Is there a setting to improve data transmission quality on a GSM phone?

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Cindy - 02 Apr 2007 22:23 GMT

I have a "Fixed Wireless Terminal model GW1000BL" which is a device
that takes a SIM chip and supplies dial tone back to any RJ11 device
plugged into it. I am trying to use this terminal as a means to
communicate alarm signals from my home alarm to the central station.
I can get low speed pulse signals (called 4+2 in alarm speak) to go
through - but when I try a higher rate protocol called Contact ID -
the transmission fails. I dont know if the issue is a frequency
limitation in the cell system design (Rogers Canada GSM) or perhaps a
setting on the Fixed Wireless Terminal that could be adjusted to
improve the throughput.

The owners manual for the terminal talks of parameter settings that
cen be changed - but they are all unfamiliar to me. The ones that
seem like they might be of interest include:

ISD Call (Enable/Disable)
Loop Interruption
PR Outgoing Call (Enable/Disable)
16 khz Outgoing Call (Enable/Disable)
16khz Pulse Duration
Dial Time Out
16khz default value
16khz table

Would anyone out there know if any of the above parameters might
improve the data transmission rate for the terminal?

Thanks, Cindy

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John Henderson - 03 Apr 2007 10:08 GMT

> I have a "Fixed Wireless Terminal model GW1000BL" which is a
> device that takes a SIM chip and supplies dial tone back to
[quoted text clipped - 23 lines]
> Would anyone out there know if any of the above parameters
> might improve the data transmission rate for the terminal?

Is this the unit? http://tinyurl.com/2s74xb

If so, there's very little useful technical information on the
web site, even under "Specifications".

I imagine you're dialling a modem at the central station. If
so, you really need to establish an OTA (over-the-air) data
call rather than a voice call. These have very different
characteristics in the cellular world.

I can see no indication that the unit supports data calls,
although perhaps it does. But it is possible to carry very,
very low speed data over a GSM voice call, and perhaps that's
what's happening, and causing the restriction. The compression
used for voice is very unfriendly to data.

Maybe your user manual specifically mentions something about
handling data. Unfortunately, there doesn't seem to be an
electronic copy of the user manual on the company's web site.

Do you give the unit the number to be dialled, or is it
preconfigured somewhere inaccessible? If you configure it, are
there any promising-looking options in the vicinity?

John

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Cindy - 08 Apr 2007 21:32 GMT

> > I have a "Fixed Wireless Terminal model GW1000BL" which is a
> > device that takes a SIM chip and supplies dial tone back to
[quoted text clipped - 51 lines]
>
> - Show quoted text -

Yes, the unit in your photo is the one I have. I do give the unit the
phone # to be dialed & there are settings that can be changed - only
thing is -the descriptions in the user manual are VERY vague.

I emailed the manufacturer & got the following message back:

Dear sir,

> For GW1000BL, user can change 16KHz default value, pls firstly dial

> ***99*979023# to enter programming set mode, and type 0600*time#

> time that u can set any time that u want to send pulse. so that is

> configurable.

Thing is - I don't know what the 16KHZ setting does. I emailed back
to them to ask what the default setting is - so that I could reset it
back to that setting if I mess it up by changing it. I am still
waiting for a reply back from them.

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John Henderson - 08 Apr 2007 22:27 GMT

> Yes, the unit in your photo is the one I have. I do give the
> unit the phone # to be dialed & there are settings that can be
> changed - only thing is -the descriptions in the user manual
> are VERY vague.

These 16 KHz settings are well outside my knowledge comfort
zone. I think it may have something to do with sampling
frequency - the rate at which an analog signal is sampled when
being digitized. But I thought that was usually 8 KHz for
telephony.

Hopefully someone else can jump in with more info.

(Further comment below).

> I emailed the manufacturer & got the following message back:
>
[quoted text clipped - 15 lines]
> that I could reset it back to that setting if I mess it up by
> changing it. I am still waiting for a reply back from them.

I'd be asking for the actual recommended values to plug in for
"time" in the above, as well as the value which sets it back to
the default. Perhaps there's something you can do to reset the
whole device to factory defaults - handy to know if you're
experimenting.

John

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xPosTech - 09 Apr 2007 03:18 GMT

>>> I have a "Fixed Wireless Terminal model GW1000BL" which is a
>>> device that takes a SIM chip and supplies dial tone back to
[quoted text clipped - 68 lines]
> back to that setting if I mess it up by changing it. I am still
> waiting for a reply back from them.

Sounds like that unit is using DTMF for slow speed (dual tone
multi-frequency...the 4+2). The FWT probably has bandpass filters that
strip freqs outside the voice range ie. any thing above about 3.5 KHZ.
The 16KHZ won't get through.

Someone please correct me if I'm wrong.

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Ted
I wasn't born in Texas but
I got back here as soon as I could
(Don't forget to take out the trash)

"How hard can it be?" -Kinky Friedman

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