|Subject:||Re: VLF: New experiments on 17.47 kHz planned...|
|From:||Markus Vester <[email protected]>|
|Date:||Wed, 29 Aug 2018 06:03:52 -0400|
|Dkim-signature:||v=1; a=rsa-sha256; c=relaxed/relaxed; d=mx.aol.com; s=20150623; t=1535537035; bh=BTzWPgq/+ERPZCa5gD+Tx2RHqW7k2X+rpBblvWjuBaI=; h=From:To:Subject:Message-Id:Date:MIME-Version:Content-Type; b=sBzKUSTwn/ZNOMm7SW2R+NWe74Jdmqq3QJem7Cl/t9IyT5rRV184BoAdQKSSIlE8u NSZvENAExSlHe5x4XH3XQ+dfa1FbLodK7pKz2ErwNUY/MPc3iYWD31rEnJnmGzYe0j f55CiFrkovkKGn9nKc+EgNcys+7f3unQPwl80xG4=|
Hi Stefan and Edgar,
I am still deeply impressed by your groundbreaking work. With close to 12 dB SNR after three nights, it looks like you could chat at a rate of one character per day.
The Excel plots are a nice way to observe the carrier with different integration times and optimize time and bandwidth. It looks like there is another weaker maximum after 21 UT, shortly after sunrise in Hobart (now 20:41 UT).
For a more intuitive interpretation, I would suggest to plot the middle of the integration time rather than the start time on the x axis, i.e. offset each curve to the right by half the duration. Then all curves should more or less peak at the time of a propagation maximum. There may also be a minor offset in the SNR scale because the noise power is slightly underestimated due to rolloff of SpecLab's decimation filter, I think the carrier SNR is really about 0.8 dB lower than indicated on the y axis.
The NWC phase plot at DL0AO shows a negative phase slope around -45° per hour, so it may be worth to also plot SNR with a small negative frequency offset (~ -35 uHz), possibly gaining a bit more at long integration times.
After decoding your message, I have set up the DL0AO 17.47 kHz instance to unspread the PSK, so it may be used as a local control of transmit phase and sequence timing.
Von: DK7FC <[email protected]>
An: rsgb_lf_group <[email protected]>
Verschickt: Mo, 27. Aug 2018 15:12
Betreff: Re: VLF: New experiments on 17.47 kHz planned...
After transmitting carriers for the last 5 days, there are 3 good days to stack, the others were noisy.
The resulting SNR via start time plot for different carrier length is attached. With some uncertainty we can say that these days the ideal start time for the path from DL to VK7 is 17:50 UTC and the message duration should be between 2.5...3 hours.
This evening i'm going to start an attempt for a 2 character EbNaut message. With some luck, just 2 days, i.e. 2 stacks will be enough to get a clear decode.
f = 17470.1000 Hz
Start time: 27.Aug.2018 17:50:00 UTC (daily)
Symbol period: 12 s
CRC bits: 23
Duration: 02:56 [hh:mm]
Antenna current: 1.2 A
Am 24.08.2018 14:02, schrieb DK7FC:
|<Prev in Thread]||Current Thread||[Next in Thread>|
|Previous by Date:||LF: Re: 2200m EbNaut Beacon Trial 24-26 August, Rob Renoud|
|Next by Date:||Re: VLF: New experiments on 17.47 kHz planned..., DK7FC|
|Previous by Thread:||RE: VLF: New experiments on 17.47 kHz planned..., hvanesce|
|Next by Thread:||Re: VLF: New experiments on 17.47 kHz planned..., DK7FC|
|Indexes:||[Date] [Thread] [Top] [All Lists]|