**DCS DCP Manufacturers' Meeting**

Savannah, GA

Wednesday, June 13, 2007

**Minutes**

**[Call to Order]{.underline}**

The Savannah Manufacturers' DCS DCP meeting began at 9:00 a.m. in the
Hyatt Regency Hotel. There were 27 participants who signed the
attendance sheets that included DCP manufactures and DCS users. Peter
Woolner of Noblis introduced himself and began the first of his
presentations which were to focus on the new set of DCS Certification
Standards. Copies of the presentations are included as attachments to
these minutes and can be found along with the minutes at the DCS Web
Site <http://noaasis.noaa.gov/DCS/index.html> and select the
Manufacturers' Meeting tab.

**[Certification Standards (Peter Woolner/Noblis)]{.underline}**

**[300 and 1200 BPS Required EIRP]{.underline}**

It was emphasized that the 2 dB ranges that had been proposed at the
Ashville meeting would have to be increased to at least 4 dB. Also, it
was mentioned that the satellite transponder is more efficient with a
minimum possible EIRP range and that a wider range of EIRP would require
a higher minimum EIRP. The latest proposed EIRP ranges were then
presented as: 37 to 41 dBmi for the 300 bps service; and 43 to 47 dBmi
for the 1200 bps service. It was said that these ranges provide a safety
margin. A basic criterion governing the choices was the provision of
acceptable performance into a DRGS having a G/T equaling 15 dB. Worst
case conditions were reviewed and can be seen in the attached
presentations, i.e. when GOES 11 or GOES 12 were loaded with 112
channels with an average EIRP of 48.7 dBmi, then transferred to GOES 13
and the first DCP changed to the new (low) EIRP requirement. This is
never expected to actually occur, but is the limiting case in which the
low EIRP DCP is required to operate into a DRGS.

**[Transition]{.underline}**

It was pointed out that in order to experience the large reduction in
EIRP there is the need to coordinate the transition to GOES N/O. GOES
N/O has 14 dB more downlink EIRP. The transition study has assumed the
worst case loading scenario where GOES 11/12 has 112 channels at 47.7
dBmi while GOES N/O each will be capable of handling 214 channels at
40.3 dBmi. The first step in the transition is assumed to be 111
channels on GOES N or O at an average of 47.7 dBmi plus one channel at
37.0 dBmi. These are considered a guide for use in the transition
process.

Since the changeover/transition process does not exactly follow a 2 for
1 ratio due to the transition algorithm, unused GOES 11/12 channels
(e.g. channels 1 and 100) could be counted as part of the changed
channels. At the meeting a table was presented and is included in the
web posting that shows 10% incremental transition stages for worst case
average uplink EIRP and with a 1 dB margin for both 300 and 1200 bps
into a 15 dB/K DRGS.

It was said the any early DCP transitions to the new standards could
reduce the average EIRP on GOES 11/12 thereby increasing the number of
low EIRP transmitters and decreasing the overall average EIRP. It was
hopefully noted that some of the standards version 1.0B based DCPs might
meet the new 2.0 specifications thus opening the possibility of
transition beginning with GOES 11/12. There was a reminder that some of
the version 1.0B DCPs may have EIRPs that are too high to meet the
version 2.0 standards. But if they do, are stable, and meet the timing
requirements, they could be in use for years. Since NOAA has the ability
to monitor the individual DCP EIRPs relative to the pilot level,
improvements to the pilot control system will allow for better systems
characterization and provide increased accuracy to the monitoring of the
overall system.

A change to a version 2.0 DCP will be able to be made at any time after
the Wallops CDA installs version 2.0 upgraded demodulators. Of course,
the extra channels will not be usable until the GOES 13 satellite is
made operational. DCPs can be compliant and function to operate with
GOES 11/12 under the version 2.0 standards. However, to operate
successfully through the GOES 11/12 satellites, the DCPs would need the
high EIRP range allowed by the version 1.0B standards. They would then
have to be re-programmed by the manufacturer to operate at the low power
range required for the version 2.0 standards when they start to use the
GOES N or O satellite. This change would not need to be made immediately
the new satellite became operational, but some time limit would need to
be set so these DCPs would not significantly impede the overall
transition to the lower EIRP range. It was mentioned that the presence
of a DCPC link could make this power reduction a much easier task for
those users.

