Basic devices in the car audio system

Entertainment in the form of music, news or even movies, generated from a series of audio devices found in a car. The series device known as a car audio system.

What tool or device contained in car audio system?

• Car Head Unit - Head unit is the core of a car audio system, part of the car audio system that plays sound. The continued development of technology makes the head unit is no longer only serve as a radio receiver FM / AM CD player and a player, some have additional functions to be able to play MP3s. There is also a car head unit that has the ability to play DVDs complete with monitors and can be connected with IPOD.
• Power Amplifier - The function of the power amplifier is to amplify the signal coming out of the head unit. In the world of various types of car audio power amplifiers are divided into several classes, such as class A, B, AB, and D. Each class power amplifier has the advantage that its usefulness can be tailored to our needs in building a car audio system. In addition to class division, the division of power amplifiers can also be seen from the number of channels (channels) and the amount of power generated by the power amplifier.
• Speaker - A device that functions convert electronic signals into audible sound. The speakers were divided into several parts / components, namely, subwoofers, woofers, mid-range, and tweeter. In order for speakers to work properly, required a series of electronic components that serves as a filter (cross over).
• Processor - With advances in technology processors play a significant role in a car system. Inside there is a processor features like time correction, cross-over-active, etc. equalizer. With the functions it will be very easy at the time of tuning car audioaudio system.

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Substation SCADA System – Design Guide

For electrical engineers, designing the Supervisory Control and Data Acquisition system (SCADA) for an electrical substation can be a daunting task, if not confusing with the different ways you can connect various Intelligent Electronic Devices (IED’s) based on protocols each device supports. This article serves to help you understand this system so you can design one as well.

SCADA system implements automation using two distinct functionalities. The first one is the supervisory control of the system and the second one is the data acquisition. Let’s begin with the data acquisition.

Data Acquisition

Breaker control relays, transformer monitoring devices, protection relays are just a few devices in a substation that monitor and gather data on the systems. Storing this data on the device itself serves no purpose. Considering the fact that most substations are automated and are left unmanned, transmitting this information to power grid control centers for control or engineering offices for system analysis, is the way to go.

The Remote Terminal Unit (RTU) panel in a substation control house serves to implement the data acquisition part by concentrating the data. It utilizes a data concentrating device that has lots of I/O ports on it. When connected to all the IED’s (in a star topology typically), this device polls them to gather the data and transmits it to a remote master and/or client server stations. I/O ports on modern concentrators are not just limited to serial RS232 ports, they come fitted with ethernet ports such as fiber ports and RJ45 ports (for CAT5 cable). These ports enable Internet Protocol (IP) based station LAN or WAN networks. See fig. 1 for some of the popular data concentrators in the power industry.

Fig.1 Substation SCADA and Gateway device for monitoring, control and telecommunication

 

Let’s move on to IED communication now. IED’s like a microprocessor relay transmits information like alarms, equipment status (of equipment it is monitoring), trip information, etc. to the RTU via its communication port. Specifying the right communication cable is the first step in setting up the communication path. To make these two devices actually “talk”, however, you will need to make two things happen.

1. Both the concentrator and the relay must speak the same language. Industry favorites are Modbus TCP/IP, Serial, and DNP3.0 with the latest being IEC 61850. In addition to these, some proprietary protocols like Mirrored Bits by Schweitzer can be used for communication provided only Schweitzer devices are used to build the network.
2. Configure the concentrator to locate the relay in the substation network. Map all the digital points in the relay that need to be polled.

Each IED that generates data which needs to be collected, needs to have a unique address assigned to each one of its data points. The data concentrator will then poll these data points and transmit the data to a remote master. Big substations like those classified as bulk power substations can have as many as 20,000 or more data points. With ever growing functions offered by modern microprocessor based relays, it is easy to pile-up on more and more data points for monitoring or control. Fortunately, with drag and drop functionality and standard data point templates of many IED’s, a modern data concentrator makes mapping of thousands of data points less burdensome for engineers.

Legacy SCADA systems, which you will likely come across in some old substations, have  the data points from various devices such as microprocessor relays, auxiliary relays, pilots relays, smoke detectors in the control room, etc. hardwired to the RTU’s digital status input boards. One advantage of this physical hardwiring is that it does not require mapping of the IED’s. However, as simple as it may seem, it is expensive to terminate every data point on the terminal blocks.

Supervisory Control

Among the available data points, only about 10% are utilized to implement some form of control function. To obtain this control input, data must be transmitted to a control center to elicit a supervisory response. This requires moving data on the WAN.  However, supervisory functions can be implemented locally using the concentrators powerful logic functions. When necessary they can be used to analyze system events and provide circuit breaking (in control circuits), interposing relay, or latching relay functionality.

