[time-nuts] Re: GPS failed
Björn
bg at lysator.liu.se
Wed Jul 13 14:50:59 UTC 2022
Sent from my Phone
> On 13 Jul 2022, at 02:34, Bob kb8tq via time-nuts <time-nuts at lists.febo.com> wrote:
>
> Hi
>
> The âtypicalâ Symmetricom cone shaped GPS antennas are targeted at
> cell phone tower applications. Being mounted on the same structure
> as multiple cell transmitters puts them in a significant RF environment.
> They have a *lot* of filtering built into the antenna to try to prevent overload
> issues.
>
> As with a lot of things, Symmetricom simply rebrands antennas made by
> others. Not all cone shaped antennas are identical. However itâs a pretty
> good bet that most of them are very similar to what Symmetericom ( and
> the other folks ) supply for cell applications.
>
> The âother endâ of the range are the multi band saucer shaped âsurveyâ
> antennas. They tend to have a lot less filtering and be more focused at
> allowing the user to access a wide range of frequencies ( both GNSS and
> supplemental services) via a single device. Lots of filtering also tends to
> mess up delay here or there, thatâs not a great thing for high precision
> work.
>
> Bob
>>
Bob,
That was true 10-15 years ago. Good quality surveying antennas often has quite decent filtering on each band they are designed for.
/Björn
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