Tx and Rx at different sample rate

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Joined: Wed Mar 08, 2023 9:13 am

Tx and Rx at different sample rate

Post by algafix »


Is there any way of transmitting and receiving simultaneously on the BladeRF micro 2.0 at different sample rate?

I want to transmit a narrow band signal (say 1MHz) but receive a complete view of the spectrum say (40MHz), without saturating the USB connection. I use the bladerf-cli repeat=0 mode to start the transmission and then I start the reception.

But when the reception starts, the sample rate of the transmission gets modified to the sample rate of reception because the AD9361 has only one BBPLL. Is there any workaround aside from setting the same sampling rate for Tx and Rx? Like a multiplayer/divider that I can set only for the Tx or Rx channels?

I am asking this because I haven't seen this restriction anywhere, hence I may be doing something wrong or missed the documentation page.

Posts: 149
Joined: Thu Feb 28, 2013 11:14 pm

Re: Tx and Rx at different sample rate

Post by robert.ghilduta »

The bladeRF 2.0 micro's AD9361 reuses the same sample clock between the RX and TX basebands. So the AD9361's RX and TX will sample at the last sample rate set for either channel. USB 3.0 bandwidth should be sufficient to simultaneously handle 40MSPS on RX and TX. If this is not sufficient, it may also be possible to a modulator in VHDL so then only RX is transmitted over USB. Please take a look at how tone_generator ( https://github.com/Nuand/bladeRF/tree/m ... _generator ) is instantiated in the foxhunt revision ( https://github.com/Nuand/bladeRF/blob/m ... oxhunt.vhd ) and controlled in NiOS ( https://github.com/Nuand/bladeRF/tree/m ... oxhunt/src ).
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