This shows you the differences between two versions of the page.
Both sides previous revision Previous revision Next revision | Previous revision | ||
faq:freedom-from-feedback [2015/04/05 17:00] hess |
faq:freedom-from-feedback [2015/10/14 11:06] (current) fachet [GSM-R] |
||
---|---|---|---|
Line 1: | Line 1: | ||
====== Freedom from Feedback ====== | ====== Freedom from Feedback ====== | ||
- | Deutsche Bahn requires a decoupling of up to -60 dBm. According to a simulation of one of our antenna supplier a distanec of 350 cm is sufficant to fulfill this requirements | + | |
- | Source: {{:faq:entkopplung_gsm-r_-_v02.pdf|}} | + | As a theoretical rule of thumb, a good decoupling requires a distance of 5 to 10 λ.(([λ] Lambda = Wave length = v/f with v∼3×10<sup>8</sup> m/s.))\\ |
+ | However, in practive often a distance of 3 λ is sufficient. \\ | ||
+ | |||
+ | At 2.1 GHz (e.g. UMTS) the formula returns 300'000'000/2'100'000'000 = 300/2100 = 0.14m. | ||
+ | |||
+ | Three λ will then be 0.42m i.e. 42cm. | ||
+ | |||
+ | ===== GSM-R ===== | ||
+ | For GSM-R Deutsche Bahn requires a decoupling of up to -60 dBm. According to a simulation of one of our antenna supplier a distance of 350 cm is sufficant to fulfill this requirements | ||
+ | |||
+ | Source: {{{{:faq:simulation_report_decoupling_gsm-r_v06.pdf|}} | ||
+ | |||
+ | Quelle: {{:faq:simulation_report_entkopplung_gsm-r_v06.pdf|}} |