Frequency comparison

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JA5FP's picture
Last seen: 4 hours 10 min ago
Joined: 2009/04/14 - 07:58
Frequency comparison

Hello all!
Many stations receive WSPR signal in-time. So, it is useful for many purposes including "Propagation check","Antenna evaluation" etc.
Another tool is for "Frequency comparison" I think. How does it work?
Under three stations(A, B and C) are in connected, define Fa:A's carrier frequency fa:A's tone frequency fab:A's received tone frequency at B(displayed on text window) fac,Fb,fb,fba,fbc,Fc,fc,fca and fcb are the same manner.
Following relations are established in receive side.
fab=(Fa+fa)-Fb fac=(Fa+fa)-Fc fba=(Fb+fb)-Fa fbc=(Fb+fb)-Fc
fca=(Fc+fc)-Fa fcb=(Fc+fc)-Fb
Then,we get following functions. Data obtained through WSPRnet.
fab-fac=Fc-Fb fba-fbc=Fc-Fa fca-fcb=Fb-Fa
This means transmitter's relative frequency difference between each two stations.
If one of them has extremely correct frequency standard, whole satations have
absolute frequency accuracy.
Note carrier frequency is not often the "Dial frequency".
de JA5FP Yukihisa