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• #2
This is on Bangle.js 2? I don't really know I'm afraid - you'd have to look at the datasheet. They do all say that though
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• #3
$GPTXT,01,01,01,ANTENNA OPEN*25
I guess that an open antenna detection must be implemented in additional hardware, which may not be there in Bangles.
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• #4
Hi Gordon, I cannot find datasheet for SMA Q3. Do you have one?
If you have disassembled watch, did you see an antenna there? -
• #5
If you have disassembled watch, did you see an antenna there?
Yes - of course!! You can even see it in the KickStarter video
Info is at https://www.espruino.com/Bangle.js2
GPS is AT6558, datasheet http://www.icofchina.com/d/file/xiazai/2016-12-05/b1be6f481cdf9d773b963ab30a2d11d8.pdf
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• #6
AT6558 datasheet tells that a passive or active antenna can be connected. Statuses are:
Open - no current
OK - normal current
Short - high currentMy understanding it applies to active antennas that consume power.
I am not sure if some significant current can go through a passive antenna. My understanding is that a passive antenna cannot work as a resistor type load, may be it may work as a inductive/capacitive load for high frequency AC current.
The document does not tell if the chip can recognize a passive antenna, is it connected or not.
I hope a passive antenna is connected.I've found interesting article. https://www.u-blox.com/sites/default/files/products/documents/GNSS-Antennas_AppNote_%28UBX-15030289%29.pdf
It states that all antennas have 50 Ohm impedance.
But AT6558 does not look like measures impedance, it rather measures DC current in VANT_IN - ANT_BIAS chain. With a passive antenna that current should be 0A.
In AT6558 datasheet Figure 9-2 "passive antenna scheme" shows active antenna with LNA.
Also it says:
10.1 Active Antenna Feed and Detection
The following figure, the chip active antenna detection circuit can detect the state
of the active antennaSo, I think Antenna Open status is normal for a passive antenna.
NMEA ANT sentence shows $GPTXT,01,01,01,ANTENNA OPEN*25
What does it mean? Is there no antenna? Or is it not connected electrically? Or is not turned on programmatically?