Building a single frequency network with 2 BladeRF

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steven-r
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Joined: Mon Jul 05, 2021 1:40 am

Building a single frequency network with 2 BladeRF

Post by steven-r »

Hi everyone!

I am currently working on a project for a Swiss company, the goal is to build a single frequency network able to broadcast DAB/DAB+ using two BladeRF xA9 and the ODR-mmbTools by opendigitalradio.org, this means the SDRs must transmit precisely timestamped DAB samples. I wondered if someone could help me to know about the feasibility to accomplish this work with Nuand's products.

One of the constraints is that the SDRs cannot be physically connected (wired) to a common reference clock, but to an individual GPSDO module for each one. This way, the SDRs can be positioned a long distance from each other and are still synchronized. In order to do this, they must have the ability to connect with a 10 MHz and a 1 PPS signals from the GPSDO. The 10 MHz signal would replace the internal 38.4 MHz BladeRF oscillator and each rising edge of the 1 PPS signal would define the internal SDR time.

By looking at Nuand's website at the link https://www.nuand.com/frequently-asked-questions/ (section “How do I use a 10 MHz reference”) , I noticed the BladeRF does not accept any other external frequencies that are not 38.4 MHz because of the Cypress FX3 USB driver. It would be nice if the BladeRF operated not only at 10 MHz but also at a frequency that is a multiple of 2048 for this application.

So, here are my two questions:
1. Can we replace the internal frequency of the BladeRF by an external frequency of our choice?
2. Is it possible to define the BladeRF internal time at each rising edge of an external 1 PPS signal?

I thank you for your help and I am looking forward to reading your answer.

Steven
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