Hardware Engineering

Hardware Engineering provides sustaining engineering to the NEXRAD program by continually working on day to day issues associated with interference and level two support of operational radar issues. Our long term projects associated with the Service Life Extension Program (SLEP), sustaining engineering, and routine obsolescence help ensure the radars turn tomorrow.

Interference Analysis

There are multiple types of interference that degrade radar data quality ranging from physical blockage to Radio Frequency (RF) interference emanating from external sources.

We will work with a site when they have been notified by an outside entity that a new structure or physical blockage is proposed in the forecast area of the site. We have performed analysis on a Mine Tailings mound being created by a neighboring mining company. We identified the geographic location of the mound and performed an analysis as to how tall the mound would have to become to begin blocking the radar signal. Air traffic control towers, airplane hangars, water towers are the primary man-made structures we have analyzed for potential radar blockage. However, we also provide calculated RF energy levels at the proposed structure location to determine if the transmit energy from the WSR-88D will cause concern for exposure to non-ionizing radiation for personnel or possible bulk cable interference.

As the RF spectrum becomes more crowded, commercial cell phones, Wi-Fi and radar interference has become more commonplace. If an interference strobe has been identified by WFO personnel, and is persistent, we will conduct an analysis of the interference. We begin with desktop research of the RF sources in the area, working with local site personnel, the most familiar with the neighboring towers and buildings, querying the various RF source databases, and we will generate a list of possible candidates. When possible we will contact owners of the suspect equipment and schedule on-off tests to verify that they are the source. We also work with the various government agencies (NTIA, FCC, DOD, FAA) in resolving the interference. Results of our efforts vary. In some cases we can resolve the issue quickly, and a few times the interference resolves itself without explanation. Other times, resolution can take years, such as when the source is intermittent or not easily identified.

Radar

We work on all aspects of the radar operational hardware, from the RF generator to the antenna feed horn. The various Service Life Extension Programs (SLEP) (Signal Processor, Transmitter, Antenna/Pedestal) have been designed to reset the clock on the WSR-88D. Combining this with our Routine Obsolescence efforts, we are extending the life of the radar well into the 2030s.

Sustaining Engineering

Here are a few examples our Sustaining Engineering Efforts:

ECP0667 is an engineering effort to remove the phase shifter stepper motor assembly from the RF Pallet. Testing with the phase shifter stepper motor removal and RF Pallet waveguide and interface panel installation was completed at ten sites. Modification Note 245 RF PALLET PHASE SHIFTER REMOVAL & AME MOUNTING HARDWARE MODIFICATION was created and field deployment began in 2024. Currently, seventy-four NEXRAD sites have completed Modification Note 245.

ECP 1073 is an engineering design to prevent the Antenna Mounted Electronics (AME) unit from falling off the NEXRAD pedestal arm. Several locations contacted the ROC Operations Hotline about their AME unit being detached from the pedestal arm. Engineering found the vibration isolator mounts used to attach the AME unit to the pedestal arm were constructed with an adhesive for bonding the mounting screws to the isolator mounts. Aging and constant torquing being applied to the isolator mounts from the AME weight and pedestal arm movement eventually weakened the bonding and the AME unit became detached. Engineering designed new brackets with safety chain links to prevent the AME unit from becoming completely detached while maintaining the vibration isolation from the pedestal movement. The new safety brackets are part of the Modification Note 245 kit. Currently, seventy-four NEXRAD sites have completed Modification Note 245.

ECP 0952P INVESTIGATE RECEIVER BIAS ACROSS RECEIVER DYNAMIC RANGE is an engineering design to provide a more stable receiver bias across the receiver dynamic range. Engineering designed an RF Dither circuit assembly that reduces the non-linearities in the horizontal and vertical receiver paths. Ten NEXRAD sites had the dither circuit installed. The test results at each site indicated a more stable differential linearity after the installation. Deployment kits are scheduled to be procured in FY 2027.

ECP 1091P INVESTIGATE CHANGES TO IF BANDPASS FILTERS is an engineering design to reduce external RF interference. New bandpass filters with a narrower bandwidth were installed at operational sites in the radar receiver cabinet which help reduce the interference from external noise sources. Deployment kits are scheduled to be procured in FY 2027.

ECP 1156 REMOVE THE NWS REDUNDANT SITE COLD STANDBY STATE AND UPDATE HARDWARE is an engineering design to standardize the RDA cabinet by replacing an NWS redundant fan cable assembly with a standard fan cable assembly used at all NWS sites. This will remove the NWS redundant cabinet fan assemblies from the RDA power administrator unit so that the power administrator ports for the fan cables will no longer be required. Deployment is scheduled for FY 2027.

Troubleshooting and Fleet Wide Support

While maintaining non-IT hardware, located within the RDA compound, we work with ROC electronics technicians, Configuration Management Specialists and Technical Writers to develop troubleshooting guidelines, diagrams and schematics. We travel to field sites for kit proofs and talk with local personnel to determine what else can be done to improve overall reliability and reduce maintenance time.

We work hand-in-hand with the National Weather Service Training Center (NWSTC) to help ensure training materials are accurate and up to date.

Weekly to daily discussions are held with the National Reconditioning Center (NRC) discussing repair techniques and best practices to ensure parts are repaired to achieve maximum reliability and quality

We routinely work with the National Logistics Support Center (NLSC) to ensure shipping materials are optimized to protect NEXRAD components from damage while being stored or in transit.

Routine Obsolescence

At any given time, this department is working multiple components to determine suitable substitutes or methods to repair existing components. At present we are in various stages of qualifying:

• Damper Motors
• AME Step Attenuator
• AME Chassis
• RF Pallet - Single and Redundant
• RF Generator
• A multitude of NEXRAD Test Equipment
• Fuel Level Sensor
• Signal Processor Interface Panel (SPIP) Subassemblies/Components
• Optical Encoder
• Azimuth Rotary Joint
• Trigger Amplifier
• Charging Switch
• 4PS1