TEST & MEASUREMENT
Fig. 6 a & b: A comparison of the different BLE testing methods. Source: Rohde & Schwarz
The upcoming BLE test mode
Rohde & Schwarz is currently developing a signaling test
solution for BLE devices based on RF PHY test cases. The tests
are comparable with the RF test cases for Bluetooth Classic
devices and do not require a control cable. The BLE device and
the tester are wirelessly connected and in adaptive frequency
hopping mode. The test solution uses the same interface to
transmit both control commands and test data. The additional
control commands required for the signaling test mode are
simply transferred to the device (EUT) via a firmware update.
The different physical layers (LE1M, LE2M and LELR) can be
changed and tested. The same procedure applies to the packet
type, the payload and the parameters of the dirty transmitter
tests. Another highlight of BLE receiver testing is that the R&S
CMW can now determine the bit error rates (BER) in addition to
the packet error rates (PER). This makes the new BLE signaling
test mode highly interesting for various development tasks.
Overcoming a key automotive Ethernet system level test challenge
By TLee Morgan he move to advanced driver-assistance systems (ADAS),
smart safety systems and connected and autonomous
cars requires reliable in-vehicle networking and highbandwidth
connections. Cars can now contain as many as
100 electronic control modules (ECUs) connected to sensors
located around the car through multiple yards of cable harnesses.
Traditional automotive networks such as CAN, CAN-FD,
LIN, MOST, and FlexRay simply don’t provide the necessary
bandwidth to support all of the devices and applications found
in modern cars, much less the autonomous highly connected
cars of the future.
The need for greater performance and integration across vehicle
subsystems is driving an industry wide move to Automotive
Ethernet. Although the automotive standard has its origins
in Ethernet, it incorporates significant changes at the physical
layer to meet automotive requirements. The first version of the
standard was known as BroadR-Reach and is being supplanted
by the IEEE versions known as 100BASE-T1 (802.3bw) and
1000BASE-T1 (802.3bp).
The standard being designed into most cars today is
100BASE-T1, which supports 100 Mbps operation in the very
noisy automotive environment. This data rate is significantly
faster than traditional bus systems such as the CAN bus.
Future designs will use 1000BASE-T1, at 10X the data rate. As
signaling moves to higher data rates, so too does the need for
comprehensive design validation at the system level to ensure
interoperability and reliable operation across the many ECUs
and sensors; design considerations that were safely overlooked
in the past now start to matter.
To achieve greater signal bandwidth, Automotive Ethernet
uses a full-duplex communication link over a twisted pair
cable with simultaneous transmit and receive capabilities with
PAM3 signaling. Full-duplex communication with PAM3 signaling
can make visualization of Automotive Ethernet traffic and
signal integrity testing very complex. This article explores a new
method for overcoming a key challenge when testing full duplex
communications at the systems level, namely the need to cut
the cables to gain access to full duplex signals.
Why system-level testing?
Test specifications for Automotive Ethernet have been defined
by the OPEN Alliance for component, channel and interoperability,
encompassing integration of ECUs, connectors and
untwisted cables. In order to meet reliability requirements, testing
must be performed under the noisy conditions found within
the vehicle. This in turn requires the ability to characterize and
visualize signal integrity and traffic at the system level under
real-world conditions.
Some examples for where you might want to perform signal
integrity testing at the system level include:
• TC8 signal quality testing
• ECU component characterization and testing
• Automotive Ethernet cable, connector, cable length and routing
characterization and testing
• Electromagnetic susceptibility (EMS) testing or Gaussian
noise testing
• Bulk current injection testing
Lee Morgan is a Senior Technical Marketing Manager with
Tektronix – www.tek.com
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