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precision_timing:comparing_gps_antennas [2013/01/08 19:00] |
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| + | ====== Comparing GPS Antennas ====== | ||
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| + | I have tried several models, the original Trimble Bullet, the HP 58532A and several pucks, including a nice Trimble mag-mount unit. Two of the pucks are designed for marine use, with a decent waterproof case and mounting, but they are in an all plastic case. There have no part number that I could see, I need to look closer to see if there is a manufacturer's mark. They were obtained on eBay from a long forgotten vendor... | ||
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| + | I am not sure how Trimble rates the mag-mount antenna, but it probably was not designed for permanent outdoor installation, even though it is heavy and looks very well made. | ||
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| + | They were compared by plugging them into my main Thunderbolt receiver and checking the time to complete self-survey. Because of the constantly changing constellation, it is difficult to compare antennas otherwise over a short time. I felt the self-survey was a useful indicator even though I am perfectly aware it is just that. Self survey takes several hours (2 to 8 in my experience, depending on the combination of antenna and receiver). | ||
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| + | It seems my main Thunderbolt receiver (original OEM design with built-in | ||
| + | supply) is more sensitive than the two Group-buy Thunderbolts I also have, as it does complete self-survey faster and seems to report more satellites, even though I have not yet attempted to log that information over a period of time to give an objective result. Another project for the winter.... That could also be due to a different internal configuration of the receivers, even though I have not seen any difference in look-up angle settings and such. | ||
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| + | All antennas were compared while inside the house, in the upstairs ham shack/office/lab, so pretty close under the shingles covered roof and facing south. | ||
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| + | The Bullet I have is less sensitive than the others. I receive fewer satellites with it and it takes much longer for the self-survey to complete, I do not use it. I got it with my main Thunderbolt receiver and it was not new when I got it. All other antennas were bought new. | ||
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| + | The HP and the pucks seems to give about the same signal strength and take about as long to complete the self survey. The HP will go outside when I have a chance to install it, it's still way too hot over here to do anything outside that you don't HAVE to do... | ||
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| + | I bought the HP on eBay, new, for $50 with shipping, compared to about $25 each for the pucks, including shipping costs. Unless you are satisfied with an indoor antenna (in which case I would say: "What are you doing on time-nuts?"), I can't justify saving $25 by using a puck compared to the wonderful piece of design and technology that the HP 58532A is. By the pound, you get much more with the HP :-) | ||
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| + | Didier KO4BB | ||
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| + | PS: Bugs have antennae, receivers and transmitters have antennas: http://en.wikipedia.org/wiki/Antenna | ||