is wideband good approach for PSTN for voice and fax services

[mfawan]

AA


is that good approach to use wideband for PSTN


i want to design a system which caries Voice and Fax services over PSTN by using wideband channel. the datarate for voice is 28.8kbps,

also i am intrested to use different channels for Fax and voice.

please give me some professional remarks and any helping meterial

Best Regards

 

[chuckey]

PSTN networks are only rated up to 3 KHZ!!! The local ends are often 90+ years old and are subject to all sorts of cross talk - mainly dialling induction, mains hum and miscellaneous pops and clicks. Also their attenuation can be extremely variable. Its hard to synthesise these in a lab. Also the PSTN operator will put a limit on your send level, so you don't cross talk with other users.
Frank

 

[Ice-Tea]

ADSL works just fine on PSTN lines, they take into account the variable attenuation of the channel by "chopping" it into small pieces and characterise each one.

That said, I doubt your telco operator will appreciate you highjacking their line

 

[Audioguru]

I measured the round trip frequency response of telephone lines in the city. 3kHz was at -12dB and high voice vowels sounded very muffled. Consonant sounds from voices did not exist. I complained to Bell and they said it was normal and their limit is -15dB!