Image data not being sent using Ubuntu 18.04 (Melodic) if using wifi [closed]

asked 2021-08-03 13:30:14 -0600

nasher128 gravatar image

Hi all.

I'm rattling my brain here. I have an Nvidia Jetson with Ubuntu 18.04 and I'm running Melodic. I've configured this as a standalone WiFi hotspot and I'm able to connect to the hotspot using my laptop and perform ping, SSH, and view publish topics from roscore running on my Jetson. At this point, I assume I have full communications established.

However, I cannot seem to stream any image data from the Nvidia Jetson to my laptop whilst my Nvidia Jetson is in WiFi hotspot mode (even though I can SSH, ping, and view topics..). I don't have this problem if my laptop and Nvidia Jetson connect to a dedicated WiFi access point.

How is it possible I can SSH, ping, and view topics whilst my Nvidia Jetson is configured as a WiFi hotspot but I cannot stream any video data It's really frustrating.

Any help please?

Thanks

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Closed for the following reason the question is answered, right answer was accepted by nasher128
close date 2021-08-05 11:41:27.547136

Comments

This is a repeat of #q383607. Please do not close a question just so you can repost it. You are free to edit a question with clarifications or additional info if you want to bump it in the activity page.

Mike Scheutzow gravatar image Mike Scheutzow  ( 2021-08-03 14:47:45 -0600 )edit

Is your laptop maintaining a continuous wifi connection to the hotspot? Also, what do you mean by "stream video data"? Is it messages on a ros topic?

Mike Scheutzow gravatar image Mike Scheutzow  ( 2021-08-03 15:12:29 -0600 )edit

Ahhh sorry about closing the topic. I just wanted to clarify a few things. My laptop is maintaining a continuous connection to the hotspot. The hotspot (my Nvidia Jetson) is continuously publishing "raw" camera images (obtained from my raspberry pi cameras) and I'm trying to get my laptop or my android phone to view the data in real time. This all works as expected if I connect via my router. Also, when I run ifconfig, my wlan0 interface shows no data being sent out.

I think this is a network related issue. It's as the ROS master node isn't routing data over to the wlan0 interface

nasher128 gravatar image nasher128  ( 2021-08-04 12:28:57 -0600 )edit

If a host has multiple network interfaces active, you almost always have to set environment variable ROS_HOSTNAME or ROS_IP to tell ros which local interface the ros messages should use. This rule applies to all computers that run ros nodes. Have you done this?

Mike Scheutzow gravatar image Mike Scheutzow  ( 2021-08-04 15:41:16 -0600 )edit

THANK YOU SO MUCH!

The problem was I didn't set the ROS_IP address. You have to export this to all terminals which are publishing the topics and also within the terminal use to run the roscore.

nasher128 gravatar image nasher128  ( 2021-08-05 11:41:09 -0600 )edit