Langstone Update

Forum for discussion about the Langstone Microwave Transceiver that shares some features with the Portsdown. Wiki: https://wiki.microwavers.org.uk/Langstone_Project
g4eml
Posts: 210
Joined: Thu Apr 26, 2018 9:36 am

Langstone Update

Post by g4eml » Sat Apr 25, 2020 7:25 pm

I have implemented a few updates to the Langstone code today. Mostly to improve the error handling.
If the SSB_TRX.py fails to start this is now detected and the error messages are displayed. They are still a bit obscure but better than nothing.
I have also modified the code so that it doesn't hang if the Pluto becomes unresponsive. It will still need a reboot in this case but at least you can now use the menu to shut down the Pi.

Updating instructions, these are a little more than normal because I have changed the .bashrc file which needs to be copied to the pi home directory.
(I am not sure how to do this using git).

SSH into the pi.
cd Langstone
./stop
./update
cp .bashrc ..
./run


If you are building a Langstone for the first time then these updates are included in the standard build.
If you have not updated your Langstone before you may not have the update script. In this case just do 'git pull' to get the latest files.

I am still looking into the strange 80KHz -40dB spurs during transmit. These seem to be something to do with the way GNU Radio is working. If I send the configuration commands to SSB_TRX manually from the console then the spurs don't appear. If I send the same commands from the GUI program they do. So I am hopeful I can work out what is going on.

Colin G4EML

User avatar
i2NDT
Posts: 88
Joined: Thu Nov 12, 2015 9:26 pm

Re: Langstone Update

Post by i2NDT » Sun Apr 26, 2020 9:51 am

hi Colin,
I did the update and got this:

ERROR:- SSB_TRX.py failed to start.
ERROR: Unable to find host: Name or service not known
Traceback (most recent call last):
File "/home/pi/Langstone/SSB_TRX.py", line 332, in <module>
main()
File "/home/pi/Langstone/SSB_TRX.py", line 325, in main
tb = top_block_cls()
File "/home/pi/Langstone/SSB_TRX.py", line 55, in __init__
self.pluto_source_0 = iio.pluto_source('ip:192.168.2.1', BaseFreq, 529200, 2000000, 0x800, True, True, True, "slow_attack", 64.0, '', True)
File "/usr/lib/python2.7/dist-packages/gnuradio/iio/iio_pluto_source_swig.py", line 126, in make
return _iio_pluto_source_swig.pluto_source_make(*args, **kwargs)
RuntimeError: Unable to create context

which I guess is correct as I haven't (yet...) a Pluto connected.

Claudio
i2NDT Claudio
Dalmine, Italia

g4eml
Posts: 210
Joined: Thu Apr 26, 2018 9:36 am

Re: Langstone Update

Post by g4eml » Sun Apr 26, 2020 10:36 am

Hi Claudio,

Yes, that error message is what you get if the Pluto is not present or is set to the wrong IP address.

If you just want to test the display without a pluto you can log in using SSH

cd Langstone
./GUI

That will run just the display part of the program. It should have a red message saying the Pluto is not responding but everything else should work. It will let you test your touchscreen and mouse.

Colin.

User avatar
i2NDT
Posts: 88
Joined: Thu Nov 12, 2015 9:26 pm

Re: Langstone Update

Post by i2NDT » Sun Apr 26, 2020 2:20 pm

thanks Colin!
also for the TCXO.

Claudio
i2NDT Claudio
Dalmine, Italia

g4eml
Posts: 210
Joined: Thu Apr 26, 2018 9:36 am

Re: Langstone Update

Post by g4eml » Fri May 01, 2020 5:50 pm

I have today updated the master Langstone Github.
Changes are as follows:-

Waterfall and spectrum display added. Thanks to Rob M0DTS
At the moment this only spans +-20 KHz from the center frequency. This may be increased at a later date.
Waterfall Reference level setting added to the Settings menu.
Settings menu updated so that it does not pause the main code.
Rx and Tx LOs are now turned off when not required. This removes some of the birdies on receive and some spurs on Transmit.
Several other bug fixes.

To update just SSH into your Pi

cd Langstone
./stop
./update
./run

Colin G4EML

g4eml
Posts: 210
Joined: Thu Apr 26, 2018 9:36 am

Re: Langstone Update

Post by g4eml » Sun May 03, 2020 5:38 pm

A further update today.

Tx now uses zero frequency IF which removes some of the unwanted spurs.
The Rx LO is also now shifted in frequency while transmitting as I found it was mixing with the Tx signal and creating more unwanted spurs. (even though it was 'disabled', obviously that doesn't completely shut it down.)

The Tx spectrum now looks much cleaner. the few remaining spurs seem to be better than -70dB.
The lower bands (70, 144 and 432) still have significant harmonics because they are basically square wave outputs from dividers. Filtering will be required. The higher bands look better as I suspect these are sinewave signals.

Rx now uses a 50KHz to 150KHz IF. This avoids using the part of the spectrum near to the DC spike and gives a much more consistent noise level.
There are still a few 'birdies' on receive most of which are at multiples of the 40Mhz clock frequency.

The FFT stream from the GNU Radio module can now be turned off and on by the software. This helps when initializing and prevents the file buffers from filling up and blocking the code. As a result the saved settings are now correctly loaded on startup.


73 Colin G4EML

User avatar
i2NDT
Posts: 88
Joined: Thu Nov 12, 2015 9:26 pm

Re: Langstone Update

Post by i2NDT » Mon May 04, 2020 1:34 pm

hi Colin,
sorry to disturb you once more...
this morning I received my Pluto!
I connected it to the Langstone RXT togheter with mouse and switched on.
I got the error message for the missing audio card (not yet arrived...) but typing ./GUI I got the screen with all keys operational as well as the mouse.
than I updated the software to the last version and rebooted.
but this time no alarm messages and the gui which appered was incomplete (no frequency display) and none of the keys was operational.
switched off, removed mouse and pluto and on again.
now I get the alarm for the missing pluto (but not for the audio card) and when I dial ./GUI nothing happens and cannot enter any more commands.
I also connected a keyboard to the PI to replace putty but nothing changed: typing ./GUI the system seems to go idle somewhere and does not accept other commands.

Claudio
i2NDT Claudio
Dalmine, Italia

g4eml
Posts: 210
Joined: Thu Apr 26, 2018 9:36 am

Re: Langstone Update

Post by g4eml » Mon May 04, 2020 1:45 pm

Hi Claudio,

I had to change the way the GUI works because the previous change was causing problems. It allowed the GUI to run without the Pluto but also meant that sometimes commands were not working. So it won’t now work without both the sound and Pluto.

It sounds like your system is ready to work when you get the sound card.

If you are entering ./GUI multiple times you might end up with it running more than once which will cause problems.

Colin.

User avatar
i2NDT
Posts: 88
Joined: Thu Nov 12, 2015 9:26 pm

Re: Langstone Update

Post by i2NDT » Mon May 04, 2020 1:56 pm

OK!
still waiting for the card...ordered early last week.
Mouser was very fast with the pluto: ordered on friday (1st may...) it arrived this morning from Texas!

Claudio
i2NDT Claudio
Dalmine, Italia

g4eml
Posts: 210
Joined: Thu Apr 26, 2018 9:36 am

Re: Langstone Update

Post by g4eml » Mon May 04, 2020 4:52 pm

Hi Claudio,

Yes Mouser are very good I use them quite a lot. In normal times it takes 2 working days for delivery. Digikey are similar.

73
Colin

Post Reply

Return to “The Langstone Microwave Transceiver”