- What Is Land Mobile Radio (LMR)?
Land Mobile Radios (LMRs) are two-way communication devices used for person-to-person voice transmission. Despite the proliferation of cellular technology over the past thirty years, LMR remains in extensive use for many important government and commercial applications.
Land mobile radio subscriber units include portable handheld radios and mobile vehicle-mounted products commonly used by police and other public safety services. LMR infrastructure components include antennas, repeaters, base stations, and the backend connections that link them together.
As technology has progressed over the years, LMR systems have incorporated more advanced digital technology and trunked systems that utilize computer-controlled access for efficient allocation of channels to subscribers.
The North American designation of Land Mobile Radio falls under the broader global category of Professional Mobile Radio (PMR) which encompasses all widely used mobile radio network technologies. The PMR acronym is also used to represent Private Mobile Radio, the LMR equivalent in the United Kingdom (UK).
- VIAVI LMR Test Equipment
Land mobile radio communication has established a reputation for high reliability and failsafe network performance that has been continuously enabled through comprehensive test and maintenance practices. The wide selection of LMR test equipment offered by VIAVI supports radio deployments for industries including public safety, healthcare, utilities, public transportation, and railroad management.
Radio test equipment capabilities reflect this diverse user base with relevant features such as Positive Train Control (PTC) which ensures RF parameter compliance with strict railroad safety standards and Vocoder technology. These features and standards allow technicians to graphically evaluate digital audio signals.
Additional land mobile radio constituencies include private security firms and government agencies of all types, such as homeland security, the military, police, and border patrol. These sensitive applications require a high degree of information assurance while retaining the flexibility and interoperability necessary for adaptive missions and objectives.
A VIAVI radio communication test set can support the demanding standards of these industries through precise modulation accuracy testing, frequency error measurement, graphical channel analysis, and receiver sensitivity testing.
As the subscriber population has continued to expand and diversify, the land mobile radio support system has also benefitted from advanced communications test set technology. This network includes independent contractors for radio network installation, two-way radio dealers, and radio maintenance and calibration service providers.
VIAVI provides solutions for this extended support infrastructure, including user-friendly automated signal mapping for in-building coverage analysis and drive testing features. These solutions enable signal strength verification over pre-defined geographic grids or positions.
- Who Uses Land Mobile Radio?
The spectrum of users supported by VIAVI LMR test equipment ranges from small private firms to government operations with thousands of active radio subscribers and many site locations. Large organizations such as railroads or utility companies may perform radio maintenance and repair activities in-house using their own personnel and radio test sets.
Smaller entities and municipalities, such as schools and local fire departments, are more likely to contract a manufacturer’s (OEM) service depot or independent two way radio dealer to complete these tasks. Smaller companies are also more likely to subcontract installation activities to the radio manufacturer or other independent party with some larger organizations also choosing to defer to this external expertise.
This growing complexity of land mobile radio service and installation options underscores the balance between LMR operational readiness achieved through proactive maintenance, and the budgetary constraints that potentially limit radio test set and technician availability. Highly-integrated Communications Service Monitors (CSMs) with automated radio test and alignment functions can be an essential enabler for meeting both objectives effectively.
- How Often Should LMRs Be Tested?
Each land mobile radio equipment manufacturer has established best practices for the preventative maintenance of specific LMR technologies and devices. These standards have been established based on the observed drift and optimum maintenance intervals established for ongoing performance. This typically results in a one-year preventative maintenance cycle for all portable and mobile radios. Additional maintenance is required for infrastructure components as well as incidental (reactive) maintenance for unforeseen radio damage and hardware failures.
An annual maintenance cycle may seem manageable from a single radio perspective, although the combined test and reporting burden for organizations deploying thousands (or tens of thousands) of land mobile radio devices can be considerable. Using manual test and alignment methods, a typical time allotment is approximately 60 minutes per radio plus additional time for post-test report generation. With high subscriber counts and little opportunity for parallel activities, this annual maintenance burden can quickly overwhelm many public service organizations or private users.
The Auto-Test applications integral to a VIAVI radio communication tester reduce this time allotment to seven to ten minutes per radio including model-specific testing, alignment, and report generation. This allows the annual test and maintenance process for six or more radios to be completed in the same one-hour window. The model type of the radio under test can also be detected automatically when the test and/or alignment functions are executed, adding further convenience and versatility.
- Radio Test Procedures for LMR
Major land mobile radio manufacturers have developed detailed product specific test and calibration procedures for their LMR portfolios. Each procedure defines criteria relevant to the applicable frequency range, channel configuration, LMR technology standard, and trunking convention employed. Common test metrics for all manufacturers include basic audio performance, frequency verification, transmission power, and sensitivity. Robust radio test procedures provide a roadmap for highly trained RF technicians to maintain ongoing service integrity.
