Finding LMR Solutions Through Coverage Testing and Signal Measurements


January 27, 2022 by Dominick Arcuri, Subject Matter Expert

You’re not alone if you’ve found that your public safety radio systems’ performance has diminished over time or that the network doesn’t meet your users’ current needs. Throughout this past year, Televate has been honored to work with several public safety agencies to address their Land Mobile Radio (LMR) systems’ shortcomings. Utilizing signal measurements and coverage testing, Televate has assisted a number of agencies to either confirm system performance, or to identify system issues to be addressed to restore full system performance. Below, we’ll discuss a few of these system challenges and the types of testing that can lead to their solutions.

Existing System Testing

On several occasions, Televate was asked to measure and characterize existing radio system coverage in a county or municipality to establish a baseline for modifications or new enhancements. This generally consisted of measuring coverage of an existing legacy system but sometimes also included measuring a regional or neighboring system to determine partnership or interoperability opportunities. For example, in one Midwest county, Televate measured the performance of a legacy VHF paging system and compared that to the coverage of the regional 800 MHz trunked network in the area. This was done in a single drive test, where both systems were measured at the same time. The results were mapped, characterized and summarized and an actionable recommendation was provided to the county’s central dispatch director. The testing and resulting report validated that the regional 800 MHz network would deliver substantially better service than the local legacy VHF network culminating in a successful transition from the legacy paging network to more reliable paging network with improved coverage and clearer voice quality.

In another similar engagement, Televate measured, mapped and characterized legacy system coverage as well as coverage from a statewide 800 MHz trunked network.  Televate used the results to develop a conceptual system design, estimated cost, and specific action plan to guide the county toward its objective to improve coverage, enhance interoperability, and to become an integral part of the statewide system.

During an engagement with a coastal county, Televate engineers measured and mapped out existing system coverage and compared it to expected performance based on typical results and simulated propagation performance.  The results provided insight into potential problems with the system and led to a series of recommendations for correcting the issues and implementing key system enhancements.

In fact, Televate has found that real-time system measurements frequently lead to pinpointing system problems that had not previously been identified.  For example, while taking measurements of a VHF conventional simulcast system, Televate located areas experiencing intersystem interference (ISI) that resulted in poor voice quality.  The information guided the system technicians to locate a faulty time reference essential for managing simulcast time delays and correct the problem.  On another occasion with an 800 MHz trunked simulcast system, the signal measurements led to the identification of a repeater that was not transmitting at full power and causing coverage problems.

New System Acceptance Testing

In multiple system implementation engagements where Televate served as the LMR system technical expert and implementation project manager, Televate took part in the contractual acceptance testing process.  Televate oversaw the testing to ensure the process was fair, the client was receiving an accurate assessment of the new system’s coverage and that the system supplier provided everything required by the contract.  In each case, the testing entailed:

  • Identifying a statistically sufficient grid testing pattern that covered the entire client service area
  • Equipping multiple test vehicles with GPS-enabled equipment and test radios configured for various testing (or attenuation) levels such as on-street or in-building coverage
  • Equipping the primary or backup dispatch facility with console equipment
  • Recruiting and training a sufficient number of volunteer test personnel
  • Developing an effective and efficient testing procedure, and
  • Performing the test and recording Delivered Audio Quality (DAQ), Bit Error Rate (BER) and Received Signal Strength Indicator (RSSI).

During the testing, the Televate engineer monitored the process and progress, provided judgement on scoring of the individual test grids and also provided interpretation of the results.  Additionally, the Televate engineer was sometimes called upon to fill in as a tester either in one of the test vehicles or by operating one of the dispatch consoles.  Once the testing was completed, the Televate representative reviewed the test report for accuracy and completeness and provided independent verification on whether the system provider’s contractual commitment had been achieved.

Some examples of recent testing successes of Televate-supported projects include the following:

  • A county of approximately 575 square miles tested for on-street and 8-dB in-building coverage – Nearly 1,900 tiles tested in three days with two test teams.
  • A county of approximately 560 square miles tested for on-street and 10, 12, and 20-dB in-building coverage – Nearly 1,200 tiles tested in three days with two test teams.
  • A county of almost 900 square miles tested for on-street, 6, 15 and 23-dB in-building coverage – Nearly 3,300 tiles tested in six days with four test teams.
  • In a very large and comprehensive acceptance test, Televate led a team that tested BER and DAQ over more than 2,200 square miles over several months using multiple test teams on-road, off-road, and by boat. Tests demonstrated greater than 99% coverage over this entire area.

Each of these systems passed the coverage testing with minimal failures or none at all, and each met their contractual commitments.

If your current public safety radio system is not meeting the needs of the communities’ first responders, or its coverage performance is not as good as it has been in the past, please contact us to see how Televate can help and put you on a path for improved performance.