening Post Log form by the SRO. The Scribe complete a separate log form to help collaborate on the information received. The Scribe may also check off each reported Survey Location on a copy of the reporting team’s Survey Area Map. The SRO’s log form should be considered to be the official record and the Scribe’s copy as an aid.

During initial sessions, it is preferable to have the Team’s Amateur Radio Operator (ARO) be the SRO. The ARO should brief participants on effective radio protocol. Other participants should act as the SRO during later sessions to gain experience in the Incident Command Post Neighborhood Radio Operator (NRO) role. If the workload overwhelms the ARO, the NRO role may be established. The NRO would be responsible for all NET FRS/GMRS communication in the Service Area.

Rover teams

Each Rover Team should have a minimum of two participants: the Driver/Scribe and the Navigator/Radio Operator who provides directions to each Survey Location.

After arriving at a Survey Location and parking safely, the Navigator/Radio Operator steps out of the vehicle and radios the Command Post. Meanwhile, the Driver/Scribe records the time and location on the Rover Team Log form. After location information has been communicated to the Command Post, the Rover Team agrees on and records a radio voice quality value before proceeding to the next Survey Location.

Measured locations are checked off on the Radio Survey Map as the Rover Team progresses through their assigned Survey Area. The Navigator/Radio Operator may use a map application on their mobile phone to clear up any ambiguity in Survey Locations or for any navigation issues.

When the Rover Team reports its last Survey Location, it informs the Command Post that its survey is complete and that they are returning to the Command Post.

Listening post - optional

Listening posts are optional but may be placed at locations that may be important during a major disaster. Listening Post locations might include an Alternate Incident Command Post, BEECN sites, or Fire Stations. Each Listening Post should have a minimum of two participants.

Upon arrival, the Listening Post checks in with the Command Post and records the radio voice quality value for the conversation. The Listening Post then listens passively to and evaluates the Radio Voice Quality of Rover Team broadcasts for the duration of the Survey Session. The participants will collaborate to decide on a radio voice quality value.

Radio Voice Quality Values

Radio voice quality is rated on a six-point scale, from 5 for the "best" to 1 for the "worst" and 0 for no signal at all.

Intelligibility	Value	Color
No noise, full quieting. Broadcast/phone quality.	5	Dark green
Slight noise, fully readable.	4	Light green
Marginal voice communication. Occasional unintelligible words, noisy; weak audio level.	3	Yellow
Unreliable, difficult to copy, frequent repeats are needed.	2	Orange
Unintelligible, signal is barely evident.	1	Red
No audio signal is detectable.	0	Black

Radio Mapping Session: Process

The Radio Survey Session begins with participants gathering at the Radio Survey Command Post. Survey participants should check in using NET Form 2A Personnel Check In and provide mobile phone numbers on the form to provide a backup communication channel.

Listening Posts are provided with copies of the Radio Survey – Command/Listening Post Log form and the location of the Listening Post. Rover Teams are provided with copies of the Radio Survey – Rover Team Log form and the Survey Area Map for their assigned Survey Area.

It is good practice to assign Rover Team participants to parts of the NET Service Area with which they are less familiar. Rover Teams should examine the Survey Locations in their designated area to develop a travel plan. Generally, each Rover Team should start by reporting from locations nearest the Command Post and record results at each Survey Location while traveling away from the Command Post.

Expect that the SRO will be handling Rover Team messages at the rate of one message every two minutes or less.

Modifications to the Radio Coverage Survey Action Plan may be announced at this time.