Improving GNSS performance #82
Replies: 9 comments 9 replies
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Hello Peter,
I already fully assembled my unit just haven't had a chance to Mount it due
to hurricane season and medical reasons. I really want to do this fix but
think in going to have to cut apart my transponder as I heat shrinks it all
the way together line the instructions said. Do you have any advice?
Thank you for your time and help,
David
…On Tue, Sep 21, 2021, 11:15 Peter Antypas ***@***.***> wrote:
For those who have recently obtained a kit and haven't completely mounted
it: If you are reasonably good at basic SMD soldering, please follow the
instructions here to significantly improve your unit's GNSS precision:
1. *DO NOT* cover the transponder board with clear heat shrink tubing.
It severely detunes the GPS antenna. If you have already completed that
step, then carefully cut through the heat shrink to uncover the PCB. You
still need the clear heatshrink to keep the lower antenna assembly together
and to act as the secondary water seal. Your lower antenna assembly should
look like this:
[image: IMG_1296]
<https://user-images.githubusercontent.com/1565933/134207058-53243d0b-f029-4cb3-b4ca-6a8476ec4892.JPG>
1. Use something moderately sharp to scrape a bit of solder mask to
allow a "pi" shape matching network to form on the GPS antenna trace as
shown below. Remove the existing capacitor and mount these components
instead:
[image: IMG_1301]
<https://user-images.githubusercontent.com/1565933/134207624-bf0a87ad-03ed-4b7f-84bf-da6491bc0d12.JPG>
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Did I send you extra heat shrink with it or not? If not, I'll just send you
some.
…On Tue, Sep 21, 2021 at 7:19 PM Rudder2 ***@***.***> wrote:
Hello Peter,
I already fully assembled my unit just haven't had a chance to Mount it due
to hurricane season and medical reasons. I really want to do this fix but
think in going to have to cut apart my transponder as I heat shrinks it all
the way together line the instructions said. Do you have any advice?
Thank you for your time and help,
David
On Tue, Sep 21, 2021, 11:15 Peter Antypas ***@***.***> wrote:
> For those who have recently obtained a kit and haven't completely mounted
> it: If you are reasonably good at basic SMD soldering, please follow the
> instructions here to significantly improve your unit's GNSS precision:
>
> 1. *DO NOT* cover the transponder board with clear heat shrink tubing.
> It severely detunes the GPS antenna. If you have already completed that
> step, then carefully cut through the heat shrink to uncover the PCB. You
> still need the clear heatshrink to keep the lower antenna assembly
together
> and to act as the secondary water seal. Your lower antenna assembly
should
> look like this:
>
> [image: IMG_1296]
> <
https://user-images.githubusercontent.com/1565933/134207058-53243d0b-f029-4cb3-b4ca-6a8476ec4892.JPG
>
>
> 1. Use something moderately sharp to scrape a bit of solder mask to
> allow a "pi" shape matching network to form on the GPS antenna trace as
> shown below. Remove the existing capacitor and mount these components
> instead:
>
> [image: IMG_1301]
> <
https://user-images.githubusercontent.com/1565933/134207624-bf0a87ad-03ed-4b7f-84bf-da6491bc0d12.JPG
>
>
> —
> You are receiving this because you are subscribed to this thread.
> Reply to this email directly, view it on GitHub
> <#82>, or unsubscribe
> <
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>
> .
>
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The main idea is to cut through each layer of heat shrink tube deep enough that you can separate it by hand, and not so deep that you end up gushing the enclosure, or the antenna tube itself or whatever is underneath it. I typically use an X-ACTO knife for this. |
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Hello Peter,
I just checked and no, I don't have extra shrink wrap. I never seen shrink
wrap that big before so getting more sent probably is best.
I'm so happy that there is away to upgrade the units we already bought. I
thought was going to have to purchase a new board. Thank you for the
continued engineering.
I have a UBlox GNSS on my BoatIO hat and yes, it needs an active antenna to
be accurate so your decision to stick with the current chip was good for
our application. I only bought the hat with the GNSS on it because MAIANA
wasn't ready and I needed a GPS fast. It will be nice to have a backup GPS
onboard. Things happen and redundancy it key, as I learned on my last trip
to Key West.
Thank you for all your time and awesome engineering!
