Re: Packet TX and RX on E312

[Marcus D. Leech]

On 06/23/2020 01:17 PM, Cameron Matson wrote:

I've tried from 125K to 16M (which if I request anything higher is what the device seems to cap it at).  The lower sample rates on the RX side actually do solve the O problem, which I guess makes sense, but the tG and U are still there on the TX side, and no packets seem to be decoded.

Cameron

The CPU on the E310 is a dual-core ARM9 CPU clocked at 866MHz.  That means that it can't move very many samples (particularly full-duplex)
  per second for a "complex" signal flow that involves modulaton/demodulation.  When doing pretty-much *nothing* to the samples, the interface
  can move a few Msps.  That goes down quickly as you actually have to do anything to the samples.  The E310 has a larger FPGA, and the
  "marketted use case" is to do most processing in the FPGA.

Now, as to why, at lower rates, you cannot decode, that's a debugging exercise perhaps not related, per se, to the E310, but just
  the experimental setup.

How are the two radios "connected" -- via antennae or a cable?  If cable, make sure you have plenty of attenuation in-line (30-40dB),
  otherwise you risk damage to the receiver at worst, and at best, driving the receive chain into non-linearity, producing distortions and
  unwanted mixing products within the first gain stage(s).

On Tue, Jun 23, 2020 at 12:03 PM Marcus D Leech <patchvonbraun@gmail.com> wrote:

What sample rate ranges have you tried?

Sent from my iPhone

On Jun 23, 2020, at 12:57 PM, Cameron Matson <ncmatson95@gmail.com> wrote:



Hello all,

I'm new to gnuradio and SDR so I hope there isn't something obvious I'm missing.  I'm trying to get a packet based system set up.  I'm using gnuradio 3.7 and UHD 3.14 that I cross compiled and loaded onto two E312s.

I'm trying to use the uhd_packet_tx and uhd_packet_rx examples as a staring point.  I made the necessary modifications to run it as a non-gui flowgraph, but left all the variables untouched.  Both the flow graphs run, but:

• the Tx flow graph shows an initial tG flag and then a  U flag after every burst (which I understand has something to do with tag offsets mismatching https://github.com/gnuradio/gnuradio/issues/1976)
• The Rx flow graph immediately starts outputing O flags, and no packets are recieved.

I've tried playing around with the frequency and sampling rates without much success.

Any help on where to start would be greatly appreciated.

Thanks,

Cameron