Best way to test basic operation of BladeRFx40

Discussions related to embedded firmware, driver, and user mode application software development

Moderator: robert.ghilduta

Post Reply
goodboytower
Posts: 6
Joined: Thu Oct 18, 2018 4:32 pm

Best way to test basic operation of BladeRFx40

Post by goodboytower » Tue Nov 13, 2018 5:19 pm

Hey all, I've got the BladeRF x40 version, and I'm able to get it up and running (2 solid lights, 1 blinking) but I'm trying to figure out the best way to transmit a tone just to detect it with a spectrum analyzer. I only found documentation that required a signal generator but with matlab that I'm not able to accomplish on a tiny low power Raspberry Pi. I'm working on a school project and just want to show proof-of-concept before making two handsets call each other. So, does the BladeRF-cli have a built-in function to broadcast any kind of signal tone to detect that the transmitter is working? I tried tx start but I couldn't pick anything up on the spectrum analyzer.

User avatar
rtucker
Posts: 77
Joined: Sun Jan 25, 2015 10:38 am

Re: Best way to test basic operation of BladeRFx40

Post by rtucker » Tue Nov 13, 2018 6:21 pm

Greetings!

We have a walk-through of how to verify basic functionality at: https://github.com/Nuand/bladeRF/wiki/G ... -Operation

My usual "smoke test" is to transmit /dev/urandom, which will produce a nice big blob around the center frequency. Something like this will produce a 5 MHz wide blob around 2.4 GHz, at about 0 dBm:

Code: Select all

set samplerate tx 5M
set frequency tx 2.4G
set gain tx 60
tx config file=/dev/urandom repeat=0
tx start
I hope this is useful! If this doesn't work, please reply back with the output of the 'print' command so that we can verify that all the settings are right.

Thanks :)
Rey Tucker (she/her)
Systems Engineer, Nuand LLC
Rochester, NY, USA

#WontBeErased

goodboytower
Posts: 6
Joined: Thu Oct 18, 2018 4:32 pm

Re: Best way to test basic operation of BladeRFx40

Post by goodboytower » Tue Nov 13, 2018 6:57 pm

Thanks for the quick reply! Here is the output of my print after following your instructions. I used 900MHz for the frequency as I'm trying to broadcast ethically on a frequency that won't overlap real American cell phone frequencies. Does everything look right?

Code: Select all

 RX1 Bandwidth:  28000000 Hz
  TX1 Bandwidth:  28000000 Hz

  RX1 Frequency: 2484000000 Hz
  TX1 Frequency:  900000000 Hz

  RX1 AGC: Disabled

  GPIO: 0x000000b7
    LMS Enable:         Enabled
    LMS RX Enable:      Enabled
    LMS TX Enable:      Enabled
    TX Band:            Low Band (300M - 1.5GHz)
    RX Band:            High Band (1.5GHz - 3.8GHz)
    RX Source:          Baseband

  Loopback mode: none

  RX mux: BASEBAND - Baseband samples

  Gain RX1 overall:   33 dB (Range: [-1, 60])
               lna:    6 dB (Range: [0, 6])
            rxvga1:   30 dB (Range: [5, 30])
            rxvga2:    3 dB (Range: [0, 30])
  Gain TX1 overall:   60 dB (Range: [17, 73])
            txvga1:  -17 dB (Range: [-35, -4])
            txvga2:   25 dB (Range: [0, 25])

  Sampling: Internal

  RX1 sample rate: 1000000 0/1
  TX1 sample rate: 5000000 0/1

  SMB Mode:   Disabled

  trimdac: Operation not supported

  vctcxo_tamer: Operation not supported

  Expansion GPIO register: 0xffffffff
  Expansion GPIO direction register: 0x00000000

  Hardware status:
    RF routing:
      TX: auto
      RX: lna2

User avatar
rtucker
Posts: 77
Joined: Sun Jan 25, 2015 10:38 am

Re: Best way to test basic operation of BladeRFx40

Post by rtucker » Tue Nov 13, 2018 7:22 pm

Yup, this should work!
Rey Tucker (she/her)
Systems Engineer, Nuand LLC
Rochester, NY, USA

#WontBeErased

goodboytower
Posts: 6
Joined: Thu Oct 18, 2018 4:32 pm

Re: Best way to test basic operation of BladeRFx40

Post by goodboytower » Tue Nov 13, 2018 7:36 pm

Thanks so much! Last questions, is there a "sweet spot" for sample rate to a cell phone, and what gain on the BladeRF would be best to not broadcast any further than inside my room?

User avatar
rtucker
Posts: 77
Joined: Sun Jan 25, 2015 10:38 am

Re: Best way to test basic operation of BladeRFx40

Post by rtucker » Thu Nov 15, 2018 1:47 pm

The sample rate must be greater than your expected signal bandwidth, and in general, it's nice if it is an integer multiple of the symbol/chip rate. For example, W-CDMA/UMTS uses a chip rate of 3.84 Mchips/sec for an occupied bandwidth of 5 MHz, so 7.68 Msamples/sec is the minimum I'd use.

For transmit power, the rule that I usually go by is to use the minimum transmitter power necessary to carry out the desired communications (see also FCC §97.313(a)). Start quite low, and bump up if required.

For what it's worth, 902-928 MHz is (among other things) an amateur radio frequency band, so if you have an amateur radio license (and can meet the various other requirements), transmit power is much less of a concern.
Rey Tucker (she/her)
Systems Engineer, Nuand LLC
Rochester, NY, USA

#WontBeErased

Post Reply