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faq:freedom-from-feedback [2015/04/21 16:21] – hess | faq:freedom-from-feedback [2015/10/14 11:06] (current) – [GSM-R] fachet | ||
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====== Freedom from Feedback ====== | ====== Freedom from Feedback ====== | ||
- | As a theoretical rule of thumb, a good decoupling requires a distance of 5 to 10 λ. (([λ] Lambda = Wave length)) | + | 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< |
- | In practive, in most cases a distance of 3 λ is sufficient. \\ | + | However, in practive often a distance of 3 λ is sufficient. \\ |
- | \\ | + | |
- | < | + | |
- | & | + | |
- | </ | + | |
At 2.1 GHz (e.g. UMTS) the formula returns 300' | At 2.1 GHz (e.g. UMTS) the formula returns 300' | ||
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Three λ will then be 0.42m i.e. 42cm. | 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 | 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:entkopplung_gsm-r_-_v02.pdf|}} | + | Source: |
+ | |||
+ | Quelle: {{: |