I wonder if anyone can shed light on some problems I have been having with the SUP-2400 up converter? I am using it to convert 437MHz up to 1963MHz. It is driving a number of recent digital satellite receivers which are multi-standard, ie switch automatically between DVB-S/S2, H262/4/5. The problem is that it will work with a DVB-S signal, but not a DVB-S2 one. I have tried several SUPs with the same result and also several satellite receivers. If I bypass the SUP by setting the transmitter to the SUP output frequency, 1963MHz, everything works perfectly, so the transmitter (DATV Express and yes, I have done multiple restarts!) and receiver are OK. I've looked at the SUP output on the spectrum analyser and it seems fine. Surely the SUP is a dumb frequency converter (mixer/oscillator) and cannot be having any selective effect? The only clue I can think of is that with a SUP, the local oscillator is above the received frequency (as set in the satellite receiver), whereas with the LNB the receivers are designed to work with, the LO is below. Some sort of signal inversion? I would be grateful for anyones thoughts, the problem is holding up the GB3ZZ re-building process.
73 Shaun G8VPG.
Problems with SUP-2400 upconverter
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Re: Problems with SUP-2400 upconverter
I have done some further tests with two other up converters. One by DG0VE with a 900MHz LO producing an output at 1337MHz. The second a home-brew design with an 1152MHz LO producing an output at 1589MHz. Both work perfectly with all modes and codecs on two different receivers. The SUP is doing something that is spooking these receivers and I have tried three SUPs, all the same.
73 Shaun G8VPG.
73 Shaun G8VPG.
Re: Problems with SUP-2400 upconverter
Hi Shaun
If it is DVB-S2 only, then maybe it is to do with the phase noise of the SUP2400 - although my main rx system uses one and I have received S2 with no problems....
Hope the build is going well.
73
Noel - G8GTZ
If it is DVB-S2 only, then maybe it is to do with the phase noise of the SUP2400 - although my main rx system uses one and I have received S2 with no problems....
Hope the build is going well.
73
Noel - G8GTZ
Re: Problems with SUP-2400 upconverter
Hi Shaun
Both the other up-converters that you have tried are low-side LO, so no frequency inversion (which has the effect of reversing the I and Q connections). It sounds like your commercial DVB-S2 receivers cannot handle frequency inversion.
Can you try it with MiniTioune and a Serit tuner? In expert mode, you should see IQ Swap ON or OFF just above the Timing Lock meter. And it should work with DVB-S2, inverted or not.
Dave
Both the other up-converters that you have tried are low-side LO, so no frequency inversion (which has the effect of reversing the I and Q connections). It sounds like your commercial DVB-S2 receivers cannot handle frequency inversion.
Can you try it with MiniTioune and a Serit tuner? In expert mode, you should see IQ Swap ON or OFF just above the Timing Lock meter. And it should work with DVB-S2, inverted or not.
Dave
Re: Problems with SUP-2400 upconverter
Noel & Dave,
Thank you for your help. I had a half built mk.II Minitioune in the shack, so this morning I finished it. It works fine, but I can see the IQ is reversed when I use the SUP, so I think that is the answer. I think we need to use a different 437MHz up converter with the LO on the low side. Since we have filters and pre-amps up the line, something simple like one of the Global up converters with a 1GHz LO or a home-brew equivalent should do the job.
73 Shaun.
Thank you for your help. I had a half built mk.II Minitioune in the shack, so this morning I finished it. It works fine, but I can see the IQ is reversed when I use the SUP, so I think that is the answer. I think we need to use a different 437MHz up converter with the LO on the low side. Since we have filters and pre-amps up the line, something simple like one of the Global up converters with a 1GHz LO or a home-brew equivalent should do the job.
73 Shaun.