EVA M8M AssistNow & Reset

0 votes

We are using EVA M8M with AssistNowOnline in very challenging signal conditions. When we upload AssistNowOnline data to the module immediately after a cold boot (no VBackup), we get ~40sec TTFF which is great for our signal conditions.

However, if we cold boot the module, and let it try and acquire a fix without AssistNowOnline data aiding, (lets say, at least 15sec), and then upload the aiding data, we often never get a fix, and sometimes after 300-500sec.

We have tried to cold, warm and hot start the module prior to upload of aiding data but that seems to have only a marginal effect, as the TTFF is still longer than a cold boot with immediate aiding upload.

Our question is: what should be done prior to upload of aiding data to get the same low TTFF even if the module was already running for a while?

Thank you.

 

Update, Oct 25:

To clarify what we are seeing:

Hardware cold start

* remove power from all power pins of EVA M8M

* apply power to all power pins of EVA M8M

* wait 3sec to let module boot

* send aiding data

* TTFF: ~40sec

 

Software restart:

* with power continuously applied to all power pins of EVA M8M

* send either one of 3 UBX restart message (same result on TTFF regardless which message we send)

  • cold start: B5 62 06 04 04 00 FF FF 02 00 0E 61
  • warm start: B5 62 06 04 04 00 01 00 02 00 11 6C
  • hot start: B5 62 06 04 04 00 00 00 02 00 10 68
* wait 2sec for reset to commence
* observe module has reset (uCenter)
* send aiding data
* TTFF: ~500sec (sometimes no fix ever)
 
the above results are the same if we do this from uCenter or from hour host MCU. 

 

by pixbroker asked Oct 22, 2016
by pixbroker edited Oct 25, 2016
149 views
0 votes
"We have tried to cold, warm and hot start the module prior to upload of aiding data but that seems to have only a marginal effect, as the TTFF is still longer than a cold boot with immediate aiding upload."

On the surface  - this makes no sense.   You have "tried to cold start the module prior to sending aiding data" - and TTFF is longer than cold starting with immediate aiding data".  These two scenarios are identical, no?
by √Črei answered Oct 25, 2016
I have updated the original post with additional details clarifying our observations.
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