Satellite constellation
The arrangement in space of a set of satellites. Scale
The distance on a map that corresponds to the same points on the earth. SDRAM (Synchronous DRAM)
A type of DRAM designed to deliver bursts of data at very high speeds using automatic addressing, multiple page interleaving, and a synchronous (or clocked) interface. SDRAM can support bus speeds of up to 100MHz today and will probably support bus speeds of up to 200MHz in the future. Search The Sky
A message shown when a GPS receiver is gathering satellite almanac data. This data tells the GPS receiver where to look for each GPS satellite. Secure Digital card (SD card)
These cards combine high storage capacity, rapid data transfer, flexibility and security — all in a card sized no larger than a postage stamp. SD memory cards keep digital files secure for distribution, and are also easy to reformat, making them ideal for a wide variety of uses. The cards also hold a variety of file types, so they're as versatile as they are small. Selective Availability (S/A)
A policy adopted by the Department of Defence to introduce some intentional clock noise into the GPS satellite signals thereby degrading their accuracy for civilian users. S/A limited the accuracy of civilian GPS systems to 300 feet or less 95% of the time. This policy was discontinued as of 1st May 2000 and now SA is turned off. Sequential Receiver
GPS receiver in which the number of satellite signals to be tracked exceeds the number of available receiver channels. This type of receiver must sequentially step between channels to track satellites. Serial port
This is the Port">communications port on your computer; it's also called the COM or RS-232 port. It's called serial because, although it has nine pins and many wires, the PC sends data on only one wire and receives data on one other wire. All the data bits have to follow one another on the single wire, as opposed to the parallel port, where eight separate wires transfer each bit of a byte. Short Message Service (SMS)
(also called text messaging) A function available on digital GSM networks allowing text messages to be sent and received via the network operator to a mobile phone, or from the Internet, using an “SMS gateway” website. Signal to Noise Ratio (SNR)
The ratio of incoming signal strength to the amount of interfering noise as measured in decibels on a logarithmic scale. Sim (Subscriber Identity Module) Card.
A smart card used in the GSM system and stored inside a GSM phone. The SIM contains, among other things, subscription-related information and identification data for authentication and billing purposes. Sim Free
Sim free products are not sold with Sim cards. They are compatible with any Sim card and do not require any additional programming or add-ons. SiRFstarIII
With its rapid time-to-first-fix and high sensitivity, the SiRFstarIII architecture is designed to meet the rigorous demands of wireless and handheld LBS applications, and provides superior location performance, both indoors and out, for 2G, 2.5G, 3G asynchronous networks.The SiRFstarIII architecture packs a performance punch, achieving time-to-first-fix of one second for aided starts in outdoor GSM environments and acquiring signals down to -159 dBm. This makes real-time navigation practical, including in many indoor environments, through urban canyons, and under dense foliage. Unlike the lengthy sequential search process of traditional GPS architectures, the SiRFstarIII architecture, with the equivalent of more than 200,000 correlators, enables fast and deep GPS signal search capabilities, resulting in significant improvement over today’s architectures that contain a few hundred to a few thousand correlators. SiRFXTrac
Complimenting SiRF's existing product line of GPS solutions, SiRFXTrac is a high sensitivity GPS software solution. SiRFXTrac extends the operating range in which GPS can be used - dramatically increasing the versatility of GPS-enabled products such as PDA)">personal digital assistants (PDA's), automotive navigation solutions, AVL applications, and other location aware consumer devices.If loaded with SiRFXTrac high sensitivity software, GPS-enabled mobile consumer devices will be able to continue operating in far more locations than ever before possible. Sleeve
An attachment for a PDA which allows you to use items like network or modem cards, PCMCIA or CF cards, digital cameras, a GPS/GPRS phone, or an extra battery pack with a PDA. Slow switching channel
A sequencing GPS receiver channel that switches too slowly to allow the continuous recovery of the data message. Smart Card
A credit card or SIM card sized plastic card with an embedded microcircuit that contains memory, a microprocessor and an operating system controlling the use of the data or applications stored in the memory. A smart card is a secure storage place for confidential information. The most common smart card is the SIM card used in mobile phones. Smartphone
A smartphone is generally considered any handheld device that integrates personal information management (PIM) and mobile phone capabilities in the same device. Often, this includes adding phone functions to already capable PDAs or putting "smart" capabilities, such as PDA functions, into a mobile phone. Software
A program or set of instructions that controls the operation of a computer. Distinguished from the actual hardware of the computer. Space Based Augmentation System (SBAS)
Any system that uses a network of geostationary satellites and ground stations to enhance the performance of a Global Navigation Satellite System (GNSS) by providing signal corrections and additional satellites with known and constant positions. Space Segment
The satellite portion of the complete GPS system. Speed Over Ground (SOG)
The speed at which the GPS unit and the person operating it are moving with respect to the earth's surface(ignoring tidal and current activity). Spherical Error Probable (SEP)
A measure of accuracy in navigation. The radius of a sphere within which there is a 50 percent probability of locating a point or being located Speaker
Sounds alarms, ringtones and plays back sound recordings. Speed Made Good (SMG)
Required speed to destination given the current course. Spoofing
The deliberate transmission of fake signals to skew the position calculations of a GPS receiver. The spoofer mimics a GPS satellite, rather like a pseudolite, but with disruptive intent. Spread-Spectrum
The received GPS signal is wide bandwidth and low power. The L-band signal is modulated with a pseudo-random noise code to spread the signal energy over a much wider bandwidth than the signal information bandwidth. This provides the ability to receive all satellites unambiguously and to give some resistance to noise and multipath. Static Positioning
Location determination when the receiver’s antenna is presumed to be stationary on the earth. This allows the use of various averaging techniques to greatly improve accuracy. Standard Positioning Service (SPS)
The GPS single receiver (stand-alone) positioning service available to any user on a continuous, worldwide basis. It is intended to provide access only to the C/A-code and the L1 carrier. Statute Mile
A unit of length equal to 5,280 feet or 1609 metres Straight-Line Navigation
The act of going from one waypoint to another in the most direct line and with no turns. StrongARM
A family of high-performance RISC-based microprocessors from Intel. StrongARM chips are used in handheld devices such as PDAs and palmtops. The StrongARM technology was jointly developed by Digital Equipment Corporation and Advanced RISC Machines (ARM). In 1997, Intel acquired Digital's chip manufacturing facilities and continues to make the Alpha and StrongARM chips. Stylus
A stylus is a pointing object that you use to navigate on a touchscreen. It works in a similar way to a mouse or trackball. Synchronous
Refers to events that are synchronised, or co-ordinated, in time. Communication within a computer is usually synchronous and is governed by the microprocessor clock. Signals along the bus, for example, can occur only at specific points in the clock cycle. Symbian
Symbian OS (formerly EPOC) owned by Ericsson, Panasonic, Nokia, Samsung, Siemens and Sony Ericsson. the Operating system on Smartphones by these companies. |
