LNA - Low Noise Amplifier - Any specs available?

IoT Modules Legacy HL Series
1

Going through the documents, I am a bit confused. I see PAD C43 is for EXT_LNA_GPS_EN.

Couple of questions:

  1. I assume this pin is to on/off an external LNA? If so, how is it controlled?

  2. Are there specs on this pin such as voltage?

In the documents, all I have found is “this signal indicates whether the GNSS receiver is active and can be used to enable an external LNA.” Is it recommended to only enable/disable the LNA or to actually power the LNA from this pin?

2

Hi @tremmert

Which product HL series (HL8548-G or others) are you using?

EXT_LNA_GPS_EN ON indicates whether the GNSS receiver is active and can be used to enable an
external LNA, especially during GNSS low power mode.
It is set according to the AT+GPSCONF command. If you set AT+GPSCONF=1,1, the EXT_LNA_EN should be high whenever GPS receiver is activated.
EXT_LNA_EN will change to low if GPS receiver is deactivated or you change the configuration by AT+GPSCONF command.

3

Hi Donald,
I am currently testing with a HL7800 series and will be switching to the HL7802.

Thank you for the clarification, that is what I assumed, however, I wasnt sure based on the limited detail in the documents.

Thank you!

4

Hi tremmert ,

For HL7800, HL7802 products:

  • Enable GNSS LNA feature (AT+GNSSCONF=1,1)
  • Start a GNSS session
    • AT+CFUN=0
    • AT+GNSSSTART (starting a GNSS session will trigger LNA_EN to change)

<config_value_1> Requested value 1 of the configuration type
For <config_type>=1:
0 LNA_EN output signal is always OFF
1 LNA_EN output signal is automatically driven

Please refer to AirPrime - HL78xx - AT Commands Interface Guide - Rev10.pdf for more details.
https://source.sierrawireless.com/resources/airprime/software/airprime_hl78xx_at_commands_interface_guide/#sthash.9zgFKsgl.dpbs

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