plot
10 GHz 'Beaconspot' reports as of Oct 2011


spare
        Main and standby 3cm beacon units


pa
              1W PA and driver module


ant
 3cm Waveguide slot antenna and location


East



south



west
north


Select 'view image' on your browser for larger pictures



3cm beacon keyer:  IK0WRB


1sy year drift
First year drift (3cm)


second year drift
Second year drift (3cm)

GB3CAM    Cambridge microwave beacons
IO92WI          Wyton           Cambridgeshire                                                                                                         
 
3cm:  10368.755 MHz                                1.2cm:   24048.870 MHz

reports always welcome, either direct ( gb3cam[at]earf.co.uk ) or via www.beaconspot.eu                       
                                                                                                                                                                                      


Latest news
25.10.11   We now have a red LED light beacon beamed between Cambridge and Newmarket. See:
http://www.earf.co.uk/light_beacon.htm



The first of the two Cambridge microwave beacons came on-air on 11th June 2008. This was the 10 GHz
beacon.  Although Wyton is only some 35m asl, the beacon antennas are 30m above ground level - well
above the local tree cover. There is some obstruction due to other antennas on the same site however.
.
beacon-details


beacon antennas		 LHS:  24 GHz multiplier/PA/antenna.                         
RHS:  10 GHz antenna.

These units are mounted on the eastern side of the  tower (the camera is looking SE).

cabling
 The antenna's are located about  
15m from the rack.

On 3cm, the transmitter power
is 3W, but this is reduced by loss
in the cable to 0.5W at the
antenna.
 



Current 3cm beacon frequency error history 
  (measured every Wednesday against a rubidium standard):
measurement
date
 17.08.11 24.08.11
 30.08.11 07.09.11
 14.09.11
21.09.11
 28.09.11
 05.10.11     13.10.11    
Frequency
error		  -49 Hz
-38 Hz
 -57 Hz -50 Hz
-62 Hz
-33 Hz
-54 Hz
-50 Hz
 -31Hz

measurement
date
 26.10.11
 02.11.11  09.11.11  16.11.11 13.11.11
30.11.11
 0712.11
 14.12.11
 21.12.11
Frequency
error		 -19 Hz
-54 Hz
-35 Hz
-68 Hz
-32 Hz
-57 Hz
 -53 Hz -24 Hz
-51 Hz

measurement

date		 28.12.11 04.01.12  11.01.12 18.01.12 25.01.12
01.02.12
          
          
          
Frequency
error		 -54 Hz -51 Hz
-63 Hz
-63 Hz
-31 Hz
-71 Hz




current drift
      Frequency drift last year F-drift/2010-2011 


   The reference oscillator used in this beacon is a 25 year old Racal 9420 unit. It operates at 5 MHz.

  There is short term drift in the order of +- 10 Hz, due to the combination of controlled oscillator drift and high loop
   time-constant, and as can be seen from these graphs, a long term stability of about +- 75 Hz, due to drift in the
   5 MHz reference.

  Something to think about: A 50 Hz error at 10 GHz equates to a clock that gains or loses 150 milli-seconds per year.
For more 1.2cm details see:  http://homepage.ntlworld.com/john.g4bao/page12.htm         For more 3cm details see: http://www.earf.co.uk/3cm_proposal1.htm