Transcript DCPR Power Ranges Proposed for CS v.2.0 Peter Woolner

DCPR Power Ranges
Proposed for CS v.2.0
DCS Manufacturers Meeting June 13, 2007
Peter Woolner
Noblis
[email protected]
703-610-1724
1
Power Levels for CS v.2.0
• The 2 dB ranges proposed at Asheville are not
practical: a range of at least 4 dB will be
necessary
• The satellite transponder functions best with the
minimum possible EIRP range
• Wider range of EIRP must also result in higher
minimum EIRP
• Higher EIRPs consume extra input power at the
DCP location
• Assumes no CDMA during the transition
2
Recommended EIRP Ranges
• Proposed EIRP ranges for system design:
– 300 bps: 37 dBmi to 41 dBmi
– 1200 bps: 43 dBmi to 47 dBmi
• Assumes reception at DRGS with 15 dB/K G/T
and “worst case” transponder loading
• Other relevant factors:
– Based on actual measured GOES-13 performance
– Assumes DCP and DRGS at 5 degrees elevation
• Availability of power control would provide an
additional significant margin of safety
3
Reason for this Choice
• Basic Criterion: Under worst case conditions, the
first v.2.0 DCP on GOES 13 must provide
acceptable performance into a DRGS with a G/T
of 15 dB
• “Worst case” is maximum GOES 11/12 loading,
i.e. 112 channels at average EIRP of 48.7 dBmi,
all the meeting v.1.0B EIRP requirements
• Proposed minimum EIRPs give Eb/No of 11.7
dB for these conditions
• I do not expect the worst case to actually occur
but cannot quantify the improvement
4
Assumed Transition Progression
• The proposed large reduction in EIRP is only
viable if the transition is coordinated with the
change to GOES N/O
– GOES N/O has 14 dB more downlink EIRP
• Transition assumes “worst case” loading on GOES
11/12 to “worst case” on GOES 13
– GOES 11/12: 112 channels at 48.7 dBmi
– GOES-13: 214 channels at 40.3 dBi
• Channels are changed from v.1.0B to v.2.0 and
new channels are added at a fixed ratio
5
Transition Rule
• Additional channels must not be added faster
than old channels can be converted
– E.g. change 10% of old channels to new CS (equals
11 channels)
– Can then operate 10% of 210 (21 channels) at the CS
v.2.0 EIRP levels
• Channels that were not used on GOES 11 or 12
(e.g. channels 1 and 100) can be counted as
part of the “changed” channels
• Rule can be applied to whole channels or to
specific time periods if the allocation process
can handle the complexity
6
Minimum EIRPs on GOES 13
• Assumes “worst case” average uplink EIRP
• Includes 1 dB margin
Minimum Uplink EIRP (dBmi) with Worst Case Transponder
Loading, into 15 dB/K DRGS, at Stated Transition Stage
Transition Stage
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
For 300 bps DCPs
38.0
37.8
37.5
37.3
37.1
36.8
36.5
36.2
35.9
35.5
35.2
For 1200 bps DCPs
44.0
43.8
43.5
43.3
43.1
42.8
42.5
42.2
41.9
41.5
41.2
7
Transition Options
• Early transitions to CS v.2.0 DCPs could reduce
average EIRP on GOES 11/12 and decrease
number of low EIRP transmitters
• Some CS v.1.0B DCPs could meet many v.2.0
requirements
– EIRPs per v.1.0B are too high to count as v.2.0
– Timing, stability, ACI, etc. could make them “good
neighbors” and remain in use for years
– NOAA can monitor actual EIRPs relative to the pilot
level and identify every DCP by address
8
Early Change to v.2.0
• Any DCP can be changed to a v.2.0 unit at any
time after Wallops receivers are upgraded to
comply with v.2.0 (DRGS upgrade?)
