# Presentation: 817225

## DCPRS CERTIFICATIONSTANDARD STATUS

- DCS MANUFACTURERS MEETING MAY 18, 2006
- Peter Woolner
- Mitretek Systems
- _[pwoolner@mitretek.org](mailto:pwoolner@mitretek.org)__ _
- 703-610-1724

## Status of Original Items as of May 2006

|   | ITEM NAME | Agreement Date | Agreement Result | CS Paragraph | Comments |
| --- | --- | --- | --- | --- | --- |
| A | Timing Accuracy | Aug-04 | 0.25 S | 2.1 |   |
| B | Message Format | Aug-04 | Reword | 3.1 | FSS, preamble, new code |
| C | Data Scrambling | Mar-04 | Reword | 3.2 | No requirement change |
| D | Encoder Flush | Mar-04 | 32 bits | 3.4 | Added definition of "OFF" |
| E | Interleaver | Aug-04 | Delete | NA | Not useful |
| F | Prohibited Characters | Aug-04 | Delete | NA | Redundant |
| G | EOT | Aug-04 | Binary only | 3.6.2 | Not required for other modes |
| H | Maximum Message Length | Aug-04 | To Fail-safe | 4.6 | See item Q below |
| I | Transmit Frequency Adjustment | Aug-04 | Delete | NA | No longer needed |
| J | RF Power Output | Aug-04 | 48/51 +/-1 | 4.1.1 | NEW QUESTIONS |
| K | Operating Frequencies | Nov-05 | New Plan | 4.2.1 | Use center half of old channel |
| L | Long Term Frequency Stability | Aug-04 | 100 Hz | 4.2.2 | NEW QUESTION |
| M | Modulator Stability | Aug-04 | Delete | NA | Combined with item N |
| N | Phase Noise | NONE | OPEN | 4.4 | NOT RESOLVED |
| O | Narrow Band Transmit Spectrum | Nov-05 | 25/35 dB | 4.5 | Meet NTIA requirement |
| P | Mid-Band Transmit Spectrum | Nov-05 | 43+10Log(P) | 4.5 | Meet NTIA requirement |
| Q | Fail-Safe | Aug-04 | 32/128 k | 4.6 | Near 110 seconds |
| R | DCPI Link | Aug-04 | Delete | NA | Make separate document |
| S | Test Notes | NONE | OPEN | App. A | SUGGESTIONS REQUIRED |

## CS Progress Since 11/05

- Prepared and distributed a draft CS
- New Emission Designators (Para 1.2)
- Specified New FSS (Para 3.1)
- Proposed Phase Noise (Para 4.4 +)
- Added Transmit Spectral Masks (Para 4.5)
- Confirmed this is Normal NTIA Procedure but using narrower measurement bandwidth
- Created Table of Frequencies (App. D)

## Summary of Stellar Filter Study Results

- The Study showed there was very little difference in the performance of the Bessel and the Root Raised Cosine (RRC) filters if both are 8th order or higher.
- Sidelobes at -25 dB down from carrier were set by SSPA distortion and were largely independent of filter type.
- The RRC filter had somewhat less implementation loss than Bessel filters but required more back-off to meet sidelobe requirements.
- Both differences were close to the accuracy limit of the simulation.
- Both types of filter can easily support the proposed reduced channel spacing of 750 Hz.
- Most unexpected result was the RRC filter performance remains good as filter reduced to fourth order, but the Bessel filter requires at least eighth order to meet the sidelobe requirements.
- This fact was considered a good reason to recommend use of fourth order RRC filters with 65 coefficients (plus ISI performance).

## Application of Filter Results

- NOAA will require RRC filters at WCDAS
- Strongly recommend all other receive systems require the same type filters
- Proposed WCDAS filter requirements:
- RRC* for 150 and 600 sps
- Excess bandwidth = 1.0*
- Fourth order with 65 taps or more
- 	(*: currently listed in section 4.5 of C.S.)
- Are other public specifications necessary?

## NTIA Mask, Doppler, and Frequency Tolerance for 300 bps

**225 Hz + 25 Hz + 125 Hz = 375 Hz**

## NTIA Mask, Doppler, and Frequency Tolerance for 1200 bps

**900 Hz + 25 Hz + 200 Hz = 1125 Hz**

## NTIA Mask, Doppler, and Frequency Tolerance (Concluded)

- Summary:
- Reference is peak of **MODULATED** waveform
- Need 25 Hz for Doppler due to trend for large inclination on GOES satellites
- 1200 bps links will regrow sidebands sooner than 300 bps links as they use higher power
- Recommendation:
- Frequency tolerance up to 125 Hz for both 300 and 1200 bps is OK if vendors want it

