UHF-Satcom.com - Ka-Band monitoring - Updated: (25/08/2010 22:34:26 +0100)

BTW: There are some great Ka-Band LNB's currently on Ebay, that will retune easily for the Military Ka band. Don't forget to say UHF-Satcom.com sent you!

  The picture to the left shows the HughesNet LNB as mentioned above. This unit was from Ebay, and is actually really great value for money. The LNB was intended to work in the 19.7GHz to 20.2GHz band for satellite based Internet, as part of the 'WildBlue' systems which are sold in the USA and Canada. The oscillator can easily be retuned to 19.2GHz, giving a coverage of 20.2GHz to 21.2GHz, with virtually no loss of input sensitivity, despite a band pass filter being in place. The dimensions for the waveguide input face of this LNB can be found here. There is a reasonably high resolution picture of the LNB's PCB here. The LNB has inputs for Horizontal and Vertical, but as yet it has not been possible to switch between them, either with 13/18V or with 22KHz tone.

Ka band sky survey - 80 East to 60 West.

Satellite		RF Freq		Modulation
Position / Name		MHz		characteristics
===========================================================================
72.5E			20295		Transponder
UFO F-10		20415		Transponder
			20475		Transponder
			20595		Transponder
			20700		Beacon

60E			20700.000 	Beacon, TT&C on +-1024kHz of centre, carriers +- 2048 kHz of centre
WGS 2			20847.275 	Multiple Carriers, poss. ranging tones
			20870.705 	Multiple Carriers, poss. ranging tones

47E			20245		Carrier
Syracuse 3A

39E			20298		Carrier
PAN 35815		20402		Carrier
			20700		Carrier
			21103		Carrier
			Note: This satellite transmits some massively wideband data which appears as a huge lump of noise
				
Astra 3B		20199 V		Carrier 28 dBW average EIRP
23.5E	
		
Sicral 1		20250		Beacon + TTC
16E			20899.750	Carrier
			21041.750	PSK
			21042.775	PSK 500KHz wide
			21093.275	UHF TPX loop - Downlink from 293.275MHz uplink
			21108.175	UHF TPX loop - Downlink from 308.175MHz uplink
			
Hotbird-6		19700.982	Beacon	
13E			19729.18	Transponder
			19748		Transponder
			19748.36	Transponder
			19825.08	Transponder
			19842		Transponder
			19844.26	Transponder
			
Sicral 1B		20250		Beacon + TTC	
11.6E			20855		DVB data
			
Eutelsat-W3A		21404		Beacon
7E			21462		Transponder
			21587		Transponder

Syracuse-3B		20249.976	Beacon / continuous carrier
5.15W

WGS-3			20219		DVB data
12W			20310		DVB data
			20700		Beacon, TT&C on +-1024kHz of centre, carriers +- 2048 kHz of centre
			20735		DVB data
			20785		DVB data
			21097.27	Beacon

UFO-9			20699.994	Propagation Beacon + FHSS Modem (carriers +-203.5KHz)
22.5W			20295		Transponder 
QRT from 12:30z on 	20415		Transponder
31st August 2006	20475		Transponder
			20595		Transponder (DVB GBS downlink - CNN & Fox news)

Update 14th April 2009 - Since the launch of the Kepler space-craft, some effort has been expended in putting together a 32GHz down converter from commonly available parts.

The photos above show two views of the down converter assembly that is mounted at the dish feed. A scalar feed and associated 32GHz circular waveguide transfers the signal to the down converter unit which came out of a microwave link. On the back of the down converter are the DC-DC converters for FET bias as well as -24VDC generation for the phase locked oscillator. In this system, the local oscillator runs at 34.2GHz and high-side mixes, giving an IF in the region of 1GHz to 2.5GHz. The LO is derived from a 111.0389610MHz reference, which is multiplied up 308 times to reach the final LO frequency. The 111MHz reference is GPS locked for stability, and results in around 40-60Hz of signal wander at 32GHz. Sun noise is detectable albeit at very low levels of noise increase.

The current Ka band "LNB" is shown to the right; (You can click the picture for the full sized version). The LNB consists of a ~5GHz phased locked oscillator from M/A Com, the output of which feeds a X4 multiplier.

This gives an LO around 19-21GHz. The LO is fed to a mixer / IF amplifier that came out of an old DMC microwave link operating at 22GHz. The input filter has been suitably modified and the IF section completely replaced with a pair of MMIC broadband gain blocks. The entire unit runs from 24V DC.

The 'front end' is the usual Direct-TV Ka band LNA.

Update 24th September 2006 - Ka LNB has now been chopped in half to produce two LNA units. The LNA has retained the existing Ka band feed, and now provides LHC and RHC outputs on SMA connectors. Useful gain has been measured from 17GHz to 22GHz. The pictures below show the modified LNB.

Front view showing the Ka feed horn and 2X SMA outputs.

Back view showing RF screening assembly.

Ka-band LNB now arrived - pending modification to use the LNA stages. Click on the large LNB picture to show the voltages and control points in the LNB. After careful study of the LNB design, it may be useful to know that the LNA stages should be useable at 24GHz.

2 X Ka and 1 X Ku LNB from DirecTV.

 Click images for full resolution pictures.

2 X Ka and 1 X Ku port with septum feed

(above) Block Diagram of Ka-Band down converter.

(above) Ka-Band converter under test

The block diagram above shows the basic concept of the converter - the local oscillator is generated from a 10MHz GPS locked oscillator, which is then multiplied up to 20GHz, resulting in a DC to 2 GHz IF. The 20GHz LO is generated with a modified M/A-Com phase locked oscillator, which generates 5GHz from a 100MHz reference. This 5GHz signal at around +10dBm is fed to a Celeritek X4 multiplier, resulting in a local oscillator signal at 20GHz (10dBm). The incoming RF signal, is mixed with the 20GHz local oscillator to give an IF in the 600MHz to 1.8GHz region. For testing purposes, the local oscillator has been set to 19.1GHz.

The IF is amplified using the usual MAR-6 specials, and fed to a communications receiver, which is also locked to the same 10MHz GPSDO as the local oscillator chain. Note: The AOR 8200 shown in the picture below was used for initial testing - this receiver is not locked to a GPS frequency standard. The receiver was used as an alignment aid for peaking the dish on the satellite. Since UFO-9 moves a few degrees in elevation, hourly peaking sessions are needed.

UFO-9 suffered an anomaly starting at 12:30z on 31st August 2006. The actual 20.7GHz beacon disappeared a few minutes after its initial anomaly. The satellite is now in a graveyard orbit and has been identified visually to confirm this. This satellite was a handy 20.7GHz test signal! The UFO-2 satellite which takes over from UFO-9 does not have any Ka capability for GBS or beacons. UFO-9 is listed as an uncontrollable space asset - its probably beyond recovery and should be considered inactive.

Some more info on GBS / UFO-9 is available on the restricted access pages.

(above) Ka-band down-converter in test phase - listening to the GBS beacon from UFO9

(above) Ka feed with AA battery for comparison.

(above) Ka feed and LNA on the dish!

The front end now in use is a Direct-TV Ka band LNB that has had the oscillator disabled, and a SMA socket fitted to take the amplified 20GHz signal out. This is then fed via semi-rigid to the mixer as described above.

(above) 20699.994GHz (20.7GHz nominal) beacon from UFO-9 at 22.5 degrees West. Note in the FFT, traces of a FHSS modem can be seen.

(above) The four photos above were received from UFO-9's GBS transponder.