Re: RF Switcher and Current Monitor Sample


Thanks a lot, Joerg,

I thought about your idea about using PIN diodes by making a decision based
on signal strength. Definitely it is a good idea and will work. I possibly
can devote one pin from the DSP inside of the GPS receiver to control the RF
circuit. However, I appreciate a pure "hardware" solution and an easy one,
better inside of the RF circuit itself. For this reason, I still prefer a
current monitor plus a RF switch solution, and I am using 2 active antennas
with almost the same gain. Could you please recommend me a few current shunt
monitor (want bigger output current compared to INA138 with 100uA max output
when the differential input voltage is 0.5V), and a few RF switch (want
lower DC power consumption than SKY13268-344 with 100uA max. consumption) if
you are familiar with these parts?

John



"Joerg" <notthisjoergsch@xxxxxxxxxxxxxxxxxxxxx> wrote in message
news:0ofwe.608$j04.567@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> Hello Johnson,
>
>> I am currently working on a GPS Receiver that is able to support both
>> internal and external antenna. I would like the system to detect the
>> external antenna and switch to the external antenna automatically. I
>> remembered I once read a sampe from a magazine that required a RF
>> switcher and a Current Shunt Monitor (like INA138) to detect the current,
>> but I forgoty where it was. ...
>
> The classical approach would be to use PIN diodes to switch between the
> antennas. At regular intervals your circuitry (behind the receiver output)
> could switch to the external antenna and make a decision based on signal
> strength. The decision could, for example, be contingent on seeing a
> signal at all or you could decide based upon which antenna delivers the
> best signal.
>
> Regards, Joerg
>
> http://www.analogconsultants.com


.

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