Dbhz

dBHz Decibels relative to 1Hz

Used as a measure of the lock and re-lock signal to noise ratio when acquiring a satellite based position.

[http://www.gpsworld.com/gpsworld/article/articleDetail.jsp?id=121495&sk=&date=&pageID=6 this] references this unit.

For the initial position calculation of position a GPS chipset needs to find at least 4 satellites with a strong enough signal (28 dBHz or more) and it must keep those satellites and the signal strength for approximately one minute in order that it can download the data from the satellites that is essential for calculating your position (this it the ephemeris data explained earlier).

Source [http://www.pocketgpsworld.com/howgpsworks.php PocketGPSWorld]