Comtech EF Data CIC-35 LVDS to ASI - Manual (Page 15)

CIC-35 LVDS to ASI Interface Converter Revision 0
MN/CIC35.IOM
6
Chapter 4. TROUBLESHOOTING
The CIC-35 may take several seconds to acquire the input data stream. This is normal
since the clock recovery PLL is required to acquire the input clock over a decade range of
rates without prior knowledge of the input rate.
The ASI converter expects a 188 byte MPEG format at the input. The frame consists of a
sync byte (0x47) followed by 187 bytes of payload. The data rate programmed into the
CDM-600 / 600L is the serial data rate of the entire framed stream. So if the ASI stream
is 5 Mbps, the modem data rate is also programmed to 5 Mbps.
The converter also expects the input data to be a continuous stream rather than a bursty
format. Contact the factory if there are any questions about operation with bursty ASI
formats.
4.1 LED I
NDICATORS
There are two LED indicators on the CIC-35. The GREEN LED is the transmit side PLL
indicator lock. When the converter is locked to the incoming byte rate, this LED will be
lit.
Ensure that the modem is programmed to the incoming framed serial bit rate correctly as
indicated above. If the modem reports FIFO slips on the transmit side while the GREEN
LED is lit, the modem is most likely programmed to the incorrect data rate.
If the input ASI signal is absent or if the signal level is too low, the LED will be OFF,
and the CDM-600/600L modem will recognize this condition and respond with an active
alarm.
The red LED is a Receive Violation Symbol (RVS) indicator. When lit, it indicates that
the ASI receiver chip (transmit side) is seeing line code violations.
The serial stream in the ASI interface is encoded in an 8B/10B line encoding format. If
the receiver chip encounters any line code violations, a one-shot circuit will turn on the
RED LED for approximately one second. The primary cause of this condition is an ASI
signal that has experienced severe slope attenuation from excessively long cable runs.
Another is use of low quality coax cable or impedance mismatches. Though the interface
may run error-free with code violations, it is highly recommended that the anomalous
condition be corrected.