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How to Measure Active Antenna'bias voltage from GPS receiver - RF
Cafe Forums
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| florent
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Post subject: How to Measure Active Antenna'bias voltage from GPS receiver
Posted: Thu Apr 19, 2012 12:32 pm
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Joined: Thu Apr 19, 2012
10:44 am
Posts: 2 |
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Dear all,
A dummy question.
I've got a
GPS receiver chip. This chip has a [+3,+5]VDC voltage
bias for active antenna.
I wonder if it is
possible to measure the presence of the voltage
bias on RF port ?
The aim is to validate that
the voltage is compliant with the LNA inside my
active Antenna.
Basically, I though to directly
connect the voltmeter on the central conductor of
SMA port. Is it good ? Or is there a problem of
mismatch ?
Best regards and thank you by
advance.
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Kirt Blattenberger
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Post subject: Re: How to Measure Active Antenna'bias voltage from GPS
rece
Posted: Fri Apr 20, 2012 7:49 am
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| Site Admin |
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Joined: Sun Aug 03, 2003
2:02 pm
Posts: 476
Location: Erie, PA
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Greetings florent:
The receiver input is
almost certainly tolerant of any RF impedance as
long as you are not worried about RF performance
during the measurement, which you are not. If you
can find the datasheet for the GPS IC, it will probably
contain a warning about shorting the Rx input if
it is a problem. The DC impedance of any modern
DMM is extremely high (>1 MOhm), so you should
have no problem making the voltage measurement.
If you are still leery of placing the probe on the
input, wrap the lead around your finger a few times
to add a little inductance to the probe line as
an RF choke.
_________________ - Kirt Blattenberger
RF Cafe Progenitor & Webmaster
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florent |
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Post subject: Re: How to Measure Active Antenna'bias voltage from GPS
rece
Posted: Mon Apr 23, 2012 7:14 am
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Joined: Thu Apr 19, 2012
10:44 am
Posts: 2 |
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Dear Kirt,
Thank you very much for your answer.
I've performed the DC measurement : 3,25VDC
which is the order of magnitude that I saw on various
datasheet.
In fact, I haven't the reference of
the receiver. Let me explain : I'm working on an
analysis concerning GPS signal default. The GPS
receiver chip is included inside an embedded computer.
I've contacted the manufacturer to get the name
of the GPS receiver but without succeed.
That
is the reason why, I would just perform a first
check of the DC bias voltage. I hope to get the
datasheet from the manufacturer.
In all case,
I thank you again for your support.
Your forum
and web site is a great source for young dummy engineer
like me.
Best regards,
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Posted 11/12/2012
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