In this case once the allowed number of transmissions

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Unformatted text preview: actly determine the amount of delay described in item (a) above). 5.1.9.3 Operation on a Deep Space Link A smaller value of T1_Initial may be useful for deep space communications with long roundtrip light times. It can be used to force automatic retransmission of the entire Sent_Queue a specified number of times prior to receipt of any acknowledgement CLCWs. Assuming Timeout_Type is set to ‘1’ (see 5.1.10.3), FOP-1 will be suspended once the maximum number of transmissions is made. Its operation will then be resumed to process the acknowledgement CLCWs. In addition, a small value of T1_Initial can be used to allow the ‘Set V(R)’ Control Command to be sent without having to verify its acceptance via a CLCW before sending the Type-AD Transfer Frames. In this case once the allowed number of transmissions of the Set V(R) is made, the user shall be alerted and can then issue an ‘Initiate AD Service (without CLCW Check)’ Directive. To improve the efficiency of COP-1 for deep space missions on links with long light time delays, a systematic retransmission mechanism can optionally be provided outside COP-1. The systematic retransmission can be used for Type-AD or Type-BC Transfer Frames and operates in addition to any automatic retransmissions performed by COP-1. For a description of the systematic retransmissions, see reference [3]. The additional transmission time used by the systematic retransmissions can be taken into account when calculating the value for T1_Initial. NOTES 1 The systematic retransmission is outside FOP-1 and has no effect on FOP-1 behavior specified in the state table (see 5.3) nor on FOP-1 variables such as the State (see 5.1.2) or the Transmission_Count (see 5.1.10.4). The FOP-1 variables have no effect on the systematic retransmission mechanism. 2 At the receiving end, if FARM-1 receives a duplicate Type-AD Transfer Frame, as a result of FOP-1 automatic retransmission or as a result of the systematic retransmission, then FARM-1 rejects the Transfer Frame. CCSDS 232.1-B-2 Page 5-6 September 2010 RECOMMENDED STANDA...
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This document was uploaded on 03/06/2014.

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