[time-nuts] Rooftop antenna and splitter

[Bill Slade]

Hello Denny,

Things to keep in mind:

  1.  To keep noise performance, LNA gain at the antenna should be at least 10 dB above total losses in antenna cable & distribution network.  13-16 dB above is better.  Something like this would be more than suitable for a 30 ft run: https://www.pasternack.com/flexible-0.403-rg8-type-50-ohm-coax-cable-pvc-jacket-pe-b400-p.aspx
  2.  amplified splitter best (I see that's what you have in your web links).

If cable losses are under 13dB or so, a 26dB gain antenna should be fine.  40dB gain will not give you any better performance.  In fact, excess LNA gain makes GNSS receiver tracking more susceptible to disruption by possible interference (e.g. from harmonic distortion, reciprocal mixing effects, etc.) depending on how good the band filters in the antenna are and what interferers are nearby.

Cheers,

Bill



On 27.01.19 05:10, Denny Page via time-nuts wrote:

Hi all,

I’m looking for recommendations on an antenna / splitter configuration. I currently have six GPS/GLONASS/Galileo timing devices, each with it’s own puck antenna in a window. I have an opportunity to move to a (single) roof top antenna, with a splitter to feed the individual devices, and I am looking for recommendations on which antenna and splitter people would recommend.

So far, I am looking at the following antennas:

 PCTEL GNSS1-TMG-26N (https://www.pctel.com/antenna-product/global-gnss-timing-reference-antenna-gnss1-tmg-26n/)

 PCTEL GNSS1-TMG-40N (https://www.pctel.com/antenna-product/global-gnss-timing-antenna-gnss1-tmg-40n/)

And the following splitters:

 GPS Networking ALDCBS1x8 (https://www.gpsnetworking.com/products/aldcbs1x8)

 GPS Source S18 (https://www.gpssource.com/collections/gps-splitter/products/s18-1x8-standard-gps-splitter)

The run from the antenna to the splitter will be 30-35 feet, and from the splitter to the units will be 3-5 feet. I’m wondering about the need for the 40dB vs the 26dB. I haven’t looked at any passive splitters, but even with the 40dB I’m thinking won’t offer enough to support even a 1x6 splitter.

I would appreciate any thoughts folk have to offer.

Thanks,
Denny


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