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Looks like you are using an active GPS antenna which certainly means it has a LNA built-in. If you are setting-up the modem in GSM mode, at higher transmit power (if I recall correctly can go up to +30dBm) you may eventually damage the LNA output stage and therefore not get anything out of your GPS antenna. It does seem like an unlikely scenario though, you ...


2

If you use your favorite search engine and search for terms like "nb iot roaming" you'll find plenty of other pages backing this. I'd interpret this (2017) document from the GSMA in a way that it says "NB IoT specifations have been written very quickly, Roaming might be added later" https://www.gsma.com/iot/wp-content/uploads/2017/08/CLP.28-v1.0.pdf This ...


2

It seems that somehow your "replacement of wire" has caused a situation where the received signal is partly being sent back or being coupled onto your microphone circuit. Possibly both receiver and microphone wires are running adjacent without any shielding. At the least you should use twisted pair for these wires. If you pay attention to this aspect, ...


1

I contacted a testing lab and they explained several details to me. I do need radio certification. This certification is called IC (Industry Canada). I should use a cellular module in my product that already has radio certification. This way I can leverage their certification (provided I use an antenna with the same or less gain and keep the device above ...


1

Neil's answer is good, but I'll add a couple more points that might affect your choice of geometry There are good empirical formulas available (and online calculators that implement those formulas) for choosing microstrip trace width to achieve a desired characteristic impedance. The online calculators for coplanar are more likely to disagree with each ...


1

'Better' and 'most efficient' are not words that are useful to use. Both microstrip and coplanar have their own advantages and disadvantages. However, often it's the integration with the significant ICs on the board that's the key factor. Some ICs have pinouts that invite connection directly to coplanar (with a GND-sig-GND set of pins) or microstrip (with a ...


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