Phase and range stability of 2.5 and 25 MHZ standard frequency transmission outside and inside buildins

In open areas GPS serves a good navigation service with meter accuracy. However, in rural areas and especially inside buildings the accuracy is often bad. Reflections from other buildings, multimode propagation and wall attenuation may prevent the operation of GPS totally. MIKES has an operational 25 MHz standard frequency and time transmitter and an option to use transmission at 2.5 MHz as well. Those frequencies are internationally allocated for time transmitters. Otaniemi Campus area was selected as the test site. The phase stability was studied in open areas in the campus and inside two buildings, using both of the above mentioned frequencies. The phase values were converted to distances. Open area phase tests indicated the superiority of 2.5 MHz frequency compared to 25 MHz. The lower frequency was nearly five times less sensitive to reflections than the higher frequency. But inside buildings, 25 MHz frequency seemed to be better than 2.5 MHz, albeit the accuracy was quite poor in both cases. The explanation is, that high frequencies penetrates easier into buildings through openings, like windows.