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Using an External Antenna

Boost Your Reception in Weak Signal Areas:

CDMA EVDO dipole antennaOne of the best features of the HTC Touch is the ability to connect an external antenna to boost the CDMA cell signal, for both voice and data. As I travel, I sometimes find locations where there is only marginal reception, or no reception at all.

I bought an external dipole antenna (13 db gain) that is designed for CDMA (picture, right), with a patch cord that adapts it for use on the tiny RF input connector on the back of the unit.

If you're looking for it, it's under the self-portrait mirror, just beside the camera lens. If you remove the back cover, you can pop the mirror out of the back casing to allow access to the antenna input. The mirror is attached to a short plastic tether that keeps it captive so you don't lose it, and you can pop the mirror back in when you don't need the antenna.

When measuring signal strength and trying to optimize antenna location, the usual bar indicator is not very useful as it can only show large changes in signal strength.

However, all phones have a technician's 'field test' mode that shows a variable signal strength on the decibel scale, and the Touch is no exception.

The code for the Touch is ##33284#. If you punch this into the phone keyboard, as soon as you enter the last # character it will recognize the code and enter test mode (no need to hit the 'send' key because it isn't a phone call).

There are 3 different screens: one for voice and 1X data (the old, slow data system that is still used on some towers), one for EVDO, and one for GPS. You can also adjust the refresh rate from the default of 3 seconds to a faster rate of 1 second.

Here's what the field test mode screen for EVDO looks like (it's called HDR for High Data Rate, which is the old name for EVDO):

HTC Touch field test mode code 

This is what I receive in my office without an external antenna (that is a good signal strength reading). The two parameters of interest are Rx Signal Strength and Rx Power, you can use either one to measure relative signal strength (I've used Rx Power here).