C-band Sats – Part 6: 134E Apstar 6, 138E Telstar 18, 140E Express AM5 (?)

The satellite-hunting story continues (thanks to a little more free time), this time looking at Apstar 6, Telstar 18 and what I believe to be Express AM5. These spectrums were taken during the period of 24th-26th March, but I’ve only just got around to looking more closely at them.

134°E Apstar 6

Apstar 6 is one of APT Satellite’s fleet which services the Asia-Pacific market, including Australia. It carries a number of DVB-type services and is fairly well known. Interestingly, they are based in Hong Kong, as is AsiaSat.

A scan using CrazyScan seems to show the satellite is brimming with activity across the whole extended and regular C-band segments, with almost no free bandwidth.

TP N: 1
Frequency: 3733.159 Mhz
Symbol rate: 29999 KS
Polarization: Vertical
Spectrum: Normal
Standard/Modulation: DVB-S2/8PSK
FEC: 3/4
RollOff: 0.20
Pilot: off
Coding mode: CCM
Long frame
Transport stream
Single input stream
RF-Level: -40 dBm
Signal/Noise: 11.3 dB
Carrier width: 35.999 Mhz
BitRate: 66.868 Mbit/s
----------------------------------------
TP N: 2
Frequency: 3761.234 Mhz
Symbol rate: 26999 KS
Polarization: Horizontal
Spectrum: Normal
Standard/Modulation: DVB-S2/8PSK
FEC: 3/4
RollOff: 0.35
Pilot: off
Coding mode: ACM/VCM
Long frame
Transport stream
Single input stream
RF-Level: -40 dBm
Signal/Noise: 11.5 dB
Carrier width: 36.449 Mhz
BitRate: 60.181 Mbit/s
----------------------------------------
TP N: 3
Frequency: 3841.228 Mhz
Symbol rate: 27499 KS
Polarization: Horizontal
Spectrum: Normal
Standard/Modulation: DVB-S/QPSK
FEC: 3/4
RollOff: 0.35
RF-Level: -40 dBm
Signal/Noise: 10.7 dB
Carrier width: 37.124 Mhz
BitRate: 38.014 Mbit/s
----------------------------------------
TP N: 4
Frequency: 3895.431 Mhz
Symbol rate: 4284 KS
Polarization: Vertical
Spectrum: Normal
Standard/Modulation: DVB-S2/16APSK
FEC: 4/5
RollOff: 0.20
Pilot: on
Coding mode: CCM
Long frame
Transport stream
Single input stream
RF-Level: -43 dBm
Signal/Noise: 5.5 dB
Carrier width: 5.141 Mhz
BitRate: 13.653 Mbit/s
----------------------------------------
TP N: 5
Frequency: 4021.220 Mhz
Symbol rate: 29999 KS
Polarization: Vertical
Spectrum: Normal
Standard/Modulation: DVB-S2/8PSK
FEC: 3/4
RollOff: 0.20
Pilot: off
Coding mode: CCM
Long frame
Transport stream
Single input stream
RF-Level: -34 dBm
Signal/Noise: 10.2 dB
Carrier width: 35.999 Mhz
BitRate: 66.868 Mbit/s
----------------------------------------
TP N: 6
Frequency: 4031.952 Mhz
Symbol rate: 2689 KS
Polarization: Horizontal
Spectrum: Normal
Standard/Modulation: DVB-S2/QPSK
FEC: 3/4
RollOff: 0.25
Pilot: off
Coding mode: CCM
Long frame
Transport stream
Single input stream
RF-Level: -38 dBm
Signal/Noise: 10.7 dB
Carrier width: 3.361 Mhz
BitRate: 4.001 Mbit/s
----------------------------------------
TP N: 7
Frequency: 4052.646 Mhz
Symbol rate: 9629 KS
Polarization: Horizontal
Spectrum: Normal
Standard/Modulation: DVB-S/QPSK
FEC: 3/4
RollOff: 0.35
RF-Level: -38 dBm
Signal/Noise: 9.7 dB
Carrier width: 12.999 Mhz
BitRate: 13.311 Mbit/s
----------------------------------------
TP N: 8
Frequency: 4160.821 Mhz
Symbol rate: 2963 KS
Polarization: Horizontal
Spectrum: Inverted
Standard/Modulation: DVB-S/QPSK
FEC: 3/4
RollOff: 0.35
RF-Level: -44 dBm
Signal/Noise: 9.9 dB
Carrier width: 4.000 Mhz
BitRate: 4.096 Mbit/s
----------------------------------------
Total Scan Time = 3420.668s

The BLScan report seems to be more like the Lyngsat listing – despite the busy spectrum, there aren’t that many DVB services there. I suppose this is a classic example of geostationary satellites being more than just satellite TV.

There’s a few mixtures of modes, some are ACM/VCM but lockable briefly on the Prof 8000. On the whole, there’s really not that much to watch on this satellite, so the rest of it is probably data services.

Interesting Signals

The spectrum screenshots in horizontal and vertical respectively show just how busy the satellite is – although there are a few clear spaces evident due to the increased frequency-resolution compared to a CrazyScan swept signal-strength plot.

While scanning around this satellite, I was particularly enamoured by this type of slotted TDMA/FDMA narrow-band data system (near 4014.35Mhz Horizontal). This had carriers roughly 300khz wide and very short burst transmissions. The timing on the left is probably not accurate (limited by the update rate due to narrow RBW selection).

Moving along slightly to 3961.24Mhz horizontal polarity, we see a much wider system that spans about 36Mhz (a full transponder). It’s so mesmerizing to see the data loading varying every second, producing ribbons of dashes which almost look like electrophoresis separation of DNA. Within the ribbons, there seem to be the occasional CW tone, as if to do some remote frequency tuning of VSAT uplink equipment, most of it sitting smack-bang in the middle of a guard band and not “hurting” any other transmission.

