GPS AMP

[Craig]

I`am using a inline amplifier for boosting the single from the outdoor
antenna to be able to use the GPS indoors for trying out diferent types of
software on a desktop computer.

Problem, if the GPS is to close to the AMP it could cause overloading.
The GPS dose not have any where to physicaly conect a anttena so a loop
would have to be constructed and connected to the Amp, but to do this I
would have to reduce the power comming out of the Amp so the GPS could be
place up against the Amp with out overloading.

Dose anyone have any circuit diagrams for this or ideas.

Thanks Robert

 

[Ken Taylor]

"Craig" <craigu238@hotmail.com> wrote in message
news:3fe1ba0a$0$1731$5a62ac22@freenews.iinet.net.au...

I`am using a inline amplifier for boosting the single from the outdoor
antenna to be able to use the GPS indoors for trying out diferent types of
software on a desktop computer.

Problem, if the GPS is to close to the AMP it could cause overloading.
The GPS dose not have any where to physicaly conect a anttena so a loop
would have to be constructed and connected to the Amp, but to do this I
would have to reduce the power comming out of the Amp so the GPS could be
place up against the Amp with out overloading.

Dose anyone have any circuit diagrams for this or ideas.

Thanks Robert

The first question has to be "Why are you using an amp?". We have 50 metre

runs of cable here on some of our GPS antennas, with no amp's. We've also
looked at using splitters on some of these, with the attendant attenuation,
and there is no problem with levels we'd have then (we've checked by putting
attenuators in line). I can only see problems using an amplifier,
particularly if it's a cheaper one.

However, if you insist on doing this (I don't pretend to know your reasons)
get a good quality attenuator from HP (Agilent), Narda, Minicircuits or a
similar place. Or even Pasternack, who are lower quality but cheaper and
still usable. Locally to Aus try Av-Comm or Melbourne Satellites. You want
an L-Band attenuator (for 1600MHz), probably 6dB or so.

All these places are on the web. Sorry, I haven't had my second cuppa yet
and can't find anything.

Cheers.

Ken

 

[Peter Johnson]

I`am using a inline amplifier for boosting the single from the outdoor
antenna to be able to use the GPS indoors for trying out diferent types of
software on a desktop computer.

Problem, if the GPS is to close to the AMP it could cause overloading.
The GPS dose not have any where to physicaly conect a anttena so a loop
would have to be constructed and connected to the Amp, but to do this I
would have to reduce the power comming out of the Amp so the GPS could be
place up against the Amp with out overloading.

Hi Robert,

What you're trying to achieve is normally referred to as a 'GPS re-radiating
antenna' so if you try that search phrase in Google you'll find plenty of
commercial sources, and most seem to be reasonably priced. We use one in the
office here and have found them to work well. I think I went searching using
those terms once before and found a few schematics as well although that
took a bit more hunting around.

For your setup using the inline amplifier I assume it's a wide-band LNA
style and not a power amplifier, so I doubt you will overload the GPS
front-end because most have a reasonable dynamic range. The easiest way to
attenuate the signal would be to physically seperate the loop from the GPS
receiver until you find the range that works best.

If you're using an active antenna and supply the DC bias voltage the
in-built LNA may also give you enough gain to get the signal to the receiver
if the loop is placed around it.


Regards,

Peter Johnson, CommLinx Solutions
http://www.commlinx.com.au/