Hello Jay and John,
Thanks for the detailed, and carefully laid-out test. Very interesting
reading.
IMHO Opera was a bit over-hyped in the beginning, making claims which
were not justified by *fair* on-air tests, and a test like yours
(simultaneous transmission at equal power levels, using the the same RX
and TX antennas) brings it back to reality. Testing one day (or even
one hour) with one mode, and the next day (or hour) with another mode
isn't fair considering changing conditions (diurnal effects, path loss,
QRN, etc).
All the best,
Wolf .
Am 25.10.2012 04:14, schrieb [email protected]:
Here is some further info for discussion on WSPR vs. OP.
On 8/23/12 WD2XES and WD2XNS conducted a 'heads up' test of WSPR vs
OP4 on 136 kHz. The test started at 2230Z on 8/23/12 (in daylight),
continued throughout the night, and concluded at 1030Z on 8/24/12 (in
daylight). Conditions were normal for a summer evening with typical
amounts of static. Distance between XES and XNS is 72 miles.
At the WD2XES transmitting end John combined both WSPR and OP4 signals
into a common phasing transmitter, amplifier and transmitting antenna.
Transmitted power levels were identical for each mode and very QRP -
60 mW or less. WSPR and OP4 frequencies were within a kHz of each other.
At the WD2XNS receiving end a common receiving antenna was used
feeding a single GPS disciplined receiver. Audio output from the
receiver was applied to a single sound card / computer setup which ran
an instance of each program.
Results can be found at http://www.w1vd.com/WSPROP4082312A.pdf .
Notes:
1) At 0230Z John made a significant reduction in transmitted power
level to better explore the weak signal performance of the two modes.
This produced the desired results with 'at the threshold' receptions
through 0420Z. No receptions were noted between 0420Z to 0902Z and
were probably due to an increased static level during that period.
Signals climbed back out of the noise again at 0902Z and reception
continued through the testing period.
2) The OP4 results were 'time shifted' to align with the corresponding
WSPR start times.
3) There are a few instances where the OP4 results are not spaced on
exactly 4 minute intervals ... this is likely caused by Opera
reporting 'slipping' into the following minute.
Conclusion:
WSPR has an advantage over OP4 in weak signal performance. Also, keep
in mind that WSPR requires half the amount of transmission time and
transmits more information. In our opinion, OP8 would be more in line
with WSPR in terms of weak signal performance. In that case WSPR gets
the job done in one fourth the time taken by OP8 and transmits more
information.
Jay W1VD WD2XNS WE2XGR/2
John W1TAG WD2XES WE2XGR/3
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