Tag Archives: Comparison

Which are Better – Round Cables or Flat Cables?

Both types of cables are available in the market—round ones and flats, and people use them according to the requirements of the application. As round cables were the first to arrive on the market, the industry has been using them as standard for long, in applications ranging from renewable energy to automation and manufacturing in general.

Flat cables arrived late on the scene, and offer a niche solution presently. However, they are gaining ground steadily for applications within the civil-aircraft markets, semiconductor industry, medical field, and for supplying data and power to machines. Flat cables are also called festoon cables, and the overhead crane companies actively use them for applications where winding cables around spools is difficult.

Comparison of Electrical Performance

The protection for internal EMI depends heavily on the construction of the cable. In general, flat cables do not transfer data very well. Individual shielded pairs within flat cables are necessary to provide coupling and crosstalk protection from pair to pair.

Most shielding materials to not hold a flat format and tends to become round. This makes it difficult to place a shield on the flat cable overall. This also makes it difficult to protect and shield a flat cable from the effects of external EMI. The naturally round shielding tendency provides greater protection against influences of external EMI on round cables.

The length of a cable, its quality of insulation, and the resistance of its conductors determines the voltage drop or attenuation on a power cable and this is immaterial whether the cable is round or flat. In both cases, higher quality of insulation and proper positioning of the ground wire improves the attenuation. Certain industries demand very high-performance (low attenuation and crosstalk) flat cables. With proper shielding, it is possible to transmit both power and signals through the same cable.

Comparison of Mechanical Performance

Cables in the industry face mechanical stresses of four main types—S-bend, rolling flex, tic-toc, and torsion. The natural capability of being able to move in multiple axes at the same time makes round cables capable of withstanding all the stresses. For instance, round cables can flex 30 million times in certain applications. On the other hand, flat cables can withstand only rolling flex, as the movement is only in one linear axis.

Movements in several axes such as during torsion can lead to flat cables binding, or twisting beyond a certain point. When under torsional loads, flat cables can spool and twist over a certain length. Preventing this requires every component of a flat cable to be integrated at the right position and twist. It also requires the cable to be embedded or wrapped with a PTFE (Teflon) tape for minimizing the frictional forces during torsion.


Round cables can maximally utilize the space inside the smallest required cross-sectional area. Drilling a round hole is easier than cutting a rectangle. Therefore, most machine or panel openings use round cables where using a flat cable may be more difficult, as it has an elongated cross-section. However, it is possible to stack flat cables to make them fit together in a smaller space than it is with round cables.

Android vs. Linux – Which OS is better?

Is Android A Better OS Than Linux?

Android has established itself as an important operating system for mobile devices. Google developed Android as an open source OS based on the Linux kernel. Google selected the Linux kernel because of its proven driver model, existing drivers, process and memory management, networking support and several other core operating system services. However, the Google team had to make several changes to make Android capable of operating mobile devices successfully. Differences with standard Linux are highlighted here.

The target architecture

Although the Linux kernel supports several architectures, right now, Android supports only two: ARM and x86. The ARM platform is more prevalent on mobile phones while the Android-x86 targets mainly the Mobile Internet Devices or MIDs used for general-purpose desktop/laptop/server computing systems. This being the fundamental difference between the two Operating Systems, it provides a strong insight into further divergence between the two.

Modifications in the kernel

Android does not use the standard Linux kernel straightaway, but uses it with some enhancements. These include alarm driver, shared memory driver, inter-process communication interface, power management, low memory killer, kernel debugger and logger. Google has contributed all the kernel enhancements back to the open source community under GPL.

Bionic C library

The GNU C library used by most Linux distributions makes use of the Native POSIX Thread Library or NPTL, which offers high performance, especially in server applications. However, disk space footprint and memory requirements of NPTL are far too large for resource-limited systems such as mobile devices.

This led Google to create a new C library called Bionic. It has fast execution paths, avoids edge cases and remains a simple implementation. As mobile devices are single user systems, for security reasons Google has removed the settings for groups and passwords, keeping only a unique user id and group id. Bionic operates with the limited CPU and memory resources available on Android platforms.

The Dalvik Virtual Machine

Android uses a virtual machine to run applications. Most top cell manufacturers such as Samsung, Motorola and Nokia use J2ME, a mobile optimized version of the Java virtual machine. In contrast, Android uses the Dalvik Virtual Machine, which is a standard Java platform. The dex files used by Dalvik are more compact and optimized to perform well on mobile devices with slow CPUs, limited memory, no swap space and limited battery power.

File system

Most desktop/laptop/server applications use magnetic hard disks, which the standard Linux systems manage with the latest Ext journaling file system. However, magnetic drives are physically too large, too fragile and consume too much power. To provide a robust file system, embedded systems use solid-state memory devices such as NOR for code execution and NAND for storage. Block erasure and memory are important features of solid-state memory, which the Ext file system does not handle. Therefore, Android uses an optimized Linux flash file system called YAFFS and this deals with lifetime limitations, bad block management and error correction for maintaining data integrity in NAND flash systems.

Power management

Standard Linux systems manage power though APM or ACPI. Android does not use either, relying more on its own PowerManager module, which is a Linux power extension. The module has low-level drivers for controlling the peripheral supported such as screen display and backlight, keyboard backlight and button backlight.