# Towards mmWave Altimetry for UAS: Exploring the Potential of 77 GHz Automotive Radars
## 3 State of the Art, Regulation, Opportunities, and Challenges
### Rationale for Chipset Selection  
Renowned automotive radar modules are being manufactured by Bosch, Delphi, Toyota, Continental, Fruno, and Denso. There have been some valuable comparative studies on these radar modules [40; 47]. However, these systems offer relatively higher levels of abstraction and, therefore, are not a good candidate for academic research. Moreover, they are expensive since they are poised to serve plug-and-play applications. A state-of-the-art review was conducted as part of the Arctic challenge to compare the radar sensors available in the market [48]. The review summarized that amongst the solutions available on the market, the RFCMOS single-chipset architecture offers the lowest level of abstraction with computational resources available on the chip to host customized software.  
In line with the benefits and flexibility being offered by the radar-on-chip architecture, numerous manufacturers have entered this market. This flexibility to orchestrate customized waveforms allows for the accumulation of short-range, medium-range, and long-range radars into a single chip by leveraging the chirp parameters, signal processing, and beamforming techniques. This dynamic range offering aligns perfectly with the operational requirement of UAS altimetry throughout the flight operation. Manufacturers of these radars include Analog Devices, Infineon, NXP, Texas Instruments, and ST Microelectronics. The body of this work is based on the Texas Instruments IWR1843 [49]. The rationale behind this decision lies in its exceptional features, rich literature, and community support. Boasting a two-dimensional antenna array, equipped with DSP, MCU, HWA, and a complex baseband architecture with the highest sampling rate among all available sensors in the Texas Instruments repertoire, IWR1843 stands out. Additionally, it offers the largest on-chip memory. These specifications hold relevance from the perspective of future work. The associated discussion concerning signal processing and dynamic testing is covered in Section 6. Nevertheless, choosing the most appropriate chipset at the early stages of a project is bound to ensure long-term dividends.  
It is crucial to note that, at the time this article is being published, the dynamic nature of technological advancements may bring new sensors on the horizon. A review of recent advances in mmWave radar sensors offered a comparison of complete radar systems and single-chipset transceivers in a common table [8]. This served as a good repository for a comparison of the specifications but offered little insight apropos the efficacy for a specific use case. To this end, there is no comprehensive state-of-the-art survey concerning the performance comparison of chipsets available in the industry for the specific application of UAS altimetry. As such, this article disclaims any assertion of conducting a comprehensive comparison of all the mmWave radar chipsets available on the market. Instead, the study aims to select the most suitable sensor while considering its hardware constraints as a limitation and strives to derive performance metrics for the intended use case.