Can't get GPS Data for L96-M33

IoT Modules GNSS Module
1

Hello Quectel Team,
I’m trying to make a PCB for Quectel L96 - M33 GPS module, but I can’t get GPS data, where when I read the serial data, it only shows data like this:

$GPRMC,000812.896,V,0.00,0.00,060180,N,V34,
$GPVTG,0.00,T,M,0.00,N,0.00,K,N32,
$GPGGA,000812.896,0,0,M,M,44,
$GPGSA,A,1,103,
$GPGSA,A,1,200,
$GPGSV,1,1,00,065,
$GLGSV,1,1,00,178,
$GPGLL,000812.896,V,N76,

I use the internal antenna by connecting pins 16 and 17 (RF_OUT and RF_IN) using a 0R resistor, but the coordinate data is still not visible.
I’ve tried outside and waiting for 24 hours, to get a GPS Data, but it still can’t get a GPS data. Is there a solution for my problem?

I’m using firmware : $PQVERNO,R,L96NR01A03S,2018/07/30,04:17*6B
Do I need to do a firmware upgrade?

I’m waiting for the answer, and thank you for your attention

2

Hi agentbolot93,

Your firmware version is the latest.
Could you please provide:

  1. Log file with a longer period, preferrably from an open-sky testing environment.
  2. Your Circuit Design Diagram (If you would like to), for us to have a check. You can send it via private message.

Best regards,
Meiji

3

Hi Meiji,
I tried to send a file attachment, but the new user can’t upload the document (txt or .zip file). I only attached some of the test log data that I did open sky testing, as shown in the image below:

Log Test Quectel GPS
Log Test Quectel GPS725×794 163 KB

4

And for Circuit Design, here is the Schematic Design of my PCB

gps schematic
gps schematic976×624 57.5 KB

I just added the RTC battery only. For the circuit, I followed the reference design to use an internal antenna. Do I need to improve this design?

5

Hi agentbolot93,

1- In the design level, the connection between RF_OUT and RF_IN is correct. Could you please test if the circuit between RF_OUT and RF_IN is intact in harware level?

2- If the test in 1- suggests an intact circuit , please use another L96-M33 to check if you are able to receive signals with the same design.

Best regards,
Meiji

6

Hi Meiji,

Thank you for your quick response.

  1. For the first test, I can already confirm that the RF_OUT and RF_IN are intact.

  2. Tests testing has been done with 4 another L96-M33 modules, and all of the modules cannot receive GPS data. Any other suggestions?

7

Hello, we have personally encountered this issue and are still trying to figure out a solution. If you come across a fix/solution to this, an updated solution to this forum would be greatly appreciated. Thank you!

8

Hi agentbolot93, hi Adrian_DeLeon,

The PCB beneath the internal antenna needs to be clear, without any copper cladding. Could this be the cause?

Best regards,
Meiji

9

Hi Meiji,

The PCB design that I made, I have given a hole at the bottom of internal antenna, according to the reference design. Is my PCB design correct?

Board_PCB
Board_PCB486×581 86.3 KB

10

Hi agentbolot93,

The design on this layer is correct, could you please provide the PCB design for all layers in order to check?

Best regards,
Meiji

11

Hi Meiji,

I uploaded a schematic image on the GPS section. In the picture below, it can be seen that there are several layers such as the bottom layer, top layer and mechanical layer. I’m still giving a hole under the antenna, so the design I made should be in accordance with the requirements.
image

12

Hi agentbolot93,

The hole beneath the antenna part is in accordance with the requirements.

However,

  1. It shows poor connection of GND pins in bottom and top layers. (Holes needed for GND.)
  2. It’s not clear to us, if any external components outside the frame of your screenshot can bring any interference. To examine this, it’s recommended to power L96-M33 only (and stop all other parts), to get a testing result without potential interference.

Best regards,
Meiji

13

Hi Meiji,

Thank you for your advice. As you suggested, I’ve tried removing all my components, and what remains is the Quectel L96-M33 GPS module, 0R resistor to connect RF_OUT and RF_IN only. I did this experiment in an open field with sunny weather conditions from noon to late afternoon. The result, still remains, data does not appear. Do you have any other suggestions regarding the use of this internal antenna?
log_data_gps_20220302_asc.zip (295.2 KB)

image
image652×751 143 KB

14

Hi agentbolot93,

From our communication so far we didn’t find out any possible cause. Have you ever used an external antenna, so that we know the modules are able to receive signals through external antenna? (To confirm the modules you got are able to get signals.)
(External active antenna, externally powered)

Best regards