This paper reviews current trends in the paging industry, describes typical pager designs, presents the test requirements of modern pagers, and discusses the contribution to pager testing of the HP 8648A signal generator with Option 1EP, the pager signaling option.

Today there are over 88 million subscribers of paging services throughout the world. By the year 2000, the number of subscribers is expected to grow to over 140 million. To meet this demand, pager manufacturers will need to produce over 30 million pagers per year. This makes pagers one of the leading RF devices in production today.

The design and testing of pagers from concept to production requires sophisiticated test equipment. In addition to the typical RF measurements, a paging signal is required to test the finished product. This article will review modem paging formats, typical pager designs, and methods for testing pagers.

Paging Review

A paging network (see Figure 1) begins at the connection to the public switched network or telephone lines. The caller can initiate a page through voice mail or a paging operator, or can leave a message by entering touchtones from a telephone. Pages are assembled in the paging terminal and sent to the network controller, where they are combined into batches based on their final destination. Billing and management are also controlled at this point.

[Figure 1 ILLUSTRATION OMITTED]

Many paging companies cover more than just one geographical area. For example, the company may serve an entire state or even country. The network controller specifies the site controllers for which the batched messages are intended and sends them out. Each site, covering a particular geographical location, can contain one or more paging transmitters. Once the site controller receives the batch of pages, it uplinks them to the paging transmitters, which then transmit the batch of pages at the same time on the same frequency using a simulcast technique. Simulcast means that two or more transmitters are used to transmit identical information at the same time. This allows the system to provide seamless coverage on a single frequency.

Many different types of paging formats are currently in use. The most common and only worldwide standard at this time is POCSAG (Post Office Code Standardization Advisory Group), also known as RPC1. The digital formats currently under development are FLEX (a Motorola trademark), ERMES (European Radio Message System), and FLEX-TD (RCR-43). FLEX is receiving worldwide attention and has been implemented in North America, China, Indonesia, Singapore, and Thailand. ERMES is intended mainly for use in Europe. Japan has developed its own paging format, FLEX-TD, which is based on FLEX.

Table I shows a comparison of some of the main characteristics of current paging formats. A bit more detail regarding the protocol of each format is given in the following paragraphs. Probably the most important reason for the creation of the newer digital formats is the ability to send more information, faster, to more people.