Hi Jim
Not too sure where to aim this but here we go.
I have made some progress with LimeMini/Soapy/Quisk/Linux Mint20 and, related, worked with the Pluto board.
Colin, G4EML, has made a huge contribution to VHF/UHF TV and radio.? First he has developed the Langstone transceiver
https://wiki.microwavers.org.uk/Langstone_Project and
https://github.com/g4eml/Langstone
This runs on the Raspberry Pi4 for both the Lime and Pluto boards.? Operating frequencies are limited only by the respective boards.? It is set up for ssb/fm/am/cw.? Code is mainly Python, developed using GNURadio.? It is open source.? Colin is top notch and extremely generous, as talking with me recently at the Dunstable Downs radio rally.? His software downloads and works very easily, even for non-experts.
First he confirms that it is impossible to turn off transmit on the Lime board while receiving, just as you found.? This is also the case for Pluto.? For Rx the trick that he uses is to reduce the gain of Tx and shift Tx frequency.? I think this gives 60dB or more reduction on transmit, and Tx is not attached to an antenna while receiving given any ordinary antenna/pa switching.? Word on the block is that there are more spurious issues with Pluto than with Lime.? Both are used extensively in amateur TV in the UK and for accessing QQ-100.
I have implemented Colin's trick for Lime / Quisk / Linux Mint by small modifications to my hardware file, as attached - see "My additions".? They could be made more sophisticated.? In particular I am overriding the "Tx gain total" setting.? Also attached are various pics.? They show operation, before and after modifications on 23 cm, residual RF on Rx.? I am now running 4 watts pep on 2m with success, while Rx works fine on 4m, 2m, 70cm, 23cm and 2320MHz - local beacon.
I seem to recall from somewhere in the muddled write-up of Lime/GNU/Pothosthat the rx and tx sample rates must perhaps be the same?? Both 48 kHz and 100 kHz work correctly but I have yet to do more extensive experiments. Both Lime and Pluto operate well as broadband receivers, 2MHz and more, with Quisk.? Sometimes Lime runs with Tx = 48kHz, Rx= 2000kHz, sometimes not.
Sometimes a "writeStream" error is flagged up on transmit, eg.
PTT on !
Soapy writeStream fail:
Soapy writeStream short write; -6 < 2040
Soapy writeStream fail:
Soapy writeStream short write; -6 < 2040
Soapy writeStream fail:
Soapy writeStream short write; -6 < 394
Soapy writeStream fail:
Soapy writeStream short write; -6 < 2040
Soapy writeStream fail:
Soapy writeStream short write; -6 < 393
Soapy writeStream fail:
Soapy writeStream short write; -6 < 2040
Soapy writeStream fail:
Soapy writeStream short write; -6 < 410
PTT off !
Mostly this occurs on all modes, sometimes just ssb, often after prolonged use but not always.? Just occasionally it continues on Rx, that is "PTT off !" On the config screen Rx Sample Rate, Rx Bandwidth and Tx Sample Rate are all baffling, even after hours of playing around!
Finally I should like to access local repeaters which require a CTCSS tone.? I had thought this was implemented via "Offset kHz" and "Tone Hz" in the config settings?? So far I have had no success.? Please should I be doing something else?
Non of these last is a complaint:? Quisk is just brilliant for me!
Thanks & vy 73
Bob? g3udi
