Location: MJ89GP, 9.6623 N 76.5275 E, in the village of Sreekandamangalam, about 8 km north of Kottayam, Kerala, India, time zone UT + 5:30.
Antenna: active E-probe, 40 cm wire in a palm-leave shed, simple BF245C preamp.
Receiver: FiFi-SDR (modified frontend, temperature stabilized Si570), LO 135 kHz or 137 kHz.
Computer: Medion Akoya netbook, battery operated, internal soundcard 11025 IQ /s, SpecLab FFT 21 mHz, 10s /pix.
Receive sessions: During a total of eleven 90-minute sessions, DFCW signals from DK7FC were succsessfully detected eight times.
2012-02-07 0:09 - 01:28 (local morning)
LO 134.9998 kHz (thus freq scale 0.2 Hz high), HGA22 135430.0 Hz, noise blanker not yet enabled.
DFCW traces from DK7FC just detectable at 136172.0 +- 0.075 Hz.
2012-02-08 00:49 - 02:00 (morning)
Scale 0.2 Hz high, no noise blanking, local QRM carrier on 136172.1 Hz, no DFCW seen as DK7FC was not transmitting.
2012-02-08 06:38 - 07:06 (daytime test at local noon)
Scale 0.2 Hz high, HGA about 12 dB SNR in 21 mHz FFT, local QRM lines on 136172.1 and 136074.0 Hz.
2012-02-08 16:04 - 17:32 (evening)
Scale 0.2 Hz high, noise blanker enabled at 16:09 (also on during all following sessions), local QRM line around 136172.1 Hz.
DK7FC (QSYed to 136171.8 Hz to evade QRM line) 18 dB SNR, HGA about 58 dB SNR in 1.5 x 21 mHz noise bandwidth.
2012-02-13 17:39 - 19:12 (evening)
Freq. scale still 0.2 Hz high, DK7FC 136171.8 15-20 dB, intermittent QRM from netbook touchpad around 136174.3 Hz.
2012-02-14 17:18 - 18:45 (evening)
Freq scale corrected now, 136172.1 local QRM goes off at 17:41, DK7FC back on 136172 10 dB SNR.
2012-02-15/16 23:49 - 01:11 (morning)
LO switched to 137.0 kHz, observing Eu and TA slots simultaneously, plots of both DCF39 (138830.6) and HGA22 (135430.0 Hz).
DK7FC on 136172 abt 20 dB SNR (straddling local QRM line), DCF max 30 dB, HGA max 35 dB SNR in 1Hz noise bandwidth.
12-02-16/17 22:56 - 00:26 (morning)
DK7FC up to 15 dB SNR, 136172.1 local line on and off, 136174.3 touchpad, DCF 31 dB, HGA 38 dB (1Hz).
2012-02-18 21:12 - 21:46 (night)
Temporary location: hotel rooftop in Varkala on the coast, suffering from high QRM / mains hash, nil DFCW seen, DCF 26 dB, HGA 33 dB (1Hz).
2012-02-21 19:08 - 20:44 (evening)
Back to Sreekandamangalam, DK7FC 18 dB, DCF 40 dB, HGA 47 dB (1Hz).
2012-02-22 16:52 - 18:30 (evening)
Last session, DK7FC 22 dB, DCF 34 dB, HGA 42 dB (1Hz), IQ audio data files of Eu and TA segments (3.8 MB zipped).
DF6NM Colour-DF LF Grabber - DK7FC LF-DX Grabber