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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