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The RVP10 can operate both Magnetron-based Weather Radars and Weather Radars powered by Solid State Power Amplifiers (SSPA) relying on pulse compression. First radar systems incorporating the RVP 10 have been delivered.
This contribution presents the results from data quality assessments performed with the RVP10. These include a period of side-by-side operation with an RVP9 in split-signal setup, as well as stand-alone operation of the RVP10 in Vaisala’s WRM200 research Weather Radar.
The Radar Signal Processor RVP10
The RVP10 is a new design, incorporating state-of-the-art components and applying up-to-date methods and technologies. It delivers state-of-the-art security and is easy to update and maintain. The RVP10 features improved support for solid-state transmitters through pulse compression, hybrid pulsing, blending, and calibration. Its independent and parallel FIR filtering enables dual-pulsewidth and dual-frequency strategies on each receive channel.
Hardware Properties
The RVP10 consists of IF Digital Receiver IFDR10 and Signal Processor Server RVP10SRV. This new processing platform brings more range bins, better resolution, increased processing power, and flexibility to the post-processing. The flexible architecture provides modular, highly configurable hardware, and an open software design with public APIs.
The IFDR10 provides receive, transmit, I/O for trigger and other low-latency signal needs, and IF detector functionality in a single, compact network-attached FGPA-based product. The FPGA can perform up to 448 billion multiply/accumulate cycles per second. The IFDR10 samples up to 4 receive channels and 2 burst channels of IF inputs and computes I and Q data from them. The I and Q data is transmitted over 10 Gigabit Ethernet to the RVP10SRV signal processor for further processing into moments.
The RVP10SRV Signal Processor Server is a server class computer with a dual processor multicore Xeon processor running Linux. The RVP10SRV, running RDA software, computes the radar data moments from the I and Q data provided by the IFDR10. The moments can be distributed internally on the RVP10SRV or externally to other computers running IRIS or third-party software.
The RVP10 provides A/D and D/A conversion with a resolution of 16 bit at a sampling rate from 180 MHz to 240 MHz (software selectable). It features a dynamic range of up to 106 dB without compression and an IF range of 10 MHz to 120 MHz. The RVP10 allows for a pulse repetition frequency (PRF) between 50 Hz and 20 kHz. Its input saturation level is +12.0 dBm at 50 Ω.
Capabilities
The RVP10 allows for a wide range of sophisticated operation modes. These include Transmit Signal phase coding, Transmit Signal reversing and transmitting pulse groups. The RVP10 can transmit CW signals, as well as Linear FM (LFM) and Non-Linear FM (NLFM) signals, and allows sampling of the Transmit signal at the antenna.
The RVP10 allows a maximum pulse width of up to 200 microseconds, and range bin sizes varying from 15 m up to 600 m. The maximum number of range bins is either the full unambiguous range at minimum resolution or 8168 range bins per channel (whichever is less). The full unambiguous range can be up to 1024 km.
The RVP10 allows for various dual-polarization modes: alternating, simultaneous (STAR), H-only and V-only. Dual PRF velocity de‑aliasing ratios can be 2:3, 3:4, or 4:5 for 2X, 3X, or 4X velocity unfolding.
Data Quality
The data quality provided by the RVP10 has been assessed in two ways. Initially, an RVP10 has been operated in parallel with an RVP9, both connected to the same, equally split Receiving Signal from the Vaisala WRM200 Research Weather Radar. In a later phase, the RVP9 had been removed, and the Vaisala WRM200 Research Weather Radar was exclusively operated by the RVP10.
Intercomparison with Predecessor RVP9
An RVP10 has been operated in parallel to an RVP9 over a 4-month period for intercomparison purposes in the Vaisala WRM200 research Weather Radar at Kerava near Helsinki. Both Radar signal processors were supplied with the same signal from the radar front end. Consequently, the signal power, and hence the signal-to-noise ratio (SNR) at the signal processor inputs, was about 3 dB lower than normal.
In direct intercomparison, both signal processors showed a good match for the radar observables. This is shown for the observable Zh in Figures 1a (RVP9) and 1b (RVP10). It should be noted that SNR cut-off for the signal processors was slightly different, so RVP10 is displaying observations at ranges further away from the radar if compared to RVP9.
Stand-alone Assessment
Since January 2023, the Vaisala WRM200 research Weather Radar at Kerava near Helsinki is operated exclusively by an RVP10 radar signal processor. Assessments of the radar data quality in this configuration have been made for data from 24/04/2023, when non-freezing precipitation (light rain and drizzle) was recorded at the test field next to Vaisala’s headquarters in Vantaa near Helsinki. The results are shown in Figures 2a and 2b. The prior shows a narrow distribution of the differential phase ΦDP as expected for the prevailing rain intensities. The latter displays a narrow distribution for the correlation factor ρHV with a peak close to 1 and over about 85% of the cumulative distribution at values of ρHV > 0.96. The radar is earmarked for a hardware refurbishment with the goal to further improve data quality.
Conclusions
Vaisala’s new radar signal processor RVP10 marks a significant technical upgrade from its predecessor RVP9. It provides vastly improved capabilities. An RVP10 has been compared to a co-located RVP9 using split input signals from the Vaisala WRM200 research radar at Kerava. This showed identical returns for the radar observables. Subsequently, the radar data quality assessment of the Vaisala WRM200 research radar at Kerava exclusively operated by an RVP10 has shown good results.
Further details, and a more comprehensive data quality assessment, will be presented at the conference. This will include assessments from the intercomparison period that cannot be presented here due to space restrictions.
Supplementary URL: https://www.vaisala.com/en/products/weather-environmental-sensors/digital-receiver-signal-processor-rvp10
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