Here comes a third installment of satellite hunting, and this time, we’re looking for four relatively quiet satellites which we don’t know of any steady Ku band signals beamed to Sydney. Will I be successful? You’ll have to read on to find out!
Intelsat 8 at 169 degrees East
Intelsat 8 holds a special place in my heart, because it was serving a primary orbital role when I first started dabbling with Ku dishes. Launched in November 1998 as PAS8, later renamed to Intelsat 8, this satellite was a quite a strong one serving Australia with only Horizontal polarity signals in the Ku High band. This means I can use a regular “wideband” 10700 LNB (transponder plan excerpted from frequencyplansatellites.altervista.org). Most significant for me was that the satellite was the one carrying TVB pay TV signals. Its lifetime officially reached the 15 year mark in 2013, and was taken out of primary orbital service in August 2012, replaced by Intelsat 19 which increased capacity and bought Vertical polarity signals to Australia as well. I followed the launch of Intelsat 19, which was unusual in that it had a solar panel anomaly during launch causing a reduction of power to 75%.
It has now been moved a few degrees from the 166 degrees East slot that it used to occupy, to 169 degrees East to take over from Intelsat 2 and still serves C-band programs at present. The Ku band payload does not seem to have any listed TV traffic at this time, and this may be because of the 169 degree slot being close to 166 degrees and 172 degrees which could result in slight interference.
Having a Ku only receive system, attempting to identify the satellite required the use of the spectrum analyser as the primary method of detection. According to the frequency plan, the beacon was expected to be at 12747H/L and 12748V/L.
Capturing the Beacons
Using the spectrum analyzer, the dish was turned to Intelsat 19’s position at 166 degrees, and then the dish was nudged to the east and elevation bumped down slightly to try and capture the beacons.
Both beacons were captured successfully, with clear modulation as telemetry beacons. Both beacons were captured in their linear orientations (circular polarity may be used for orbit transfer activities). The separation between the two beacons was measured at 950kHz approximately, which is close to the 1Mhz expected. The difference can be due to drift in the beacons on the satellite (many specify about 25khz in 24 hours, 125khz through lifetime), plus the drift in the receiving LNB’s local oscillator which is notoriously unstable.
I tweaked the dish to increase the signal as much as possible to ensure the maximum collection of signal from Intelsat 8. A closer look at both telemetry signals reveals the subcarrier structure. I’m not sure whether the inter-modulation lines are actually sent by the beacon or are a result of the LNB’s phase noise or non-linearity. Given that the regular TVRO LNBs were not designed for “analog” or narrowband signals, it’s not unexpected.
Horizontal Polarity Beacon
Vertical Polarity Beacon
The Crazyscan results shows some waviness but also shows some potential carriers, one of which locks at a low SNR.
That particular carrier is familiar to me because I remember seeing it on Intelsat 19 in the adjacent slot, and it’s on the vertical polarity, which doesn’t come from Intelsat 8 in Sydney anyhow. A quick scan of Intelsat 19’s “permanent” dish shows the same carrier locking with a very high strength, showing just how strong the signal is.
That reminds us that we should remember that while the 3dB beamwidth is 2.1 degrees for the 75cm dish, there is still significant response at 3 degrees – to the point of “lockability” if the signal is strong enough. As a result, the spectra is “polluted” by signals spilling in from the adjacent satellites.
For completeness, I decided to take spectrum graphs, although they’re not very meaningful in light of the above.
Intelsat 5 at 157 degrees East
It’s another Intelsat satellite! I feel that every satellite has its own “story”, and this one has one too. Initially named PAS5, this was a satellite was launched in August 1997, and was built using leading edge xenon ion propulsion systems, dual-junction GaAs solar cells and nickel-hydrogen battery. The battery itself degraded faster than expected in 1998, leading to load-shed during eclipse events, and a total-loss insurance payout of US$185m. The satellite has been operated on leases for a significant part of its life.
The Wikipedia article seems to say that Intelsat 5 was decommissioned and deactivated on 19th October 2012, last stationed at 169 degrees East and sent into a higher junk orbit. However the two-line element information seems to suggest it’s actually not junked and instead is “parked” at 157 degrees East, inclined.
I decided to trawl through Intelsat’s Investor Relations site to look at their Form 20F document. Excerpted below, the inclined orbit satellite listings seems to show that Intelsat 5 should keep going until Q4 2020, making this a very long lived satellite, but its orbital location is marked as 50.15 degrees East (no known satellite here at this time).
This makes for a very confusing situation, but I do trust Celestrak’s TLE data, so I’m going to look for it at 157 degrees East. This particular position is, however, a difficult one as it overlaps with Optus satellites at 156 degrees East and 160 degrees East. Luckily, a check of the band plan at frequencyplansatellites.altervista.org tells me that the satellite uses the Ku-Low band which neither of the Optus satellites use. This means there’s a possibility I can hear it clearly despite the two other satellites nearby.
Intelsat 5 is now operating about 1.95 degrees inclined at this time, indicating that it is in “life extension” mode. Generally inclined services are less numerous because of the need for two axis tracking for uplinking and reliable downlinking, so I’m not expecting to hear much. Only the steerable spot beam can be pointed at Sydney, and I haven’t known Intelsat 5 to ever send any services here. The inclination of 1.95 degrees isn’t much (signal strength swings expected from a fixed dish, but the 75cm should be able to hear it all around its “wobble”).
