Single Chip MM-Wave Radar

Damien Clarke - Senior Consultant, Data Exploitation

By: Damien Clarke
Lead Consultant

25th April 2019

4 minute read

Home » radar » Page 2

Recent advances in radar technology have led to the production of a range of inexpensive highly integrated single chip millimetre-wave radar sensors by Texas Instruments. These chips implement a Frequency Modulated Continuous-Wave (FMCW) radar operating at either 76 – 81 GHz or 60 – 64 GHz. This provides sufficient bandwidth to produce a range resolution of a few centimetres at the same time as measuring object velocities via Doppler shift. In addition, through the use of multiple transmitters and receivers Multiple-Input and Multiple-Output (MIMO) techniques can be used to measure the angular position of an object. With a suitable 2D antenna array it is possible to simultaneously measure both azimuth and elevation angles.

The processing power necessary to calculate the range, velocity and angles to multiple targets is also present within the chips. In the IWR6843, for example, this is achieved via a C674x DSP, an FFT hardware accelerator and an ARM R4F Microcontroller. This also enables the ability to perform object tracking within the chip. A single inexpensive chip can therefore continuously output a point cloud (object ID, range, azimuth, elevation and radial velocity) of multiple unique objects present in the scene.

A common application for such radar sensors is the detection of moving vehicles at a distance. The video below shows an example of two cars driving towards and then away from a radar placed above the road. Raw data is extracted from the chip and processed to emulate what would normally occur within the chip. The left hand chart shows a Range-Doppler map where the two vehicles are clearly detected at all ranges. All static objects have been removed from this image to more clearly reveal moving objects. The central plot shows those range-Doppler cells which are determined to contain non-background objects (i.e. cars). The right hand plot then calculates the 2D position (in metres) of the two cars. Note that a car will produce multiple radar echoes (i.e. radiator, wing mirror, tires, number plate, etc) at different ranges and therefore a cluster of detected points are produced from each car.

The ability of such a sensor to directly output a processed point cloud enables a wide range of possible applications at a low cost. These include the following:

    • Advanced driver-assistance systems (ADAS)

 

    • Autonomous ground vehicles

 

    • Unmanned Air Vehicles (UAV)

 

    • Traffic monitoring

 

    • Pedestrian and people counting

 

    • Intruder detection

 

    • Vital signs detection

 

    • Gesture recognition

 

    • Fluid level sensing

 

Creating a new product using a Texas Instruments mm-wave radar chip requires development in several areas. Firstly, as with all FMCW radar it is necessary to understand what radar configuration to use to achieve the desired data output parameters, i.e. range resolution, max range, velocity resolution, etc. It is also necessary to modify the processing chain implemented on the chip to optimise the performance. Hardware changes will also be required, in particular the design and manufacture of a suitable mm-wave antenna array is of key importance. This will have several effects, but commonly this is used to increase the maximum detection range. Finally, it is also necessary to produce an electronics design for the additional components which must be integrated with the radar chip to create a final product.

Recent advances in radar technology have led to the production of a range of inexpensive highly integrated single chip millimetre-wave radar sensors by Texas Instruments. These chips implement a Frequency Modulated Continuous-Wave (FMCW) radar operating at either 76 – 81 GHz or 60 – 64 GHz. This provides sufficient bandwidth to produce a range resolution of a few centimetres at the same time as measuring object velocities via Doppler shift. In addition, through the use of multiple transmitters and receivers Multiple-Input and Multiple-Output (MIMO) techniques can be used to measure the angular position of an object. With a suitable 2D antenna array it is possible to simultaneously measure both azimuth and elevation angles.

The processing power necessary to calculate the range, velocity and angles to multiple targets is also present within the chips. In the IWR6843, for example, this is achieved via a C674x DSP, an FFT hardware accelerator and an ARM R4F Microcontroller. This also enables the ability to perform object tracking within the chip. A single inexpensive chip can therefore continuously output a point cloud (object ID, range, azimuth, elevation and radial velocity) of multiple unique objects present in the scene.

A common application for such radar sensors is the detection of moving vehicles at a distance. The video below shows an example of two cars driving towards and then away from a radar placed above the road. Raw data is extracted from the chip and processed to emulate what would normally occur within the chip. The left hand chart shows a Range-Doppler map where the two vehicles are clearly detected at all ranges. All static objects have been removed from this image to more clearly reveal moving objects. The central plot shows those range-Doppler cells which are determined to contain non-background objects (i.e. cars). The right hand plot then calculates the 2D position (in metres) of the two cars. Note that a car will produce multiple radar echoes (i.e. radiator, wing mirror, tires, number plate, etc) at different ranges and therefore a cluster of detected points are produced from each car.

