Nrf91 GNSS Almanacs and ephemeris

Question

Hello , I would like to make a question regarding GNSS . So GNSS has a single fix mode ( https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/nrfxlib/nrf_modem/doc/gnss_interface.html#single-fix ) and I would like to know if in this mode the download of almanacs and ephemeris is done . What I think its happening is : 
 
 GNSS cold start since there is no almanacs and ephemeris 
 We get a valid fix and also wait a few minutes to download the almanacs and ephemeris data 
 The modem reports the valid fix after downloading the data 
 The GNSS is turned off 
 
 Thank you for the help !

Håkon Alseth · Accepted Answer

Hi, 
 
 I would like to know if in this mode the download of almanacs and ephemeris is done . What I think its happening is : 
 
 GNSS cold start since there is no almanacs and ephemeris 
 We get a valid fix and also wait a few minutes to download the almanacs and ephemeris data 
 The modem reports the valid fix after downloading the data 
 The GNSS is turned off 
 In the case of a fully cold start, your understanding is close to correct. In Step 2, the fix is reported after all necessary data has been downloaded, like ephemerides, almanac, time of week etc. 
 The last part, ie. turning off the GNSS, is up to the application. If you are using the gnss sample, there's an option for testing TTFF (time to first fix). 
 
 Kind regards, 
 Håkon

Nrf91 GNSS Almanacs and ephemeris

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