## FREQUENCY PLAN #1

**CHAN**
**1**

**CHAN**
**3**

**CHAN**
**5**

**CHAN**
**2**

**CHAN**
**4**

**CHAN**
**7**

**CHAN**
**6**

**CHAN**
**9**

**CHAN**
**8**

**CHAN**
**11**

**CHAN**
**10**

- 401.701000

- 401.701750

- 401.702500

- 401.703250

- 401.704000

- 401.704750

- 401.705500

- 401.706250

- 401.707000

- 401.707750

- 401.708500

- 300 bps
- Channels

- OLD 1.5 KHZ
- CHAN 1

- OLD 1.5 KHZ
- CHAN 2

- OLD 1.5 KHZ
- CHAN 3

- OLD 1.5 KHZ
- CHAN 4

- OLD 1.5 KHZ
- CHAN 5

**Low Pilot**
**401.70000**

**CHAN**
**12**

- 401.709250

- OLD 1.5 KHZ
- CHAN 6

- EVEN NUMBERED (RED) CHANNELS ON EAST SATELLITE
- ODD NUMBERED (BLUE) CHANNELS ON WEST SATELLITE

## Proposed Transition Process 

- CHAN 15

- OLD 1.5 KHZ
- CHAN 12

- OLD 1.5 KHZ
- CHAN 13

- OLD 1.5 KHZ
- CHAN 14

- Proposed Transition Process

- OLD 1.5 KHZ
- CHAN 11

- OLD 1.5 KHZ
- CHAN 12

- OLD 1.5 KHZ
- CHAN 13

- OLD 1.5 KHZ
- CHAN 15

- OLD 1.5 KHZ
- CHAN 16

**11E**
**21**

**12E**
**23**

**13E**
**25**

**11W**
**22**

**12W**
**24**

**14E**
**27**

**13W**
**26**

**15E**
**29**

**14W**
**28**

**16E**
**31**

**15W**
**30**

**16W**
**32**

- OLD 1.5 KHZ
- CHAN 14

- OLD 1.5 KHZ
- CHAN 11

- OLD 1.5 KHZ
- CHAN 12

- OLD 1.5 KHZ
- CHAN 15

- OLD 1.5 KHZ
- CHAN 16

**11E**
**21**

**12E**
**23**

**13E**
**25**

**11W**
**22**

**12W**
**24**

**14E**
**27**

**13W**
**26**

**15E**
**29**

**14W**
**28**

**16E**
**31**

**15W**
**30**

**16W**
**32**

- OLD 1.5 KHZ
- CHAN 13

- OLD 1.5 KHZ
- CHAN 14

- OLD 1.5 KHZ
- CHAN 11

- OLD 1.5 KHZ
- CHAN 16

**11E**
**21**

**12E**
**23**

**13E**
**25**

**11W**
**22**

**12W**
**24**

**14E**
**27**

**13W**
**26**

**15E**
**29**

**14W**
**28**

**16E**
**31**

**15W**
**30**

**16W**
**32**

- ASSUMES THERE ARE NO 100 BPS USERS ON NEARBY CHANNELS
- (Red channels on GOES East, blue channels on GOES West)

- STEP
- 1

- STEP
- 2

- STEP
- 3

## Old and New 300 bps Adjacent

## Phase Noise Requirement

- Current proposed C.S. requirements are
- Bias or offset = 1.0 degree
- Total RMS phase error due to all causes except bias = 2.5 degrees
- Produces a total of 3.5 degrees RMS for the complete DCPR path
- Produces a BER contribution of 10-9 due to total phase noise

## Phase Noise Calculation for DCPR

| Angular limit to produce errors in 8PSK = 45/2 | 22.5 | degrees |
| --- | --- | --- |
| Source of Phase Noise Contribution | Allocation (degrees) | Single Meas'mt |
| Satellite Transponder | 1.0 | 1.0 |
| Wallops Receive Path | 2.0 | 2.0 |
| DCPR Receiver | 1.0 | 1.0 |
| DCPR Transmitter | 2.5 | 3.5 |
| RSS Total | 3.5 | 4.3 |
| x*σ for 10E-9/E-6 BER | 6.1 | 6.1 |
| Sigma * RSS Total | 21.4 | 26.1 |
| Offset/Bias Limit | 1.0 | 0.0 |
| W/C Phase Noise | 22.4 | 26.1 |

## Possible EIRP Reduction

- Every user would benefit if all uplink power levels were reduced – However:
- All calculations must be compatible with NOAA defined “worst case” loading
- 205 uplinks at 48.5 dBmi EIRP
- Include satellite NPR (16 dB on GOES-P)
- Work into DRGS with G/T = 15 dB/K
- If 300 bps reduced by 5 dB to 44 – 42 dBmi and 1200 bps reduced by 2 dB to 50 – 48 dBmi, the estimated EB/N0 for each is 12.7 dB

## How Can EIRP be Reduced?

- Requires ability to adjust power on site
- (a) Gradual reduction of transmitters with highest EIRP, a few at a time
- Requires many years cooperation by all users
- (b) DCPI Power Control for all DCPRS
- Short term DCPI costs
- Power cost benefits only in long term
- Low EIRP design only useable ***after*** required powers have been reduced

## Test Measurements

- Transmit spectrum
- With random modulation, sweep with 1 Hz resolution bandwidth, averaging allowed
- Compare peak level with sidelobe levels
- Phase noise
- Measure several thousand symbols using a random data stream and a Vector Signal Analyzer to give average and RMS jitter for each point on the modulation constellation

## Prime Power

- Current C. S. section 4.0 requires operation over ±15% from nominal voltage
- New proposal to allow the manufacturer to specify any desired range
- Also proposes the transmission be inhibited if the range is exceeded
- I suggest add to Fail-Safe as third item
- Performance unknown if limits exceeded
- Ultimate step to prevent harm to other users

## Other Suggestions

- Antenna Labeling
- Require a label to identify approved antennas
- Output Power minimum
- Change to -2 dB from nominal is suggested
- 300: _49_ to 44, 1200: _52_ to 50 is possible
- Carrier phase noise
- Change to 1.25 degrees for carrier jitter
- Pilot Policy
- Current frequencies 401.700 and 401.850 MHz
- 401.850 is 250 Hz below Ch. 200 center
- 402.000 would be 250 Hz below Ch. 400 center