www.Agilent-Tech.comProductsServices & Supportwww.HP.com
Agilent-Technologies LogoSemiconductor Products
SPG home
 HPRFhelp home

 APCO 25

 What's New
 How to Buy
APCO Project 25

APCO Project 25 Specifications
spectrum: VHF (136-178 MHz)
UHF (low: 400-470 MHz, high: 450-520 MHz)
800 MHz trunking (805-825 / 850-870 MHz)
modulation: QPSK-C, 6.25 kHz bandwidth
C4FM, 12.5 kHz bandwidth
aggregate bit rate: 9.6 kbps
vocoder: IMBE (Improved MultiBand Excitation), operating at 4.4 kbps
low speed data channel: 88.9 bps
transmit power: 2 - 8 W continuous (representative)
Telecommunications Industry Association (TIA) documents:
TSB 102, Project 25 System and Standards Definition
Interim Standard 102.AAAA, Project 25 DES Encryption Protocol
Interim Standard 102.BAAA, Project 25 Common Air Interface
TSB 102.BAAB, Project 25 CAI Conformance Testing
Interim Standard 102.BABA, Project 25 Vocoder Description
TSB 102.CAAA, Project 25 Transceiver Measurements and Methods
TSB 102.CAAB, Project 25 Transceiver Performance Recommendations
National Security Agency (NSA) document:
NSA Specification V23-94-1, Project 25 Type 1 Encryption (classified document).
Project 25 technology makes significant use of Intellectual Property Rights (IPR) of Motorola. Motorola recently published an open letter announcing they would provide licenses for its modulation, channel protocol, and trunking patents required in the Project 25 standards, as well as essential encryption patents, royalty free to signatories of the industry's IPR-Memorandum of Understanding (IPR-MOU).

The CQPSK modulator consists of a table look-up, the two outputs of which (I and Q) are Nyquist filtered and then amplitude modulated, in phase and quadrature phase, before summing. The information bits are processed by the look-up table to yield a 5-level I signal and a 5-level Q signal. The I and Q signals are filtered with a Nyquist Raised Cosine Filter. The I signal is then multiplied by the carrier and the Q signal is multiplied by the carrier after it has been delayed by 90 degrees. The modulated I and Q carriers are then summed together to yield the modulator output.

The C4FM modulator consists of a Nyquist Raised Cosine Filter, cascaded with a shaping filter, cascaded with a frequency modulator.

List of Standards

Privacy Statement Terms of Use

this page last updated: 1 October 1999