[srslte-users] cell_measurement example - invalid RSRP

Ismael Gomez ismael.gomez at softwareradiosystems.com
Mon May 1 23:39:20 UTC 2017


Yes exactly

El lun., 1 may. 2017 19:29, Ifly88 <ifly88 at protonmail.com> escribió:

> Then I could get a LTE signal generator with known RSRP output and then
> modify 'rx_gain_offset' until the 'cell_measurement' RSRP matches the
> signal generator.
>
> Does this sound reasonable?
> -------- Original Message --------
> On May 1, 2017, 11:13 AM, Ismael Gomez <
> ismael.gomez at softwareradiosystems.com> wrote:
>
>
> Hi,
>
> Yes that rx_gain_offset should reflect the difference in dB between the
> power estimated in the digital domain compared to the power at the antenna.
> In USRP systems we use the RSSI sensor to automatically calibrate it. For
> the bladeRF, you should find a way to do that automatically or calibrate it
> manually for your gain and frequency settings.
>
> On Mon, 1 May 2017 at 14:01 Ifly88 < ifly88 at protonmail.com> wrote:
>
>> Has anyone noticed that the RSRP in the 'cell_measurement' example is
>> incorrect?
>>
>> The values I'm getting from 'cell_measurement' are greater than positive
>> +30dBm on a commercial network where the real measured value is about -90
>> dBm. 'cell_measurement' is about 120db off.
>>
>> The bladeRF is set to 6 db LNA, 27 db RXVGA1, and 30 db RXVGA2. I am also
>> using the XB 300 with a 20 db LNA with an NF of 1.5 dB.
>>
>> Debugging shows the 'rx_gain_offset' used to calculate the RSRP is 30db
>> on line 362.
>>
>> Any ideas where the problem might be? I've been staring at the source
>> code all day but I barely know C.
>>
>>
>>
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