The ability of such a sensor to directly output a processed point cloud enables a wide range of possible applications at a low cost. These include the following:

    • Advanced driver-assistance systems (ADAS)

 

    • Autonomous ground vehicles

 

    • Unmanned Air Vehicles (UAV)

 

    • Traffic monitoring

 

    • Pedestrian and people counting

 

    • Intruder detection

 

    • Vital signs detection

 

    • Gesture recognition

 

    • Fluid level sensing

 

Creating a new product using a Texas Instruments mm-wave radar chip requires development in several areas. Firstly, as with all FMCW radar it is necessary to understand what radar configuration to use to achieve the desired data output parameters, i.e. range resolution, max range, velocity resolution, etc. It is also necessary to modify the processing chain implemented on the chip to optimise the performance. Hardware changes will also be required, in particular the design and manufacture of a suitable mm-wave antenna array is of key importance. This will have several effects, but commonly this is used to increase the maximum detection range. Finally, it is also necessary to produce an electronics design for the additional components which must be integrated with the radar chip to create a final product.

Further Reading

EW BrightSpark, James Henderson One Year On

James Henderson - Consultant, Antennas & Propagation

By: James Henderson
Consultant, Antennas & Propagation

27th February 2019

Home » radar » Page 2

Following the BrightSparks award ceremony in May last year, most of my work has been on developing an electronically-scanned radar unit operating at mm-wave frequencies, applicable to autonomous ground and air vehicle monitoring and control. This has been a particularly interesting and challenging project as the design has been driven by a demanding requirement to create a small, low power, high performance sensor.

The key area of innovative design that I am particularly proud of is combining two 48-element antenna arrays on to the same PCB as the electronic circuitry. To achieve a low cost, the arrays are realised through a combination of 3D printing and PCB techniques.

This development posed many technical challenges owing to the often conflicting PCB-related requirements of antenna and RF circuitry. However, integration and performance benefits make this approach worthwhile.

System calculations

Initial work on this project required comprehensive system calculations to exactly understand the design requirements. System level planning is informative when determining how to distribute the required tasks.

Often, a number of subsystems could potentially solve the same technical challenge but only when looking at the problem as a whole can you assess how the elements of the system can best work together.

Scanning the radar beam

A key aspect of the design was how to scan the radar beam. In a previous project the antennas were mechanically moved to build up a 3D view of the scene. In contrast the new requirement was to scan the antenna beams electronically, which has many advantages over mechanically scanned systems. Electronic beamforming can be implemented digitally, at the analogue front end, or even within the antennas themselves.

In this design, the scanning mechanism was an integral part of the antenna array, which significantly simplifies other aspects of the system leading to a small sensor having low power consumption. However, this approach required lateral thinking when designing and constructing the PCB to achieve the target performance. For the first iteration of the design the electronics worked as intended, but the antenna performance was lower than expected.

Further investigation revealed the reason for the drop in performance and emphasised the many and varied challenges associated with working at mm-wave frequencies.

Special Interest

The second design iteration gave performance closely matched to my system calculations. This confirmed that the design operated as intended, which was extremely satisfying.

This whole process has exposed me to some particularly interesting design work and has consequently encouraged me to initiate a Special Interest Group within Plextek that specialises in the design and development of mm-wave electronic systems.

Following this project I expect to see substantial interest in operating at mm-wave bands, enhancing the capability of mm-wave circuits and I’m excited to be working with these cutting-edge technologies in the future.

The CEO of Plextek, Nicholas Hill, added:

“BrightSparks is a fantastic way to show your employees’ work is valued. It’s so important to get young people enthusiastic about their engineering careers and award recognition is a great motivational boost. The BrightSparks award last year won by James Henderson was well deserved and he has continued to shape his engineering career by contributing to key company projects here at Plextek.”

Following the BrightSparks award ceremony in May last year, most of my work has been on developing an electronically-scanned radar unit operating at mm-wave frequencies, applicable to autonomous ground and air vehicle monitoring and control. This has been a particularly interesting and challenging project as the design has been driven by a demanding requirement to create a small, low power, high performance sensor.

The key area of innovative design that I am particularly proud of is combining two 48-element antenna arrays on to the same PCB as the electronic circuitry. To achieve a low cost, the arrays are realised through a combination of 3D printing and PCB techniques.

