1. WINMOR…A Sound Card ARQ Mode for Winlink HF Digital Messaging
Rick Muething, KN6KB/AAA9WK
PowerPoint Presentation available at

2. Overview WINMOR Today’s Objectives
WINMOR… A work in progress… Follow-on to SCAMP
Motivation… Why another sound card mode?
Unique requirements for a message oriented protocol
RF Footprint and Robustness Agility
Modulation schemes investigated
Implementation details
DSP processing diagram
Tuning, Modulation, Demodulation, Error recovery methods
Screen captures of the WINMOR “Virtual TNC”
WINMOR Movies!
Measurements Using the HF channel simulator
Preliminary Comparisons with Pactor 1, 2, and 3
Deployment strategy
Remaining work to be done

3. Today’s Objectives WINMOR
Provide you an update on a promising sound card mode targeted
at message systems.
Give some (within our time limits) of the technical details on how
we are approaching this.
Show some preliminary test results and “apples-to-apples”
comparisons with the defacto standard Pactor.
Encourage others to learn about and get competent in DSP as it
applies to amateur radio.
Get feedback from you on alternate approaches and suggestions
for implementation and deployment.

4. Acronym Cheat Sheet! WINMOR
CCIR Consultative Committee on International Radio (now The ITU-R)
WGN White Gaussian Noise (a simple HF channel model)
MPG CCIR Multipath Good (a standard moderate HF channel model)
MPP CCIR Multipath Poor (a standard poor HF channel model)
OFDM Orthogonal Frequency Division Multiplexing
PSK Phase Shift Keying (carrier phase is modulated) BPSK(2), QPSK(4)
FSK Frequency Shift Keying (frequency of the carrier is modulated)
4FSK FSK using one of 4 tones per symbol (2 bits per symbol)
QAM Quadrature Amplitude Modulation (phase and amplitude are modulated)
16QAM Phase and Amplitude modulation with 16 states (4 bits per symbol)
FEC Forward Error Correcting (use of error correcting codes)
MCA Multiple Carrier Assignment (same data to multiple carriers)
RDFT Redundant Digital File Transfer (mode by Barry Sanderson, KB9VAK)
ARQ Automatic Retry reQuest (mechanism to eliminate errors)
FFT Fast Fourier Transform (digital method of a discrete Fourier Transform)
IFFT Inverse Fourier Transform ( Frequency to Time transform)
NCO Numerically Controlled Oscillator (done in software)
I, Q The “In phase” and “Quadrature” channels of the Fourier Transform
TNC Terminal Node Controller (RF Modem)
DSP Digital Signal Processing
Hilbert Transform A mathematical transform to generate I and Q

5. WINMOR… A work in progress
WINMOR = WINlink Message Over Radio
An outgrowth of the work presented on SCAMP at DCC 2004:
SCAMP put an ARQ “wrapper” around Barry Sanderson’s RDFT then integrated
SCAMP into a Client and Server for access to the Winlink message system.
SCAMP proved it COULD be done and it worked in GOOD channels but…
Barry’s batch oriented DLLs were slow and required frame pipelining…
Increasing complexity and overhead
RDFT only changed the RS encoding on it’s 8PSK multi carrier
waveform to achieve a 3:1 range in speed/robustness… not enough
RDFT was inefficient in Partial Frame recovery (no Memory ARQ)
RDFT was a 2.4 KHz mode…limited to narrow HF sub bands.
SCAMP’s Simple multi-tone ACK/NAK did not carry Session ID info
…increasing chances of fatal cross session contamination.
WINMOR is an ARQ mode generated from the ground up to address the
limitations of SCAMP/RDFT and leverage on what was learned.

6. Motivation
WINMOR
Winlink has grown over the years and expanded applications…
Many RVers and Boaters use it for remote and weather
Now many more adopting it for Emergency Communications:
ARES/RACES EmComm
MARS
UK Cadet
Humanitarian Missions (IHS, Red Cross, Salvation Army etc)
Emergency applications dictate special requirements:
Station Cost is an issue:
Limited budgets and resources…
Seldom used (often equipment sits idle unless drills,
training, or actual emergency)
Consistency across multiple stations…. Training issues.
VHF is used but HF is needed to bridge out of affected areas.
Many with limited budgets get by with Pactor 1 and accept
it’s throughput and robustness limitations.
What is needed and much requested is a lower cost “plug and play”
alternative to Pactor that approaches P2 and P3 performance.

