Transcript Small station EME on 23 and 70 cm using WSJT JT44

SMALL STATION EME
ON 70 AND 23 CM USING JT44
BY AL, K2UYH
OBJECTIVES
 GET
YOU INTERESTED IN WORKING EME.
(Most hams still believe exotic equipment,
huge antennas, and very high power are
needed to work EME.)
 SHOW THAT YOU CAN ENJOY THE THRILL
OF MOONBOUNCE WITH A MODEST SETUP.
(Basically the equipment you already have.)
 INCREASE EME ON 432 AND 1296 MHz.
(There is already a lot of small station EME on 6 & 2 m.)
WHY WORK MOONBOUNCE
70 & 23CM
 IT
IS EXCITING!
 THE MOST FUN IN HAM
RADIO IS MAKING RARE,
UNUSUAL, OR DIFFICULT
CONTACTS.
 EME ALLOWS YOU TO
WORK WORLDWIDE DX
ON ANY BAND - 6 M UP.
 A WAY TO INCREASE
YOUR GRID SQUARES,
STATES & COUNTRYS.
EME
K2UYH
A BIG STATION IS NOT NEEDED!
OH3MCK
MY 1ST JT44
CONTACT WAS ON 23 CM WITH
OH3MCK.
OH3MCK WAS USING 2 X 22 dBi YAGIS
(LINEAR POL.) AND 40 W.
2ND JT44 QSO WITH OH1FF/p
 OH FIELD DAY STATION
ALSO ON 23 CM
 USING A 1.8 M DISH (CIR. POL?) AND 50 W
 WE COULD HAVE QSO’D VIA CW, BUT
JT44 DEFINITELY HELPED!

1ST JT44 ON 70 CM WITH ES8X
144 MHz
432 MHz
EUR.
VHF FIELD DAY STATION ON
KIHNU ISLAND (KO18xc).
4 x 12 EL YAGIS (WITH ELEV.) AND
300 W PA.
KIHNU IS A SMALL
ISLAND ABOUT 40
KM OFF THE COAST
OF ESTONIA IN THE
GULF OF RIGA,
BETWEEN ESTONIA
AND LATVIA.
(IN ESTONIA)
1ST JT44 ON 70 CM WITH ES8X
144 MHz
432 MHz
EUR.
VHF FIELD DAY STATION ON
KIHNU ISLAND (KO18xc).
4 x 12 EL YAGIS (WITH ELEV.) AND
300 W PA.
K2TXB OPERATES JT44 ON 2 m
 RUSS
USES 2 X KLM 16 LBX YAGIS ON A
POLAR MOUNT AND A KW.
 WORKED 42 STATIONS IN 15 COUNTRIES
AND 15 STATES
EME PRACTICE
 EME
OPERATED USING CONVENTIONAL (CW & SSB) OR
DIGITAL MODES
 SOME STATIONS ARE EXPERIMENTING WITH DIGITAL
MODES AS PUA43 THAT PROVIDE MANY DB ADVANTAGE,
BUT REQUIRES SPECIAL EQUIPMENT AND TRADES TIME
AND PRECISE FREQUENCY FOR SIGNAL LEVEL.
 MOST DIGITAL EME IS WITH JT44.
 JT44 USES STANDARD EQUIPMENT, WORKS IN VIRTUALLY
REAL TIME AND HAS RELAXED FREQUENCY STANDARDS.
JT44 BASICS -TX
 EACH
TRANSMISSION IS 30 SECONDS
LONG AND CONSISTS OF MESSAGE AND
SYNC INFORMATION.
 THE MESSAGE IS 22 CHARACTERS LONG
AND REPEATED 3 TIMES.
 THE SYNC IS INTERSPERSED WITH THE
MESSAGE AND SENT ABOUT HALF THE
TIME.
 A UNIQUE FREQUENCY IS ASSIGNED TO
LETTERS, NUMERALS AND PUNCTUATION
CHARACTERS (43 TONES) + SYNC = 44!
JT44 BASICS - RX
AT THE END OF THE RECEPTION PERIOD JT44:
 SEARCHES FOR TIME SYNC (SYNC PATTEREN)
OVER –4 TO 1 SECOND DELAY PERIOD.
 SEARCHES FOR FREQ OFFSET (+/- 600 Hz).
 DETERMINES AND DISPLAYS MESSAGE.
 AVERAGES CHARACTERS IN EACH TIME SLOT
OF THE 22 CHARACTER MESSAGE.
AVERAGING
 WHEN A SIGNAL IS
STRONG CAN GET FULL COPY IN
A SINGLE SEQUENCE – (QSO in < 2.5 min!)
 OFTEN SIGNALS ARE WEAK AND THE MESSAGE
GARBLED – (This is where JT44’s averaging pays off.)
