Octagon SF-8008 with low SR

  • No it does not do offsets. Unlikely perhaps. Yes you do need to modify the PLL, not because of stability but because the tuner will not work below 950 MHz. Therein lies your solution to offsets. Lock the PLL LNB with a variable reference and use that to compensate of the lack of offset tuning in the RX. I.e. The signal always appears at (say) 1 GHz as far as the RX is concerned.


    Mike

  • No it does not do offsets. Unlikely perhaps. Yes you do need to modify the PLL, not because of stability but because the tuner will not work below 950 MHz. Therein lies your solution to offsets. Lock the PLL LNB with a variable reference and use that to compensate of the lack of offset tuning in the RX. I.e. The signal always appears at (say) 1 GHz as far as the RX is concerned.


    Mike

    OK thanks for reply. How do I mod my PLL LNB ? DVB Dream gets the beacon fine btw without any LNB mod using my TBS 5927 USB sat receiver

  • I don't know, you will have to use google to find out for your LNB. Most of us just open them up and work out how to do it. If you can't do that intuitively, this might not be a task you should take on, rather get someone who has some experience to do it while you watch. That way you learn, which is the point after all.


    Whatever Dream does is irrelevant. The tuner in the SF8008 is different - but in that case why not use this USB RX?


    Now - has anyone found some reliable firmware for the SF8008? Good hardware is frequently let down by unreliable crash prone not properly tested firmware and the SF8008 is no exception to this.


    Mike

  • G0MJW Mike the biggest issue on the SF8008 is that there was nobody doing some reverse eng. to draw a brief schematics of the main parts. there is no knowledge what is limiting this nice device to do a much better performance. The main question is: Is this limitation driven by the hardware or could it be implemented in a better SW.

  • DD0KP this is the problem but there is no information on where to start without the source code so I don't think it will happen. We saw the classic case of someone being strung along earlier by the manufacturer. They always say yes, in the future but the future never comes. It does work fairly well and the chipset can do it, so my earlier suggestion about tuning a fixed frequency and then adjusting the LNB LO is a good one. It would even be possible to put a narrow filter in there to greatly improve the performance with respect to not locking onto adjacent signals. The reasl fix might be possibly in software, but not if we do not have the code.


    Mike

  • Yes you do need to modify the PLL, not because of stability but because the tuner will not work below 950 MHz. Therein lies your solution to offsets.

    Do we know for certain that the hardware of the SF8008 sat receiver does not tune below 950 MHz and this isn't a software limitation?


    The SF8008 also runs OpenATV. I have tried (but so far: failed) to build my own image from source code - once I have that working I can see if there is a software limit that can be bypassed.


    Did anyone open the tuner module? Do we know what silicon is used there, and if perhaps the silicon can be coerced to work on lower frequencies?

  • pe1hzg I do not have a SF8008 at the moment. But I asked many people to help which photos of the components to check wish possibilities we have. Nothing until now happened.

  • Do we know for certain that the hardware of the SF8008 sat receiver does not tune below 950 MHz and this isn't a software limitation?


    The SF8008 also runs OpenATV. I have tried (but so far: failed) to build my own image from source code - once I have that working I can see if there is a software limit that can be bypassed.


    Did anyone open the tuner module? Do we know what silicon is used there, and if perhaps the silicon can be coerced to work on lower frequencies?

    We know it can't tune out of band as delivered, with the software available but we don't know if the tuner can tune out of band. It probably can, given the right firmware and support components, but with no information, we can't know for certain how much it can be pushed, if at all. I looked inside and there is nothing to see unless one opens up the tuner can. It might be worth sniffing the control lines, or perhaps better buy a minitiouner.


    Mike

  • I do not have a SF8008 at the moment. But I asked many people to help which photos of the components to check wish possibilities we have. Nothing until now happened.

    I opened it up and voided the warranty on mine, and this is what I found:



    It seems this is an RDA5815. It is possible to find datasheets for it, and the specs says it goes as low as 230 MHz (!) but the datasheets i found do not include programming info.


    I'm still struggling to rebuild OpenATV from source (before I can attempt to make changes) but I thought this would be of interest.

  • That's useful. I see a 27 MHz TCXO there too which could be useful - sniff it's output and send it back along the coax to the LNB.... there is info on the web about this tuner, register settings etc. Minimum RX bandwidth is 4 MHz so it might not be good for lower bandwidths and that explains why it selects any signal on the transponder with the right symbol rate.


  • Interesting....Btw I find my TBS 5927 USB receiver with DVB Dream will tune fine down to 10.492 and with symbol rates down to 1000...so surely there are other sat boxes which do so also, shame it doesn't seem to be the SF8008

  • SF8008 Receiver owner: :)

    http://forum.dxtv.de/wbb/threa…t=&hilightuser=0&page=169

    Please test new software, new software allows kHz input and thus exact frequency setting to 250 or 333 kSym is much easier.  So far, the smallest step was 1MHz

    Please download software here... http://openeight.de/index.php?open=sf8008


    Your experience with it, please post here !!!!!!


    Thank you to the Octagon support team !!


    ( "zuerst mal manuelle, auto, satfinder... alles durchtesten (nebenwirkungen etc.) danach kann man auch Kanallisten und blindscan angehen" - first manual, auto, satfinder ... everything by testing (side effects, etc.) then you can synonymous blind scan and channellist approach. )

  • you do not have to be a member of forum, anyone can download it, there are 254MB direct download in computer from openeight page.


    ---> save on memory card -----> put it into SF8008 ------> follow SF8008 instruction.

  • You can and yes the LNB still needs to be modified or some other way to get the IF into the SF8008 tuning range. However, the receiver at the moment will happily capture signals MHz away from the set frequency, so it generally captures the strongest signal of the right symbol rate. There needs to be a further update to prevent this or setting to a finer frequency does not help as much as it could.