NHarishParticipantNHarish January 4, 2023 at 6:44 pm
I have a BB60D RTSA. Need to measure GPS signal (Amplt vs Freq) at a particular location inside a large vehicle with a passive antennae.
Is it possible to do so ?
Should I be connecting the passive antennae directly to the RF Input port of BB60D or what gain value of amplifier should I use to amplify the signal before ?
Andrew January 5, 2023 at 8:37 am
- This reply was modified 10 months, 3 weeks ago by Andrew.
I have not done this myself, but it appears possible with some limitations. See the linked article below.
A typical GPS antenna has ~30dB of gain, but even this is not enough to get a spectrum plot capable of characterizing the signal. The author in the article uses 60dB of gain through active antenna and additional LNA and just manages to get the signal above the noise floor. Being that you want to measure inside your vehicle, there will be additional attenuations from the chassis.
On the spectrum analyzer side, you will want to make sure the receiver is configured for maximum sensitivity and a low RBW. You also need to make sure no signals exceed +20dBm into the front end of the receiver with that much gain. An RF limiter or filter might be necessary.
I hope this helps.
Justin CrooksModeratorJustin Crooks January 5, 2023 at 10:03 am
I would recommend an active GPS antenna. As long as it has >20 dB of gain, you probably won’t benefit much from an additional amplifier. But these will be low level signals, and might be difficult to measure directly. More accurate measurements could be made by capturing I/Q and processing it using GPS algorithms.
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