Empathy List Archives

DW

Dana Whitlow

Tue, Nov 27, 2018 1:44 PM

I want to run about 4 separate GPS units of disparate
manufacture from a single antenna. My plan is to
provide power for the antenna via a bias tee (power
inserter) at the bottom end of the antenna's cable, then
use an isolating splitter on the receiver side of the bias
tee to split to the various receivers.

My question is: how much isolation between receivers
is likely to be necessary? Real life splitters are only
so-so in isolation performance (15-25 dB), and may
e significantly worse if the antenna's LNA's output is
a poor match. So I'm wondering if I'm going to need
more amplifiers in the splitter's outputs just for the sake
of adequate isolation between the GPS receivers.

Thanks,

Dana K8YUM

I want to run about 4 separate GPS units of disparate manufacture from a single antenna. My plan is to provide power for the antenna via a bias tee (power inserter) at the bottom end of the antenna's cable, then use an isolating splitter on the receiver side of the bias tee to split to the various receivers. My question is: how much isolation between receivers is likely to be necessary? Real life splitters are only so-so in isolation performance (15-25 dB), and may e significantly worse if the antenna's LNA's output is a poor match. So I'm wondering if I'm going to need more amplifiers in the splitter's outputs just for the sake of adequate isolation between the GPS receivers. Thanks, Dana K8YUM

MC

Mike Cook

Tue, Nov 27, 2018 2:16 PM

Hi,
I am using Mini-Circuits ZN4PD1-50+. They are about 30dB in the GPS frequency band. I hang 4 receivers each off three of these mixing Motorola, Ublox, Trimble and Navspark and never had an issue.
Mike

Le 27 nov. 2018 à 14:44, Dana Whitlow k8yumdoober@gmail.com a écrit :

I want to run about 4 separate GPS units of disparate
manufacture from a single antenna. My plan is to
provide power for the antenna via a bias tee (power
inserter) at the bottom end of the antenna's cable, then
use an isolating splitter on the receiver side of the bias
tee to split to the various receivers.

My question is: how much isolation between receivers
is likely to be necessary? Real life splitters are only
so-so in isolation performance (15-25 dB), and may
e significantly worse if the antenna's LNA's output is
a poor match. So I'm wondering if I'm going to need
more amplifiers in the splitter's outputs just for the sake
of adequate isolation between the GPS receivers.

Thanks,

Dana K8YUM

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I am not a a vegetarian because I love animals. I’m a vegetarian because I hate plants.

Hi, I am using Mini-Circuits ZN4PD1-50+. They are about 30dB in the GPS frequency band. I hang 4 receivers each off three of these mixing Motorola, Ublox, Trimble and Navspark and never had an issue. Mike > Le 27 nov. 2018 à 14:44, Dana Whitlow <k8yumdoober@gmail.com> a écrit : > > I want to run about 4 separate GPS units of disparate > manufacture from a single antenna. My plan is to > provide power for the antenna via a bias tee (power > inserter) at the bottom end of the antenna's cable, then > use an isolating splitter on the receiver side of the bias > tee to split to the various receivers. > > My question is: how much isolation between receivers > is likely to be necessary? Real life splitters are only > so-so in isolation performance (15-25 dB), and may > e significantly worse if the antenna's LNA's output is > a poor match. So I'm wondering if I'm going to need > more amplifiers in the splitter's outputs just for the sake > of adequate isolation between the GPS receivers. > > Thanks, > > Dana K8YUM > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. I am not a a vegetarian because I love animals. I’m a vegetarian because I hate plants.

T

timeok@timeok.it

Tue, Nov 27, 2018 2:30 PM

Dana,
As described in the following HP GPS splitter the isolation is > 40dB.
https://www.febo.com/time-freq/gps/hp58516a/HP_58516A.pdf
I use one of these 8-channel splitters.
I had a bad experience using a passive splitter of the minicircuits in the 10MHz distribution in my lab.
An instrument that accidentally generated instead of receiving the reference disturbed all other related instruments.
In this case, an isolation of 25-30dB proved to be insufficient.
Therefore, I recommend using a GPS splitter with active components such as the classic HP models and other brands.
Luciano
www.timeok.it

Da "time-nuts" time-nuts-bounces@lists.febo.com
A "Discussion of precise time and frequency measurement" time-nuts@lists.febo.com
Cc
Data Tue, 27 Nov 2018 07:44:23 -0600
Oggetto [time-nuts] RF isolation requirements for multiple GPS receivers
I want to run about 4 separate GPS units of disparate
manufacture from a single antenna. My plan is to
provide power for the antenna via a bias tee (power
inserter) at the bottom end of the antenna's cable, then
use an isolating splitter on the receiver side of the bias
tee to split to the various receivers.

