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</o:shapelayout></xml><![endif]--></head><body lang=DE link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US'>One thing, maybe your MCR has drifted, due to ageing?! <o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US'><o:p> </o:p></span></p><div style='border:none;border-left:solid blue 1.5pt;padding:0cm 0cm 0cm 4.0pt'><div><div style='border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0cm 0cm 0cm'><p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'>From:</span></b><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'> OpenBSC [mailto:openbsc-bounces@lists.osmocom.org] <b>On Behalf Of </b>Sipos Csaba<br><b>Sent:</b> Monday, October 26, 2020 3:16 PM<br><b>To:</b> openbsc-request@lists.osmocom.org <openbsc@lists.osmocom.org><br><b>Subject:</b> Fwd: NMT-450 - partial success<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><div><div><div><div><p class=MsoNormal>Hi,<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>I know it is a bit off topic, but as osmocom-analog has no dedicated mail list and my every attempt to contact Andreas lead to silence, I thought this is the closest one to discuss it.<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>I try to create an NMT-450 network with Motorola MCR4800XL phones, and a LimeSDR-mini. As the phones are locked to "Hungary" using a specific raster and a large gap in the middle, first I needed to dig out the details, find out the country code and create a patch so at least the phone is willing to lock onto the DS signal. I managed to do all that, so now the phone is actually able to decode the network and lock onto the signal.<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>My issue is with the uplink: when the phone tries Traffic Area update (the phone's uplink transmission burts is clearly seen with a spectrum analyzer), the network side is not able to detect the uplink burst at all. Not even as bad, or incorrectly formatted frame. Andreas has a site which describes how to set up the uplink side and do some tests: <o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal><a href="http://osmocom-analog.eversberg.eu/docs/sdr.html" target="_blank">http://osmocom-analog.eversberg.eu/docs/sdr.html</a><o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>I followed that guide and when the uplink burst from the phone arrives, the RX IQ constellation monitor indicates a correct burst with proper power (the burst is nicely round and in the green area). If I try to set up a call to the phone using the correct country code and phone number, the phone clearly responds to the paging request, as the 3 paging attempt generates 3 uplink bursts. Again, with no reception/decoding on the network side. Tried with two phones of the same type, the effect is the same.<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>I have two questions:<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>1. Where to send patches for the osmocom-analog project?<o:p></o:p></p></div><div><p class=MsoNormal>2. Does anyone have an idea what can be wrong with my setup?<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>One more thing I noticed: compared to the channel frequency used to set the NMT network up, the uplink is a couple kHz shifted:<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal><a href="http://www.imagebam.com/image/d17e881357285965" target="_blank">http://www.imagebam.com/image/d17e881357285965</a><o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>As it can be seen, the uplink burst appears 3-4kHz left relative to the downlink signal. <o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>The network is started with the following command:<o:p></o:p></p></div><div><p class=MsoNormal>nmt -k 239 -k 235 -Y HU,1 --limesdr-mini --sdr-rx-gain 20<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Any and all help is appreciated.<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Regards,<o:p></o:p></p></div><div><p class=MsoNormal>Csaba<o:p></o:p></p></div></div></div></div></div></div></body></html>