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
g0mjw
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Joined: Sat Sep 20, 2014 9:15 am

Re: Langstone Update

Post by g0mjw » Wed May 13, 2020 4:06 pm

That's where F5OEO's firmware comes in.

radiogareth
Posts: 492
Joined: Wed Jan 06, 2016 9:46 am

Re: Langstone Update

Post by radiogareth » Wed May 13, 2020 5:02 pm

No problems, will check for diodes and as the signals are on the RPI and I'll be integrating my lone SMA relay into the Langstone box, its all going to work :-)
Ran it up on my R&S analyser today, 50 & 70 have lots of strong harmonics (think I read its due to being squarer at those freq's...) and got the following powers.
6m -8.4dBm
4m -5.3dBm
2m -0.9dbM
70cms +2.0dBm
23cms -1.1dBm
13cms -1.4dBm
On 6,4&2 my little +35dB amp gave 1 watt out. Very handy.
I can't measure power above 2.7GHz but have a purple heatsink Stealth amp that says -6dBm drive max on its data sheet and also an IONICA PA for the band. I've previously used the Pluto with DVBExpress for DATV tests on 3.4 GHz so I don't think I can overdrive either amp with the Pluto but it would be handy to know what peoples Pluto gives out at 3.4GHz on Langstone - e.g. FM.
TX power control works a treat too.
Gareth

G8GKQ
Site Admin
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Re: Langstone Update

Post by G8GKQ » Wed May 13, 2020 7:28 pm

Hi Gareth

The power levels that I measured at 2.4 and 5.7 GHz are on this wiki page https://wiki.microwavers.org.uk/Langstone_Projec

Your measurements seem to be a little lower than mine, but within amateur test equipment tolerances.

Dave, G8GKQ

radiogareth
Posts: 492
Joined: Wed Jan 06, 2016 9:46 am

Re: Langstone Update

Post by radiogareth » Wed May 13, 2020 8:15 pm

Thanks Dave, I'll start with 50% power then into a DL and see what Vf from the amp gives. The Data sheet implies some approximate values as a guide.

I've also been wondering about the Daffodil Audio dongle - mainly as it has speaker drive capability and buttons for vol and mute. Its the C-Media one listed below:

pi@raspberrypi:~ $ lsusb
Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 001 Device 006: ID 0456:b673 Analog Devices, Inc.
Bus 001 Device 005: ID 045e:0084 Microsoft Corp. Basic Optical Mouse
Bus 001 Device 007: ID 0d8c:000c C-Media Electronics, Inc. Audio Adapter
Bus 001 Device 003: ID 8086:0808 Intel Corp.
Bus 001 Device 002: ID 2109:3431 VIA Labs, Inc. Hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

With NEITHER plugged in I get this:

pi@raspberrypi:~ $ lsusb
Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 001 Device 006: ID 0456:b673 Analog Devices, Inc.
Bus 001 Device 005: ID 045e:0084 Microsoft Corp. Basic Optical Mouse
Bus 001 Device 002: ID 2109:3431 VIA Labs, Inc. Hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

So it looks like it's the 'Intel Corp' (bet its never been near Intel!!) unit that works 'native' with the Langstone.

At this point its 'go and google' audio issues on a RPI, but I don't want to mess up whats working. Booting the Langstone with JUST the Daffodil plugged in stops the FFT and freq display so I'm out of my depths here ;-)

I might just have to add a small audio amp.....but a bit of digging found the same daffodil card.
https://computers.tutsplus.com/articles ... -mac-55876 although for an earrlier RPi......

Gareth

M0DTS
Posts: 426
Joined: Sun Feb 24, 2008 9:03 pm

Re: Langstone Update

Post by M0DTS » Wed May 13, 2020 8:32 pm

The PTT info was from Evariste but it's all documented in the ad9361 datasheet.

iio_device_debug_attr_write(phy,"direct_reg_access","0x27 0x00"); //ptt off
iio_device_debug_attr_write(phy,"direct_reg_access","0x27 0x10"); //ptt on

iio_device_debug_attr_write(phy,"direct_reg_access","0x26 0x10"); //maybe required to set GPIO pin to manual control mode.

I had tested and it worked but i accidentally overwrote the code today with the updates ...!
There are three other GPIO 'bits' left for band switching too :-)

Rob

g4eml
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Re: Langstone Update

Post by g4eml » Wed May 13, 2020 9:44 pm

Hi Rob,

That's interesting, my interpretation of the datasheet was that you could not access the debug attributes with libiio. Sounds like I was wrong. I will add it to the next release.

I have been doing a lot of rewriting today to split the Tx and Rx GNU Radio Flowgraphs into separate python tasks. I can then freeze either one when its not being used and reduce the CPU loading. It seems to have fixed the Latency drift we were getting. I think running both Tx and Rx all the time was overloading the Pi. I can still run both in sat mode for monitoring the downlink while transmitting but normally only the Tx or the Rx needs to be running.

73
Colin.

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

Re: Langstone Update

Post by g4eml » Wed May 13, 2020 9:52 pm

Gareth,

if you enter aplay -L it will display a list of all the audio devices.

The code is currently using 'hw:CARD=Device Dev=0'

if you can identify the hw: entry for your audio dongle make a note of it. The 'CARD=' part is the name of the device. The recommended one is called 'Device' but some others seem to be called 'Headset' .

You can then edit the SSB_TRX.py file to change the name.
I will try to work out a way of automating this.


73
Colin.

M0DTS
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Joined: Sun Feb 24, 2008 9:03 pm

Re: Langstone Update

Post by M0DTS » Wed May 13, 2020 9:59 pm

Ok that's good, i wondered if it was possible to control the parts of the flow graph, good to hear it is.
Noted the delays seem to have disappeared.

The listing of audio devices is a pain, was looking at that too, not all info is in one place!

I've just tried the GPIO code again and it works fine.
Will be testing a mast mounted PLUTO on 3.4GHz tomorrow.. hopefully it all works ok!

Rob

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i2NDT
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Joined: Thu Nov 12, 2015 9:26 pm

Re: Langstone Update

Post by i2NDT » Thu May 14, 2020 9:51 am

talking about PTT, do you think it's worth to have the GPIO PTT signal to be emitted several millisecond before the pluto PTT command?
this in order to switch on the antenna relay and amplifiers before the pluto starts transmitting.
a sort of built-in sequencer...

and, if someone is going to prepare a new GPIO breakout board, one or more optocouplers for PTT or other commands could be added?

thanks

Claudio
i2NDT Claudio
Dalmine, Italia

g4eml
Posts: 206
Joined: Thu Apr 26, 2018 9:36 am

Re: Langstone Update

Post by g4eml » Thu May 14, 2020 12:16 pm

Hi Claudio,

That’s already happening. There is a built in delay between the PTT output and the RF output.

However I would still recommend people use an external sequencer in any amplifier.

Colin

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