Here is another interesting mail from Murray
La5vna
From: [email protected] [mailto:[email protected]] On Behalf Of Murray Greenman
Sent: 18. januar 2012 01:41
To: [email protected]
Cc: [email protected]
Subject: [Knightsqrss] Just how good is OPERA?
Have you been wondering just how good Opera is? I thought I'd run a careful test, comparing with MEPT_JT (WSPR).
There is much more to be learned than I can present here, as from my observations the modes seem to behave differently on different paths. However, I can present here the results of a careful two-hour study west to east, mid-evening on 30m over a 2200km range.
I transmitted both modes, WSPR followed by OPERA2. Each occupies about two minutes, and the baud rates are similar. The transmission pairs were repeated every 10 minutes. The frequencies were chosen to satisfy OPERA and WSPR software running on the same computer from the same receiver.
The transmitter chain, the computer model and even the software was identical for both modes - the only change was that the synthesizer was driven from different scripts on the two different computers (I swapped modes by manually swapping USB cables). The transmitter was a DG8SAQ Si570 synthesizer driving a 74HC240 buffer chip running at 6V, giving 100mW output.
If you look at the attached results, you will see that over the two hour duration of the test, every single WSPR transmission (100%) resulted in a spot from VK2DDI. In that time the same number of OPERA2 transmissions were made, and only 3 of these were successfully received (25%).
It is also obvious that the reported SNR is somewhat lower for the OPERA2 spots. Is this because the mean transmitted power power in an ASK mode is halved? I would therefore expect on average only 3dB lower than WSPR.
It should be stressed that these results relate to just the one path, and just one evening. Another listener, ZL2AFP, on a 500km north-south path, received more OP2 spots than WSPR spots. There is much yet to learn about (for example) the behaviour of this mode under mid-latitude NVIS conditions.
I encourage you to run your own tests under other conditions, but be careful to run identical setups for each mode.
73,
Murray ZL1BPU/ZL1EE
