GPS is off response

Notecard API
1
  • I plugged a Pulse W3906 antenna into the Notecard to test GPS functionality (card has functions for months without it).
  • The notecard is near a window
  • I am getting as a response to card.location:
    {‘status’: ‘GPS is off {gps-inactive}’, ‘mode’: ‘periodic’}
    A cellular phone positioned right next to it “sees” 6 satellites, not great but it gets a lat/lon

The response is a bit cryptic:
Is it because my antenna is no good? The GPS circuitry on the notecard not properly enabled?
Is there a way to get more info as to what is going on?

2

Update:

  • switched to a Pi4 running Cat-M1
  • installed an external antenna: External Antenna | Adafruit Ultimate GPS HAT for Raspberry Pi | Adafruit Learning System ( Active Antenna - 3-5V 28dB)
  • using the GPS hat (described above) with that same antenna, same position (i.e. outside, the cord is real long), I read GPS data no problem
  • remove the GPS hat, place the external antenna on the Notecard
  • made sure that the DIP switch on the hat is ON (default)
    → same result as the posting above, GPS is off.
    Obviously I am missing something…
1 Like
3

Hi @Francois,

Which Notecarrier model are you using? FYI the Notecarrier-A models don’t support external GPS antennas (more info).

Thanks,
Rob

4

@RobLauer I am using the Notecarrier Pi (aka hat). BTW I’ve been given a last minute chance to do some wardriving in Puerto Rico this long weekend, that’s why I’m trying to get the GPS running.

5

is there a way to debug to see if the issue is with the GPS not acquiring signal or something else happening?

6

@Francois Do you have access to another Notecarrier, or do you just have the Notecarrier-Pi with you?

While I expect the antenna you have selected to work, there are a number of variables here, and would like to see if we can eliminate the Notecard as the source of the problem.

7

I have a Notecarrier B (I think), the one that is about the same size as the Notecard. I have connected now to my laptop with the Pulse W3906 antenna. Same result – which is why I am thinking I might be missing something totally obvious:

> {"req":"card.motion.mode"}
{"start":true}
> {"req":"card.motion.mode","start":true,"seconds":2,"sensitivity":4}
{"start":true}
> {"req":"card.motion.mode"}
{"start":true}
> {"req":"card.location.track"}
{
 "file": "gps.qo",
 "start": true,
 "minutes": 60
}
> {"req":"card.location.track","file":"gps.qo","start":true,"heartbeat":true,"hours":1}
{
 "file": "gps.qo",
 "start": true,
 "minutes": 60,
 "heartbeat": true
}
> {"req":"card.location.track"}
{
 "file": "gps.qo",
 "start": true,
 "minutes": 60,
 "heartbeat": true
}
> {"req":"card.location"}
{
 "status": "GPS is off {gps-inactive}",
 "mode": "periodic"
}
8

can you do a screen share?

9

Yes, contacting you on Skype

10

@Francois Can you attach the external GPS antenna to a metal surface?

Often with these external patch antennas there’s an expectation of a ground plane which is assumed if it is attached magnetically. One of our engineers does lots of testing with an external patch antenna, but it is mounted to a metal plane. We haven’t tested without that plane yet, so we don’t know exactly what impact that will have.

Also, I found out more about GPS lock. The onboard GPS needs at least a 25dB SNR for at least 3 satellites. We may not have been getting that. The standard GPS trace info only shows the max of available satellites. We should be able to use the +gpsmax on the trace info to see the details SNR information.

While I requested the use of +gpsmax, I think I formatted incorrectly.

trace +gpsmax

should do it.

If you can test outside, maybe with the antenna on the roof of a car, I suspect it will improve.

11

@gwolff I put the external antenna on metallic pot holder (ext has magnet at the bottom). Got 11/11 sats in 41 seconds. No fix.
Then issued the command trace +gpsmax instead of trace on +gpsmax but the info scrolls too fast to tell.
Forum won’t allow uploading .log file, sending to Skype

12

@gwolff Never got the carrier B to work reliably.
1- Back to the Carrier Pi, switched from 1.0. to 1.1
2- Made sure GPS DIP was Active
3- Place the Adafruit external antenna on a metal surface (antenna has a magnet)
4- Put the antenna outside
5- Tighten the tiny connector on the Carrier for good measure
6- Rebooted
7- Set card.location.mode to continuous (and hub.set to periodic)
8- Waited several minutes
Success!

Further testing indicates that 3,4 and 6 are not a factor.
Item 7 is: when hub.set is in continuous and card.location.mode in periodic, it does not acquire/search for the satellites. Possibly because it takes an unusually long time for the notecard to acquire a sat fix (several minutes). Same antenna/position with an Adafruit GPS hat locks in just a few seconds.

Other suggestion:
Given that external antennas (including the recommended Taoglas MA256.A.LBI.001) use SMA connectors, the uFL adapter weight/rigidity does not permit to truly secure the connection to the notecard. Perhaps another connector?

13

@Francois
Just clarifying, the trace info you sent me was captured after the first minute or so of operation. Is that correct?

14

@gwolff I used the tail of the log file. From the times it looks like it begins 20 seconds into and continues to 9+ minutes

15

Hi Francois. First of all, thank you for the updated log file.

I did get this to our engineering team when you uploaded it and we are still investigating. I will keep you posted of progress.

Thanks very much.

16

@gwolff back at my office now, I will run the another test with CoolTerm, external antenna and Carrier Pi. While in PR I noticed that it takes a very long time for the Carrier A to get a sat fix after a power off, over 20 minutes even with a clear view of the sky.

17

Thanks for the feedback Francois. We will probably need to investigate that separately as the Notecarrier A adds an additional variable of a different antenna and RF layout.

We expect customers to be able to use the active antenna and the Notecarrier B or Notecarrier-Pi. We use that combination frequently, and have not seen such weak GPS signal strength. We are wondering if it happens to be the GPS patch antenna you are using. I know you sent a link, but can you confirm the model number? We are interested in testing with the same antenna.

18

I am using the external antenna from Adafruit:

When used with the GPS hat Adafruit Ultimate GPS HAT for Raspberry Pi A+/B+/Pi 2/3/Pi 4 [Mini Kit] : ID 2324 : $44.95 : Adafruit Industries, Unique & fun DIY electronics and kits it was amazingly accurate and rapid.

19

Using the Notecarrier Hat + an external antenna GPS does not get a fix in the following configuration:
{“req”:“hub.set”,“mode”:“continuous”}
{“card.location.mode”,“mode”:“periodic”}
{“card.motion.track”,“start”:true}

I do see the motion events routed to notehub but there is no location available in a {“req”:“card.location”}
The only way to make this work is to first set the card.location.mode to continuous, wait after power on for a fix (7 minutes or so), then switch back to the configuration above.

20

Thanks very much Francois. I did get the log and am reviewing now.