My question is: how much isolation between receivers
is likely to be necessary? Real life splitters are only
so-so in isolation performance (15-25 dB), and may
e significantly worse if the antenna's LNA's output is
a poor match. So I'm wondering if I'm going to need
more amplifiers in the splitter's outputs just for the sake
of adequate isolation between the GPS receivers.

Thanks,

Dana K8YUM

time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

Dana, As described in the following HP GPS splitter the isolation is > 40dB. https://www.febo.com/time-freq/gps/hp58516a/HP_58516A.pdf I use one of these 8-channel splitters. I had a bad experience using a passive splitter of the minicircuits in the 10MHz distribution in my lab. An instrument that accidentally generated instead of receiving the reference disturbed all other related instruments. In this case, an isolation of 25-30dB proved to be insufficient. Therefore, I recommend using a GPS splitter with active components such as the classic HP models and other brands. Luciano www.timeok.it Da "time-nuts" time-nuts-bounces@lists.febo.com A "Discussion of precise time and frequency measurement" time-nuts@lists.febo.com Cc Data Tue, 27 Nov 2018 07:44:23 -0600 Oggetto [time-nuts] RF isolation requirements for multiple GPS receivers I want to run about 4 separate GPS units of disparate manufacture from a single antenna. My plan is to provide power for the antenna via a bias tee (power inserter) at the bottom end of the antenna's cable, then use an isolating splitter on the receiver side of the bias tee to split to the various receivers. My question is: how much isolation between receivers is likely to be necessary? Real life splitters are only so-so in isolation performance (15-25 dB), and may e significantly worse if the antenna's LNA's output is a poor match. So I'm wondering if I'm going to need more amplifiers in the splitter's outputs just for the sake of adequate isolation between the GPS receivers. Thanks, Dana K8YUM _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.

BK

Bob kb8tq

Tue, Nov 27, 2018 3:23 PM

Hi

I’ve run …. errr … lots ( > 40) of GPSDO’s on a common antenna with a single
amp and passive splitters. I’ve never seen any issues. That includes cases
with multiple ports un-terminated ( so not terrific isolation).

Bob

On Nov 27, 2018, at 8:44 AM, Dana Whitlow k8yumdoober@gmail.com wrote:

I want to run about 4 separate GPS units of disparate
manufacture from a single antenna. My plan is to
provide power for the antenna via a bias tee (power
inserter) at the bottom end of the antenna's cable, then
use an isolating splitter on the receiver side of the bias
tee to split to the various receivers.

My question is: how much isolation between receivers
is likely to be necessary? Real life splitters are only
so-so in isolation performance (15-25 dB), and may
e significantly worse if the antenna's LNA's output is
a poor match. So I'm wondering if I'm going to need
more amplifiers in the splitter's outputs just for the sake
of adequate isolation between the GPS receivers.

Thanks,

Dana K8YUM

time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

Hi I’ve run …. errr … lots ( > 40) of GPSDO’s on a common antenna with a single amp and passive splitters. I’ve never seen any issues. That includes cases with multiple ports un-terminated ( so not terrific isolation). Bob > On Nov 27, 2018, at 8:44 AM, Dana Whitlow <k8yumdoober@gmail.com> wrote: > > I want to run about 4 separate GPS units of disparate > manufacture from a single antenna. My plan is to > provide power for the antenna via a bias tee (power > inserter) at the bottom end of the antenna's cable, then > use an isolating splitter on the receiver side of the bias > tee to split to the various receivers. > > My question is: how much isolation between receivers > is likely to be necessary? Real life splitters are only > so-so in isolation performance (15-25 dB), and may > e significantly worse if the antenna's LNA's output is > a poor match. So I'm wondering if I'm going to need > more amplifiers in the splitter's outputs just for the sake > of adequate isolation between the GPS receivers. > > Thanks, > > Dana K8YUM > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there.