- What Are The Challenges of Testing LMRs?
With a high degree of marketplace diversity, exacting test requirements, and lofty reliability expectations, LMR testing can quickly become a complicated and challenging undertaking. Signal generators, spectrum analyzers, power meters, frequency counters, computers, and sensors must be interconnected and configured appropriately to constitute an accurate and repeatable communications test set. This can become a long and arduous process, prone to hardware compatibility issues, setup errors, operator-to-operator variation, and inordinate test and reporting times.
Technical resource constraints can further worsen these challenges as electronics industry expansion continues to place an unprecedented strain on the radio frequency talent pool. The high demand for specialized and thoroughly experienced RF technicians continues to rise even as career RF professionals retire and newly trained technicians gain practical PMR test experience.
- Benefits of Using a VIAVI Test Set
Many of the native challenges to LMR test and maintenance practices are addressed through the automation available in an advanced radio communication test set. The consolidation of equipment into one integrated, and intuitive form factor also alleviates test pains.
Automated programs eliminate opportunities for errors and make it possible to meet the exacting test specifications of each land mobile radio manufacturer with minimized setup and greatly reduced cycle times. This high degree of repeatability is extremely valuable for maintaining consistency and minimizing any deviation in test results between technicians.
- What Land Mobile Radio Brands Does VIAVI Test?
The versatility, ease-of-use, and portability of VIAVI radio test solutions allow the LMR test and maintenance requirements of all leading OEMs to be executed with efficiency and precision. Ongoing collaboration with these manufacturers has led to VIAVI radio test set features that now include the widest available selection of OEM approved Auto-Test applications.
Partnerships established across the industry have resulted in LMR test equipment continuity that extends from the lab to the field. Leading brands already supported by availble automatic test and alignment programs include BK Technologies, Collins Aerospace, L3Harris Technologies, Hytera, Icom, Kenwood/EF Johnson, Motorola, and Tait Communications.
- LMR Test Sets From VIAVI
The rich history of land mobile radio has seen a multitude of technologies developed to address the communication needs of commercial, military, and public safety subscribers. Industry-leading radio manufacturers such as Motorola, Kenwood/EF Johnson and L3 Harris continue to impart their own extensive knowledge and insight to the elite VIAVI test set offerings.
The 3920B Series Radio Test Platform has become the industry standard benchtop communications service monitor. Standard onboard features include a 4 MHz dual channel oscilloscope, a -140 dBm (typical) DANL full-featured spectrum analyzer, and a three-port digital multimeter. Unique features that enable a high level of LMR testing and specialization include Vocoder technology and a site monitoring application to provide automated data logging of receiver sensitivity.
The 3920B supports all major LMR standards and technologies with Auto-Test and alignment capabilities. An integrated PC, unlimited save/recall, and remote control make testing quick and repeatable.
Portability has become an invaluable asset for radio test equipment that often follows land mobile radio subscribers into extreme and challenging environments.
The hybrid design of the 8800SX Digital Radio Test Set brings the rich feature set and fully automated test and alignment functionality of a bench level instrument to the field. The industry’s largest display and an expanded channel analyzer with markers are among the many impressive features packed into this ruggedized 17 lb radio test solution. An optional 500W internal Bird power meter supports the testing of remote repeater sites.
Advanced digital features of this radio communication test set include P25 Phase 2 analysis, a TETRA base station test, Positive Train Control (PTC) for Class 1 railroad operators, and advanced modulation plot capabilities.
The handheld 3550R Touchscreen Radio Test System provides an LMR test options in a compact form factor capable of withstanding extreme weather and handling conditions including temperatures ranging from -20˚C to +55˚C.
This compact device comes with full analog and digital test capabilities. It can perform the following tests: direct connect radio type testing, frequency error testing, power measurement, modulation accuracy testing, and sensitivity measurements.
Additional test capabilities include antenna system analysis and highly accurate distance to fault measurement for cable testing and troubleshooting. Utilized in conjunction with VIAVI signal mapping applications, the ultra-light 3550R becomes an important element of the ideal radio communication test set for indoor LMR signal coverage testing.
Signal mapping software is indispensable for the design, installation, and verification of two-way land mobile radio and cellular distributed antenna systems (DAS) and bi-directional amplifiers (BDA’s). The NEON® Signal Mapper automatically calculates indoor locations and correlates with radio signal data, simplifying the verification process by eliminating manual check-in.
Seamless georeferencing and 3D visualization produces highly detailed signal and position information even in buildings without GPS access. A signal quality metric supplements standard metrics to verify compliance with the International Fire Code (IFC) and National Fire Protection Agency (NFPA). The NEON Signal Mapper also works outdoors with measurement correlation maintained continuously as the user leaves or enters a building.