**[System Channel Loading]{.underline}**

Measurements were made during August 2006, March 2007, and April 2007,
to estimate system loading. Channel 163 statistics were presented as an
example. The full 24 hour monitor period on April 8, 2007 showed that
95% of the allocations were occupied but only 37% of the available
transmit time was actually used. The lowest percent used for a channel
was 3.3% which was probably a random channel. The average percent used
was 17.2%. This was a much lower system loading than what we expected.
This lead to the speculation that version 2.0 DCPs could possibly be
operated at lower EIRP than originally thought with the GOES-11 and -12
satellites. The monitored average indicated 25 to 30 channels emitting
45 dBmi, with a worst case of 61 channels. A March 2007 measurement
revealed an average of 30 channels with 45 dBmi with a peak of 55
channels at 45dBmi and an April survey yielded the same 45 dBmi average.

**[Possible EIRP Options]{.underline}**

Some potential choices were presented that would positively affect the
effective satellite efficiency levels. There could be a reduction of the
high EIRP levels and of the peak simultaneous DCP transmissions. There
is also the choice to set a high level of EIRP for GOES 11/12 operation
and then reduce the level for GOES N/P/O. The ability of remotely
controlling DCP EIRP was discussed, for which the proposed DCPC link
would be helpful. The consideration was also mentioned of allowing the
version 2.0 EIRPs to be high enough for all satellites. Lastly, the
version 2.0 DCPs could be kept out of service until an operational
GOES-13 is achieved.

A chart was presented by Peter that illustrated the possible EIRP ranges
verses loading. The calculations were made for the ranges' midpoint
using a 1 dB margin. The chart can be reviewed on page 12 of the
attached DCPR Power Ranges attached presentation.

**[Presentation Summary]{.underline}**

The proposed EIRPs work well for the Wallops reception system at all of
the transitions stages using the estimations of the study. They also
work into a 15 dB/K G/T for GOES-13 using the study's estimated loading.
The successful DRGS reception at the study's EIRP levels depend on the
average EIRP level and the number of simultaneous transmissions. The
individual characteristics of each DRGS have to be considered. Also,
there will be different ranges needed for satellite generational
changes.

**[Recommendations]{.underline}**

Recommendations were made based on the above presentations. A value of
37 to 41 dBmi was made for the 300 bps service; while 43 to 47 was set
for the 1200 bps service in the GOES N/P era. The insertion of an
expanded requirement in version 2.0 was recommended that would allow up
to 47 dBmi EIRP for 300 bps and up to 50 dBmi EIRP for 1200 bps links
when using GOES 11/12. It was mentioned that while EIRP control remotely
will not be required, it would make for a much easier and quicker
transition by allowing adjustments as necessary or desirable.

There are more charts (pp. 15-19) attached that have specific data from
actual measurements taken in the field and used to arrive at the new
standards. Statistics were also quoted from these pages showing the
current average power levels are 44.7 dBmi for GOES East with a maximum
54 dBmi.

**[Open Discussion]{.underline}**

There was a question on when there would be 2 new satellites that would
allow system testing using the new standards. It was answered that it
will be about May or June, 2008 before the next launch and the current
best guess for GOES-13 to start operations is January 2011, with GOES-O
about 6 months later. Peak observed satellite usage was found to be
about 60 DCPs for the East GOES and 40 for the West. It was stated that
the transfer to GOES-13 will be transparent to DCS users if it is
handled correctly. At the transition there should be an increase in
performance and that upon moving to GOES-13 the DCS users should try to
reduce their EIRP. Peter suggested that NOAA should contact users that
are transmitting above the acceptable power level so they can then bring
their DCPs into an allowable range. It was said that there are some
current DCPs that are transmitting at 53 to 54 dBmi. It was reiterated
that DCPI is one possible way to control power adjustments. A DCP
transition date needs to be set and it should allow a reasonably long
period of time to which users can comply. It was anticipated that most
of the transition will be done during the GOES-13 lifetime. Existing
DCPs that are within a reasonable tolerance of the standards will be
able to continue operating as they have been.