7. Requirements for a Message Oriented Sound card Protocol
WINMOR
Requirements for a Message Oriented Sound card Protocol
Absolute Requirements
Standard SSB Radio hardware
Automatic connections (no manual tuning)
Error-free transmission/confirmation
Fast lock for reasonable ARQ cycles
Auto adapt to wide range of HF channels
Support true binary with compression
“Loose” ARQ timing to accommodate
OS and sound card latency.
All packets tagged with session ID
Wish List
Modest OS and CPU demands
200Hz, 500Hz, 2000Hz bandwidths
Compatible with most sound cards
Good bits/sec/Hz ( >.5 target)
Efficient Mod/Demod for low latency
Selective ARQ and Memory ARQ
for throughput & robustness
Near Pactor ARQ efficiency (70%)
Effective busy channel detection
When you analyze the details and make true apples-to-apples
comparisons you quickly realize that P2 & P3 set the bar pretty high!

8. RF Footprint and Robustness Agility
WINMOR
RF Footprint and Robustness Agility
Comparison of Some Popular Modes in ARQ Environments 1
Assumptions:
70% ARQ efficiency
(typical of Pactor)
Max RAW data rate
(good channel assumed)
200 Hz guard band used in
bandwidth calculations.
(allows automatic connections)
Net bits/sec/Hz of BW
(After ARQ overhead)
Target For WINMOR .5
MT63
PSK31
PCALE
Pactor 1
Pactor 2
Pactor 3
HF Packet
A small RF foot print requires maximizing the net Bits/Sec/Hz BUT….
We ALSO must be able to adapt the modulation for more robustness
In poorer signal conditions. This “robustness agility” is why Pactor 2
and 3 perform so well across a wide range of channel conditions.

9. Modulation Schemes Investigated
WINMOR
Modulation Schemes Investigated
One of the wish list items was to offer 3 bandwidth modes to be able to operate
In the various (or future?) bandwidth segments of 200Hz, 500Hz and < 3KHz
Current FCC regulations (arguably obsolete) require a maximum HF symbol
rate of 300 symbols / sec. This eliminates high symbol rate adaptive schemes.
Improved multipath operation is obtained with lower symbol rates (< 100 Hz)
The following modes were investigate in the early development phases:
Multi carrier OFDM BPSK, carrier spacing = 1 x symbol rate
Multi carrier OFDM BPSK, QPSK, 16QAM at carrier spacing = 2 x symbol rate
Single and multiple carrier FSK (2 FSK and 4 FSK) at spacing 1 x symbol rate
Recently the development effort has been focused on 62.5 baud BPSK, QPSK
and 16QAM and baud 4FSK using 1 (200 Hz), 3 (500Hz) and 15 (2000Hz)
Carriers spaced at 2 x symbol rate. These appear to offer high throughput
and robustness especially when combined with multi-level FEC coding.

10. Implementation Details WINMOR DSP Processing Diagram

11. Implementation Details Frame Leader…Tuning and Frame ID
WINMOR
Implementation Details Frame Leader…Tuning and Frame ID
Non reversed phase frame sync
Frame ID DBPSK
8,4 Ex Hamm Dmin = 4
Phase reversing “Two Tone” Leader
256 ms BPSK
…Data
BPSK
QPSK
16QAM
4FSK
Soft Decode with
distance threshold
Sequential 1024 Point FFTs
Algorithm has good detection
sensitivity and selection
@-5dB S/N
Frame ID defines:
Control/Data Function
Modulation Mode
FEC Coding level
Number of Carriers
Frame length
Leader defines:
Required NCO freq (interpolated to .1Hz)
Initial Symbol Sync (Envelope matching)
Framing (Frame Sync)

