Rev 0.11
Page G.703-2
Key Features
Single or Dual port G.703/E1
Unframed & Fractional E1 operation
Data rate: User selectable N x 64Kbps in PCM30-CAS or PCM31-CCS modes
Fully transparent signal conversion under unframed mode
Clock Regeneration from incoming HDB3 or AMI formatted data
CRC4 ON/OFF modes.
Diagnostic Loopbacks for both Terrestrial and Satellite side
E1 alarm monitoring for all common E1 transport stream alarms:
LOS
- Loss Of Signal. (All Modes)
AIS
- All 1's at input port. (All Modes).
LFA
- Loss of Framing Alignment. (PCM30-CAS and PCM31-CCS).
LMFA
- Loss of Multi-Frame Alignment. (PCM30-CAS only).
RAI
- Remote Alarm Indication. (PCM30-CAS and PCM31-CCS).
TS16AIS
- All 1's in TS 16. (PCM30-CAS only).
The G5 G.703/E1 interface is only available for PSM-500 Series of modems, either new or as an
upgrade to existing customer modems. This optional Interface card is designed to be installed in
the option interface position inside the main modem assembly.
2.0
Technical Specifications:
2.1.
E1 Signal Structure
The G.703/E1 interface operates at a nominal rate of 2.048Mbps. The data transferred over the
E1 transport stream is organized in frames. Each E1 frame contains 256 bits which are
comprised of 32 timeslots, each containing eight bits. The data rate of each timeslot is 64Kbps.
For 8-bit PCM encoded voice audio, each timeslot provides for an 8 kHz sampling rate.
Timeslot 0 is used for frame synchronization and alarms. Timeslot 16 is used for signaling,
alarms, or data. Timeslot 1 to 15 and 17 to 31 are used for carrying data or PCM encoded voice
audio.
There are two E1 frame formats,
Normal frame (PCM31-CCS)
Multi-frame (PCM30-CAS)
Framing is necessary in order for equipment receiving the E1 signal to identify timeslot alignment
and extract or insert the proper data. E1 signals configured with the PCM31-CCS format use the
frame alignment signal (FAS) for synchronization. When the PCM30-CAS format is used the
multi-frame alignment signal (MFAS) is used along with the FAS. The multi-frame structure also
provides channel associated signaling (CAS) for PCM30. There is also an optional a cyclic
redundancy check (CRC) in both PCM30-CAS and PCM31-CCS modes that is used to detect
errors in the data stream.Frame Alignment Signal (FAS)
