Introduction

Mobile computing is a rapidly developing area of IT. It extends business systems beyond the desktop computer giving people freedom to operate at the point of activity. It empowers them to work more effectively and more efficiently. It could bring massive cost savings to your organisation. For example, stock takes can be carried out quicker with a mobile computer than they can with pen and paper. If bar coding is used, the data is far more accurate, and it’s already in electronic form, so there’s no need to key the information into a computer again later. Using mobile computers a stocktake can be completed in a fraction of the time. Mobile computing is faster, more accurate and more convenient. Field workers can be kept up to date with the latest information from the central systems – emails, prices, stock levels, special promotions etc. Express couriers can electronically record deliveries so that a confirmation of delivery is posted to the internet and be available to clients instantly. Such is the flexibility of mobile computers, their ability to improve business systems is unbounded.

Basic Types

Mobile phone
Where the amount of data you need to send or view is small, the mobile phone is convenient. SMS messaging and WAP can be used to access central data and deliver instructions. As the new 3G telecommunications network becomes established the possibilities for digital data communication will grow. The phone networks can also provide information about a user’s geographic location, a feature that has been exploited with traffic information services.

PDA Personal Digital Assistant
General purpose tools aimed at the busy executive, these widely used devices offer diary, contact and task management, and increasingly wireless connection for internet and email. They are inexpensive and convenient, and there are thousands of companies developing third party software for them. Most often they have a graphical touch screen to display and enter data. Data on the PDA is exchanged with similar data files stored on a host computer using some king of synchronisation method usually involving an RS232, USB, infra-red or wireless connection. They are designed for frequent data synchronisation, where the host computer data is used as a back up in case the data on the PDA is lost.

PDT Portable Data Terminal
These devices are primarily used for data collection and are used extensively throughout many industries including retail, supply chain and logistics. They are more specialised a tend to be designed for a specific set of uses. They are usually more rugged than phones or PDAs and have much more extensive battery backup facilities to ensure that captured data is not lost on the event of complete power loss or similar problems. They often have inbuilt automatic identification devices such as card readers, tag readers and barcode scanners to make the task of data collection as efficient as possible. They are available in with a wide range of operating systems, although many are proprietary.

Consult the Users

Determining which mobile computer is most appropriate for your requirements can be a complicated and time consuming process but it is vitally important in ensuring the business objectives are met. One very basic rule – always ensure the users are fully consulted throughout the selection process. A negative or hostile reaction post implementation can destroy any benefits expected from the system and can result in high repair costs from equipment abuse.

Key selection criteria
Here is a list of key features of mobile computers to help you make the right choices

Operating System
There are three common operating systems used in mobile computers; Palm OS, Windows CE and DOS.

The Palm OS is used almost exclusively in PDAs. It is compact and operates on relatively inexpensive hardware. There are thousands of third party software developers and millions of users worldwide.

Like Palm OS, Microsoft’s Windows CE has a massive user base, especially for serious business use. Its close similarity and integration with conventional Windows products make it a compelling choice for organisations using Microsoft extensively. It requires a fast processor and significant memory to operate well, making the CE based PDAs more expensive than their Palm OS counterparts. A particular variant of CE is ‘Pocket PC’, which makes some compromise in terms of programming and peripheral device flexibility in return for better cross compatibility between mobile computers supplied by different manufacturers. CE offers strong expansion capabilities. SD, Compact flash and PCMCIA expansion slots are common. As most major mobile computer manufacturers are working with CE, there is sufficient incentive for a huge number of accessories and peripherals providers to spring up. This opens up a significant development path for first time users. CE is currently the dominant business standard, but will soon be replaced by .NET, Microsoft’s new more generic development offering amongst other things better networking and information exchange.

DOS is still used extensively in mobile computing and still offers the best operational resilience. Using DOS it is easy to implement systems that have one very specific function. The user is easily locked out of the system menus and can do nothing other than operate the intended application. That keeps training an support calls to a minimum. However there are almost as many different implementations of DOS as there are devices. The proprietary nature of the software developed for them means it can be expensive change to a new computer from a different manufacturer.

Linux devices are also beginning to appear, but it is unclear yet to what extent they will be adopted by business users.

Expandability
If you expect to make increasing use of your mobile computer investment over time it is important to look at how flexible the device may be in terms of adding peripheral devices such as barcode scanners, removable memory or wireless communication. Many PDAs and PDTs will have one or more expansion slots. If they are industry standard, such as a Compact Flash or PCMCIA slot you will be able to choose from a wide range of accessories. Some devices offer an ‘expansion jacket’ that slides over the computer, into which peripherals can be inserted. On other devices, the slots are internal for environmental and tamper protection. A protective cover must be unscrewed to gain access. If you are really uncertain about what applications you may want to develop in the future, look for a device that has the capability of adding at least two expansion slots.

Communication
One of the critical decisions to make is how do you want your mobile computer to communicate with your business systems. There are two fundamental choices ‘batch’ and ‘wireless’. A batch computer operates as a separate entity from your main systems. It runs an application that collects and stores data locally and displays information available from its own memory. Periodically it will be connected to a host computer to exchange a batch of information. With wireless, the mobile computer is permanently in contact with a host computer application. Its software may be a simple ‘thin client’ so that is operates as a simple data terminal relaying information to and from the central server software. It may be a ‘thick client’ where some local data processing and storage is done in addition to relaying data to the central server. Here are the relative merits of batch versus wireless:

• A wireless solution is usually about double the cost of a batch solution.
• A wireless solution operates with real time data, vital for many applications. A batch terminal only updates the central system when it is synchronised.
• A wireless device usually requires less memory as it is not storing much data locally. Batch devices may need significantly more memory, particularly if look up files are used in the application.

