Guide - Handheld Computering
We have divided handheld computers and PDAs into three environment types to assist in selection
- Office / Retail - Designed for use in light environments, e.g. offices and shop floors, where handhelds are not subjected to drops on industrial surfaces, typically these handhelds will withstand drops up to 1.2M and have no or little IP rating.
- Light Industrial - Designed for use in light industrial environments, e.g. healthcare and field service, typically these handhelds will withstand drops up to 1.5M and have a low IP rating.
- Industrial - Designed for use in harsh environments where handhelds are subjected to drops on industrial surfaces or subject to rough weather conditions, typically these handhelds will withstand drops up to 1.8M and have a high IP rating.
Handheld computers can be supplied with proprietary or Windows operating systems:
- Proprietary - developed by the handheld manufacturer, these systems typically are the entry level option, with built in application program generators that will allow the user to build a basic program for the handheld.
- Windows CE / CE.NET - is a stripped down version of Windows Mobile, containing a platform builder for developers to select the components needed to build a bespoke program. It can run on several different types of processor and has support for real time programming.
- Windows Mobile / Pocket PC - is powered by Windows CE but also houses built in applications including Office, email, VoIP, .NET Framework and SQL Server compact edition. It can run on several different types of processor and has support for real time programming.
Memory / Processor
Handheld computers have sufficient memory space required to enable solid performance for database applications. They are also equipped with powerful microprocessors to cope with the latest operating systems and programs.
Handheld computers either have as an option or come as standard with a barcode scanner to enable scanning within applications, these scanners are typically available as CCD, Laser or Imager technology.
What is CCD, Laser and Imager technology?
- CCD Readers.
CCD readers normally use light emitting diodes (LED's) to produce the light beam and a charge coupled device array (CCD) to read the reflected light. When using CCD technology you must take into consideration the fixed reading distance, the depth of field and the angle of the scan. CCD readers are usually linear scanners, with a thicker scan beam than the laser readers.
- Laser Readers.
Laser technology has a built in laser diode to emit the beam which is then deflected by an oscillating mirror. Laser technology is capable of reading over a range of distances with large depths and extreme scan angles. Laser technology is capable of reading many barcode formats.
- Imager Readers.
Imager technology uses a small camera to capture 1D and 2D barcodes. It then decodes the barcode using digital image processing. The area to read is usually illuminated by LED's and the aiming mark is provided by a laser. The light is either captured by a CCD or imager.
The choice of communication will depend on your particular application. Wireless communications are used when data transfer needs to happen in real time, if this is not needed communications can be processed in batch mode where data is downloaded to a PC or device via a cradle or cable. Some of the most popular wireless systems are;
- Wireless Personal Area Network (WPAN). The most common type of link in this category is Bluetooth and this is typically used for short range communication (up to 15M) between a PC or handheld computer and devices such as headsets, mobile printers and cordless scanners.
- Proprietary wireless networks. An example is Datalogic narrow band, Star system, which allows up to 32 scanners to communicate with a single base station and up to 2000 scanners in the same area.
- Wireless Local Area Network (WLAN). The industry standard for this type of wireless network is 802.11 b/g (also known as Wi-Fi). Wireless LANs are typically used to link computers or other devices within buildings with a wireless range of up to 50M from the nearest access point (some coverage outside of buildings is also possible). Most laptops, PDAs and handheld terminals come with this type of wireless network as standard. As this type of wireless network is low cost and easy to install, it is increasingly found in shops, offices, factories, warehouses and homes.
- Wide Area Networks (WANs) are computer networks that allow data communication over large distances, e.g. between regions and countries. This type of wireless network would be the system of choice for mobile workers such as field sales and delivery people. Many modern devices cater for WAN technology; PDA cell phones come with a WAN capability as standard, and Rugged PDAs and handheld terminals have the option for a WAN capability and simply require a SIM card (Subscriber Identity Module) to be fitted to allow access to the internet and wireless data communication. The international standard for WAN communication is GSM, (Groupe Spécial Mobile, also known as the Global System for Mobile communication). There is now a newer version, GPRS (General Packet Radio Service) designed specifically for internet use and data communication.
- Most handheld computers except the lowest cost choices are supplied with touch screen technology offering options for up to date technology such as signature capture.
- Screen resolution standard for touch screen handheld computers is now 3.5 inch colour QVGA display (320 x 240) going up to VGA (640 x 480) maximum.
Handheld computers are built to withstand being dropped onto concrete ranging from 1.2M to 1.8M dependant on the environment they are going into. (See Environment).
The IP (Ingress Protection) rating given to an electrical device is a two digit code indicating the level of protection it conforms too. The first digit represents protection against penetration by solid objects accessing hazardous parts, the second describing the enclosures, protection against the ingress of water.
RFID is short for radio frequency identification and it is a small electronic device consisting of a small chip and antenna which can convey information. The main purpose of RFID is to help you identify or track a specific product, animal or even person using radio frequency signals.
RFID scanning is now readily available as an option within a handheld computer, these built-in RFID readers can either be low frequency, high frequency or ultra high frequency.
- Cradle - Either single or four bay chargers to charge the battery whilst in the handheld computer, these cradles are also typically used for communications with a computer or network.
- Battery Charger - Usually four bay chargers to purely charge the battery outside of the handheld computer.
Cases: Handheld computers can be supplied with protective cases to increase the life of the handheld by offering extra protection against drops and the elements. For bulk purchases cases can be branded with company names and logos.
Maintenance: Handheld computers can now be bought from manufacturers including Motorola and Intermec with maintenance contracts.Meaning that the handheld can be covered against accidental damage, ideal for warehouses and on the road where the handheld may be subject to rougher treatment.
What is the difference between a handheld computer and a PDA?
A handheld computer is traditionally more keyboard based with a function keys and a Qwerty or Alpha numerical keyboard whereas a PDA tend to have a larger touch screen and only a handful of function keys.