This development posed many technical challenges owing to the often conflicting PCB-related requirements of antenna and RF circuitry. However, integration and performance benefits make this approach worthwhile.

System calculations

Initial work on this project required comprehensive system calculations to exactly understand the design requirements. System level planning is informative when determining how to distribute the required tasks.

Often, a number of subsystems could potentially solve the same technical challenge but only when looking at the problem as a whole can you assess how the elements of the system can best work together.

Scanning the radar beam

A key aspect of the design was how to scan the radar beam. In a previous project the antennas were mechanically moved to build up a 3D view of the scene. In contrast the new requirement was to scan the antenna beams electronically, which has many advantages over mechanically scanned systems. Electronic beamforming can be implemented digitally, at the analogue front end, or even within the antennas themselves.

In this design, the scanning mechanism was an integral part of the antenna array, which significantly simplifies other aspects of the system leading to a small sensor having low power consumption. However, this approach required lateral thinking when designing and constructing the PCB to achieve the target performance. For the first iteration of the design the electronics worked as intended, but the antenna performance was lower than expected.

Further investigation revealed the reason for the drop in performance and emphasised the many and varied challenges associated with working at mm-wave frequencies.

Special Interest

The second design iteration gave performance closely matched to my system calculations. This confirmed that the design operated as intended, which was extremely satisfying.

This whole process has exposed me to some particularly interesting design work and has consequently encouraged me to initiate a Special Interest Group within Plextek that specialises in the design and development of mm-wave electronic systems.

Following this project I expect to see substantial interest in operating at mm-wave bands, enhancing the capability of mm-wave circuits and I’m excited to be working with these cutting-edge technologies in the future.

The CEO of Plextek, Nicholas Hill, added:

“BrightSparks is a fantastic way to show your employees’ work is valued. It’s so important to get young people enthusiastic about their engineering careers and award recognition is a great motivational boost. The BrightSparks award last year won by James Henderson was well deserved and he has continued to shape his engineering career by contributing to key company projects here at Plextek.”

 

 

Further Reading

Plextek and Wave Tech Partner to Revolutionise Airport Runway Safety

Nick Koiza, Head of Security Business features in ‘Counter Terror Business’ magazine this week. He discusses Plextek’s recent collaboration with RF signal technology company, Wave Tech on a foreign object debris detection radar that has the potential to save lives.

To read the full article on page 10 please click here.

For more information, contact Nick via nicholas.koiza@plextek.com

By Marcus C. Walden

Abstract: This paper describes the design and characterization of a frequency-scanning meanderline antenna for operation at 60 GHz. The design incorporates SIW techniques and slot radiating elements. The amplitude profile across the antenna aperture has been weighted to reduce sidelobe levels, which makes the design attractive for radar applications. Measured performance agrees with simulations, and the achieved beam profile and sidelobe levels are better than previously documented frequency-scanning designs at V and W bands.

Read more…

Millimetre Wave Radar: A New Skyline for Autonomous UAS

Millimetre Wave Radar: A New Skyline for Autonomous UAS

James Henderson - Consultant, Antennas & Propagation

By: James Henderson
Consultant, Antennas & Propagation

23rd August 2017

Home » radar » Page 2

When people talk about what technology is going to be available in the future, most 10-year-olds will imagine a world where we’re all flying around with jet packs on our backs, or being waited on by Humanoid robots. But as an engineer involved in cutting-edge technology, I like to think about a more realistic short-term answer to such a question.

One of the biggest developments over the past decade has been in enabling the autonomy of road vehicles and, whilst various technology companies are promising self-driving cars in the near future, the smaller step of driver aids has become the norm for modern cars. As with most large scale industry advances where huge sums of money are invested in their development, new technologies often open up opportunities to other industries.

This has certainly been the case with the development of cheap millimetre wave (mm-wave) devices. These have come off the back of automotive radar modules for adaptive cruise control and automatic braking assistance. But rather than looking for large vehicles in lanes on the motorway, there are many alternative applications for a mm-wave radar sensor, both for use in civil and military scenarios.

For me, the futuristic application which this enables is that Unmanned Aerial Systems (UAS) could soon be the common method for automatically delivering all manner of items. From completing takeaway meal orders to medi-kit drops for personnel on the front line – I may not be alone in having this vision but I can say that I’ve played a part in their development.

However, enabling the ability of autonomous flight for small UAS is not a trivial task. There are many difficulties involved with allowing swarms of UAS to safely navigate through the concrete jungle of an urban environment. They would need to avoid buildings, power lines, trees, and potentially other UAS on different errands.