David
…On Tue, Sep 21, 2021, 21:28 Peter Antypas ***@***.***> wrote:
Did I send you extra heat shrink with it or not? If not, I'll just send you
some.
On Tue, Sep 21, 2021 at 7:19 PM Rudder2 ***@***.***> wrote:
> Hello Peter,
>
> I already fully assembled my unit just haven't had a chance to Mount it
due
> to hurricane season and medical reasons. I really want to do this fix but
> think in going to have to cut apart my transponder as I heat shrinks it
all
> the way together line the instructions said. Do you have any advice?
>
> Thank you for your time and help,
>
> David
>
> On Tue, Sep 21, 2021, 11:15 Peter Antypas ***@***.***> wrote:
>
> > For those who have recently obtained a kit and haven't completely
mounted
> > it: If you are reasonably good at basic SMD soldering, please follow
the
> > instructions here to significantly improve your unit's GNSS precision:
> >
> > 1. *DO NOT* cover the transponder board with clear heat shrink tubing.
> > It severely detunes the GPS antenna. If you have already completed that
> > step, then carefully cut through the heat shrink to uncover the PCB.
You
> > still need the clear heatshrink to keep the lower antenna assembly
> together
> > and to act as the secondary water seal. Your lower antenna assembly
> should
> > look like this:
> >
> > [image: IMG_1296]
> > <
>
https://user-images.githubusercontent.com/1565933/134207058-53243d0b-f029-4cb3-b4ca-6a8476ec4892.JPG
> >
> >
> > 1. Use something moderately sharp to scrape a bit of solder mask to
> > allow a "pi" shape matching network to form on the GPS antenna trace as
> > shown below. Remove the existing capacitor and mount these components
> > instead:
> >
> > [image: IMG_1301]
> > <
>
https://user-images.githubusercontent.com/1565933/134207624-bf0a87ad-03ed-4b7f-84bf-da6491bc0d12.JPG
> >
> >
> > —
> > You are receiving this because you are subscribed to this thread.
> > Reply to this email directly, view it on GitHub
> > <#82>, or
unsubscribe
> > <
>
https://github.com/notifications/unsubscribe-auth/AKLZHFQFNTIVETIDTUQGCNLUDCVQVANCNFSM5EO35RSA
> >
> > .
> >
>
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#82 (comment)
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How big is the chance to make it worst or even destroy the antenna part? |
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I only recommend doing this if you're comfortable with this process. The detuning is not fatal, it just makes the GNSS not precise enough for critical navigation. |
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As it will become the only GPS source on our ship I need to fix it. |
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I am also interested for the europe source. |
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Let me further qualify what I said: By "critical navigation" I mean something like negotiating a tight, unmarked opening in a reef. I haven't seen more than 6 meters of error as things stand now. |
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Hello. I am about to assemble the kit. |
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No, the board came with a 12pF series capacitor, so that needs to be replaced. |
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Sh!t. Where do i find such small things :/ |
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Some folks have inquired about the possibility of applying conformal coating to the PCB. I just ordered one silicon and one acrylic conformal coating spray from MG Chemicals to see how much effect they will have on the GNSS antenna. Results probably next week ... |
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MG Chemicals Silicone spray gets a passing grade. No appreciable effect on GNSS or AIS tuning:
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Their acrylic spray also works fine, so either will do. I'm partial to silicon though, so that's what I'll use from now on. |
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That's very good to know - thanks for testing
…----- On 17 Oct, 2021, at 23:56, Peter Antypas ***@***.***> wrote:
MG Chemicals Silicone spray gets a passing grade. No appreciable effect on GNSS
or AIS tuning:
[
https://user-images.githubusercontent.com/1565933/137647910-83fa7ba8-1ed4-4085-8898-be36684bf963.JPG
]
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Alright, this is it. We have repeatable results. |
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For those who have recently obtained a kit and haven't completely mounted it: If you are reasonably good at basic SMD soldering, please follow the instructions here to significantly improve your unit's GNSS precision:
That's it. This will tune the antenna properly when mounted inside the PVC enclosure and improve position accuracy. It will also allow the unit to make use of GPS + GLONASS constellations.
From now on, all kits I ship will have this modification. The assembly manuals have been updated already.
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