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Re: moving to 8 digits of lat/lon (gpxlogger, maybe elsewhere)?

From: John Ackermann N8UR
Subject: Re: moving to 8 digits of lat/lon (gpxlogger, maybe elsewhere)?
Date: Thu, 3 Sep 2020 15:46:03 -0400
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.8.0

On 9/3/20 3:29 PM, Gary E. Miller wrote:

I'm using the u-blox ANN-MB-00-00 dual-freq mag mount antenna, which
seems a bit touchy.  It absolutely wants a ground plane (I'm using a
metal pie tin) and the solution often dropped to float when there
were sky obstructions.

Uh, wait a minute.  If the pie tin is > 50mm it is not doing what you
think it is doing.  See Section 5 of this u-blox doc:


Thanks for the pointer to that. Interestingly they don't talk about the effect of ground planes bigger than about 100mm square -- and a vehicle-mounted mag mount is likely to have a much larger metal surface. I wonder how a several-wavelength ground plan impacts things...

Anyway, the pie tin was a temporary expedient, adopted when I found that without something under the antenna, I could get only a FLOAT soluton; adding the pie tin got me a FIX solution within a few seconds.

Once I figure out the best way to feed more than 3.3V down the cable, I have a nice Ashtech survey antenna available for field use.


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