Hi Ray, Ray Jackson wrote: > Hi all, > > We are running SpanDSP with Callweaver and have been having issues > sending faxes using the TxFax module. to certain fax machines (Brother > machines in particular). I realise this is more a SpanDSP question, > but we ran a fax check report with our local Telco and the report > states that our fax service is 'OVER equalised (4dBm)'. A copy of the > technical info in the report can be found at: > > http://gravsol.com/faxtechnical.png > > I also hear that Brother fax machines don't like to be over > equalised. Is there a way of adjusting SpanDSP's equalisation levels > somehow - would I have to go into the source to do this or can I pass > a parameter via Callweaver? Any assistance would be greatly appreciated. There are a number of things other than spandsp between the signal generation, and your measurement point. I just made the following snapshot of the spectrum coming out of the V.17 modem in spandsp - http://www.soft-switch.org/V.17_spectrum.png It looks much less smooth than the graph in the telco report, because it is a short term snapshot of a rapidly varying signal. If I produced a longer term image it would look smoother. However, the key point is my graph does not show the sprectral tilt which the telco's graph shows.
I guess you have an analogue path between txfax and the telco's measurement point, and this is producing the results they see. 4dB tilt across the spectrum and very little group delay variation is actually a good path. Most analogue paths will give worse results than that. It is worth noting that their analyser recorded a 100% error free result. Are you running the very latest spandsp code? if not, get the latest snapshot. A number of FAX compatibility issues (annoying little FAX protocol issues, and not modem ones) have been addressed in the last few weeks. Regards, Steve _______________________________________________ Callweaver-users mailing list [email protected] http://lists.callweaver.org/mailman/listinfo/callweaver-users
