User's Manual

Product Features
Modulation Technique
15www.javad.com
1.3. Modulation Technique
The design will be based on high-level modulation techniques which include:
The following are its key benefits:
1. Provides an excellent spectral efficiency (up to 2.3 bps/Hz for D16QAM), it is better than
any product available on the market.
2. Forward Error Correction scheme (FEC) is based on Hamming Code known as a Perfect
Code. Although Hamming Code is not very powerful, it is easy to implement and does not
require much DSP resources.
3. More powerful Reed-Solomon FEC coding scheme improves the tolerance to interference
and ensures the highest link quality at distances range higher than 15 miles (24 km) and
roaming speeds of up to 60 mph (96 km/h).
1.4. Network Topologies
LMR400 is developed to support Point-to-Point link (PTP) using Time Division Duplex (TDD)
protocol and Point-to-Multipoint (PMP) network topology using Time Division Multiple Access
(TDMA) protocol.
The media access contention between wireless nodes in PMP network (Remotes) can be resolved
by an external controller (TRIUMPH GNSS Receiver) located on base station (Base). The
CONNECT command is intended to establish the link with a specific Remote.
The RTS and CTS data flow control lines (Request-To-Send and Clear-To-Send) can be used on
Remote side to support TDMA protocol implementation.
6.25 kHz 12.5 kHz 25 kHz
DBPSK – Differential Binary Phase Shift Keying 2.4 kbps 4.8 kbps 9.6 kbps
DQPSK – Differential Quadrature Phase Shift Keying 4.8 kbps 9.6 kbps 19.2 kbps
D8PSK – Eight Phase Shift Keying 7.2 kbps 14.4 kbps 28.8 kbps
D16QAM – Sixteen Quadrature Amplitude Modulation 9.6 kbps 19.2 kbps 38.4 kbps
GMSK – Minimal Shift Keying with Gaussian Filtering
N\A
*
*. N/A – Not Applicable
4.8 kbps 9.6 kbps