 IF THE SAME MESSAGE IS SENT EACH SEQUENCE,
JT44 WILL AVERAGE THE RESULTS OF ALL PERIODS.
 THE MESSAGE WILL CORRECT ITSELF WITH EACH
SUCCESSIVE PERIOD.
VE7BBG’S SIGNAL
COR RUNS A 7.5’ DISH AND 120W AT THE FEED
TIME SYNC –
FREQ –TIME AMP -
ECHO MODE – WANT TO TRY EVEN IF DON’T USE JT44 FOR EME!
 LET’S YOU
EVALUATE EME SYSTEM CAPABILITY.
 NOT GOOD FOR COMMUNICATIONS.
 ON 70 CM COPIED ECHOES WITH 200 W ON HORZ WITH
TROPO STATION.
STATION REQUIREMENTS
IT DEPENDS ON HOW BIG THE STATION ON THE
OTHER SIDE IS?
 ON 70 CM – SINGLE LONG YAGI AND > 100 W. ***
WANT TO ELEVATE (REALLY A MUST)!
***
PREAMP AT THE ANTENNA (AND PA AT ANT).
*** POLARIZATION ROTATION?
 ON 23 CM – SINGLE LONG LOOP YAGI OR 5’ DISH
WITH CIRCULAR FEED AND > 50 W.
*** CIRCULAR POL GAIN + 3 dB!
PORTABLE EME – DL3OCH STYLE
 BODO
USES IC-706, HB TRANSVERTER WITH 100 W
AND A 59 EL YAGI (5 m long & 18.7 dBd)FROM HIS CAR.
 BESIDES DL, HE HAS OPERATED FROM 3A AND HB0.
YOU NEED A COMPUTER AND SOUND CARD
 SHOULD
RUN 32 BIT VERSIONS OF THE WINDOWS
OPERATING SYSTEM AND BE FAST ENOUGH TO
HANDLE JT44 AND SEVERAL OTHER TASKS.
 A 300 MHz PENTIUM OR BETTER WITH WINDOWS 98
OR PREFERABLY WINDOWS 2000 OR XP WILL BE
MORE THAN SUFFICIENT.
 NEED TO INTERFACE THE COMPUTER TO YOUR RIG
1) PTT FROM SERIAL PORT (VOX will work),
2) TX AUDIO FROM AUDIO OUT OF SOUND CARD, &
3) RX AUDIO TO INPUT OF SOUND CARD.
(DL3OCH uses Acer laptop – 650 MHz Celeron)
OTHER SPECIAL REQUIREMENTS
 FREQUENCY ACCURACY AND
STABILITY
*** WANTS TO BE WITHIN +/- 600 Hz.
(No problem on 144 MHz, but on 1296 – Can tune?)
*** FREQ DRIFT < FEW Hz IN 30 SECS.
*** I USE A GPS STANDARD.
 DOPPLAR SHIFT CORRECTION
*** NOT IMPORTANT ON 144, BUT SIGNIFICANT ON
432 (can be > 1 kHz) AND 1296 (can be > 3 kHz).
*** MUTUAL DOPPLAR CAN BE VERY DIFFERENT
FROM LOCAL ECHO SHIFT!
*** JT44 HAS BUILT IN CORRECTION.
(DL3OCH – nothing special)
OTHER REQUIREMENTS CONT’D
 MUST KNOW TIME TO
~ 1 SECOND.
*** I USE RADIO SHACK WWV CLOCK AND SET MY
COMPUTER BEFORE SKEDS
*** SOFTWARE IS AVAILABLE TO AUTOMATICALLY
TO UPDATE YOUR CLOCK VIA THE INTERNET
<http://www.thinkman.com/dimension4/>.
*** CAN ALSO USE GPS STANDARD.
 MUST BE ABLE
TO TRACK THE MOON
*** JT44 HAS BUILT IN TRACKING.
(DL3OCH has GPS & digital radio clock)
CONCLUSION
 EME
WITH JT44 IS NEW AND CHALLENGING.
 IT’S NOT JUST HAVING A YAGI, A100 W AND A COMPUTER!
 THE COMPUTER DOES NOT DO EVERYTHING FOR YOU!
 IT IS PRETTY EASY WITH A BIG STATION, BUT THERE IS STILL A
LOT TO IT: ACCURATE FREQ AND TIME, MOON TRACKING,
DOPPLAR, POLARIZATION (ON 432).
 WITH A WEAK STATION, ALL THE ABOVE PLUS YOU MUST
UNDERSTANDING HOW TO USE JT44 FULLY (EXCLUDE/INCLUDE,
CLEAR, FOLD, FREEZE, CLIP, ETC.)
 FOR SKEDS CHECK INTO K1RQG’S 20 M NET (14.345 MHz 1600Z
SAT & SUN) AND READ 70 CM & UP EME NEWSLETTER
<http://www.nitehawk.com/rasmit/em70cm.html> .