Need someone in Argentina, Brazil, Mexico or South Africa to record a LW signal - Page 1
Forum section: electronics / rf-microwave

author: philpem
author_rank: Frequent Contributor
timestamp: February 18, 2016, 11:55:22 pm
content: Hi guys,A few of you might remember my attempts at reverse-engineering Datatrak. I'm making some progress -- I've got my Locator unit to sync up to my fake "trigger" signal (the sync marker which marks the start of a timing chain burst). Sadly I need a bit more...There are still a few active Datatrak networks that I know of:- Argentina: 146.455kHz and 133.2275kHz- Malta (may or may not be still active): 146.1780kHz and 132.9199kHz- Mexico: 146.155kHz and 132.9275kHz- South Africa: 160.650kHz and 143.474kHzI'm after a recording of several minutes of the signal on these frequencies, from a reasonably good quality receiver, in lossless format (a WAV or FLAC file, at a sample rate of 44100 or higher). Mode would be upper sideband, with the receiver tuned about 1kHz lower than the frequencies shown above (so as to push the warbling of the Datatrak signal to near the middle of the audio and IF filter bandwidth).Ideally I need the flat, unfiltered receive audio, like you'd use for PSK31 and other digital modes.A five-minute recording should give me enough to decode the format of the Clock subcode (I need to find the start, then see it increment). The longer the recording, the better, though. Several ten-or-so minute recordings over a few days would be the gold standard, but I'm not going to push my luck hereCan anyone help a struggling engineer with a crazy project?Cheers,Phil.

author: ivan747
author_rank: Super Contributor
timestamp: February 19, 2016, 01:26:47 am
content: I would suggest you try to tune to these frequencies using websdr.org. You could find that the propagation conditions are good enough o make a recording using one of the receivers in that website.Edit: I can now see the problem: there are no LF receivers anywhere near the locations you want to receive from. Malta might be your best bet, since it's close to Europe, which has some funcional LF receivers. Still a long shot.

author: philpem
author_rank: Frequent Contributor
timestamp: February 21, 2016, 01:32:19 am
content: Quote from: ivan747 on February 19, 2016, 01:26:47 amSadly it looks like the European LW receivers don't have enough range to pick up the Maltese signal -- or the Maltese signal is no longer transmitting

author: dcarr
author_rank: Regular Contributor
timestamp: February 21, 2016, 06:42:49 am
content: My location is about 300 miles north of the Mexican border in Texas. Is that close enough to detect the signal? Also, what kind of antenna is usually used for this? I don't have a LF radio, but it seems like this frequency is low enough that perhaps something else could be adapted.David

author: philpem
author_rank: Frequent Contributor
timestamp: February 24, 2016, 09:30:46 pm
content: Quote from: dcarr on February 21, 2016, 06:42:49 amIt's certainly worth a shot -- someone managed to pick up the signals from the UK chain in Germany a few years back, using an amplified loop antenna!The usual suspects for LF antennas are wire loops with preamps (an MPF102 FET with some support components) to convert from the high impedance loop to 50 Ohms for the receiver. If the signal is strong enough you might be able to pick it up with a whip -- the original Datatrak antennas were just lengths of wire connected to a preamp.As far as radios -- a few HF radios will tune down to LF signals in this range. My Yaesu FT897D will, but it needs an input pre-amp to get any decent receive performance. I believe some of the Icoms will too.Thanks,Phil.

author: blitzking
author_rank: Newbie
timestamp: August 28, 2016, 08:41:56 pm
content: Quote from: philpem on February 21, 2016, 01:32:19 amIs there somewhere called Maltacloseto Europe???

author: zapta
author_rank: Super Contributor
timestamp: August 28, 2016, 10:03:50 pm
content: Quote from: blitzking on August 28, 2016, 08:41:56 pmWas it moved recently?

author: Len
author_rank: Frequent Contributor
timestamp: August 28, 2016, 10:52:48 pm
content: Quote from: zapta on August 28, 2016, 10:03:50 pmIt was shoved out into the Mediterranean. Apparently neither Europe nor Africa wants it.