[time-nuts] GPS antenna selection

[Tom Miller]

Do you have a picture of the balcony?


----- Original Message ----- 
From: "Herbert Poetzl" <herbert at 13thfloor.at>
To: <time-nuts at febo.com>
Sent: Thursday, August 04, 2016 5:29 PM
Subject: [time-nuts] GPS antenna selection


>
> Dear fellow time-nuts!
>
> I'm currently investigating my options regarding
> GPS antennae (of course for time related purposes)
> and I'm really confused by the variety they come
> in ... (my apologies in advance for the long post).
>
>
> Setting:
>
> I'm living in a three storey house with a sloped
> roof, a covered balcony and a larger garden with
> huge trees on the Austrian countryside (Europe).
>
> I've walked around with my smartphone (older one)
> and I get a GPS position fix within 35s in the
> garden (nine satellites shown), within 100s on
> the balcony (also nine satellites), and not a
> single satellite can be seen indoors.
>
> The obvious choice would be to put the antenna on
> top in the middle of the slanted roof for a perfect
> sky view, but this brings a number of problems as
> the roof is very hard to reach and quite high.
>
> I have my 'lab' at the floor where the balcony is,
> so I'm considering putting an antenna there and
> run about 5-15m of coax cable to the GPS receiver.
> The advantage there is that the antenna would be
> somewhat protected (it still gets very hot during
> summer and very cold during winter, but no rain
> and no snow) and easy to reach for maintenance.
>
> The third alternative would be to put the antenna
> somewhere in the garden and have a rather long
> cable running to the house and up to my lab.
>
>
> Antennae:
>
> Looking on eBay and Amazon shows a huge pricerange
> for active GPS antennae with and without cable.
>
> It seems to start at about 10 bucks with rather
> small black boxes [1] designed for cars, probably
> containing a 25x25 ceramic GPS antenna and an
> amplifier, progresses over very interesting out-
> door constructions for boats and whatnot [2] in
> the 20-100 bucks range and finally tops with high
> end devices [3] way above 100 bucks.
>
> The information about the cheap devices is usually
> very scarce, but typically boils down to:
>
> 1575.42 +/- 5MHz
> 24-28dB LNA Gain with 10-25mA at (3-5V)
>
> 7dB f0 +/- 20MHz
> 20dB f0 +/- 50MHz
> 30dB f0 +/- 100MHz
>
> They seem to use RG174 and come with SMA as well
> as BNC connectors (and a number of others as well).
>
> The mid range devices seem to use larger antennae
> with smaller tolerances (+/- 1MHz) and larger
> voltage ranges for the amplifier (3-13V).
>
>
> Questions:
>
> - What are the key specifications which need to
>   be verified before buying a GPS antenna?
>
> - How can they be compared based on incomplete
>   specifications?
>
> - Is a place on the roof or in the garden worth
>   the trouble over the covered balcony?
>
> - Are there any typical pit-falls or general
>   tips and tricks regarding mounting and cable
>   connection to the receiver?
>
> Many thanks in advance and my apologies again for
> the rather lengthy post. Please feel free to point
> me to previous discussion regarding this topic.
>
> All the best,
> Herbert
>
>
> [1] 
> http://www.ebay.com/itm/99-Good-GPS-Antenna-SMA-Screw-Needle-10m-Super-Signal-Navigation-DVD-Antenna-/171802461614
> 
> https://www.amazon.com/Waterproof-Active-Antenna-28dB-Gain/dp/B00LXRQY9A
>
> [2] 
> http://www.ebay.com/itm/Standard-Horizon-XUCMP0014-GPS-Antenna-f-CP150-CP160-CP170/331364914004
> 
> https://www.amazon.com/Garmin-010-12017-00-GPS-GLONASS-Antenna/dp/B00EVT2HSE
> 
> https://www.amazon.com/SUNDELY®-External-Marine-Antenna-connector/dp/B00D8WAVTC
>
> [3] 
> http://www.ebay.com/itm/NEW-FURUNO-GPA018-Gps-dgps-Antenna-/182223355414
>    https://www.amazon.com/Garmin-nmea-2000-orders-over/dp/B0089DU96A
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to 
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.