Capturing the Beacons
The plan lists the beacons as telemetry on 11451H/V/R, 11452H/V/R and plain beacon on 11454L/R. I positioned the dish so that I could hear a mixture of both Optus satellite slots on Ku-High, and then swapped over to Ku-Low to go looking. Then I refined the dish’s pointing to improve the signal as much as possible.
It was received with slight unbalance on both polarities, but the skew on the LNB was verified, so it is likely to be operating in RHCP mode. The signal was also somewhat weak, which would be characteristic of the polarization mismatch and probably the lack of beam pointing at Australia. There are sidebands which suggest that the beacon is operating telemetry.
Unfortunately, none of the other beacons were receivable, and may have been turned off or not operating. I don’t know of any other satellites in the slot, or with a beacon at this frequency in the vicinity (none of the Optus satellites use Ku-Low). As a result, I’m fairly certain, although weak, this is likely a signal from Intelsat 5.
No actual carriers were resolved, and no spectral analysis was taken. The Ku High shows the interference from Optus satellites in adjacent slots.
Measat 2 at 148 degrees East
Measat 2, also known as Africasat 2, was one of two satellites launched by Malaysia in November 1996 carrying both C and Ku band payloads. The satellite was specified with an 11 year lifetime, which nominally expired in 2007. It’s brother satellite, Measat 1, was sent to a graveyard orbit in April 2013, while Measat 2 continues operations at this time.
The Ku downlink is specified for 10.95 to 12.62Ghz, covering most of Ku-Low and Ku-High. The transponder layout suggests we should hear signals (if any) in the upper band segment of Ku-Low (according to frequencyplansatellites.altervista.org). No programs are carried on the satellite according to Lyngsat. The SatBeams footprint site and Measat’s site seems to have an active Ku Eastern Australia beam.
The satellite is now operated in inclined mode, with an inclination of about 6.16 degrees at this time. This will require re-pointing the dish during the day to keep a hold on the signals.
Looking for the Beacon
The satellite has two beacons in the C-band, and one in Ku at 10915.5 Mhz in Horizontal polarity. This Ku beacon is listed on frequencyplansatellites.altervista.org, but not on SatBeams.
I waited until the satellite was to cross the Clarke belt, and swung the dish to 152 degrees East, where Optus D2 was, fixed the skew offset and tried to swing slightly lower and towards the west. Using the real-time spectrum analyzer, I was unable to locate the beacon’s signal in the noise. There is a possibility that the beacon is not being sent on the East Australia Beam or the beacon is not active as the C-band beacons are listed on SatBeams and not the Ku band beacon.
Regardless, I initiated a blind aim, based on nudging off Optus D2 until the signal was entirely gone and lowering elevation slightly.
So it seems that I couldn’t hear the beacon, nor could I hear any services. I might not have been able to aim the satellite accurately, or more likely, the satellite is not sending any signals to Eastern Australia at this time.
Apstar 9A at 142 degrees East
Now we come to the last satellite for this part, Apstar 9A. As it turns out, Apstar 9A is actually ChinaStar 1, renamed Zhongxing/ChinaSat 5A on lease to APT (as a “seat warmer” at 142 degrees East) until APStar 9 arrives later 2015. ChinaSat 5A was launched in May 1998, with an expected lifetime of 15 years which nominally expired in 2013. Checking historical LyngSat listings, the satellite was carrying very little traffic in 2010 at 87.5 degrees East, and at the present moment, it is not listed in Lyngsat at all, which implies its “silence”.
Looking up frequencyplansatellites.altervista.org, under ChinaSat 5A, the satellite transmits on both polarities in the Ku-High band (see excerpt below). There are two beacons in the C band, and two beacons in the Ku band, which are at 12749.5H and 12250.5V.
Capturing the Beacons
Not having been able to find Measat 2, I didn’t like my chances of finding Apstar 9A. However, with some careful diligent moving around, I seemed to have found something.
Detection of the beacon could be falsely claimed because of the spurs of the analyser. The small peak in Horizontal trace seems to be the actual beacon, whereas the marker set in the Vertical trace is actually a generated spur from somewhere. The signal from the satellite is actually pretty weak.
We can improve the determination by looking at a DPX split-screen view:
At a different span size, the Horizontal split seems to show some data on the left trace, which disappears on the Vertical trace, indicating we have a beacon!
A closer look at the spectrogram seems to show frequency drift as well, which is characteristic of LNB-converted signal. So we have a moderate amount of confidence we are aimed correctly at Apstar 9A.
Unfortunately, no detection of the lower beacon was made.
No active transponders were seen – the slope of the cable attenuation and the waviness of the imperfect impedance in the coax are all that’s visible.
The same result is echoed by the spectrum analyzer with some spurs which seem to be transient at times.
An attempt was made to explore four of the less popular satellites in the Ku band. Of them, positive identification of Intelsat 8 and Intelsat 5 were made, with a moderately confident identification of Apstar 9A. Measat 2 was not heard. Surprisingly, Intelsat 5 does not seem to have been graveyarded despite the information available online. Of all the satellites, none were carrying active Ku band services at this time.