| 10
GHz
'Beaconspot' reports as of Oct 2011 |
|
Main
and standby 3cm beacon units |
|
1W
PA and driver module |
| 3cm
Waveguide slot antenna and location |
Select 'view image' on your browser for larger pictures
3cm beacon keyer: IK0WRB
First year drift (3cm)
Second year drift (3cm)
.Third 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 19.06.13 An Infra-red beacon has been added along side the red beacon - see link above for details |
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.
.
 |
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).
|
Current
3cm
beacon
frequency error history
(measured every Wednesday against a rubidium standard):
(measured every Wednesday against a rubidium standard):
| measurement date |
13.06.12 | 20.06.12 |
27.06.12 | 04.07.12 |
11.07.12 |
18.07.12
|
25.07.12 |
01.08.12 | 08.08.12 |
| Frequency error |
-40
Hz |
-42
Hz
|
-5 Hz | -4 Hz |
-32
Hz
|
-17
Hz
|
-28
Hz
|
-20
Hz
|
-21Hz |
| measurement date |
15.08.12 |
22.08.12 | 29.08.12 | 05.09.12 | 12.09.12 |
19.09.12
|
26.09.12 |
03.10.12 |
10.10.12 |
| Frequency error |
-24 Hz |
-29
Hz
|
-20
Hz
|
-47
Hz
|
-51
Hz
|
-68
Hz
|
-7 Hz | -26 Hz |
-71 Hz
|
| measurement date |
17.10.12 | 24.10.12 | 31.10.12 | 07.11.12 | 14.11.12 |
21.11.12
|
28.11.12 |
05.12.12 |
12.12.12 |
| Frequency error |
-13 Hz
|
-22 Hz
|
-21 Hz
|
-59 Hz
|
-25 Hz
|
-4 Hz
|
-30 Hz
|
-48 Hz
|
-66 Hz
|
| measurement date |
19.12.12 | 26.12.12 | 02.01.13 | 09.01.13 | 16.01.13 | 23.01.13 | 30.01.13 | 06.06.13 | 13.02.13 |
| Frequency error |
-37 Hz | -16 Hz | -48 Hz | -29 Hz | +18 Hz | +24 Hz | +83 Hz | +31 Hz | -31 Hz |
| measurement date |
20.02.13 | 27.02.13 | 06.03.13 | 13.03.13 | 20.03.13 | 27.03.13 | 03.04.13 | 10.04.13 | 17.04.13 |
| Frequency error |
+18 Hz |
+24 Hz | +60 Hz | +33 Hz | +47 Hz | +25 Hz | +18 Hz | +35 Hz | +57 Hz |
| measurement date
|
24.04.13 | 01.05.13 | 08.05.13 | 15.05.13 | 22.05.13 | 29.05.13 | 05.06.13 | 12.06.13 | 19.06.13 |
| Frequency error
|
-40
Hz
|
+8 Hz
|
+64 Hz
|
+56 Hz
|
+34 Hz
|
+62 Hz
|
+28 Hz
|
+71 Hz |
Frequency
drift
last year
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