What GPS receiver does the nRF9160 use?

[Hank Schraeder]

I doubt Nordic developed a brand new GPS receiver for the 9160.  Where does it come from (manufacturer and model)?

The Thingy91 Asset Tracker out of the box example has some apparent software bugs.  The nRF Cloud $GPGGA display message ALWAYS says the receiver is tracking 5 satellites.  Is this a hard coded number in the software, or is the receiver only capable of seeing a maximum of 5 satellites at a time?

Is the $GPRMC message available from your GPS receiver?  I need speed and heading.

The cellular signal strength reading is ALWAYS -42dBm which means it must be hard coded in the software.  Does Nordic have any plan to fix this and provide a software update for the Asset tracker?

[Marjeris Romero]

Hi Hank,

The nRF9160 has its own on-chip GPS receiver. For more information please check the GPS receiver section in the nRF9160 product specification, here.

To test the GPS receiver in the Asset tracker example you need to go outside and hold the button for 10 seconds, see our getting started guide.

Best regards,

Marjeris

[Hank Schraeder]

Disappointing reply. 

Let's try again.  Your product specification for the GPS does not specify who your GPS receiver manufacturer is, anything about the GPS message formats available, or how many satellites can be tracked simultaneously.

 1)  Who did you get your GPS receiver from and what model?????  Ublox???  Other????

 2) How many satellites can be tracked simultaneously? 

The cellular signal strength parameter is extremely important for corporations developing applications for tracking devices travelling thousands of miles.  We want to know how the signal strength varies in different regions, and especially if we lose roaming connections.

 3)  The current signal strength showing for your Asset Tracker demo on the nRF Cloud site is locked at -42 dBm.  This is an obvious software (or maybe hardware?) error.  Will Nordic fix this?

The answers to these 3 questions are critical for continued development of the 9160 at our company.  I you can't answer then please forward to your engineering branch to an expert in the GPS / Cellular / Asset Tracker software application section.

[Marjeris Romero]

Hi Hank,

1. If it's not specified in the PS, I cannot comment further. If you want more information about GPS features you can send me a private message and I can send your RSM contact information to you.

2. This depends on how many satellites are available in your area. At my end I see between 5-9 satellites depending on where do I test GPS coverage and the enviroment around. Have you tested outdoors in open sky?

3. This one looks like a bug, I have now reported it internally. In the meantime you can use AT command "AT+CESQ" via the LTE link monitor to read out the RSRP. It is the last number, with an offset from -140 dBm, please take a look at nRF91 AT commands reference guide here.

Best regards,

Marjeris

[Hank Schraeder]

There are usually at least 20 satellites available anyplace at any time because the good modern receivers can see both the orbiting US GPS (27 operational) and Russian (24 operational) Glonass systems.  Since you can't divulge which receiver you're using I can't tell how many I should actually be seeing if using a good RF front end.

Last time I checked, your Asset Tracker demo is still broken as far as cellular signal strength is concerned. Apparently nobody is working what should be a quick fix on your end.  Every time we give a customer demo I have to explain that Nordic is aware of the software error but apparently hasn't had time to fix it.  Since "internal" reporting isn't working is there an external way for someone to get notified? 

Will be sending a "private message" so I can get more info on your GPS receiver.  Don't know why one of your customers should have to do this since many others will be asking the same questions in the future.

[Marjeris Romero]

Hi Hank,

There's already a pull request to fix the asset tracker RSRP notification bug here: https://github.com/NordicPlayground/fw-nrfconnect-nrf/pull/1104

It's waiting for review and will be merge into the master branch soon.

We only have support for GPS L1 C/A, not Glonass, see nRF9160 SiP product brief and the section about the GPS receiver in the Product Specification, here.

How many satellites you will be able to see will depend on your location. I recommend testing in open sky.

BR,

Marjeris

PS. the pull request has been merged now.