Does anyone know if a failure of the antenna side of the F9P module is a common occurrence? I’ve had two fail on me, one is the SparkFun GPS-RTK-SMA Breakout - ZED-F9P and the other is the ublox C099 eval board. The units still communicate just fine over usb, they just stopped seeing any satellites. I can see occasional but fleeting appearances of signals on the ubx-nav-sig message, but they have no signal strength reported and disappear shortly. Mostly just BeiDou. It’s like there is no signal amplification going on.
For both boards, they were only powered by the usb connection and were indoors and protected from the elements. The antenna works fine with my one remaining F9P. I need to get another RTK board but am wondering if I should stick with the F9P.
Do you know what voltage your active antenna needs, and what its current draw is?
I’m wondering if it is drawing slightly too much current, causing the voltage to dip to a point where the Low Noise Amplifier no longer works?
We include a 10 Ohm protection resistor on our boards to protect against antenna shorts. I’m sure u-blox do the same - we copied their reference design.
You could check by measuring the DC voltage between the SMA centre pin and GND / 0V when the antenna is connected. If it drops below say 3.0V, that might explain it.
I have two of these, and swapping, they both seem to work fine when connected to a working f9p.
Are you saying that if there is a transient antenna short, it could lead to a burn-out of the resistor and/or a permanent failure of the amp? I can’t say whether it was the same antenna connected in both cases, but the boards, once deaf to satellites have remained that way.
Check you get around 3.3V out of the RF SMA center pin on the GNSS SMA connector.
That you connect the antenna to the correct connector.
There is a protection circuit on the supply, the L1 120nH inductor would be the most vunerable to acting like a fuse, but that’s probably rated 150mA https://content.u-blox.com/sites/default/files/C099-F9P-AppBoard-ODIN-W2-uCX_UserGuide_(UBX-18055649).pdf#page=47
The board is also very busy, powering via USB is apt to be inadequate. I’d suggest a 7V DC 9W supply to the Barrel Connector.
The boards typically shipped with the ANN-MB-00 antennas
I have two ANNN-MB-00-00 antennas and the voltage at the center pin is a steady 3.012V regardless of which one is connected, which is a drop from 3.287 when no antenna is connected.
Hey Clive, the C099 was working fine and then just stopped without any physical, configuration or software changes. Not even a power cycle. So the antenna is definitely on the correct sma and I’m not even using the ODIN side of the board. It was working for weeks in this configuration off of a good powered usb hub which is working fine. The antenna center pin is at 3.012v with an ANN-MB-00-00 connected and 3.287 disconnected.
Is there anything else to check? I’m not an electronics guy, so my understanding and ability to test from the schematic are very limited.
If I’m at a dead end, would you still recommend an F9P based module as a replacement, given that when they were working they fit my rover and base station needs very well.
So likely an issue with the RF Front-End rather than the power too the antenna. You tested the antennas with other equipment, so they are probably Ok.
Depending on the age and how/where they were purchased you might be able to RMA the C099-F9P boards.
I’ve use ZED-F9P on SparkFun and ArduSimple boards, and been happy with both.
I think we’re still a while off before the X20 models appear.
Thanks Clive. I was wondering about trying another manufacturer, perhaps the new UM980 tri-band board, but there are no reviews of it yet and I have software infrastructure invested in the F9P.
Lucky for me the F9P is on sale this week, so I’ve ordered replacements.