Leikhim and Associates is unique among many Consultants in that we have an extensive Radio Frequency
lab and possess the test equipment and expertise to perform independent tests and investigations.
Radio Frequency Interference Analysis and Investigation
Leikhim and Associates can provide RF interference analysis, investigation and mitigation. IM and TNRD
studies can be performed to determine root cause on existing networks or for frequency planning purposes
for new networks.
For those cases where interference is occurring externally from the network, Leikhim and Associates can
perform spectrum analysis, Doppler direction finding and other techniques to locate an existing interferer.
Leikhim and Associates will identify the interference source and provide a report to the Client. In cases where
interference is the fault of another licensee or other party, we will contact that party on your behalf and
will contact and will provide a report to the Federal Communications Commission as requested.
Single Point Failure Analysis
Leikhim and Associates can provide single point failure analysis on existing or new systems to determine areas
where reliability can be improved through design modifications or implementation of redundant equipment.
RF Propagation Modeling
Radio Frequency (RF) planning and propagation analysis
To ensure that a radio system design meets requirements of end users including Public Safety agencies,
Leikhim and Associates follows design guidelines prescribed in the industry approved standard EIA/TIA
TSB-88 (WIRELESS COMMUNICATIONS SYSTEMS –PERFORMANCE IN NOISE AND INTERFERENCE -
LIMITED SITUATIONS RECOMMENDED METHODS FOR TECHNOLOGY INDEPENDENT MODELING,
SIMULATION, AND VERIFICATION).
Leikhim and Associates is experienced in radio propagation analysis using a variety of industry-accepted
software modeling tools such as EDX Signal Pro, RFCAD, ComSite Design, RapTr, and Mosaic.
Proper application of EIA/TIA TSB-88 guidelines ensures that the coverage predictions and resulting designs
consider factors including; local environmental noise floor, delivered audio quality, area reliability, subscriber
antenna losses, simulcast TDI performance, voted receiver joint probability improvement.
The figure below depicts an example of land mobile radio coverage modeled using EDX Signal Pro. The color
Green is used to depict areas meeting the minimum coverage parameters for reliability and delivered audio
Yellow areas are areas of fringe coverage, which are less reliable and may not provide the specified DAQ.
Areas in white are not covered.
We believe that the use of colors in map presentations should be minimized to as few as necessary to clearly
convey the best representation of the coverage attainable instead of presenting a confusing array of
Within the design of simulcast systems, the influence of Time Domain Interference (TDI) can be problematic
in analog simulcast systems and can adversely affect P25 digital modulation through Inter-Symbol Interference
(ISI) and resulting in degraded bit error rate (BER). TDI effects require optimization of the site locations and
geometry, the antenna patterns, transmitter ERP and in some cases, delay of modulation launch times.
The following figure depicts a typical simulcast analysis employed in the development of a UHF Project 25
simulcast system. In the simulcast analysis, within the coverage contour, areas in white are captured by one of
the three transmitter sites by 16 dB or more, areas in green are served by two or more sites (not in capture)
and the artifacts in shown in red are areas within the coverage border (County line) where signals from one or
more sites are delayed greater than 33 microseconds.
Those locations in red, although receiving sufficient signal levels, may encounter distortion or failure of the
received APCO Project 25 signal. The exact location of resulting artifacts for a given design will vary somewhat
according to the many variables. The purpose for this analysis is to make the best decision on site locations
and other parameters so to attain the best outcome possible.
RF Coverage Testing
Leikhim and Associates can perform drive test plans to ensure circuit merit – delivered audio quality (DAQ)
and signal reliability requirements which meet user requirements and comply with industry standards (TSB-88).
Voice quality testing can be performed to provide meaningful subjective DAQ evaluation, both on street and
in building. .
Leikhim and Associates will witness drive testing for signal level and delivered audio quality for both on-street
and in-building performance. Drive testing will be performed with automated signal strength and/or bit error
(BER) testing equipment and voice quality will be evaluated using a meaningful subjective DAQ evaluation
Microwave Path Surveys
Leikhim and Associates is experienced in the design of digital microwave relay systems and proficient in
the use of PathLoss 4.0 software. We can provide a physical path survey to determine feasibility of difficult
A comprehensive report will be provided for each link to determine the reliability of the proposed link budget
under the constraints of the planned equipment or technology. Leikhim and Associates adheres to Industry-
standard procedures and reliability targets.
Reports will include analysis of antenna centerline tradeoffs for each end of a link. The figure below depicts a
typical microwave path with actual obstructions identified during a physical path survey.