**DERIVATION OF THE DESIGN MAXIMUM LOADING FOR DCPR**

Prepared by:

Peter Woolner

Mitretek Systems

March 6, 2006

**Summary of the Design Maximum Loading**

The worst case design channel loading for DCPR transponder is defined as
205 channels at an average uplink EIRP of 48.5 dBmi. This is a
theoretical estimate of the average power levels for the modulation
types and data rates transmitted by the platforms and is deemed by NOAA
to represent the worst case practical load set for this transponder.

**Basic Channel Assignment Rules:**

1.  The spectrum from 401.7 MHz to 402.1 MHz is divided into 532
    designated channels, 750 Hz wide, with center frequencies from
    401.70100 MHz to 402.099250 MHz, designated 1 through 532.

2.  Each 300 bps user will occupy one of these channels.

3.  Each 1200 bps user will occupy three of these channels.

4.  Odd channels are assigned to GOES-East and even channels to
    GOES-West.

5.  Assignments for 300 bps users shall be channels 1 through 369.

6.  Channels 371, 374, 377, 380, 383, 386, 389, 392, 395, and 398 are
    for 1200 bps.

7.  Channel 401 (equivalent to old channel 201 at 402.00100 MHz) and
    above are in the band used by transients and it is assumed these
    users will remain at 100 bps.

8.  It is also assumed that 10 CDMA channels can be accommodated per
    satellite. (It is not yet sure that CDMA can share the DCPR
    transponder, but 10 channels per satellite is assumed for purposes
    of calculating the worst case loading.)

**Proposed Derivation of Worst Case Channel Loading:**

1.  Each satellite is allocated 185 channels at 300 bps, 5 channels at
    1200 bps, and 10 CDMA channels. (GOES west actually has only 184
    channels at 300 bps.)

2.  For the worst case instant, only 80% of these channels will be
    active.

3.  In addition, the worst case channel loading shall include 4 channels
    on each satellite at 100 bps for transient users.

4.  Channels allocated to one satellite are assumed to also illuminate
    the other satellite at a level, **on average**, 6 dB below the level
    into the allocated satellite.

5.  The design range of uplink EIRP values is:

    a.  For 1200 bps transmissions, 50 to 52 dBmi

    b.  For 300 bps transmissions, 47 to 49 dBmi

    c.  For 100 bps transmissions, 40 to 50 dBmi

    d.  For CDMA transmissions, 44 to 46 dBmi

> The distribution assumed for worst case loading is shown in the table
> below.

6.  Transmission at EIRP values greater than listed above is not
    permitted.

7.  Transmission at EIRP values less than listed above is allowed, but
    users should be aware that variations between satellites and of the
    instantaneous transponder loading may cause unacceptable error rates
    to users with low EIRP.

**WORST CASE LOADING FOR THE DCPR TRANSPONDER**

+------------+----------+----------------+--------------+--------------+
| **Data     | **Uplink |                | **Active     | **Total      |
| Rate**     | Transmit |                | Chan**       | EIRP**       |
|            | EIRP**   |                |              |              |
| **bps**    |          |                | **per        | **Watts**    |
|            |          |                | Satellite**  |              |
+------------+----------+----------------+--------------+--------------+
|            | **dBm**  | **Watts**      |              |              |
+------------+----------+----------------+--------------+--------------+
| 1200       | 52       | 158.49         | 2            | 316.98       |
+------------+----------+----------------+--------------+--------------+
| 1200       | 51       | 125.89         | 1            | 125.89       |
+------------+----------+----------------+--------------+--------------+
| 1200       | 50       | 100.00         | 1            | 100.00       |
+------------+----------+----------------+--------------+--------------+
| 300        | 49       | 79.43          | 65           | 5162.95      |
+------------+----------+----------------+--------------+--------------+
| 300        | 48.5     | 70.79          | 45           | 3185.55      |
+------------+----------+----------------+--------------+--------------+
| 300        | 48       | 63.10          | 25           | 1577.50      |
+------------+----------+----------------+--------------+--------------+
| 300        | 47       | 50.12          | 13           | 651.56       |
+------------+----------+----------------+--------------+--------------+
| 100        | 50       | 100.00         | 1            | 100.00       |
+------------+----------+----------------+--------------+--------------+
| 100        | 47       | 50.12          | 1            | 50.12        |
+------------+----------+----------------+--------------+--------------+
| 100        | 44       | 25.12          | 1            | 25.12        |
+------------+----------+----------------+--------------+--------------+
| 100        | 41       | 12.59          | 1            | 12.59        |
+------------+----------+----------------+--------------+--------------+
| CDMA       | 46       | 39.81          | 4            | 159.24       |
+------------+----------+----------------+--------------+--------------+
| CDMA       | 45       | 31.62          | 2            | 63.24        |
+------------+----------+----------------+--------------+--------------+
| CDMA       | 44       | 25.12          | 2            | 50.24        |
+------------+----------+----------------+--------------+--------------+
|            |          | TOTALS         | 164          | 11580.98     |
+------------+----------+----------------+--------------+--------------+
|            | Average  |                |              | 70.62        |
|            | EIRP per |                |              |              |
|            | channel  |                |              |              |
|            | (Watts)  |                |              |              |
|            | :        |                |              |              |
+------------+----------+----------------+--------------+--------------+
|            | Average  |                |              | 48.5         |
|            | EIRP per |                |              |              |
|            | channel  |                |              |              |
|            | (dBmi) : |                |              |              |
+------------+----------+----------------+--------------+--------------+
|            |          |                |              |              |
+------------+----------+----------------+--------------+--------------+
|            |          |                | No of Active | Average EIRP |
|            |          |                | Channels     | (dBmi)       |
+------------+----------+----------------+--------------+--------------+
|  **        |          |                | 41           | 48.5         |
| EQUIVALENT |          |                |              |              |
| SPILLOVER  |          |                |              |              |
| LOADING    |          |                |              |              |
| FROM THE   |          |                |              |              |
| OTHER      |          |                |              |              |
| SATELLITE  |          |                |              |              |
| (= ¼       |          |                |              |              |
| DESIRED    |          |                |              |              |
| SAT        |          |                |              |              |
| ELLITE)**  |          |                |              |              |
+------------+----------+----------------+--------------+--------------+
| **TOTAL    |          |                | **205**      | **48.5**     |
| LOADING    |          |                |              |              |
| PER        |          |                |              |              |
| SATELLITE  |          |                |              |              |
| :**        |          |                |              |              |
+------------+----------+----------------+--------------+--------------+

NESDIS expects the performance of links within the above uplink EIRP
limits, and using a ground receive system G/T of 15 dB/K or more, will
provide error rates better than one in 10^6^ bits, assuming normal
propagation conditions and equipment that meets the NESDIS Certification
Standards.