From:
Brad Dye's Paging Information Resource Page
The latest on paging from Europe
APOC Brief
APOC is the latest of the three High Speed paging codes being promoted world-wide. It was announced in 1993. Compatibility is the key to APOC. Compatibility between pagers of all manufacturers, compatibility between pagers and all paging systems and compatibility with existing POCSAG networks. The features of APOC can be gradually applied to existing POCSAG systems without loss of capacity or incompatibility with existing pagers. These features are:
APOC Phase 1
This can be considered to be synchronised POCSAG, giving pagers more than a ten-fold improvement in battery life. APOC Phase 1 transmissions support POCSAG pagers.
APOC High Speed
This uses synchronisation codewords of 1200 bps, and data rates of 2400, 3200, 4800 and 6400 bps. Pagers use the synchronisation codeword (which has one of several values) to determine if the transmission is POCSAG or APOC, and at which rate. APOC pagers automatically detect and decode both POCSAG (1200 and 2400) and APOC transmissions, making roaming between POCSAG and APOC systems simple. Also APOC cycles are based on 6.8 seconds - exactly 15 POCSAG 1200 batches - which makes mixing with POCSAG very efficient. Interleaving is also used to increase message reliability
Message Compression
Text messages can be compressed quite significantly - a doubling of system capacity can be achieved. Numeric message can also be compressed if numbers only are transmitted. For 7 digit messages, capacity can be increased by 50% (2 codewords are used instead of 3).
Roaming
APOC defines how POCSAG, APOC Phase 1 and APOC High Speed pagers can roam between POCSAG, APOC Phase 1 and APOC High Speed systems. Both single frequency and multi-frequency roaming is defined. About 90 billion RICs are available for world-wide roaming.
Messaging Facilities
APOC provides operators with many facilities, including: subaddressing, group calls, subscription services, call sequencing, text formatting/colouring/fonts, binary transmission, message fragmentation, canned messages, urgent and voice messages, and extensive over the air programming options.
CAPACITY
APOC increases system capacity over POCSAG 1200 as follows:
| Code | Numeric and text | 7-digit (C) numeric | Text (C) |
| POCSAG 1200 | 1 | 1 | 1 |
| APOC 2400 | 2.10 | 3.14 | 4.19 |
| APOC 3200 | 2.80 | 4.19 | 5.59 |
| APOC 4800 | 4.20 | 6.29 | 8.39 |
| APOC 6400 | 5.60 | 8.39 | 11.19 |
C = compression used.
BATTERY LIFE
The Battery Saving Ratio (BSR) used to measure the battery saving performance is independent of data rate. Typically the BSR is 100:1 (compared with 5.67:1 for POCSAG) for message delays of less than 4 seconds.
Copies of the specification can be obtained by writing to Anthony Sharpe, Tel. +44 1223 586228; Fax +44 1223 357112.
RAMP Brief
The Radio Access Mail Protocol, developed by Philips, is a family of two way paging codes. This family is:
| POCSAG+ | Two way POCSAG |
| APOC Phase 1+ | Two way APOC Phase 1 |
| APOC High Speed+ | Two way APOC High Speed |
| RAMP | Supports up to 32000 bps |
Paging systems may be upgraded in a variety of ways. Enhancing a system from one way to two way only involves adding receive equipment to existing paging systems. Roaming between all two way and one way systems and pagers is maintained. All systems operate using 25 kHz channels. A single channel can be time shared, or two channels can be used. The uplink data rates are variable, and range from 0.5 bps (for simple applications) to 9600 bps for more demanding applications. For the simple applications, a 1:1 ratio of receive and transmit sites is achieved using omnidirectional antennas.
Questions should be addressed to:
John Bell, Philips Paging.
Email: [email protected]