Batch terminals require time to communicate with the host. As a general rule, information can be sent or received from a batch terminal at typically one thousand records per minute. If you want to transfer a very large lookup file of say 60,000 records it will take an hour. Because wireless terminals exchange data little and often this is not a problem.

Wireless terminal applications are usually much simpler. The complex parts are in the host end server application. This is easier to control and upgrade. It’s also easier for the hardware to be replaced whilst retaining the same application.

All mobile computers have some kind of local communication to allow program or firmware upgrades and, for batch terminals, to synchronise data. This will typically be infra red, RS232, USB, RS485, Bluetooth or Ethernet. The same interface must be available on the host computer. Many handhelds offer a communications / charging cradle as an accessory. These often communicate infra red to the handheld so that the physical contact wear associated with electrical connectors is avoided. In our experience this makes a significant difference to the reliability of a handheld based system. RS484 is used where multiple handhelds need to communicate with a host simultaneously.

There’s a whole range of wireless communications to choose from. For personal area networks and local communication, Bluetooth is the dominant standard. For local area networks it’s IEEE802.11b. For wide area networks it’s GSM or GPRS. For more information on each of these take a look at our beginners guide to RF communication. Some mobile computers offer 802.11b, GPRS and Bluetooth in the same unit.

Data integrity
This is especially important for data collection systems using batch data collection terminals. If an unexpected problem occurs and the handheld suffers main battery power loss, many PDTs have a back up battery to retain the data in memory. This can avoid losing hours worth of captured data. Many handhelds also offer a limited amount of flash memory. This is used primarily to protect the software applications and other critical data that does not change regularly. PDAs usually have limited or no battery backup. The main batteries can be left out for only a few minutes before data is lost. That is why they rely heavily on regular data synchronisation to ensure that a duplicate set of up to date data and applications is always available on the host computer.

Battery life
Operation time between battery charges or replacements varies considerably between devices. A typical Palm OS PDA can operate for weeks on two AA batteries, but a wireless computer operating at maximum power may only last one or two hours. Each type of peripheral device attached reduces the operation time. The biggest drain on power is wireless communication. A bar code scanner uses significant power when it operates, but very little the rest of the time. If you want to use wireless communication in a business critical application, choose a handheld that is specifically designed for wireless. They have much larger battery capacities and better radio integration. Many PDAs will run off standard AAA or AA sized batteries. Beware the ongoing consumable cost. If it’s a business application in use every day, look for a device that is supplied with a re-chargeable battery pack. Try to avoid devices using NiCAD batteries – if not treated properly their operational life will deteriorate rapidly due to a ‘memory effect’ that builds up if they are not fully charged and discharged each time. Go for NiMH or better some kind of Lithium Ion battery. They have a higher capacity and are more tolerant if irregular charge cycles.

Keyboard
Mobile computers use a number of different keypad options. Durable full keyboards are available, allowing alpha and numeric characters to be entered without using a shift key. The alpha characters are laid out in sequential or QWERTY format. There is a significant compromise between the size of the keys and the size of the handheld. Most PDT manufacturers supply devices with a limited number of keys, usually numeric plus a few control keys. That makes the units more compact and manageable, and alpha data is usually entered by scanning a bar code. Shift keys are usually available so that alpha characters can be entered via the keyboard, but it’s cumbersome and only used as a last resort. Other devices offer a limited keypad and a touch screen, which can be used to display an alpha keyboard. PDAs are primarily touch screen, plus a few control buttons. Alpha numeric keyboards are displayed for character entry, alternatively an area of the screen can be set up for character recognition. Screen based keypads are very small and require the use of a stylus.

Display
Displays are typically touch sensitive and graphical, graphical or character based. PDAs offer the most technically advanced displays, but are the most prone to damage. Character based displays are usually smaller, typically 8 lines by 20 characters, but are less prone to damage. Colour graphical displays are now commonplace, but look out for the operating time between charges - they use more current. Character based displays are almost always monochrome.

Memory
Most mobile computers have an area of read only memory (ROM) and random access memory (RAM). The ROM is used to store the operating system, the RAM is used for data. PDTs usually have battery backed RAM, PDAs don’t. Many handhelds have a limited amount of flash ROM available for the user to store application programs and critical data. Memory size is not usually critical in wireless applications, but can be in batch terminals. Most data collection applications handle character based data. If a data record (barcode, price description and quantity for example) contains 100 characters for example (including field separation and termination characters) then you will be able to store 10,000 records in 1 MB of memory. PDAs usually have an expansion slot (eg SD or compact flash). This allows the memory capacity to be massively increased if required. Removable memory has two big advantages – it can be taken out, plugged into the host computer and downloaded much quicker than sending the data through a serial data connection, and it is non volatile so that the data is protected even in the event of complete power loss to the unit.

Accessories
Make sure the handheld you are considering has all the accessories you need. A communications / charging cradle is strongly recommended. Look at all the different charging options available. Vehicle mount cradles are essential for an automotive environment.

Durability
Make sure the handheld you choose is suitable for the environment in which it will be used. PDAs can break very quickly in a heavy industrial environment - choose manufacturers such as Intermec and Hand Held Products for these areas. Carry cases and holsters are usually available for added protection. Most importantly, make sure the employees using the handhelds will be accountable for their condition. Being handheld, these devices are often dropped. Good accountability often cuts the wear and tear costs down by half.

Programming
In most cases a software development kit is available from the equipment manufacturer. This should be used in preference to any other. Most handhelds are programmed on C or some form of basic. If you do not have these skills Synergix can write your applications for you or provide an off the shelf package. We have years of experience and an extensive range of routines to choose from. Rapid Application Development tools are also available, usually specific to a small number of devices. These can be useful to quickly develop program to test out the feasibility of an application.