Frequency shift for LNB/Es'Hail

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dg7yeo
Posts: 2
Joined: Sun Mar 10, 2019 8:49 am

Frequency shift for LNB/Es'Hail

Post by dg7yeo » Sun Mar 10, 2019 8:59 am

Hi,
as I have the same issue in several SDR programms looks to me like an issue with the driver, so I posted here.

I using a SDRplay RSP1A to receive Es'Hail2/QO-100 which working fine, but when I try to enter the LO Frequency shift to get the correct Frequency shown this wont work. If I use lower values i.e. 150MHz it works OK, so seems to be a limitation of the needed value of 9750MHz

Tested with SDRuno 1.22, SDRconsole V3

Is there any way to work around this limitation? Or do I need some updated drivers?

vy73
DG7YEO
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g4rqi
Posts: 5
Joined: Wed Nov 30, 2016 6:06 pm

Re: Frequency shift for LNB/Es'Hail

Post by g4rqi » Sat Mar 23, 2019 11:17 am

Hello...

Re. when I try to enter the LO Frequency shift to get the correct Frequency shown this wont work

I have just getting this working this morning and I have given up. Did you get this working in the end or receive a reply?

73 David - G4RQI
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dg7yeo
Posts: 2
Joined: Sun Mar 10, 2019 8:49 am

Re: Frequency shift for LNB/Es'Hail

Post by dg7yeo » Fri Apr 05, 2019 3:16 pm

Hi,
I opened as well a support ticket and response was
...
Thank you for contacting SDRplay Support. Yes, having the final VFO frequency displayed is a limitation within SDRuno. This is something we are looking to add into a future release of SDRuno.

I do not have a release timeframe.
...
From my view this is not only a issue of SDRuno, it seems to be a driver issue as I have same with other SDR software, so seems to be a driver issue.
As long as the real Frquenzy is within the RX range of the SDRplay it works as it should, as soon as I use a LO bring me out of the RX range it won't work.

vy73
DG7YEO
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GM7PBB
Posts: 1
Joined: Mon Aug 06, 2018 1:30 pm

Re: Frequency shift for LNB/Es'Hail

Post by GM7PBB » Sun Jun 30, 2019 4:59 pm

Any update on this issue? bit strange when a £20 dongle works better that a £250 unit with Oscar100/Es'Hail2 hmmm thought I had found a use of the SDRPlay but looks not, back on the self it goes :-)
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sdrplay
Posts: 977
Joined: Wed Jan 07, 2015 7:58 am

Re: Frequency shift for LNB/Es'Hail

Post by sdrplay » Sun Jun 30, 2019 5:22 pm

Maybe my misunderstanding, but there is no fault with the RSP product or the drivers. As long as the specified RF frequency to the RSP API is within the 1 kHz to 2 GHz range that we say on our datasheets, then the API and the RSP will function correctly.

SDRuno is a free download, it's not part of our product offering and there are other SDR software packages available.

SDRuno doesn't display frequency values above 2 GHz and that will be something that we look at in the future. All SDR software that I am aware of that have an offset facility, deal with the offset internally and preset the offset RF frequency to the API - that would be the sensible thing to do.

You can just tune SDRuno to the offset RF frequency and it will work fine.

Best regards,

Andy

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RSP2user
Posts: 106
Joined: Mon Oct 09, 2017 7:11 am

Re: Frequency shift for LNB/Es'Hail

Post by RSP2user » Wed Jul 31, 2019 5:36 am

Hi Andy,

For receiving images from Es'Hail 2 QO100 many are now using low cost LNBFs combined with a small parabolic dish antenna and an SDR plus PC software. There is an overall system diagram here: viewtopic.php?f=5&t=4755#p16575 . There is a article here which describes an system aspects as an example, but does not use the PC software for decoding DVB/DVBS2 (it provides a good general background though): https://ukamsat.files.wordpress.com/201 ... verter.pdf . Additionally, there is software available for the SDRplay RSPs to do the DVBs and DVBS2 decoding for Es'Hail using a PC here: http://v.1337team.tk/dvb-s_gui_amsat.zip . There is a further blog on the subject here on the Amsat forum where the RSP is applied for signal reception and a PC for DVBS/DVBS2 decoding - for those interested: https://forum.amsat-dl.org/index.php?th ... &pageNo=17 . A suitable LNBF example is here: https://www.passion-radio.com/lnb-pll/lnb-dro-789.html . There is another good system example here showing the bias-T and an update on an optimum PLL LNBF to apply: http://gm1sxx.blogspot.com/2017/05/more ... l-lnb.html

All that being said, I think there may be confusion for some in that an LNB or LNBF is downconverting the frequency block from the wide band range typically 10700.000 MHz to 12750.000 MHz down to the range 950 MHz (and lower depending on the LNBF and input frequency, such as that for Es'Hail) to 2150 MHz, most of which can be received by an RSP. I think some may be having problems determining the correct frequency to tune to when using an LNB or LNBF. For example, if the video image is being transmitted by Es'Hail at 10493.122 MHz, what frequency do they tune the RSP to after the downconversion? There are usually two L.O. frequencies that can be switched in and out in the mixer for the LNBF that are selected by applying or removing a 22kHz signal on the coaxial cable to the LNBF. One L.O. frequency is 9750 MHz and the other is 10600 MHz. So an Excel spreadsheet can be quickly developed that will simply take the actual received frequency and subtract the L.O. applied, thus resulting in the output frequency from the LNBF. The formula for anyone that needs some assistance is: Input Frequency - L.O. = Output Frequency. So if the 9750 MHz L.O. is applied, the output frequency for an input frequency of 10493.122 MHz would be 10493.122 MHz - 9750 MHz = 743.122 MHz. The output frequency from the LNBF is the one that can be received by the RSP and will need to be tuned to in order to receive the signal. The wide band frequency range of Es'Hail 2 QO100 is specified at 10491.000 MHz to 10499.000 MHz. Using an L.O. of 9750 MHz (no 22kHz signal applied to the LNBF), this results in an output frequency range of 741 MHz to 749 MHz which is well within the range of the RSP. The narrow band frequency range for Es'Hail is specified from 10489.550 MHz to 10489.800 MHz and when using the 9750 MHz L.O. would result in an output frequency range of 739.550 MHz to 739.800 MHz which is also well within the range of the RSP. I think some RSP users may be interested in having SDRuno display the incoming frequency at the LNB or LNBF prior to the L.O.; however, unless SDRuno is modified to allow the user to put in a user-defined secondary L.O. or offset frequency value, SDRuno has no way of determining the L.O. of or frequency offset caused by an external LNB or LNBF. I am not sure why some users would be expecting SDRuno to indicate the incoming frequency prior to the LNB or LNBF as the external LNB or LNBF and L.O. are not part of the RSP. However, if enough users are interested in such operation to change the frequency range displayed on SDRuno, perhaps a user-defined secondary L.O. or frequency offset may be a consideration for a future update to SDRuno.

I am hoping those who are working on receiving Es'Hail wideband video images will post some images and results here on the forum.
Last edited by RSP2user on Tue Aug 06, 2019 2:39 am, edited 4 times in total.

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