E310 FM Receiver

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This tutorial describes how to receive broadcast commercial radio stations transmitting Frequency Modulated (FM) signals using the Ettus Research E310.

USRP (E310) Setup Guide

This page provides step-by-step instructions to configure a **USRP E310** for:

• Receiving signals with a Python script
• Remote control via SSH
• Using GNU Radio on a host machine

1. Hardware Connection

• Antenna

 Plug the antenna into the **RX2-A** port on the USRP.  
 :The RX2-A port is dedicated to receive (RX) operations.

• Power

 Turn on the USRP and ensure it has a stable power supply.

2. Discover the USRP’s IP Address

On your host machine (connected to the same network):

sudo snap install nmap    # Install nmap if not already present
nmap -sn 10.0.0.0/24      # Scan the local subnet

This finds the DHCP‑assigned IP of the USRP (e.g., **10.0.0.100**).

3. Assign a Static IP Address

To simplify SSH access, give the USRP a fixed IP.

a. Create the static_ip.sh Script

SSH into the USRP (using the DHCP IP) and run:

nano static_ip.sh

Paste the following:

#!/bin/sh

# 1. Flush existing IP addresses
ip addr flush dev eth0

# 2. Assign static IP and netmask
ip addr add 10.0.0.200/24 dev eth0

# 3. Bring the interface up
ip link set eth0 up

# 4. Add default gateway
ip route add default via 10.0.0.1

Each step configures the Ethernet interface (eth0) for static addressing.

b. Run the Script

bash static_ip.sh

The IP remains active until the next reboot.

4. SSH Connection

On the host:

ssh root@10.0.0.200

You now have remote shell access to the USRP.

5. Mount USRP Filesystem via SSHFS

To edit USRP files locally:

sshfs root@10.0.0.200:/ ~/remote_usrp

Mounts the USRP’s root directory at `~/remote_usrp` on the host.

6. Configure Geany IDE

To simplify the workflow, we will use **Geany**, a lightweight IDE, on the **host machine** to:

• Edit files located on the USRP (via SSHFS)
• Launch scripts remotely on the USRP (via SSH)
• Centralize all development and execution within one interface

This allows you to work entirely from the host, avoiding the need to manually SSH into the USRP or use a separate editor.

a. Open Build Commands

In Geany, go to **Build → Set Build Commands**.

b. Update the “Execute” Command

Replace with:

ssh -t root@10.0.0.200 "bash -i -c '/home/root/start_usrp_script.sh'"

This runs a remote startup script on the USRP when you press “Execute.”

c. Create the start_usrp_script.sh Script

On the USRP:

nano /home/root/start_usrp_script.sh

Paste:

#!/bin/sh

# Cleanup function on interrupt
cleanup() {
    echo "[INFO] Stop requested"
    pkill -f usrp_fm_receiver.py
    exit 0
}

# Trap INT and TERM signals
trap cleanup INT TERM

# Launch the main Python script
python3 /home/root/usrp_fm_receiver.py

Ensures the Python process is cleanly terminated on exit.

7. Running the Flow

1. In Geany, open `~/remote_usrp/home/root/usrp_fm_receiver.py`.
2. Press “Execute” to start the script on the USRP.
3. On your host, launch GNU Radio Companion and run `fm_receiver_host_udp.py` to receive the UDP stream.

The USRP script streams FM over UDP; GNU Radio handles it on the host side.

Additional Notes

• To make the IP configuration persistent, consider adding `static_ip.sh` to `/etc/rc.local` or creating a `systemd` service.
• Verify compatibility of Python and GNU Radio versions between the USRP and host.

Last updated: 30 June 2025