The present invention relates to simulation on a lab workbench of conditions that would be encountered by a mobile device during a so-called drive test, which involves transporting the mobile device along a course so that it encounters fading and changing wireless access points used normally to connect the mobile device to a wireless network but in this case used to locate the device. The instrument and method also support parametric testing of transceivers used for WiFi positioning and, optionally, GNSS positioning by the same mobile device used for WiFi positioning.