Use of the NVIDIA Jetson Nano for DATV

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G8GKQ
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Use of the NVIDIA Jetson Nano for DATV

Post by G8GKQ » Tue May 21, 2019 4:34 pm

The NVIDIA Jetson Nano can be used to drive a LimeSDR as a very capable DATV transmitter. The on-board hardware H264 and H265 encoders are particularly good. However, it is early days and the available software is not very mature. In writing this post, I am not suggesting that anyone should go out and buy a Jetson Nano (£101), as it may be a technological dead-end. However, if you do have one, the following notes may be helpful. This is not a project for you if you are not at ease with Linux computers!

My set-up uses an LKV373A for HDMI video and audio capture; this is connected to my home network and sends UDP packets containing an H264 stream. The Jetson Nano sits on the network with the LimeSDR Mini connected to it by USB. The initial set-up is described here: https://wiki.batc.org.uk/Jetson_Nano. By modifying Evariste's scripts, you can transmit 500KS DVBS-2 720p H264 or H265 from the LKV373A (HDMI input) or the Raspberry Pi camera and USB audio dongle (which must be connected if you are using the Raspberry Pi camera). C920 input is not yet supported.

Once the intial set-up is working (VERY IMPORTANT - get it working like this first!), you can disconnect the keyboard, mouse and HDMI monitor from the Jetson Nano and control it by SSH over the network. However, all control is by changing stored parameters in complex files, so is not very user friendly.

The latest Portsdown development build can provide a "front panel" to control the Jetson and Lime over the network. This is only available with the touchscreen and currently ONLY works with the LKV373A and H265 encoding. NOT Pi Camera, NOT C920, NOT H264.

To make this work, you need to update to the latest Portsdown version then, after that, do a "Dev Update" from the same screen. Then you need to edit the file /home/pi/rpidatv/scripts/jetson_config.txt with your local configuration:

Code: Select all

jetsonip=192.168.2.113
jetsonuser=nano
jetsonpw=jetson
jetsonrootpw=jetson
lkvudp=239.255.42.42
lkvport=5004
tsoutip=192.168.2.177
tsoutport=10000
The first 5 entries need to be correct. Do not worry about the tsout entries. Note that if you can't work out how to edit this file, then the project is not for you, yet.

From the touchscreen, select "Output to" "Jetson Lime". Select "Encoder" "H265". Select "Source" "HDMI". You can then select Modulation, Format, Freq, SR, FEC, and Lime Gain as you want. About 15 seconds after selecting "TX", you should have a working TX.

Note that there is no proper Transmit PTT switching yet, so watch your PAs on the calibration spike. I have not done any comprehensive testing, so some SRs/FECs may not work. Note that when you ShutDown your Portsdown , the Nano will also be ShutDown safely. That's why the file above needs the root password.

I will only provide basic support for this capability via the forum, so that I have time to improve the project.

Dave, G8GKQ
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F1CJN_alain
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Re: Use of the NVIDIA Jetson Nano for DATV

Post by F1CJN_alain » Thu May 30, 2019 8:28 am

Hello
I am trying to use the Picam with the Jetson by modifying Evariste script (waiting for my LKV373A !).
Unfortunately my Picam is 1.3 and not 2 , and I red on a forum that Jetson Nano works with the Picam 2.
So what kind of Picam did you test ?
Thanks
Alain, F1CJN

G8GKQ
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Re: Use of the NVIDIA Jetson Nano for DATV

Post by G8GKQ » Thu May 30, 2019 10:44 am

Hi Alain

The default drivers for the Jetson only support the Pi Cam V2. I tested with a Pi Cam V1 first - which I could not get to work, and then switched to a V2, which worked.

There are some internet posts about how to get a V1 camera working, but I did not have time to try them.

Dave, G8GKQ

M0SKM
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Re: Use of the NVIDIA Jetson Nano for DATV

Post by M0SKM » Fri May 31, 2019 11:23 am

Having acquired a Nano I'm getting super results on 500ks/s and 1ms/s using Evariste's DVBSDR. My problem is I don't understand how to modify the script for other symbol rates; a tutorial in CQ-TV would be great. Alternately pointers where I can find information or calculators; I'm hoping to generate scripts for 125/250 and 333 ks/s.

Unfortunately the knowledge exchanged on QO-100 chat is fragmented and hard to follow; especially when you are called away. :(

73 Steve

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Re: Use of the NVIDIA Jetson Nano for DATV

Post by G8GKQ » Fri May 31, 2019 11:29 am

Hi Steve

What input device (Pi Cam / HDMI / Ext PC) and encoding (H264/H265) are you using?

Dave

M0SKM
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Re: Use of the NVIDIA Jetson Nano for DATV

Post by M0SKM » Fri May 31, 2019 12:00 pm

Dave
I have two options; Pi camera and LKV373A with input from a PC, encoding at H256.

Steve

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Re: Use of the NVIDIA Jetson Nano for DATV

Post by G4WIM » Fri May 31, 2019 3:09 pm

Hi Steve,

I'm going down the same path and have found rightly or wrongly simply editing the script to change SR to 1000 and whatever freq and FEC works nicely. So now I have a bunch of preset scripts which appear to work ok.

Very fast encoding and excellent video / audio sync - using picam and H265 - awaiting delivery of LKV373 .

Regards Tim

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Re: Use of the NVIDIA Jetson Nano for DATV

Post by G8GKQ » Fri May 31, 2019 9:16 pm

Steve

The latest Development Release of the Portsdown code (201906060) will now control a Jetson for HDMI or Pi Cam input, H264 or H265 output from the touchscreen. Any SR/FEC (within reason). It does all the calculations.

Unfortunately, the rpidatv/scripts/jetson_config.txt file still needs hand-editing as I have not had time to implement a touchscreen menu for it.

If you are feeling brave, please give it a try. Just update to the latest version and then update to the Dev version from the touchscreen.

Dave

M0SKM
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Re: Use of the NVIDIA Jetson Nano for DATV

Post by M0SKM » Sat Jun 01, 2019 8:24 am

Hi Tim,

Well I went ahead with your suggestion and yes 125/25/333ks all worked OK. So I tested locally last night on 437MHz and got great reports. Changing mode is fiddly so the update Dave has made to the Portsdown software should be a great help. Not being a football fan I should find time over the weekend to link the Portsdown and do further tests.

Thanks Dave/Tim

G4WIM
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Re: Use of the NVIDIA Jetson Nano for DATV

Post by G4WIM » Sat Jun 01, 2019 9:18 pm

Dave,

am I correct in saying that currently the rpi does not currently control the gpio lines for tx / rx on the Lime ?

Unless I'm doing something wrong (quite likely) - that seems to be the case.

Regards Tim

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