12. Implementation Details OFDM PSK, QAM DSP Modulation
WINMOR
The Symbol Data is used to set the Real and Imaginary
Frequency magnitudes for each OFDM Carrier.
e.g. Data = 0,1 (QPSK) > FReal24 = 0 FImag24 = 1 (90Deg)
(repeat for each carrier)
128 Point Inverse FFT (one IFFT per symbol)
Time sample values for all carriers generated simultaneously!
Shape Envelope (raised cosine) to bound Spectrum
Convert to WAV file
for Sound Card

13. Implementation Details OFDM PSK, QAM DSP Demodulation
WINMOR
Use 123 point Hilbert Transform, NCO and balanced LSB Mixing to
generate I and Q samples with signal re centered on Hz
Perform 128 point FFT for each symbol using I and Q values
Use the Real and Imaginary frequency values for each carrier
to compute phase and amplitude for each symbol of each carrier.
Subtract phase values of prior symbol to get differential PSK symbol
For QAM use dynamic threshold adjustment to track Phasor
amplitude ratios in fading channels.
Decode Phase and Amplitude symbol to corresponding binary data
(BPSK = 1bit, QPSK=2 bits, 8PSK= 3 bits, 16QAM=4 bits)

14. Implementation Details FEC, Selective ARQ
WINMOR
WINMOR uses several mechanisms for error
recovery and redundancy:
FEC Data Encoding… Currently used:
4,8 Extended Hamming Dmin = 4 (used in ACK and Frame ID)
16 Bit CRC for data verification
Two-level Reed-Solomon (RS) FEC for data:
First level Weak FEC e.g. RS 140,116 (corrects 12 errors)
Second level Strong FEC e.g. RS 254,116 ( corrects 69 errors)
2) Selective ARQ. Each carrier’s data contains a Packet Sequence
Number (PSN).
The ACK independently acknowledges each PSN so only
carriers with failed PSNs get repeated.
(the software manages all the PSN accounting and re-sequencing)

15. Implementation Details Memory ARQ, MCA, Dynamic Threshold
WINMOR
3) Memory ARQ. The analog phase and amplitude of each demodulated
symbol is saved for summation (phasor averaging) over multiple
frames. Summation is cleared and restarted if max count reached.
Reed-Solomon FEC error decoding done after summation.
4) Multiple Carrier Assignment (MCA) . The same PSN can be assigned
to multiple Carriers (allows tradeoff of throughput for robustness).
Provides an automatic mechanism for frequency redundancy and
protection from interference on some carriers.
5) Dynamic threshold adjustment (used on QAM modes) helps
compensate for fading which would render QAM modes poor
in fading channels.

16. Implementation Details The “Virtual TNC” Concept
WINMOR
In trying to anticipate how WINMOR might be integrated into
applications we came up with a “Virtual TNC” concept.
This essentially allows an application to integrate the WINMOR
protocol by simply treating the WINMOR code as just another TNC
and writing a driver for that TNC…. A “Virtual TNC”
Like all TNCs there are some (<10) parameters to set up:
call sign, timing info, sound card, keying mechanism, etc
The WINMOR Software DLL can even be made to appear as a
physical TNC by “wrapping” the DLL with code that accesses it
through a virtual serial port or a TCPIP port.
Like a physical TNC WINMOR has a “front panel” with flashing
lights. But since operation is automatic with no front panel user
interaction required the WINMOR TNC can be visible or hidden.

17. WINMOR “Virtual TNC” Screen Capture: 15 Carrier QPSK
QPSK Constellation
(heavy fading)
Each pixel = 1 symbol
Connection State
Frame Type
Bytes Received
“+” decoded OK
“M” recovery after Summation
(memory ARQ)
2KHz waterfall
“-” no decode, poor ID match
(not added to summation)
“m” no decode, Good ID
(added to summation)

18. WINMOR “Virtual TNC” Screen Capture: 3 Carrier 16QAM
16QAM Circular Constellation
(White Gaussian 5dB)
Each pixel = 1 symbol
Tuning Offset
Receive Level
”+” 3 Carriers
decoded OK
Relative decode Quality
1 KHz waterfall

