Langstone Update 08/11/20

Forum for discussion about the Langstone Microwave Transceiver that shares some features with the Portsdown. Wiki: https://wiki.microwavers.org.uk/Langstone_Project
G4FRE
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Re: Langstone Update 08/11/20

Post by G4FRE » Sun Nov 15, 2020 8:31 pm

I put a mox button using a latching pushbutton on the front of my unit. Also comes in useful when using a computer headset

Dave
G4FRE
radiogareth wrote:
Sun Nov 15, 2020 7:32 pm
Having now used the Langstone AND Portsdown today for Q100 QSOs (a double first) I'm wondering if it would be possible to use the morse key input as PTT when in voice modes? Although I have wired my front panel for a 4 pin standard mic, I'm getting great use out of an old carphone hands-free unit which has great AGC, but of course no PTT. So if I'm wandering around the shack talking, I can use the on-screen PTT, but if I'm sitting in front of the rig it would be handy to press my microswitch morse key as a PTT if I'm using this particular mic.
I hope that makes sense....
Thanks
Gareth

radiogareth
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Re: Langstone Update 08/11/20

Post by radiogareth » Mon Nov 16, 2020 8:15 am

That's useful, I might be able to fit one in the back of a 4 pin plug too which would sort of solve the problem. It might just be 'one line of code' I somewhat hopefully suggest ;-)
It's only when you use stuff that extras 'like Topsy, it just grew.....'
https://en.wiktionary.org/wiki/Topsy
Gareth

g4eml
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Re: Langstone Update 08/11/20

Post by g4eml » Mon Nov 16, 2020 12:15 pm

Making the key work as a PTT would be just ‘one line of code’ but I have a feeling that it might cause problems elsewhere, and I doubt that many people have a built in morse key like yours so it would not normally be a requirement. And of course there is already a latching PTT function (MOX) on the touch screen.

Feature creep is something I am trying to avoid in the Langstone code. I am happy to add things providing they do not complicate the basic functionality.

radiogareth
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Re: Langstone Update 08/11/20

Post by radiogareth » Mon Nov 16, 2020 3:01 pm

Thanks Colin, I was wondering if they could perhaps be 'or-ed' via a couple of diodes.
It seems my 4 pin MIC will KEY the Langstone regardless of mode (ie including CW) selected but it does not give semi-break-in in CW, I need to be in CW/CWN for that to work when I use the KEY.
It was only my feature-creeping braincells at it again.....
Gareth

radiogareth
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Re: Langstone Update 08/11/20

Post by radiogareth » Tue Nov 17, 2020 2:17 pm

Not a bad match to a Pluto, maybe with a little gain-block in front.
https://www.ebay.co.uk/itm/Mini-Circuit ... 3655097743
Gareth

G4FKK
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Re: Langstone Update 08/11/20

Post by G4FKK » Tue Nov 17, 2020 9:26 pm

Not sure whether this might be scope creep as well Colin, but I finally wired up the CW GPI today. I'm not very good at sending cw without a side-tone and even worse, so I've just proved, with the delay off the satellite when using MONI. I imagine it'll be more than one-line-of-code but I was just wondering... :geek:

No worries if it's a "no".

All the best,

Martin - G4FKK

g4eml
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Re: Langstone Update 08/11/20

Post by g4eml » Wed Nov 18, 2020 12:20 am

CW side tone is something that I have on my list of things to add. The obvious place is to send the tone through the sound card but unfortunately when I tried it there was too much delay, making it unusable.

I am investigating if I can generate a sidetone from a spare GPIO pin. That should get around the delay problem but would need the signal to be externally mixed into the audio amp, probably with an RC network to add a bit of filtering. There will still be a delay caused by the software but it should be small enough to be usable.

Alternatively an external oscillator with something like an NE555 could be keyed directly from the key and fed into the amplifier.


Colin.

g4eml
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Re: Langstone Update 08/11/20

Post by g4eml » Wed Nov 18, 2020 5:22 pm

I spent some time today trying to generate a reasonable CW sidetone in software. Without a lot of success.
Using the Sound card through GNU Radio resulted in too much delay.
Generating a tone on a spare GPIO pin worked to some extent with very low latency but the resulting tone was not very nice. It had a lot of warble and frequency variation. This is almost certainly due to the way Linux handles the GPIO.

So it looks like at the moment the only way to get a good sidetone is to generate it externally directly from the key.

Colin.

G4FKK
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Re: Langstone Update 08/11/20

Post by G4FKK » Sat Nov 21, 2020 4:35 pm

Thanks for trying Colin. I'll dig out a 555 :)

73, Martin

radiogareth
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Re: Langstone Update 08/11/20

Post by radiogareth » Sat Nov 21, 2020 4:44 pm

Just wondering, rather than actually generating the tone, why not just enable (or not) a suitable oscillator using the GPIO? 555 or a 40106 Schmitt trigger oscillator with a diode towards the Pi GPIO. When low, osc is disabled. Remaining gates can be paralleled to drive a piezo or speaker.
Used this lots over the years.
Gareth

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