Issue Bridging Hermes Lite 2 Through Raspberry Pi Running OpenWrt

[Martin S.]

Hello everyone,

I’m currently trying to connect my Hermes Lite 2 to my home network through a Raspberry Pi 3B+ running OpenWrt. Here’s my intended setup:

1. My Raspberry Pi connects to my home network via Wi-Fi.
2. The Hermes Lite 2 is connected to the LAN port on the Raspberry Pi.
3. The Raspberry Pi is set up as a bridge, allowing the device on the LAN port to access the home network through the Wi-Fi connection.

With this setup, I’m able to connect a computer to the LAN port of the Raspberry Pi, and it successfully receives an IP address from the main network's DHCP server (a Fritzbox router). I can browse the internet without issues using this computer. However, when I connect the Hermes Lite 2 instead, it doesn’t appear to connect to the network and doesn’t receive an IP address from the router.

Here’s what I’ve tried so far:

• I’ve set the LAN interface on the Raspberry Pi to “unmanaged” in OpenWrt to avoid conflicts.
• The Pi’s LAN and Wi-Fi interfaces are in the same firewall zone in OpenWrt.

Does anyone have experience with this type of setup or have any ideas on how to troubleshoot further? Any help would be greatly appreciated!

Thanks in advance!

[ron.ni...@gmail.com]

Are you running a DHCP server on your Raspberry Pi to provide the HL2 with an IP address?
Can you Discover or ping the HL2 from the Raspberry Pi command line (after ssh'ing in to the Pi)? 

What IP address does the HL2 have?
You can run an SDR application on the Pi to do HL2 discovery, or run hl2_tcp -d (available from GitHub) from the Pi's command line.
When directly connected to a Pi (no DHCP server, router, or switch), my HL2 defaults to a self assigned IP of 169.254.19.221 , since I am not running a DHCP server on my Raspberry Pi.
73, Ron, n6ywu

[John Williams]

It depends on where your radio software will run. Assuming you're needing the home network to give an ip address is fine. Running your radio software across the wifi will likely fail due to packet lag/latency, imho.

Sent from my iPhone

On Oct 25, 2024, at 5:46 PM, ron.ni...@gmail.com <ron.ni...@gmail.com> wrote:

Are you running a DHCP server on your Raspberry Pi to provide the HL2 with an IP address?

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[Martin S.]

No, there ist no dhcp server running on the raspberry pi. The dhcp server ist running in the network. If I connect a Notebook via LAN to the Raspberry Pi it gets an IP. But if I connect the HL2 via LAN to the Raspberry Pi it gets no IP.

[Martin S.]

Are you serious that this will not work. I made some tests with an SDR and rtl_tcp. that work fine for me. Does it not work the same way on the HL2?

[Martin S.]

I tried something new and configured the raspberry pi with this script from this website to a wifi - ethernet - bridge:

Website

The raspi is connected to the wifi in the network. In the network is a fritzbox which provides the dhcp server. Devices which are connected to the ethernet port of the raspi get an IP from the dhcp server of the fritzbox. This works great when I connect a notebook. Only when I connect the HL2 does it not get an IP from the DHCP server.

[John Williams]

Transmitting is the issue. The buffer empties occasionally causing the relay to chatter. Search wifi on this list for more info.

Sent from my iPhone

On Oct 26, 2024, at 12:29 PM, Martin S. <inputmast...@gmail.com> wrote:



I tried something new and configured the raspberry pi with this script from this website to a wifi - ethernet - bridge:

Website

The raspi is connected to the wifi in the network. In the network is a fritzbox which provides the dhcp server. Devices which are connected to the ethernet port of the raspi get an IP from the dhcp server of the fritzbox. This works great when I connect a notebook. Only when I connect the HL2 does it not get an IP from the DHCP server.

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[ron.ni...@gmail.com]

You can use an hl2_tcp server in a nearly identical manner to rtl_tcp.  hl2_tcp.c is available from GitHub and builds and runs just fine on a Raspberry Pi (or Mac). I'm using it right now as a server on a Pi 4 to stream IQ samples from my HL2 to my iPhone.  Determine the IP address of your HL2, usually 169.254.19.221 if directly connected to a Pi via ethernet without a router, and start with:

hl2_tcp -a 169.254.19.221 -b 8

for 8-bit IQ samples, or use -b 16 for use with SDR apps that support 16-bit IQ samples (such as my iPhone app).

The connect to the hl2_tcp server using the IP address of your Raspberry Pi, port 1234, from any rtl_tcp SDR client that supports HL2 sample rates.

73, Ron, n6ywu

[James Ahlstrom]

First, this software does what you want, and also adds buffering for the Tx data.

I would be very surprised if the HL2 could pick up a DHCP address from the network. The notebook probably works because it runs Windows, and it adds IP routes for the 169.254.*.* addresses that Microsoft invented. To really understand what is going on, you need the IP address of the HL2, the RasPi Ethernet interface and the RasPi Wifi network. Traffic will not pass through the two RasPi interfaces unless there is a routing table entry to allow it.

Jim

N2ADR

[ron.ni...@gmail.com]

169.254.*.* address are IPV4 Link-Local addresses self assigned according to IETF RFC3927 , if no DHCP or static IP address is  assigned or available.  These IP addresses are not just a Microsoft assignment, but work on Solaris systems, some Linux devices (Raspberry Pi), Macs, and iOS devices (iPad and iPhone) when an HL2 is directly connected to an ethernet port or ethernet adapter, without any router in between or involved.  Since these IP addresses are associated a different interface than a Raspberry Pi's WiFi interface, one would need to specifically route or relay to get UDP packets to traverse between the two different network interfaces.  73, Ron, N6YWU

[Martin S.]

Hello James,

you write in your instructions ‘First configure your single board computer (SBC). Start WiFi and make sure it has an IP address and can connect to your PC software. Set a fixed IP address of 169.254.1.1/16 on the Ethernet port connected to the HL2.’

Can I also install OpenWRT on the Raspberry PI 3+ (then I could also use the PI as a WLAN repeater) and give the Ethernet interface the fixed IP there?

Second question: Does your HL2 Wifi adapter also work for the Thetis software?

[Martin S.]

I have now managed with the Wifi Buffer from James Ahlstrom to give the HL2 the IP 169.254.1.1. I can also access it from the home network. I can also establish a connection via Thetis and Quisk. Unfortunately, the connection drops after a few seconds and the HL2 loses its IP address.
What could be the reason for this? I use the internal Wifi chip on the Raspberry Pi and have set it to use only the 2.4GHz band. The Raspberry Pi is in the same room as the Fritzbox access point to which the Raspberry Pi is connected.
I have played around with the buffer times from 250ms to 1000ms. However, this has no effect on the connection loss.
Any ideas where the problem is coming from?