Experiences with external UMTS dongle

Visti Andresen talpa at talpa.dk
Sun Jul 5 14:33:28 CEST 2009

On Sat, 4 Jul 2009 18:24:34 +0200 (CEST)
Alexander Lehner <lehner at edv-buero-lehner.de> wrote:

> On Sat, 4 Jul 2009, Werner Almesberger wrote:
> > Timo Juhani Lindfors wrote:
> >>> My assumption is, that it takes far more than 2.5W, since the USB dongle
> >>
> >> How about measuring that? Just read the current_now file in /sys.
> >
> > Telephony can have very high current peaks, in the order of 2 A.
> > They are only short, i.e., the size of some transmit time slots,
> > so the average current is much lower, but if a design doesn't
> > adequately buffer those peaks, there will be problems.
> >
> > Problems should get worse in areas with poor or no reception.
> Yes, that makes absolutely sense. As soon as I started to transmit some 
> more data than only a ping or nslookup, the connection was gone.
> Also, I _am_ in a region with poor reception, and I have only GPRS, no 
> So maybe Timo has better reception conditions or the better hardware 
> around the Huawai chip. I have an UMTS dongle from FONIC which uses the O2 
> Network (whuaaa...).
> Alex.

Perhaps one could add a larger by pass capacitor on either the UBS stick or inside the phone?

Visti Andresen

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