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I am trying to use the HackRF One to simulate GPS to test devices in a production environment. I am currently able to get the GPS signal on my GPS receiver that I am testing, but the signal is much stronger than the devices would see in the real world. I want the GPS signal to be more representative of the outside environment to ensure that the devices I am manufacturing actually work in the field, so i am trying to decrease the GPS signal.

I know that GPS signal outside is low This document says that "the received power is -125 dBm". The HackRF One User document says that the maximum output power for 1575.42 MHz is between 0 dbm to 10dbm. enter image description here The antenna I have attached to the HackRF One has a gain of -3.34 db. So if I assume that the HackRF One is 2.5 dbm at 1575.42 MHz then I need a ~-125 db attenuator. -125dbm + 2.5dbm -3.34 db =attenuator = ~125 db. Is this math correct to assume that I need a -125 db attenuator? Am I missing something?

P.S. I am using the HackRF One in a RF chamber to do this testing to not interfere with other devices.

edit: changed "reprehensive" to representative

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    \$\begingroup\$ "reprehensive" - I do not think it means what you think it means ... "representative" perhaps? \$\endgroup\$
    – brhans
    Commented Dec 15, 2022 at 20:59
  • \$\begingroup\$ I meant "representative" I will correct it. \$\endgroup\$
    – mgwalker95
    Commented Dec 15, 2022 at 21:50
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    \$\begingroup\$ On page 17 of the data sheet to which you provided the link, is says that you can control the Tx power with a stepped 14 dB gain control (or attenuation) and a 0 dB to 47 dB variable gain (or attenuation). So by taking advantage of those, you should be able to reduce the transmit output power by 61 dB from it's maximum. Hence you would only need ~65 dB additional attenuation to achieve the power level you want. \$\endgroup\$
    – SteveSh
    Commented Dec 16, 2022 at 0:40
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    \$\begingroup\$ Enclosure: The commercial version of HackRF One from Great Scott Gadgets ships with an injection molded plastic enclosure. RF radiation from the PCB itself will very likely exceed radiation from an antenna connected through 125 dB attenuator attached to RF output. \$\endgroup\$
    – glen_geek
    Commented Dec 16, 2022 at 0:44
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    \$\begingroup\$ @glen_geek You are probably right. I might but the HackRF in another RF chamber to ensure that the HackRF is not radiating unwanted signal. \$\endgroup\$
    – mgwalker95
    Commented Dec 16, 2022 at 19:16

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