Radyne OM20 Specifications download pdf (Page 185)

OM20 Universal Outdoor Modem Appendix E

MN-OM20– Revision 5 E–3

(

IDO

)

OM20

Modem

Terrestrial

Trunk

Figure 3-11. Insert Only with Internal Frame Source

E.4 Mode Selection

The OM20 D&I can be easily configured to support several commonly used terrestrial data

formats. For E1 Data, the user can choose between PCM-30, PCM-30C, PCM-31 and PCM-31C.

For T1 Data, the user can choose between T1-D4, T1-ESF, and SLC-96. The following

paragraphs provide more information on the various mode selection capabilities of the OM20.

E.4.1 PCM-30

The PCM-30 Mode of Operation supports an E1 Interface with Multiframe Alignment (MFAS)

and Channel Associated Signaling (CAS). The user may independently program n timeslots to

drop and n timeslots to insert where n = 1, 2, 3, 4, 5, 6, 8, 10, 12, 15, 16, 20, 24, or 30. In

addition to the selected drop timeslots, the Transmit Function also extracts the appropriate

ABCD signaling bits from terrestrial timeslot 16 for transmission in IBS Frame as required.

Conversely, the Receive Function extracts received ABCD signaling bits from the IBS Frame

and inserts them in timeslot 16 of the appropriate terrestrial frame. This transmission and

reception of ABCD signaling based upon the drop and insert timeslots is performed

automatically and is transparent to the user. In PCM-30 mode, the user may not select timeslot

16 as a Drop or Insert Timeslot.

E.4.2 PCM-30C

The PCM-30C Mode of Operation supports an E1 Interface with Multiframe Alignment (MFAS)

and Channel Associated Signaling (CAS). In addition, the Drop function verifies the received

terrestrial CRC checksum and the Insert function calculates the required CRC checksum. The

user may independently program n timeslots to drop and n timeslots to insert where n = 1, 2, 3, 4,

5, 6, 8, 10, 12, 15, 16, 20, 24, or 30. In addition to the selected Drop timeslots, the Transmit

Function also extracts the appropriate ABCD signaling bits from terrestrial timeslot 16 for

transmission in IBS Frame as required. Conversely, the Receive Function extracts received

ABCD signaling bits from the IBS frame and inserts them in timeslot 16 of the appropriate

terrestrial frame. This transmission and reception of ABCD signaling based upon the Drop and

Insert timeslots is performed automatically and is transparent to the user. In PCM-30C Mode,

the user may not select timeslot 16 as a Drop or Insert Timeslot.

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Radyne OM20 Specifications Page 185