[Lowfer] OP65 late start for tonight-73 dial as usual...
Garry Hess
k3siw at sbcglobal.net
Wed Dec 11 07:09:49 EST 2013
From 2300 to 2345 four WG4XRS WSPRX-15 decodes were made, but SNRs were
only between -20 and -24 dB. That was with SDR-IQ2 (internal clock) and
eprobe1 (rooftop at 30' AGL).
Switching to opera, 65-rate decodes for that setup (k3siw-2) were:
sdr-iq2, eprobe1
06:44 73 WG4XRS Op65 -16 dB Fade 0%
05:39 73 WG4XRS Op65 -16 dB Fade 0%
04:33 73 WG4XRS Op65 -17 dB Fade 0%
03:27 73 WG4XRS Op65 -21 dB Fade 41%
02:22 73 WG4XRS Op65 -26 dB Fade 43%
Simultaneously deep-search detection opds64 gave:
sdr-iq2, eprobe1
2013-12-11 06:44:59 WG4XRS 934km 74551.769Hz 2mHz -22.3dBOp 78% 20.0dB
2013-12-11 05:39:17 WG4XRS 934km 74551.772Hz 5mHz -23.4dBOp 100% 20.0dB
2013-12-11 04:33:36 WG4XRS 934km 74551.773Hz 5mHz -21.7dBOp 95% 20.5dB
2013-12-11 03:27:52 WG4XRS 934km 74551.770Hz 3mHz -20.4dBOp 100% 18.8dB
2013-12-11 02:22:10 WG4XRS 934km 74551.771Hz 5mHz -22.9dBOp 97% 20.3dB
For SNR differences (opds64-opera65) of:
06:44 -6.3 dB
05:39 -7.4 dB
04:33 -4.7 dB
[03:27 +0.6 dB (ignore, USB link failed during this period)]
02:22 -3.1 dB
--------------
aver= -5.4 dB
A second receive setup (k3siw-1) using SDR-IQ1 (gps-locked external
clock) and eprobe2 (away from house but only 10' AGL) gave:
sdr-iq1, eprobe2
06:44 73 WG4XRS Op65 -12 dB Fade 0%
05:39 73 WG4XRS Op65 -11 dB Fade 0%
04:33 73 WG4XRS Op65 -12 dB Fade 0%
03:27 73 WG4XRS Op65 -12 dB Fade 0%
sdr-iq1, eprobe2
2013-12-11 06:45:00 WG4XRS 934km 74551.791Hz 1mHz -25.0dBOp 100% 20.0dB
2013-12-11 05:39:18 WG4XRS 934km 74551.791Hz 1mHz -25.6dBOp 97% 20.1dB
2013-12-11 04:33:35 WG4XRS 934km 74551.791Hz 1mHz -24.0dBOp 91% 20.6dB
2013-12-11 03:27:51 WG4XRS 934km 74551.791Hz 1mHz -25.5dBOp 99% 20.3dB
For SNR differences (opds64-opera65) of:
06:44 -13 dB
05:39 -14.6 dB
04:33 -12 dB
03:27 -13.5 dB
--------------
aver= -13.3 dB
The opera65 values between k3siw-1 and k3siw-2 indicate that eprobe2
outperforms eprobe1, even though it's much lower. Presumably its
distance from the house results in a lower noise floor.
I have no idea why the opds64 snrs fro k3siw-1 were low here.
Subjectively on the SpectraVue waterfall, the signal looked better than
it did with sdr-iq2, eprobe1. The waterfall levels were higher with the
second setup compared to the first because the latter had a resistive
splitter (-6 dB) in the receive path. Nonetheless, the SpectraVue
waterfall backgrounds appeared pretty comparable using the same maximum
level setting of -70 dBm. Perhaps the higher levels confused evaluation
of the noise floor.
Regardless of these observations, past receptions of DK7FC make it clear
that deep search has a real sensitivity advantage over regular opera.
Which receive setup does best may vary with signal level/direction and
time. If one regularly outperforms the other that will become evident as
more experience is gained.
--
73, Garry, K3SIW, EN52ta, Elgin, IL
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