Second Hand Car Audio & Gps Items | Second Hand Electrical Appliances & Items

Entertainment systems and, to a lesser degree, satellite navigation systems installed "as standard" by vehicle manufacturers have definitely improved, in recent years. That is not to say, however, that there is no longer scope for addition, or improvement, to these systems. Vehicle manufacturers, inevitably, must concentrate on keeping the cost to the consumer of a car, or other vehicle, as low as possible, and many "factory" systems are basic in design, as a consequence. Operability should be a byword for car entertainment, and GPS, systems, and is essential to the safety of a driver, and his, or her, passengers. Poor design can result in unnecessary distraction from the road, itself, attention to which is the primary responsibility of any driver. It is also pleasing, of course, to have a choice of systems, rather than being restricted to those provided by a vehicle manufacturer.

Car Audio Systems
The "head unit" the portion of a car audio system mounted in the dashboard console, typically including an AM/FM, or DAB ("Digital Audio Broadcast"), radio receiver, a CD, and/or a DVD player, a graphic equalizer, etc. provides overall control of an audio system, including external components, such as amplifiers and CD changers. The problem with most factory head units is that they do not provide line level, or RCA short for "Radio Corporation of America", a "plug and jack" connector for coaxial cable outputs, and therefore cannot supply a clean signal to an external amplifier. If you do want to use a so-called "aftermarket" amplifier, you will need a head unit with RCA output connectors.

On the subject of amplifiers, an amplifier is a device that receives audio signals from your head unit, and boosts them sufficiently to drive the loudspeakers in your car. The best results are achieved if you employ separate amplifiers for low and high frequency signals, but this is not absolutely necessary. In fact, many drivers choose an amplifier for low frequency, bass signals, and allow the head unit, itself, to amplify high frequency signals. This often provides a satisfactory compromise, at all but the highest volume levels.

A common problem in car audio systems is the matching of an amplifier to the loudspeakers that it is intended to drive, and, more often than not, problems are caused by using an amplifier that is too weak, in relation to its speakers. Many people make the mistake of assuming that more speakers mean a louder system, overall, but the power of a system is determined largely by its amplifier(s), not its speakers. To compensate for lack of wattage in an amplifier, the volume is cranked up, the amplifier reaches its limit, and the end is result is loud, but horribly distorted, sound. Quality, rather than quantity, is important when it comes to choosing car audio speakers, and, as is often the case, you do tend to get what you pay for. Fewer, high quality loudspeakers is likely to be a better investment than more, less sophisticated and, therefore, cheaper speakers.

Car GPS Systems
For the uninitiated, GPS stands for "Global Positioning System", and refers to a constellation of satellites in orbit above the Earth, each of which transmits low power radio signals that can be received by a GPS receiver located in a car, or elsewhere, on the surface of the Earth. GPS satellites constantly broadcast information about their location, and by calculating how far it is based on the time that it takes for signals to arrive from 3, or 4, different satellites a GPS receiver can, by using a process known as "triangulation", determine its exact position on the surface of the Earth, usually to within a few metres.

Technical capabilities aside, the interface of a GPS navigation device the part of the device at which a driver looks, and with which he, or she interacts is the critical component, if you consider that it needs to be viewed, or operated, at potentially high speeds. Many of the better GPS interfaces take their inspiration from mobile phone interfaces. They are largely symbol based, with icons that are large enough to be readily identified, and textual information is limited to that which is useful current street, or road, name, distance to next turn, and so on but, nevertheless, easy to read. Maps which are undoubtedly useful for plotting progress along a route should equally be bright, and easy to read, at a glance.

The main purpose of any GPS navigation system, of course, is to direct you to your chosen destination. Complementary functions such as "Points of Interest", or "POI" which may, incidentally, include sights and attractions along a route, as well of more mundane parking and service station information, for example have their place, but should be positioned in such a way as not to interfere with this primary function.

So-called "differential" GPS, or DGPS, for short, is a desirable feature, and allows a GPS receiver to determine its position even more accurately. Fixed DGPS stations, on the ground, are capable of calculating any errors in signals received from GPS satellites, and broadcasting these errors to any GPS receivers within range. This means that a car GPS device, equipped with DGPS, can calculate its own position very accurately indeed