– The extra channels must not be used until the new
satellite is activated but the DCP can be fully v.2.0
compliant with EIRP the only potential problem
• All EIRPs mentioned herein will work OK into
Wallops under all defined conditions
• However, EIRP needed to operate to DRGS with
GOES 11 or 12 depends on actual loading
9
GOES 11 and 12 Loading
• August 2006 measurements show:
– Average is 25 to 30 channels at 45 dBmi
– Worst case is 61 channels (2 x 1 second per day)
• March 2007 transponder AGC confirms
– Average RF equal to 30 channels at 45 dBmi
– Peaks at 55 channels at 45 dBmi (for 4 sec max)
• April 2007 data give same 45 dBmi average
– Also show usage of 3.3% to 37% of capacity in the
twelve channels common to both DRGS
10
Possible EIRP Options
• Create a program to reduce high EIRPs and the
peak number of simultaneous TXs
– Set the v.2.0 EIRPs to be compatible
• Allow v.2.0 to set high EIRP ranges for operation
with GOES 11 and 12 then require they be
lowered for GOES N/P
– Remote control of EIRP would be helpful
• Set v.2.0 EIRPs high enough for all satellites and
accept higher power requirements
• Require v.2.0 DCPs not be placed in service
until after GOES 13 becomes operational
11
Possible EIRP Ranges v Loading
Calculation made for the mid-point of each range
1 dB margin is included
Required EIRP ranges Maximum loading on
for CS v.2.0 (dBmi)
GOES 11/12 for DRGS
37 to 41 Mid = 39
30 channels at 44.5 dBmi avg
80 channels at 40.3 dBmi avg
39 to 43 Mid = 41
60 channels at 44.5 dBmi avg
80 channels at 43.2 dBmi avg
41 to 45 Mid = 43
105 channels at 44.5 dBmi avg
80 channels at 45.7 dBmi avg
12
Summary
• Proposed EIRPs work into Wallops at all
transition stages at estimated w/c loading
• Proposed EIRPs work into 15 dB/K G/T on
GOES-13 at estimated w/c loading
• Operation of proposed EIRPs to DRGS on
GOES-11/12 depends on number of
simultaneous TXs and average level
– Difficult to predict conditions to be used for DRGS
reception conditions
– Different ranges could be set for each generation of
satellites
13
Recommendations
• Recommend 37-41 dBmi for 300 bps and 43-47
dBmi for 1200 bps be accepted for GOES N/P
• Recommend additional, higher EIRP levels be
permitted for use with GOES 11 and 12
• Propose insert an additional clause in CS v.2.0
subsection 4.1.1
– Operation with EIRP up to 47 dBmi for 300 bps links
and 50 dBmi for 1200 bps links is permitted only
when transmitting to the GOES 11 or GOES 12
satellites
• Remote control of the EIRP need not be
required, but it would make it easer and quicker
for users to make adjustments at the transition
14
Backup: EIRP Summary Aug 06
All channel EIRP in dBmi measured relative to Pilot
Average Minimum Maximum
Total
E on E
44.6
27.9
53.1
160665
W on E
34.8
26.4
51.2
98492
W on W
45.7
29.2
55.5
161186
E on W
35.5
26.9
54.7
90931
15
Backup: EIRP on April 8, 2007
• Data from both Signal Engineering and
Microcom DRGS reception showed:
– Average EIRP on GOES East = 44.7 dBmi
– Maximum EIRP on GOES East = 54 dBmi
– Only for a subset of GOES East channels but
does tend to indicate stability
16
Example: Channel 163
• It seems to be almost fully allocated with
10 second time slots
• 342 allocations with 1 hour repeat intervals
• Leaves only 18 slots un-allocated
• 342/360 = 95%
• However, on April 8, 2007 the actual
transmit time was probably only 32,000
seconds
– This is only 37.0% of capacity
17
Backup: Channel Usage April 8, 2007
Channel
Number
Time Used
(%)
Channel
Number
Time Used
(%)
7
10.9
55
15.2
17
14.2
67
10.8
31
27.7
89
23.3
35
15.3
129
3.3
41
13.9
163
37.0
49
19.2
177
13.7
18
Backup: Simultaneous TXs Aug ‘06
East channels
on GOES East
All channels on
GOES East
West channels
on GOES West
All channels on
GOES West
Average
Number of ST
Maximum
Number of ST
18.7
42
27.9
58
15.0
39
26.1
61
19