Ublox NEOM8N concurrent sampling rate and LNA/SAW filters

0 votes
Hey Guys,

 

Is it possible to setup and run M8N module at 10Hz sampling rate using the GPS+GLONASS combination. I know that the datasheet says that it can only do 5Hz max, but now Im waiting for multi gnss antenna to arrive and was wondering if I can run my M8N at 10Hz, if it can keep up the sampling rate when set via UART or it will simply downscale the sampling speed to 5Hz. I have read one of the post on stackoverflow that it was mentioned that M8N could be set to run at 10Hz.

 

Also regarding the LNA/SAW filters it says that M8Q and M8N features "additional  front-end LNA for easier antenna integration and a front-end SAW filter for increased jamming immunity". When using the M8M module together with active antenna that features an LNA and Filter Out Band Attenuation (f0=1575.42 MHz). I suppose there is no longer a need for extra LNA or SAW filter for the M8M module. Is that correct?
by s1lv3r asked Aug 23, 2016
by s1lv3r edited Aug 23, 2016
1,248 views
0 votes
The *solution* rate is constrained by a number of things, whether the firmware is on ROM or FLASH, GNSS chosen, and the buffering and bandwidth of the data output connection.

If you output too much data you'll typically get a txbuf type error, and lose packets. I know 5 Hz is achievable w/GPS+GLONASS on a FLASH based M8N. If your system has high enough dynamics for 10Hz you'd also want to review how you handle time at a system level, as well as the latency in your processing loop.

If you are going to discuss other posts on other forums, provide cites.
by clive1 answered Aug 23, 2016
I have this version of of the module NEO-M8N-0-01. It specifies in the data sheet that it has the following: "ROM 2.01/Flash FW 2.01"

Its hard to say where the firmware is installed, but when I took off the shield there is not external flash storage chip like WINBOND that is on the NEO7M module that I have...

Im only outputting GNGGA string.
To read full GNGGA string it takes 1.90ms.

GNSS chosen are the default ones, GPS GLONASS QZSS and SBASS.

Isn't the M8N supposed to have a external flash chip to be able to store the firmware? Because the one I have does not have one.

It does feature the M8030-KT chipset though. Apart from that I can see that there is a SAW filter on it too..

If I tell the current M8N unit to run at 10Hz rate, will it just start loosing packets and act as a 5Hz rate basically, because its just loosing packets and outputting errors every 2nd string..


I do not mind changing the M8N to M8M module, but my concern is that if I have to add any external components like LNA or SAW filter, to my existing PCB. Will be using an active antenna with onboard LNA, also says that it has an attenuation filter for 1575.42MHz frequency. My question if using that antenna is the external components necessary for M8M module or not?

Thanks in advance for you answer, you have been a great help!
You can pull the version of firmware via UBX-MON-VER

As I recall the NEO-7M is a ROM based module, the NEO-7N has FLASH

Not sure what NEO-M8N you have, but mine has a FLASH chip in it. Will attach picture as an answer, can't add to comments.

Pretty sure it won't gracefully degrade from 10 Hz to 5 Hz,  more likely to sporadically drop epochs, or messages within epochs. Don't have the time/resources to evaluate for you.
0 votes

NEO-M8N-0-01

by clive1 answered Aug 23, 2016
This looks more or less like the M7N that I have... unfortunately the M8N does not looks anything like yours, it is a chinese replica most likely and not the original one since there is no flash unit on it...

It does feature the M8 chipset although no flash :) curious if it can keep up with the 10Hz rate, will check it out.

Thanks for your answers clive1!
The UBX-M8030 all have ROMs on them, which runs faster than the FLASH

An M8N without a FLASH chip suggests it is a fake/counterfeit module, as it wouldn't be upgradable. A picture would be instructive.
I have found one of the original modules I had M8N... and the difference is clear between the original and ding dong M8N.
0 votes

Original and Fake 

As you can see for yourself...

Since it has only the M8030 and it runs on ROM, then the 10Hz shouldnt be a problem initially. The chipset do communicate and everything looks neat, in terms or receiving strings and HDOP is fairly low at 0.3 - 0.6.

by s1lv3r answered Aug 24, 2016
website banner