<html><body><div style="color:#000; background-color:#fff; font-family:arial, helvetica, sans-serif;font-size:12pt"><div><span>I have professional experience with phased locked SDRs for DF work. The ones that I/we use were custom made and cost a LOT of money, think BMW M5.</span></div><div><span><br></span></div><div><span>The way ours work is that the receiver is fed with both a 10 MHz GPSDO reference and a 1 PPS signal. The output data, via USB, has a timestamp which is the number of microseconds from the last second marker. Each USB block contains all of the data from the eight receivers, so that they're automatically synchronised. Since we're also interested in time-of-flight the absolute time is of interest to us as well as the relationships between the eight channels.</span></div><div><span><br></span></div><div><span>The vertical antennas that we use aren't in a circle but in an ellipse, based on a research paper from somewhere which works better
than the more obvious circle. This may be because our system works on spot frequencies from around 4 MHz up to 18 MHz, and needs to provide DF data on all of them. Anyway it works....</span></div><div><span><br></span></div><div><span>We can't afford any more receivers like the above, so if HPSDR can provide something similar I think we could be interested in buying some, and I'm sure we wouldn't be alone.</span></div><div><span><br></span></div><div><span>Jonathan G4KLX (ex HB9DRD)</span></div><div><br></div><div><br></div> <div style="font-family: arial, helvetica, sans-serif; font-size: 12pt; "> <div style="font-family: 'times new roman', 'new york', times, serif; font-size: 12pt; "> <div dir="ltr"> <font size="2" face="Arial"> <hr size="1"> <b><span style="font-weight:bold;">From:</span></b> Simon HB9DRV <simon@hb9drv.ch><br> <b><span style="font-weight: bold;">To:</span></b> "'Helmut, DC6NY'" <dc6ny@gmx.de>; 'Werner Karn'
<werner.karn@googlemail.com>; 'Bruce Beford' <bruce.beford@myfairpoint.net> <br><b><span style="font-weight: bold;">Cc:</span></b> hpsdr@lists.openhpsdr.org <br> <b><span style="font-weight: bold;">Sent:</span></b> Thursday, 26 July 2012, 10:52<br> <b><span style="font-weight: bold;">Subject:</span></b> Re: [hpsdr] Fwd: 1, 2, 3, 4, 5, 6, 7....<br> </font> </div> <br>***** High Performance Software Defined Radio Discussion List *****<br><br>The solution I am looking at uses GPS-locked receivers with data being<br>generated on a specific PPS pulse, sent over the internet to a central PC<br>which determines the signal position. The receivers should be the same, must<br>be using the same central frequency and sample rate.<br><br>Two years ago or so I bought four good Trimble Thunderbolts via eBay for<br>$100 a piece - I'm very glad I did that as these are now hard to find.<br> <br>Simon Brown, HB9DRV<br><a href="http://sdr-radio.com/"
target="_blank">http://sdr-radio.com</a> <a href="http://dit-dit-dit.com/" target="_blank">http://dit-dit-dit.com</a><br><br>You are standing at the end of a road before a small brick building. Around<br>you is a forest.<br>A small stream flows out of the building and down a gully. The sunspot count<br>is 285.<br><br><br>-----Original Message-----<br>From: Helmut, DC6NY [mailto:<a ymailto="mailto:dc6ny@gmx.de" href="mailto:dc6ny@gmx.de">dc6ny@gmx.de</a>] <br><br>for diversity, beam steering, DF-application etc. you need independent<br>RF-channels in the frontend. That's the reason why Joe is using up to four<br>synchronized mercuries. <br><br>_______________________________________________<br>HPSDR Discussion List<br>To post msg: <a ymailto="mailto:hpsdr@openhpsdr.org" href="mailto:hpsdr@openhpsdr.org">hpsdr@openhpsdr.org</a><br>Subscription help: <a href="http://lists.openhpsdr.org/listinfo.cgi/hpsdr-openhpsdr.org"
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