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 Previous: Surfin': Counting Beads Into The Past |  Next: A TV Remote Control Decoder |
 The ZM2E LF setup at Quartz Hill: In the foreground is Andrew Corney, ZL2BBJ. Behind him is Bob Vernall, ZL2CA. "The wall clock is in UTC, and we were getting ready to make our first call to UA0LE at 0930 UTC," Vernall says. |
NEWINGTON, CT, Mar 30, 2004--Amateur stations in New Zealand and Asiatic Russia are laying claim to a new low-frequency world distance record. Bob Vernall, ZL2CA, told ARRL this week that ZM2E, near Wellington, New Zealand, and UA0LE, near Vladivostok, Russia, completed a two-way contact during the night of March 20 on 137.70 kHz.
"The path length is estimated to be 10,311 km (6,392 miles), which is claimed as a new world record between amateur stations on LF bands," Vernall said. "For several hours signals received at ZM2E were so strong that they could be decoded 'by ear,' despite high peaks of QRN." By noting tone-on and tone-off times and checking them against a highly-accurate digital clock, the ZM2E operators at one point were able to decode the very slow-speed (QRSS) CW without resorting to Argo DSP software signal detection. Otherwise, Vernall reported, "Argo gave very good displays even with 3-second dot length."
The Wellington Amateur Radio Club station at Quartz Hill
uses the special ZM2E call sign for work in the 136-kHz band. A DXpedition
station, UA0LE obtained permission to support its LF antennas from a 90-meter
(295.3 feet) broadcast mast.
 The UA0LE team: (L-R) Vlad Burakov, UA0LE; Vic Bondarev, UA9OC; Ed Lesnichy, RU6LA, and Andy Rodichev, RA0LGH. |
Vernall said UA0LE set up for a slow-speed CW beacon transmission on 137.7895 kHz using 60-second dits--known as QRSS60. "They used the shortened form of 'UATLE' to save time in sending," Vernall explained. Several New Zealand amateurs took part in monitoring the beacon. He and Andrew Corney, ZL2BBJ, in suburban Wellington had good copy on the beacon for the three nights leading up to the apparently record-breaking QSO, while Mike McAlevey, ZL4OL, got good results on two of the three nights over a more mountainous path.
In the summer of 2001, Vernall organized a transpacific test in which the 184-kHz signal of the Quartz Hill station, ZL6QH, was heard by Steve McDonald, VE7SL, in British Columbia, Canada. That path was 11,709 km (7260 miles). Amateurs spanned the Atlantic in both directions earlier that year on 136 kHz, and in December 2001, a new LF receiving record was set when John Currie, VE1ZJ, in Canada, received the 136-kHz signal of ZL6QH--a path calculated at 15,645 km (9700 miles).
Vernall points out that the Quartz Hill site is not far from the Pacific Ocean in the direction of Vladivostok. "Sunset in Vladivostok was around 0930 UTC, but nothing was received in ZL till much later, typically opening from around 1400 UTC till sunrise in New Zealand around 1830 UTC," he said.
On the big day, ZM2E started calling UA0LE at 0930 UTC--sunset in Vladivostok. The stations had agreed in advance that ZM2E would attempt to call on the half hour until they made contact. If UA0LE heard ZM2E, it would reply. Otherwise, it would call on the hour.
Vernall said ZM2E uses frequency-shift keyed CW--sometimes
called dual-frequency CW or DFCW--which, Vernall explains, allows for equal dot
length coding, and "is significantly quicker to send than QRSS with
conventional varicode spacing of Morse code." For example, using FSK and 60-second
dot length, it takes 20 minutes to send "ZM2E K." Using QRSS60, sending "UATLE"
takes 37 minutes. Because they need to be succinct, Vernall said, LF DX signal
reports use the same "O," "M" and "T" signal
reports developed
for moonbounce and other weak-signal communication.
 Vic Bondarev, UA9OC, points toward the tower that UA0LE used for its claimed record-breaking QSO with ZM2E in New Zealand. Additional photos are on the G3YXM's "The World of LF" Web. |
The first good UA0LE signals showed up on the computer screen at 1030 UTC, Vernall said. "Excellent reception displayed with Argo DSP software showed 'UATL,' but no E," he said. But the ZM2E team also noted that UA0LE had stopped sending just before the half hour and assumed the Russian station had not yet heard ZM2E and went to receive status just before ZM2E would attempt its next call.
At 1131 UTC ZM2E transmitted a report indicating that it had received a partial call sign, but operators still heard no reply from UA0LE. By 1250 UTC, ZM2E had a good signal from UA0LE, but it took nearly three more hours before UA0LE was able to copy the full ZM2E call sign and confirm reception. For about 50 minutes, the New Zealand operators were able to copy UA0LE by ear.
The defining moment came when UA0LE confirmed reception of the "O" report from ZM2E. "At 1650 UTC, we received 'ZM RO E,' and by acknowledging our report to them it satisfied the minimum requirements for claiming a two-way contact," Vernal said. The two stations continued to "tie the ribbons" on the QSO for another hour or so.
""We decided to send a further 'EE' [dit dit], and their response was 'CO,' and then the signals faded rapidly at 1806 UTC and it was already getting quite light at Quartz Hill," Vernall reported. "We assumed they could be sending 'CONGRATS,' but we were rapidly cut off by the rising sun."
Vernall and Corney were the operators at ZM2E. The
operators in Vladivostok were Vlad Burakov, UA0LE; Vic Bondarev, UA9OC; Andy
Rodichev, RA0LGH, and Ed Lesnichy, RU6LA, Vernall said.
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