Langstone Update 28/05/20

Forum for discussion about the Langstone Microwave Transceiver that shares some features with the Portsdown. Wiki: https://wiki.microwavers.org.uk/Langstone_Project
g4eml
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Re: Langstone Update 28/05/20

Post by g4eml » Mon Jun 01, 2020 9:52 am

Mike,

The current arrangement was trying to be compatible with the Portsdown band selection arrangement which uses external decoders.

Colin.

g0mjw
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Re: Langstone Update 28/05/20

Post by g0mjw » Mon Jun 01, 2020 11:27 am

I know but that doesn't mean we can't add another 4....

G8GKQ
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Re: Langstone Update 28/05/20

Post by G8GKQ » Mon Jun 01, 2020 11:49 am

Mike

I can't see why you don't use the BATC 3-line to 8 line PCB (known as the 8-band decoder). It includes the opto-isolators and is designed for the job.

I know from experience that the less variation in hardware design that needs to be supported by community software, the better.

Dave, G8GKQ

g0mjw
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Re: Langstone Update 28/05/20

Post by g0mjw » Mon Jun 01, 2020 11:58 am

Hi Dave,

Because I want to control 8 things but poly-phonically, so you might want to operate more than one relay at a time, e.g. with QO100 you might want to select 2.4 GHz uplink and perhaps 3cm downlink.

G8GKQ
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Re: Langstone Update 28/05/20

Post by G8GKQ » Mon Jun 01, 2020 12:12 pm

But the rest of the design does not support simulataneous transmit and receive....? Unless you have a clever software modification?

Keep it simple!

Dave

g4eml
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Re: Langstone Update 28/05/20

Post by g4eml » Mon Jun 01, 2020 12:30 pm

Actually Langstone does allow simultaneous TX and RX when the Tx and Rx offsets are set to different non zero values. (SAT Mode). A button labels ‘MONI’ will appear which unmutes the receiver during transmit. It does put a lot of extra load on the CPU though.

The current 4 band bits can be used directly with relays to support 4 transverters. The bit pattern for each band is configurable from the setup menu.

Yes, it could be increased to 8 bits but that is probably not something most would need so would be better implemented as an option.

Colin.

g0mjw
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Re: Langstone Update 28/05/20

Post by g0mjw » Mon Jun 01, 2020 12:40 pm

G8GKQ wrote:
Mon Jun 01, 2020 12:12 pm
But the rest of the design does not support simulataneous transmit and receive....? Unless you have a clever software modification?

Keep it simple!

Dave
I thought it did. Gnuradio certainly does and for QO100 you should not operate simplex. But even if not sometimes there are more than one thing to control per band so having the ability seems sensible.

Mike

G8GKQ
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Re: Langstone Update 28/05/20

Post by G8GKQ » Mon Jun 01, 2020 1:56 pm

Thanks Colin - even more capability than I realised!

Mike - the other option is that you modify the PIC code in the 8-band switch. It's all on Github, and the mapping for band select binary to the 8 outputs is here: https://github.com/BritishAmateurTelevi ... e.asm#L412

Dave

G4FRE
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Re: Langstone Update 28/05/20

Post by G4FRE » Mon Jun 01, 2020 2:36 pm

The modified PIC option was the route I chose, especially as, not using the LO filter I had some spare pins to play with

Dave
G4FRE

g0mjw
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Re: Langstone Update 28/05/20

Post by g0mjw » Mon Jun 01, 2020 5:41 pm

G8GKQ wrote:
Mon Jun 01, 2020 1:56 pm
Thanks Colin - even more capability than I realised!

Mike - the other option is that you modify the PIC code in the 8-band switch. It's all on Github, and the mapping for band select binary to the 8 outputs is here: https://github.com/BritishAmateurTelevi ... e.asm#L412

Dave
PIC code? There is no PIC involved. This is not the RF switch. Its the common ebay 8 relays with opto isolators board.

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