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Starting and Stopping the Pluto

Posted: Thu Oct 29, 2020 6:58 am
by G3WDG
I have just modified my Pluto for external (40MHz) reference, taking care to get the level correct. All seems to be working fine, apart from a frequency offset that I (eventually) cleared by setting the offset to zero (it had a stored value, presumably what was correct for the on-board reference oscillator).

My questions relates to starting and stopping the radio. When I stop and then restart the radio, it no longer seems to be working. Screenshots attached.

The only solution I have found is to close SDRC, unplug the Pluto from PC, plug it back in and restart SDRC.

Is this normal, or am I doing something wrong?

Re: Starting and Stopping the Pluto

Posted: Thu Oct 29, 2020 8:04 am
by Simon G4ELI
Hi,

I also have a 40 MHz mod. The 40 MHz signal must be present and locked before the Pluto starts, I see this information in the logfile. If it doesn't start then just attach the logfile here.

Re: Starting and Stopping the Pluto

Posted: Thu Oct 29, 2020 8:19 am
by G3WDG
Thanks Simon. Yes, the 40MHz is always present and is so before the Pluto is plugged in.
The observation is reproducible. Attached logfile of the sequence. Charlie

Re: Starting and Stopping the Pluto

Posted: Thu Oct 29, 2020 11:58 am
by Simon G4ELI
Hi, In this log it seems to work?

Re: Starting and Stopping the Pluto

Posted: Thu Oct 29, 2020 12:18 pm
by G3WDG
No, it had the same problem as identified in the above posted screenshots ie all the noise had gone, after stopping and restarting the radio. Logfile was done at the time I saw the spectrum change. Again, recovery only by closing SDRC, unplugging radio, plugging it back in (ie physically with USB connection) and restarting SDRC. This is a repeatable sequence, it it behaves this way every time.

Re: Starting and Stopping the Pluto

Posted: Thu Oct 29, 2020 2:32 pm
by Simon G4ELI
OK,

My gut feeling is that this is USB power-related, can you use the second USB connector as well?

When I start I just start - nothing special. I'm guessing that the Pluto's Linux / whatever innards aren't initialising fully.

Try this:
  • Stop the radio.
  • Unplug the USB cable, wait 5 seconds.
  • Connect the USB cable.
  • Start the radio.
If the start is successful then it's something else, you could maybe try a greater 40MHz signal. FWIW I can't start my Pluto unless the Leo Bodnar unit is running and synced at 40MHz.

Re: Starting and Stopping the Pluto

Posted: Thu Oct 29, 2020 3:04 pm
by G3WDG
Yes, following that sequence worked fine. SDRC was running all the time on this occasion, and the unplug/plug in again Pluto operation meant that on restarting the radio it worked normally.

When things are in the state that the radio does not restart properly, I did check that the Pluto is still there as far as being able to look at its files with My Computer and it was OK.

Yes, I realise the importance of having the 40MHz running before power on the Pluto, and get the same as you, ie the Pluto does not start without it.

Two things to try are 1) using a USB breakout cable I made for the (now defunct) Lime where the 5V is fed from an external PSU and 2) increase 40MHz drive by a dB or so.

Regarding 2), when doing the mod for external reference input, I used a scope to check the 40MHz voltage from the external (Bodnar) source was the same as had been provided by the internal oscillator, as there have been dire warnings about having too high risking damage to the Pluto. The internal osc is still physically in place, disabled with the 1k ohm to ground method.

Will report findings.

Re: Starting and Stopping the Pluto

Posted: Thu Oct 29, 2020 3:11 pm
by Jean
G3WDG wrote:
Thu Oct 29, 2020 12:18 pm
No, it had the same problem as identified in the above posted screenshots ie all the noise had gone, after stopping and restarting the radio. Logfile was done at the time I saw the spectrum change. Again, recovery only by closing SDRC, unplugging radio, plugging it back in (ie physically with USB connection) and restarting SDRC. This is a repeatable sequence, it it behaves this way every time.
Hi,

Did you try setting the RX Gain to something different than 'manual'? I experienced issues with RX gain set to manual, however they manifest themselves somewhat different as my Pluto started with a much higher gain than selected.
Btw, I see the same error 95 in your logfile when setting RX hardwaregain that I get as well.

73 Jean DJ0VL

Re: Starting and Stopping the Pluto

Posted: Thu Oct 29, 2020 3:18 pm
by G3WDG
Jean - many thanks!!!!

That solved the problem. I did indeed have the gain on Manual (probably was there by default, but can't be absolutely sure about that). With any of the other three options radio starts and stops perfectly.

73 Charlie G3WDG

Re: Starting and Stopping the Pluto

Posted: Thu Oct 29, 2020 3:25 pm
by Simon G4ELI
Ah,

I usually use fast attack, nice catch. Thing is, the gain isn't set until the radio is started, so it must be that the gain's being set too soon and the radio needs a while to 'warm up'.

Pity the poor programmer :( .