 Data Concentrators as Gateway Devices

Data concentrating devices provide several additional capabilities. One of them is to serve as a gateway device. That is, any connection to a WAN system is made at only one point in the substation network and is made using this device alone. A gateway device does the following:

1. It sets up a firewall, keeping intruders away.
2. It provides a secure connection allowing secure data transmission adhering to NERC CIP requirements. Remote connection can be established via the internet using VPN, leased telephone lines (dial-up), wirelessly using a microwave tower, or via hardwired fiber.
3. It supports a whole host of protocols and protocol conversion capability. This lets remote users to communicate with IED’s that not only “speak” legacy Modbus or serial but also the new DNP3.0/IEC 61850 protocol or a device specific proprietary protocol.
4. It provides web based Human Machine Interface (HMI). Its built-in web server can serve one-lines of the substation to a remote user using a web browser.  If HMI is required inside the control room, additional devices like a display monitor, keyboard, and mouse should be installed in the RTU panel.

Since real estate is premium inside a control room, replacing legacy SCADA systems with the new data concentrator enables you to do more with less (footprint).

To Network or Not To Network

Creating a LAN using ethernet switches and putting all IED’s on this network makes the system susceptible to attacks. If this system controls a bulk power substation or some other critical asset then the network must be secured. Therefore, a virtual boundary around the network must be created such that any incoming request to access an IED inside the boundary, keeping in mind that the entry point is not just at the gateway device, must be verified. Maintaining an audit trail for both electronic and physical access may become necessary for such an asset. Therefore, creating a network is not just about bringing an IP network into the substation, it is just as important to secure it, both on WAN and LAN.

You can create a network without a station LAN. If the substation is small, you can connect all station IED’s directly to the data concentrator. No ethernet switches are required. Additional I/O ports on this device can be installed as necessary.

 Design Guide for Setting Up Your Own SCADA System

Design Guide for Building a Substation SCADA System

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Technology Spending Limits and the Auto Sound System

We live in a world that is constantly changing and evolving. We see it every time we buy a new car, a new television, or a new computer. We see it every other month when the iPod is putting out a new an improved model that offers more features, more disk space, and more everything, in a smaller package (well not since they added video but until then, the gadgets were getting smaller while the features were growing exponentially). The truth of the matter is that technology seems to be advancing at a rate that is nearly impossible to keep up with. That being said, you can quite literally drive yourself insane by trying to keep up with the pace of modern technology.

What you need to do in order to maintain proper sanity is decide on a level of technology that you are comfortable and confident with and go with it until it is time (by either necessity or desire) to upgrade. You do not have to be the first to purchase the latest and greatest in software and gadgetry (this has become my mantra: I do not have to be the first to own the great big bad new toy, I will survive gadget deprivation-it isnt working yet but Im ever the optimist). The point is that you do not need to be the first to try every new thing and you will not only wear yourself out by trying but also you bank account, credit cards, and second mortgage. Technology is expensive, especially the newest and latest. If there was any doubt stroll on over to Ebay and see how much Play Station 3s are selling for at the moment-madness and lunacy do not even begin to subscribe the amount of money people are offering to pay for these devices.

Technology is a wonderful thing. It makes life easier for some and a lot more entertaining for others. The same holds true with auto sound systems. The technology exists to make them much more beneficial to car and driver than they have been in the past while offering many more features than ever before. Today you arent even limited to AM and FM. You now have the option of CDs, audio books, MP3s, XML, and digital FM radio, which offers a few bonus features over traditional radio. It really doesnt matter if you have the absolute latest. Most of us can enjoy a great deal of the wonderful technology that is available if we are willing to wait long enough for the prices to go down. I recall, and it wasnt all that long ago, when DVD players sold for no less than $100. You can get them now (about 5 years later) on a regular basis for less than $30. This is only one example of many. PS2s were around $400 when they first hit the market and now can be bought at the whopping price of $120. All around us technology evolves and grows and then prices fall.

The point is spend your money where you want to spend it rather than where you think it should be spent. If you want an auto sound system then get the best one that you feel meets your budget requirements. You do not have to have the top system in the technology food chain in order to have a great sound system that will provide you with years worth of enjoyment. You are the only one that is responsible for the decisions you make. It is up to you to decide where you want the bulk of your money invested when it comes to technological gadgets and goodies. Believe me, Im a gadget geek. I love playing with new toys and gizmos and seeing how they work-really, for me its a thrill. At the same time I realize I cant always be the first to get the new toys I so desperately want to try out so I limit myself and decide which ones are the most important. You must do this for yourself when it comes to auto sound systems.

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