Originally posted by Ressy
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Originally posted by Birdie View PostI paid SGD 1,200 ( USD 1,050 - include our 7 % GST and high cost of UPS services from USA ) for a piece of crap - Radarbox 3D.
But yeah the cost is crazy.. especially when you can get an Rpi for $50AU or so, build it up with the case, a gps a pre amp, tv stick...
A few people reckon the distance is greater on fr24box by about 15-20% over tv stick, but since radarcape has inbuilt preamp that answers the question as to why (even though in RF world, any amplification MUST be done at the antenna, else you also amplify noise), since the marine (AIS) equivalent to radarcape units can be bought off the shelf in AU for under $500 - there is no possible reason in hell (or on earth) that ADSB units should cost more, let alone twice (The AU dollar value is even less than when I posted that, so we'd probably be looking well over $AU1K now.
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The radarcape doesn't have a pre amplifier in the sense that all frequencies are amplified, it does have amplifier in the filter stage to boost the signal AFTER filtering. It is essentially a tweaked mode-s beast. http://wiki.modesbeast.com/Mode-S_Beast:System_Design
this is a picture of beast board http://ads-b.ca/fa/img_9526.htm Happens to be what flight aware use in there boxes.
this is a picture of a radarcape http://ads-b.ca/radio-board.htm now although the layout is slightly different you can see that it is the same circuit.
AIS is a completely different frequency and easier to pick up and process, it surprising how much dearer the parts are when you go up in frequency. Also things like using a proper FPGA rather than a PIC means the price difference of £2 to £20 alone. Its not hard to see how these add up to a costlier unit.Last edited by SpaxmoidJAm; 2015-06-19, 16:46.T-EGLF8
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Originally posted by SpaxmoidJAm View Post
AIS is a completely different frequency and easier to pick up and process, it surprising how much dearer the parts are when you go up in frequency. Also things like using a proper FPGA rather than a PIC means the price difference of £2 to £20 alone. Its not hard to see how these add up to a costlier unit.
Infact, that tiny 10cm antenna taped to top of my ant base (mast was lowered 10cm to accomadate test), using an active USB cable, performs far better than my 15 metre rg6 quad into a 6dbi antenna, since there is zero insertion loss.
Actually, since its just started winter here, and the coldest outside nights we see is no less than 7 or 8c with more typical of 9-14, and I don't expect much rain for a couple of months, I might even throw it back up for while when I get a chance
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