Transcript K1JT_Wurzburg - Princeton University

Open Source WSJT
12th International
EME Conference
Würzburg
August 25-27
2006
Joe Taylor
K1JT
Open Source WSJT
I.
II.
III.
IV.
V.
Motivation, brief history
Current status, usage
Some EME “politics”
Future developments
Hardware demonstration
I. Motivation for WSJT

Study coding and modulation schemes

Enable VHF/UHF QSOs at minimum S/N

Propagation modes: MS, EME, …
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Make a convenient, enjoyable, rewardingto-use program

Establish ultimate limits for weak-signal,
real-time QSOs.
EME: Design Goals for JT65
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Work at lowest possible signal levels
Conform to standard operating practices
Exchange all info required for valid QSOs
Good QSO rate for contests, DXpeditions
Very high confidence in copied information
Extremely low probability of false QSOs
WSJT Milestones
2001: FSK441 for meteor scatter
2002: JT44 for EME
2002: JT6M for MS, ionoscatter on 6 m
2003: JT65 for EME, with FEC
2005: JT65 “Deep Search” decoder;
Open Source release
2006: Linux and FreeBSD versions;
many algorithmic improvements
II. WSJT Status: August 2006
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Total users: >3000
Nearly all MS uses FSK441
JT6M popular on 6m
JT65 EME users: 300 – 600
JT65 EME QSOs: >40,000
30% of entries in 2005 ARRL
EME contest used JT65
(On 2m, >70%)
JT65 EME, Band-by-Band
6 m:
QSOs made almost daily
2 m:
1-yagi to 2-yagi QSOs common
70 cm: usage slowly increasing ?
23 cm: usage increasing
With 2.3–3m TVRO dishes, 10 Watts
is enough!
VK7MO works G4CCH on 23 cm
G4CCH, 23 cm
G4CCH, 23 cm
CW NOW?
TNX EASY QSO
TNX REX –23
73
RRR
VK7MO G4CCH IO93 OOO
First and Last G4CCH transmissions
CW NOW?
VK7MO G4CCH IO93 OOO
JT65 DXpeditions
1. VK7MO: VK9XMO, VK9CMO
2. 3Y0X, Peter I
3. ZL2RS: to many places
4. ON4IQ to HI3, FS, J4, …
Single yagi or small, transportable array
with modest power is enough on 2 m
and 70 cm -- and even 23 cm, for
working larger stations
Informal Survey (July 2006)
1. How many EME QSOs have you made using
JT65? On what bands? Using JT65A, B, or C?
2. How many QSOs that you originally considered
complete, turned out to be invalid? For what
reasons?
3. Has anyone claimed to work you in a JT65 EME
QSO that did not occur, or was not valid?
4. Are the fixed JT65 messages generally reliable,
and the formats useful?
5. Do you make scheduled, or random QSOs? Call
CQ? Answer CQs? Self-spot when calling CQ?
Tailend other QSOs?
Informal Survey, cont’d
50 responses
1. QSOs by band (round numbers)
6m: 200 2m: 11,800 70 cm: 400 23 cm: 100
Total reported QSOs: 12,500
2. Bad QSOs considered good by reporting station: 16*
3. Bad QSOs considered good by other station: 12*
4. Message structure, reliability: very good
5. Typical mix: 50% random, 50% skeds
*Bad QSOs mostly results of operator errors
JT65: Differences from CW
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Structured messages
Error-correcting code
Synchronized transmissions
Transmissions can be averaged
Copy is “all or nothing”
Roughly 10 dB advantage
JT65 Minimal EME QSO
1. CQ HB9Q JN47
2.
HB9Q K1JT FN20
3. K1JT HB9Q JN47 OOO
4.
RO
5. RRR
6.
73
Pileup Situations
1. CQ 3Y0X EC41
2.
3Y0X K2TXB FM29
3. K2TXB 3Y0X EC41 OOO
4.
3Y0X K2TXB RO
5. K2TXB 3Y0X RRR
6.
73
Callsign-tagged reports, RRRs
Percent of transmissions copied
Measured JT65 Performance
100
Shorthand
80
Sync
60
DS
40
KV
20
0
-35
-30
-25
S/N in 2500 Hz BW (dB)
-20
JT65 Decoding Thresholds
Message type
KV KV Avg DS
(dB)
(dB)
(dB)
Arbitrary
–24
–28
BC + Grid/Rpt
–24
–28
Shorthand
Sync limit: –30 dB
Short65
(dB)
–28*
–32
*Callsign must be in list
III. EME Politics
On a web site: “… only two characters need to be
decoded to print full EME messages…”
Editorial in a respected journal: “… the JT65 mode
when using the Deep Search Decoder … needs to
‘recognize’ just only 2 letters but displays a full callsign.”
Another web site: “All JT65 QSOs made using the
Deep-Search Routine are not complying with long
established EME QSO guidelines and are not eligible
[for this Top List] due to partial copy.”
✻✻✻ No Nein Non Нет… ✻✻✻
See “How Many Bits” paper near end of Proceedings !
Try the JT65 Hardware Demonstration, yourself !
IV. Future WSJT plans?
Pulsar mode ?
 Enhanced meteor scatter mode ?
 Connection to Linrad / Winrad ?
 New soft-decision RS decoder
 EME Echo and Measure modes
 30-bit JT65 messages
 Expanded waterfall: 0 – 5 kHz

Expanded waterfall bandwidth
WSJT 5.9.6
✻
✻
30-bit Messages
1.
2.
3.
4.
5.
6.
Bits
CQ de 3Y0X
30
de K2TXB
30
K2TXB 3Y0X OOO
72
3Y0X K2TXB RO 72
TXB de 0X RRR
30
73 de K2TXB
30
Notes:
 No grid locators
 Reports and Rs tagged with callsigns
 Numerical reports optional
 Messages 5 and 6 can be shorthands
 No need for a callsign list
JT65+ Decoding Thresholds
Message type
KV KV Avg DS Short65
(dB)
(dB) (dB)
(dB)
Arbitrary
–24
–28
BC + Grid/Rpt
–24
–28
–32
Shorthand
30-bit
–28*
–27
*No list required
Programmer’s Information
GNU General Public License (GPL)
 Languages:

Python for user interface
 Fortran for number crunching
 C for A/D, D/A, PTT, …
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Compile on Windows, Linux, …
 More details in Proceedings
 New contributors welcome !

http://developer.berlios.de/projects/wsjt
[email protected]
V. Hardware Demonstration
A
Audio cables
B
Headphones
Generate JT65 (or CW) at any desired S/N
1.
2.
3.
4.
5.
A makes “QSOs” with B ?
Send test messages
Listen to the signals
Stress-test the decoders
Play as you wish …
Hardware Demo (cont’d)
1. Run WSJT on
both computers,
make “QSOs”
Generated S/N in dB (2500 Hz BW)
Format: #─26
Hardware Demo (cont’d)
2. Run WSJT on
A, SimJT on B;
“torture test”
the decoders!
Hardware Demo (cont’d)
3. Do the WSJT
tutorial using
recorded EME
signals
TNX 73 GL
… de K1JT