19. WINMOR Measurement Approach The HF Channel Simulator
The way to get true repeatable comparisons!
Station 1
Computer & SignaLink USB Sound Card
WINMOR Virtual TNC
Station 2
Computer & SignaLink USB Sound Card
WINMOR Virtual TNC
SC Out
SC Out
SC In
SC In
CCIR Channel Options:
S/N –5, 0, 5, 10, 15 dB
White Gaussian Noise
Multi path:
Good, Fair, Poor
Flat Fading:
Moderate, Severe
Flutter
Audio In Audio Out
Oregon Hardware/Software
HF Channel Simulator
(used in both directions)
RS232
(Channels in red were
Used in simulations)

20. Preliminary Comparisons WINMOR 200 Hz vs. Pactor 1
10dB
5dB
0dB
-5dB
Tests Run 9/2008 by Rick Muething, KN6KB
Average of 4 channels (WGN, CCIR Multipath Poor, Multipath Good, Moderate Flat Fading)
Throughput averaged over 5 minute period
WINMOR has Ex Hamm 4,8 on ACK , RS FEC on Data

21. Preliminary Comparisons WINMOR 500 Hz vs. Pactor 1,2
10dB
5dB
0dB
-5dB
Tests Run 9/2008 by Rick Muething, KN6KB
Average of 4 channels (WGN, CCIR Multipath Poor, Multipath Good, Moderate Flat Fading)
Throughput averaged over 5 minute period
WINMOR has Ex Hamm 4,8 FEC on ACK, RS FEC on Data

22. Preliminary Comparisons WINMOR 2000 Hz vs. Pactor 2,3
15 Car
16QAM
WGN &
FLT
10dB
5dB
0dB
-5dB
Tests Run 9/2008 by Rick Muething, KN6KB
Average of 4 channels (WGN, CCIR Multipath Poor, Multipath Good, Moderate Flat Fading)
15 Car 16QAM points averaged for WGN and Moderate Flat Fading channels only
Throughput averaged over 5 minute period
WINMOR has Ex Hamm 4,8 FEC on ACK, RS FEC on Data

23. WINMOR Deployment Strategy
Produce the final Virtual TNC as a DLL (Graphics display is optional)
Integrate the DLL into the Paclink MP client and RMS Server programs
For full and immediate access to the WL2K system for beta testing.
Offer “Wrapper” functions to interface the WINMOR DLL via
a virtual serial port or TCP/IP port.
(allows easier access by other existing applications)
These slides and preliminary WINMOR spec will be posted on the
web site.
No decision to date as to licensing or open source.
WINMOR may be released through the Amateur Radio Safety
Foundation Inc. a 501C(3) public charity corporation which
supports amateur radio emergency communications.
Estimated start of beta test (Winlink 2000 system) 3 – 6 months.

24. Remaining Work to be Done
WINMOR
Investigate inner cyclic FEC codes for PSK data modes (1-2 dB gain?)
Optimize “gear shifting” algorithm (basic algorithm operational)
Integrate Busy Channel Detector (SCAMP ?) and ID (CW, Waterfall?)
Investigate crest factor minimization (possible 1-2 dB improvement?)
Investigate 15 Car 16QAM mode (2 Kbits/sec) for VHF/UHF applications.
Finalize WINMOR documentation and release
Document DLL interface and release
Build drivers for Paclink MP and RMS and beta test in Winlink.
Complete help and statistical logging functions

25. Summary
WINMOR
WINMOR looks promising and the testing to date confirms:
Sound card ARQ is possible with a modern CPU and OS
while making acceptable CPU processing demands.
( CPU Loading of < 20% on a 1.5 GHz Celeron/Win XP)
2) Throughput and robustness can be adjusted automatically
to cover a wide range of bandwidth needs and channel conditions.
(10:1 bandwidth range, 57:1 throughput range)
3) ARQ throughput in excess of .5 bits/sec/Hz is possible
in fair to good channels ( bits/sec/Hz measured)
4) Good ARQ efficiency ….70-75%
5) Throughput is currently competitive with P2 and P3 and
significantly better than P1
Thank You!