This is especially difficult in a military context, where the environment could be hostile, complex and contested. Operations can take place day, night and in all weather conditions – this would be the case for the last mile resupply requirement (as stated in this most recent Defence and Security Accelerator competition).

For both scenarios, this requires a 3-dimensional situational awareness by detecting small objects, potentially out to hundreds of metres with a level of positional accuracy to allow a fast moving UAS to navigate through a cluttered environment. In this scenario, a low size, weight and power sensor is critical to its success, and pushing radar to operate at mm-wave frequencies could be the solution.

More often than not, radio engineers choose to go up in frequency to utilise the large amounts of available bandwidth, particularly for communication systems where users are demanding ever increasing data rates, but for this application, there’s another advantage. For high definition radar to achieve small angular resolution, the antenna needs to be large with respect to the wavelength. Therefore, increasing the frequency (which will reduce the wavelength) allows us to keep the same resolution in a smaller size.

At Plextek, we have been capitalising on the small wavelength of these mm-wave devices to design a complete radar front end on a single 10 x 10 cm circuit board. This minimises size and weight, but also system complexity, where transmit and receive antennas are inherently aligned on a flat panel.

There are many difficulties with working at higher mm-wave frequencies which primarily come from the increased precision required in every aspect of the design, as well as handling the higher loss associated with high-frequency systems. But the extra effort required is sure to be worth it if it means the Poppadoms in my Indian take away are still warm when they arrive cradled underneath an autonomous UAS. Or those vital supplies are delivered efficiently to personnel engaged in combat operations to maintain operational tempo and enable successful mission outcomes.

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When people talk about what technology is going to be available in the future, most 10-year-olds will imagine a world where we’re all flying around with jet packs on our backs, or being waited on by Humanoid robots. But as an engineer involved in cutting-edge technology, I like to think about a more realistic short-term answer to such a question.

One of the biggest developments over the past decade has been in enabling the autonomy of road vehicles and, whilst various technology companies are promising self-driving cars in the near future, the smaller step of driver aids has become the norm for modern cars. As with most large scale industry advances where huge sums of money are invested in their development, new technologies often open up opportunities to other industries.

This has certainly been the case with the development of cheap millimetre wave (mm-wave) devices. These have come off the back of automotive radar modules for adaptive cruise control and automatic braking assistance. But rather than looking for large vehicles in lanes on the motorway, there are many alternative applications for a mm-wave radar sensor, both for use in civil and military scenarios.

For me, the futuristic application which this enables is that Unmanned Aerial Systems (UAS) could soon be the common method for automatically delivering all manner of items. From completing takeaway meal orders to medi-kit drops for personnel on the front line – I may not be alone in having this vision but I can say that I’ve played a part in their development.

However, enabling the ability of autonomous flight for small UAS is not a trivial task. There are many difficulties involved with allowing swarms of UAS to safely navigate through the concrete jungle of an urban environment. They would need to avoid buildings, power lines, trees, and potentially other UAS on different errands.

This is especially difficult in a military context, where the environment could be hostile, complex and contested. Operations can take place day, night and in all weather conditions – this would be the case for the last mile resupply requirement (as stated in this most recent Defence and Security Accelerator competition).

For both scenarios, this requires a 3-dimensional situational awareness by detecting small objects, potentially out to hundreds of metres with a level of positional accuracy to allow a fast moving UAS to navigate through a cluttered environment. In this scenario, a low size, weight and power sensor is critical to its success, and pushing radar to operate at mm-wave frequencies could be the solution.

More often than not, radio engineers choose to go up in frequency to utilise the large amounts of available bandwidth, particularly for communication systems where users are demanding ever increasing data rates, but for this application, there’s another advantage. For high definition radar to achieve small angular resolution, the antenna needs to be large with respect to the wavelength. Therefore, increasing the frequency (which will reduce the wavelength) allows us to keep the same resolution in a smaller size.

At Plextek, we have been capitalising on the small wavelength of these mm-wave devices to design a complete radar front end on a single 10 x 10 cm circuit board. This minimises size and weight, but also system complexity, where transmit and receive antennas are inherently aligned on a flat panel.

There are many difficulties with working at higher mm-wave frequencies which primarily come from the increased precision required in every aspect of the design, as well as handling the higher loss associated with high-frequency systems. But the extra effort required is sure to be worth it if it means the Poppadoms in my Indian take away are still warm when they arrive cradled underneath an autonomous UAS. Or those vital supplies are delivered efficiently to personnel engaged in combat operations to maintain operational tempo and enable successful mission outcomes.

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Further Reading