UHF-Satcom.com - Skynet 5A UHF/SHF monitoring                                                                             Last update 08/08/2007 11:32:18 +0100

Skynet 5A is the first of the 'new generation' of British Military satellites. It was launched on March 11, 2007 by Arianne-Space. Skynet 5A was initially placed at about 177W where it underwent testing by the USAF Satellite Control Facility. It was then relocated to its operational slot at 1W where it will be commanded by RAF Oakhanger.

S-Band TT&C has been observed on 2227.500MHz. Skynet 5A has 9 UHF transponders and 15 SHF transponders operating at X-Band. The X-Band signals wobble slightly, it is presumed that this is due to the oscillator settling down, or thermal effects. Its estimated that SN5A has about a 20dB horn antenna for Earth coverage downlink on X-Band. It is also quite possible that there is a steer able X-Band antenna of about 60cms to 1m diameter. The UHF helical antennas are probably about 8 turns to give Earth coverage. There may also be Ka band downlinks but this is yet to be confirmed.

Wanted: Any info on Skynet 5A - stuff like RF power output level, dish / antenna size / gains etc. If you have any info, please send it to the contact addresses at the bottom of the homepage. You can use the form here to anonymously submit information.

Greetings to Paradigm-Logica and the MOD, frequent visitors to UHF-Satcom.com!

UHF-SatCom frequencies (freqs xBr,pjm & Maik)

Downlink Freq Bandwidth  Notes

Transponder spectrum plot
245.800 MHz 25 KHz  
249.480 MHz 10 KHz 2 tone IMD testing 17:08 30/3/2007

249.530 MHz 10 KHz  GMSK mil comms active
249.850 MHz 10 KHz  
250.130 MHz 10 KHz  
250.200 MHz 10 KHz  
257.700 MHz 25 KHz  
261.280 MHz 25 KHz  Originally on 261.200MHz

S-Band TT&C frequencies.

Downlink Freq    Notes Transponder spectrum plot
2227.500 MHz   Coherent TPX - carrier seen drifting in and out of lock.  

SHF-SatCom frequencies.

Downlink Freq Band Width  Notes Transponder spectrum plot
7261.000 22 MHz  Active with a few PSK signals  
7287.750 22 MHz    
7314.500 22 MHz    
7340.250 20 MHz    
7365.000 20 MHz    
7401.000 36 MHz    
7447.000 40 MHz    
7494.000 MHz    Tracking beacon or TT&C (+-20KHz data) - probably QPSK
7494.045 MHz    PSK with cyclic data, possible TT&C  
7488.000 34 MHz  Regenerative beacon and tt&c etc  
7529.000 40 MHz    
7577.000 40 MHz    
7615.000 20 MHz    
7640.000 20 MHz    
7666.000 22 MHz    
7689.000 22 MHz    
7715.000 20 MHz    
7740.000 20 MHz    

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