There was a question regarding a nominal power recommendation. The
response was that maybe in the middle of the range of values would be a
good target value. Another member reasoned that the use of the maximum
value rather than the mid value might be preferable due to external
effects that tend to reduce or attenuate the signal. It was also
mentioned that in the past users who exceed the maximum value were
identified at the TWG meetings via the system's quarterly systems
activity report. It was also questioned whether NOAA really has the
ability to measure the power levels to sufficient accuracy. A further
discussion repeated the advantages to using the lowest power level
settings on a DCP. A discussion ensued of various environmental effects
that cause reduction in emitted power, such as ice, snow, and wind
disturbing the antenna.

A proposed Version 2.0 transition schedule was circulated and can be
seen as an attachment to these minutes at the DCS web site
<http://noaasis.noaa.gov/DCS/index.html>.

The power reduction is to begin by the time GOES-13 becomes operational.
A question was asked about transmitters that are already in the field
that will have to be removed from service to send back to manufacturer
for conversion to Version 2.0 standards including acceptance testing and
whatever else is needed. Aside from the legacy 100 bps DCPs, Peter
responded that all of the High Data Rate DCPs are considered Version
1.0. However, he felt that some existing DCPs will meet the new version
2.0 standards and therefore would be compatible with both the present
and future systems. Conversely, the V1.0 DCPs will not be able to
operate on the expanded channels offered with V2.0.

A vendor comment was made that users could just buy extra transmitters
to install in place of the existing ones. The existing ones could then
be converted for use under V2.0. January 2011 is the latest expected
activation date for GOES-13. However, should a failure occur to the GOES
11/12 sensor or sensor downlink GOES 13 would be called up immediately.
There was a discussion regarding possible power transitions in
intermediate steps toward the 2011 date, perhaps 2 dB at a time. It was
also mentioned that a stable pilot is an absolute requirement in order
to achieve an accurate determination of EIRP. It was concluded that
NESDIS needs improvements to its GOES DCS pilot control system. While
this has been discussed over the past year or two nothing meaningful is
underway at this time.

Peter made a suggestion about starting with a middle level power value.
He reminded all that the Wallops CDA can always backup data from the
lower level EIRP due to their larger antennas. A case study was
presented using channel 163 that has almost all of its allocated windows
occupied having only 18 time slots out of 360 that were not allocated.
But the actual usage time, i.e. a signal present in the channel, was
only 37%.

At the end of these discussions the attendees decided the topic needed
more thought.

**Action: Peter Woolner will circulate his intentions to all attendees
with a date to reply to him.**

**Required Documentation**

The details in the presentation are included in an attachment to these
minutes. The first item pertains to Required Documentation 1.1.d and
DCPRS antenna gain, polarization, axial ratio and VSWR data. Changes to
the text were suggested due to changes in 1.3.d that no longer requires
a specific model number antenna. Please see the attached presentation
for the specific text changes.

**Inhibiting Transmissions**

The next change was for Inhibiting Transmissions 2.1.1 and contains the
suggested certification text changes relating to an acceptable
algorithm. Please see the attached presentation for the precise wording.

**Carrier Turn-On Time Details**

The presentation stressed the undershoot requirement. There was a
question regarding the necessity for having 5 msec. rise time, and a
change to 10 msec. was suggested and accepted. A graphic is included in
the attached slides.

**Encoder Flush and Carrier Turn-off**.

The wording was accepted as presented.

**Short Term Frequency Stability**

It was proposed to go to less than 1 second measurement intervals to
reflect the advances in frequency counting technology and to eliminate a
turn-on transient problem.

**Phase Noise Measurement**.

The new text as presented allows multiple methods to prove compliance
with the Certification Standards. The wording was approved as presented.
Please see the posted presentation.

**Spectrum Measurement Items**

Instructions for doing this measurement have been expanded and moved to
Appendix A. The presentation pages include a typical curve that depicts
a theoretical transmit envelope with modulation side lobes as an
illustration. Notes on acceptable averaging techniques are also
included. The presentation was accepted as written.

A correction was suggested for the encoder flush and page 8, paragraph
3.4. The new wording would include "**32 zero bits shall be input to the
scrambler".**