Simple Tx/Rx setup

Hello folks,

I am attempting to transmit a bit stream from one bladeRF to another
using an SMA cable from the Tx output to the Rx input of the other. For
simplicity’s sake, I’m transmitting a finite bit stream of 1’s (not
1’s), and setting the File Source to not repeat itself.

I started by modifying …/gr_digital/examples/demod/dpsk_loopback.grc to
Tx/Rx setup as follows. I am trying to get the bladeRFs communicating at
‘baseband’ before moving on to OFDM transmission.

Tx.grc: tx.grc -
Rx.grc: <?xml version='1.0' encoding='ASCII'?><flow_graph> <timestamp>Mon Nov 4 14 -

I’ve noticed, when using a hex editor to compare the files at each
respective stage, namely that iq_in does not match iq_out.

On that note, are there any simple examples (.grc) on how to time tag IQ
samples output from the bladeRF? At the moment, I’m naively searching
finite strings based on the iq_in generated from the DPSK Mod block in
Tx.grc, so I don’t really know if I’m comparing the right samples at
time instance.

Am I missing something elementary in my setup or do I have to use
coding to prevent errors in transmission?

I do apologize if I’m being fairly thick; I’m fairly new to DSP, SDRs



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I really hope you’re using an attenuator in between the two devices.
I’m not terribly familiar with bladerf’s frontend but if it works
similar to our devices,
you’ll fry them if you don’t attenuate the TX signal going through the
SMA cable.