[[Include(/WikiToC)]]

=== Generating and Observing Basic FR3 Sine Wave ===

This experiment transmits a single-tone (sine) IF at 1.5 GHz from a USRP-2974 (Krypton) into a Pi-Radio FR3 front-end, which up-converts to an FR3 carrier (example: 10 GHz). A second [https://www.pi-rad.io/ Pi-Radio] front-end down-converts the over-the-air signal back to 1.5 GHz for a USRP-2974 receiver, where a simple ASCII DFT spectrum viewer is used to verify the tone. The Pi-Radio web UI is used to configure the FR3 conversion. 

==== Prerequisites

* COSMOS account and active reservation in Sandbox 1. 
* Familiarity with USRP-2974 (embedded X310, 10 MHz–6 GHz, 160 MHz BW).
* FR3 hardware access (2× Pi-Radio FR3 front-ends) and the fr3-tutorials.ndz disk image for the USRPs.

==== Resources required

* Nodes: sdr1-piradio, sdr2-piradio, rfdev-sdr1-piradio, rfdev-sdr2-piradio. 
* Antennas: 2× Vivaldi (Tx/Rx) connected to the Pi-Radio front-ends. (See FR3 hardware pages for antenna layout.) 
* Browser access to [https://www.pi-rad.io/ Pi-Radio] web UI on the rfdev-* nodes (port 5006).

[[Include(/UserGuide/FR3Setup)]]

==== Experiment Execution

Use the Pi-Radio web UI Frequency panel on both rfdev pages (Tx and Rx) and set:

* Low LO Frequency (GHz): 1.500000
* High LO Frequency (GHz): 10.000000

This example pairs a 1.5 GHz IF with a 10 GHz high-side LO (and a 1.5 GHz low-side LO) to place the RF tone at ~10 GHz, and back to 1.5 GHz on the receive path. (Exact placement depends on mixer sign/paths; the screenshot below shows the working settings used in this demo.) Leave Filters, Gain (except where noted), and LO Suppression at defaults for the first run

On the transmitter (sdr1-piradio), start a 1.5 GHz sine at 5 MHz baseband tone:
{{{#!shell
tx_waveforms --args "resource=RIO0" --subdev A:0 --freq 1.5e9 --ampl 0.7 --gain 30 --wave-type SINE --ant TX/RX --rate 10e6 --wave-freq 5e6
}}}

On '''sdr2-piradio''' start the character based spectrum analyzer:
{{{#!shell
rx_ascii_art_dft --args "resource=RIO0" --subdev A:0 --freq 1.5e9 --ant RX2 --rate 20e6
}}}

You should observe a stable, narrow spectral line(s) in the DFT display near the configured tone at 5MHz (with side-markers set by the viewer). The figure below shows both Pi-Radio UIs (left: Tx FE, right: Rx FE) with Low LO = 1.5 GHz and High LO = 10 GHz, the TX console (bottom-left) and the ASCII DFT (bottom-right) around 1.5 GH

[[Image(pi-sine.png, width=1000px)]]


==== Cleanup
* Stop the UHD programs (Ctrl-C).
* Power down resources to release them for others:
{{{
omf tell -a offh -t sdr1-piradio,sdr2-piradio,rfdev-sdr1-piradio,rfdev-sdr2-piradio
}}}