3Com Modem -- Digital to Analog to Digital

[Brandt Redd]

Greetings back to you, Mark!

Yup, basically when you connect a 3Com modem to a Nokia 6100 the modem is doing the digital-to-analog and back conversion--not the phone. One engineer I talked to indicated that digitizing the modem signal would impair performance even more. Apparently the frequency response of cell-phone digitizing severely damages the audio-frequency signal from the modem.

Analog modulation of a cellular signal into radio-frequency consumes more power than digital modulation. That's why the new digital phones last for days on a charge while the older analog phones can barely last 12 hours. Thus, a dual mode phone like the Nokia 6100 series has very different battery life in analog vs. digital mode. (It's analog is still better than older phones though because of better electronics).

I first experienced this problem when using my phone out in Southern Utah when I was just using the phone for voice. The local towers were strictly analog and the battery consumption went way up (just when I didn't have an outlet for my charger handy).

Still, the problem was exacerbated by an old battery. I have recently gotten a newer one and am having less trouble.

The better solution is to get a digital connection straight to the phone via the serial port or a USB connection. Then let the phone handle the digitization directly onto the RF carrier. This gives digital battery life and much higher performance. That's what the Sprint network does (when you have coverage). But AT&T doesn't offer the service yet and I don't believe the Nokia 6100 series has the capability (but I could be wrong about the latter issue).

CDPD is available in my area but I haven't been able to try it out for lack of funds. But I'm presently doing some research into mobile devices for my company so perhaps I'll have an excuse to get the company to fund it. The coverage maps show most of Metro US but that doesn't help in more remote areas.

Sorry for the long post.

BR

[Mark Sedenquist]

Greetings Brandt,

BR: The better solution is to get a digital connection straight to the phone via the serial port or a USB connection. Then let the
phone handle the digitization directly onto the RF carrier. This gives digital battery life and much higher performance. That's
what the Sprint network does (when you have coverage). But AT&T doesn't offer the service yet and I don't believe the Nokia
6100 series has the capability (but I could be wrong about the latter issue).

RW: This seems like such an obvious thing -- but I hadn't thought of it. I really appreciate your comments about the performance of the batteries while in the dual mode use.

BR: CDPD is available in my area but I haven't been able to try it out for lack of funds. But I'm presently doing some research into
mobile devices for my company so perhaps I'll have an excuse to get the company to fund it. The coverage maps show most of
Metro US but that doesn't help in more remote areas.

RW: Beware -- Those coverage maps are very generous. I may participate in a new use of the CDPD network later in the year and I will be updating this space with current and hopefully accurate information as I learn it.

BR: Sorry for the long post.

RW: Are you kidding, your commentary was very useful. Bring on some more, anytime!