What Band GSM?

The 850 MHz vs. 1900 MHz debate is like comparing apples & oranges.

Shorter wavelengths tend to fare better (read: penetrate into tunnels and
buildings) better than longer wavelengths. This is because the aperture size
determines how low it will admit RF to pass. Thus, a larger aperture will
allow lower frequencies to pass than a smaller opening. The "penetration"
also consists of signal bounce, allowing it penetrate deeper. Keep in mind
there are limits. A longer bounce path increases the possibility of
interference from a co-inciding signal bounce. Also, RF needs a clear path
so don't expect flawless performance in an all-metal elevator.

Another upshot of 1900: it can carry higher data transfer rates than 850.
The downshot is shorter wavelengths have more "path loss", so a 1900 MHz
signal needs a lot more power to go the same distance as an 850 MHz RF
source. This is a major source of coverage headaches for the carriers that
used 1900 MHz-only.

Summary: all factors equal (especially power levels at the point of entry),
1900 will cover the interior of a building better. In real life this doesn't
always happen, which is one reason why the cell sites sometimes signal the
telephone to drop down to 850MHz if the 1900MHz doesn't have a good RF path.

This information came from years of testing before it was released to the
public.

Jer wrote in message ...
>Joseph wrote:
>> On 27 Dec 2003 12:35:45 GMT, [email protected]pamfree (John S.)
>> wrote:
....>An 800 signal will penetrate better than a 1900
....


>> Well, I've been in the real world situations and I can tell you that a
>> higher frequency carrier often times will beat the performance of the
>> lower frequency carrier including penetration of buildings...

---

› See More: What Band GSM?

John Smith wrote:
> The 850 MHz vs. 1900 MHz debate is like comparing apples & oranges.
>
> Shorter wavelengths tend to fare better (read: penetrate into tunnels and
> buildings) better than longer wavelengths. This is because the aperture size
> determines how low it will admit RF to pass. Thus, a larger aperture will
> allow lower frequencies to pass than a smaller opening. The "penetration"
> also consists of signal bounce, allowing it penetrate deeper. Keep in mind
> there are limits. A longer bounce path increases the possibility of
> interference from a co-inciding signal bounce. Also, RF needs a clear path
> so don't expect flawless performance in an all-metal elevator.
>
> Another upshot of 1900: it can carry higher data transfer rates than 850.
> The downshot is shorter wavelengths have more "path loss", so a 1900 MHz
> signal needs a lot more power to go the same distance as an 850 MHz RF
> source. This is a major source of coverage headaches for the carriers that
> used 1900 MHz-only.
>
> Summary: all factors equal (especially power levels at the point of entry),
> 1900 will cover the interior of a building better. In real life this doesn't
> always happen, which is one reason why the cell sites sometimes signal the
> telephone to drop down to 850MHz if the 1900MHz doesn't have a good RF path.
>
> This information came from years of testing before it was released to the
> public.


Well, okay then, if you're gonna get all sensible about this, I'm
willing to accept RF measurements in decibels in lieu of microvolts, but
the datapoints must be for non-coincident signal paths - because
multipath can be a ***** to sort out. One building floor will have
steel lockers all over the place and another floor will have carpet on
the walls - apples and oranges everywhere. Now, how many segments was
that fella's red herring showing?


--
jer email reply - I am not a 'ten' ICQ = 35253273
"All that we do is touched with ocean, yet we remain on the shore of
what we know." -- Richard Wilbur

>because
>multipath can be a ***** to sort out.

Nearly everything's digital now. Bit error rate and signal quality are
inversely related...low or no BER=good signal, high BER=problem in RF path.
When multipath appears the bit error rate takes off, so we only take
readings with BER at or very near zero. Plus BER can be read remotely, which
saves a lot of windshield time.

Hope this helped.