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Sim IJskes sim at ijskes.orgOn 01-03-11 10:54, Holger Hans Peter Freyther wrote: >> I still don't have the right architectual image of GSMTAP i think. Do i need >> to direct wireshark to sniff on the same interface that tetra-rx opens its udp >> socket on, with a port filter, or is there a pseudo interface that listens for >> raw packets on the same UDP port? > > There is no pseudo interface. The tetra decoding program sends UDP packets to > the IANA assigned port for GSMTAP on the specified ip address. E.g we like to > use multicast addresses as this avoid seeing ICMP messages as the destination > is not reachable. > > The easiest would be to use wireshark's pseudo interface to scan every > interface and then filter for udp in the trace and select gsmtap in the > filterbar of wireshark. Ok. I've straced tetra-rx and it opens on 127.0.0.1. So i wiresharked it on lo with a port filter. That should work. But tetra-rx doesn't do a write on the udp-socket. That could of course mean there is no tetra data in the capture. I've rebuild the usrp1-tetra_demod.py in the latest grc from git trunk, and the 25Khz lowpass gives me a nasty spike on -22Khz. A 20Khz gives me a much sharper idle constellation. Do you see any problem with 20Khz lowpass? Gr. Sim -------------- next part -------------- A non-text attachment was scrubbed... Name: sim.vcf Type: text/x-vcard Size: 121 bytes Desc: not available URL: <http://lists.osmocom.org/pipermail/tetra/attachments/20110301/287bb102/attachment.vcf>