SN User's Guide - ESC Home - NASA

their platform, see “Return Data Delay” at
http://scp.gsfc.nasa.gov/tdrss/return_data_delay.htm.
RCTD measurements are requested in the SHO. After the scheduled service
ends, the NCCDS provides the measurements to the customer MOC.
b. Measurement Times. The WSC measures RCTD at the following times:
1. Immediately before the scheduled service begins.
2. Whenever equipment or services are reconfigured during the service period.
Multiple measurements will be made if there are multiple reconfigurations.
3. Immediately after the scheduled service ends.
c. Maximum Symbol Rate. Measurements are provided for symbol rates 6 Msps
for NRZ and 3 Msps for biphase formats (S-band DG2 only) per I or Q
channel.
d. Measurement Accuracy. RCTD measurements have the following accuracies:
Data rates 250 kbps: 25% of the data bit period.
Data rates 250 kbps: 1 sec. (The maximum symbol rate is defined in “c
above.)
e. Measurement Resolution. RCTD measurements are provided in units of
microseconds.
f. Time Tag Accuracy. Time tagging accuracy depends on the baseband
equipment used for the service:
MDM (4800-bit data block customers): 5 sec
SN Gateway (TCP/IP customers): 100 sec
WDISC ((TCP/IP customers): 10 ms
Revision 10 9-10 450-SNUG