Author Topic: $20 QFH GPS :)  (Read 3010 times)

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Offline @rt

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$20 QFH GPS :)
« on: October 12, 2016, 02:51:12 pm »
Hi Guys,
I guess there's not much more to say :D

Edit,,
This was supposed to be attached as well, but the image was too large.
This is my second go at a QFH antenna for GPS (1575 MHz), a little nicer than the first this time.


« Last Edit: October 12, 2016, 03:10:40 pm by @rt »
 

Offline DaJMasta

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Re: $20 QFH GPS :)
« Reply #1 on: October 13, 2016, 02:13:41 am »
Well it certainly looks nice, but how's performance?  How does it stack up against your standard ceramic antenna?
 

Offline @rt

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Re: $20 QFH GPS :)
« Reply #2 on: October 13, 2016, 04:31:05 am »
Hi, I think the U-Blox module can tell you, but I'm not talking to it serially yet to ask. They both get a lock faster than a Garmin GPS-18 indoors. It does have to be close to vertical though.
 

Offline dannyf

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Re: $20 QFH GPS :)
« Reply #3 on: October 13, 2016, 09:55:05 am »
you can get gps-equipped smartphones for less, with screen to boot.
================================
https://dannyelectronics.wordpress.com/
 

Offline Pjotr

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Re: $20 QFH GPS :)
« Reply #4 on: October 13, 2016, 11:22:54 am »
Hi, I think the U-Blox module can tell you, but I'm not talking to it serially yet to ask. They both get a lock faster than a Garmin GPS-18 indoors. It does have to be close to vertical though.
Yep, all those modules do. Can't imagine U-Blox hasn't a standard win monitor application. Simply hook up a RS232 <--> USB to it.

My own experiences with the Sarantel helicals where not better indoors compared to the standard 1" ceramic ones.
 

Offline @rt

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Re: $20 QFH GPS :)
« Reply #5 on: October 13, 2016, 01:38:43 pm »
I've got a lot of different eBay ceramics on the way, as the module has an SMA connector to change them.
 

Offline @rt

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Re: $20 QFH GPS :)
« Reply #6 on: October 15, 2016, 12:02:31 am »
This can get a position fix sitting horizontally, it just takes more time, so I assume that’s a good thing.
All that there is to do is parse, and software connect the serial NMEA to the vector mapping,
and it’s a functional GPS, which I think is a World first for these resources… otherwise please show me before I run to Hackaday :D






I can see a few traps if the online QFH antenna calculator was used.
* Not accounting for the radius of the metal stem. The calculator assumes the loop will pass through a PVC stem
when providing the result length of the loop wires. For this one, the radius of the stem needs to be trimmed from all elements.
* The bending radius input to the calculator includes the radius of the tube being bent, not just the radius of the former.
* It’s a loop antenna, so using any ferrite material nearby, or in construction including the coax sheath will probably detune, or break it.


« Last Edit: October 15, 2016, 12:05:13 am by @rt »
 


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