The is a Phase Frequency Analyzer, it is a portable, battery operated, two input device with a 4 inch display that can measure very precise frequency and phase differences between the signals applied to both inputs. The input frequency can be any frequency between 1 MHz and 300 MHz. Typical use is to measure the differences between two 10 MHz clocks. The can numerically display the phase and frequency difference, show the measurement in a graph versus time, store the measurements on a SD card inserted into an SD card slot, or send the phase measurements over USB to a PC, running a program such as TimeLab, for further display and processing. Phase and Frequency measurement accuracy is better then 1e-12 divided by the measurement time in seconds with decimation set to 1 Be aware the maximum frequency difference that can be display depends on the measurement time (Tau) and is approximately 200 Hz / (Tau in s) so for Tau is 1 s it is 200 Hz maximum difference Short instructions Connecting to TimeLab Using the playlist with all the videos Videos featuring the ATTENTION: The -H4 is only platform that can be converted into a Phase Frequency Analyzer. None of the other small VNA's can be used. ATTENTION: The does not contain an internal high stability reference. It will only perform a high accuracy phase difference measurement between two input clocks. After both the and SW you need to load the SW onto the It is always possible to restore the -H4 back to its state by loading one of the -H4 SW's Colour:black Material:plastic Size:133 x 75 x 18mm Package Contents: 1 x host 2 x 30cm SMA male-to-male ALSR100 RF cable 1 x card reader 1 x type-c data cable 1 x touch pick Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.