I couldn’t help but admire the sight, so I cleared off the spectrum, leaving the DPX waterfall in full width (and a window at double-width), the above three images being just gratuitously uploaded for aesthetic effect.

In the vertical at 4180.15Mhz, it seems like a smaller similar system may have been in use, although more lightly loaded.

This system was quite a bit weaker at 3746.44Mhz but seems to show long bursts mixed with short bursts, and some modems seem to have some double-wide carrier aggregation as well.

This near 3899.04Mhz seems to be burst-based with very short bursts. Each of them seem to have a spectral peak at the edges of the transmission, making it quite unique. They might be a function of pilot tones/preambles sent at the beginning of each burst?

This one seems to show how several systems co-exist in a very narrow space (3854.08Mhz) – the wide patterned system we’ve seen before, the line-up carrier tone, many smaller slotted systems and some continuously-transmitting ones.

Beacons

In the vertical, a number of beacons were found towards the lower end of the band at:

  • 3701.663708Mhz (Vertical, Unmodulated)
  • 3701.159708Mhz (Vertical, Modulated, ~500khz space)
  • 3699.661208Mhz (Vertical, Modulated, ~1.5Mhz space)
  • 3696.656708Mhz (Vertical, Modulated, ~3Mhz space)

The beacon at 3701Mhz seems to be AM type with an FSK stream subcarrier at 65khz and an unmodulated outer subcarrier at 131khz.

The beacon at 3699Mhz is also an AM type with two subcarriers, at 49khz and 74khz, both wider FSK type with approximately 8khz of shift.

The beacon at 3696Mhz is a carbon copy, with exactly the same parameters as the above. These latter two seem about 6dB weaker (give or take), so maybe they’re from a neighbouring satellite? A quick check shows that they show the same characteristics as detected for VinaSat 1 in the adjacent slot, so they’re probably not from Apstar 6! That just shows you the “beamwidth” of the dish. In fact, while on VinaSat 1, I could see (weakly) the beacons from Apstar 6 and made a comment about them.

A strong beacon was found on the horizontal at 4201.010468Mhz. It’s of the same type as the other modulated beacon from this satellite – AM type, subcarriers at 65khz (modulated) and 131khz (unmodulated).

This is consistent with the expectation based on published information that there are beacons at 3700.00Mhz Vertical and 4199.825Mhz Horizontal. Satellite positively identified.

138°E Telstar 18 (Apstar 5)

This satellite, while known as Telstar 18 and listed under Telesat’s pages, is actually Apstar 5. It carries a limited number of pay-TV services and covers Australia.

Despite this, the CrazyScan seems to show the regular C-band to be quite busy with a few services in the horizontal polarity in the extended C-band.

TP N: 1
Frequency: 3787.530 Mhz
Symbol rate: 3159 KS
Polarization: Horizontal
Spectrum: Normal
Standard/Modulation: DVB-S2/QPSK
FEC: 5/6
RollOff: 0.35
Pilot: off
Coding mode: CCM
Long frame
Transport stream
Single input stream
RF-Level: -45 dBm
Signal/Noise: 6.8 dB
Carrier width: 4.265 Mhz
BitRate: 5.228 Mbit/s
----------------------------------------
TP N: 2
Frequency: 3800.843 Mhz
Symbol rate: 3098 KS
Polarization: Horizontal
Spectrum: Normal
Standard/Modulation: DVB-S2/QPSK
FEC: 5/6
RollOff: 0.35
Pilot: off
Coding mode: CCM
Long frame
Transport stream
Single input stream
RF-Level: -44 dBm
Signal/Noise: 7.0 dB
Carrier width: 4.183 Mhz
BitRate: 5.127 Mbit/s
----------------------------------------
TP N: 3
Frequency: 3825.044 Mhz
Symbol rate: 3332 KS
Polarization: Horizontal
Spectrum: Normal
Standard/Modulation: DVB-S2/QPSK
FEC: 3/4
RollOff: 0.20
Pilot: off
Coding mode: CCM
Long frame
Transport stream
Single input stream
RF-Level: -45 dBm
Signal/Noise: 8.5 dB
Carrier width: 3.999 Mhz
BitRate: 4.958 Mbit/s
----------------------------------------
TP N: 4
Frequency: 3834.277 Mhz
Symbol rate: 3599 KS
Polarization: Horizontal
Spectrum: Normal
Standard/Modulation: DVB-S2/QPSK
FEC: 3/4
RollOff: 0.25
Pilot: on
Coding mode: CCM
Long frame
Transport stream
Single input stream
RF-Level: -44 dBm
Signal/Noise: 8.4 dB
Carrier width: 4.499 Mhz
BitRate: 5.355 Mbit/s
----------------------------------------
TP N: 5
Frequency: 3839.531 Mhz
Symbol rate: 4444 KS
Polarization: Horizontal
Spectrum: Normal
Standard/Modulation: DVB-S2/8PSK
FEC: 2/3
RollOff: 0.35
Pilot: on
Coding mode: CCM
Long frame
Transport stream
Single input stream
RF-Level: -44 dBm
Signal/Noise: 8.8 dB
Carrier width: 5.999 Mhz
BitRate: 8.804 Mbit/s
----------------------------------------
TP N: 6
Frequency: 3857.527 Mhz
Symbol rate: 2499 KS
Polarization: Horizontal
Spectrum: Normal
Standard/Modulation: DVB-S2/8PSK
FEC: 2/3
RollOff: 0.20
Pilot: off
Coding mode: CCM
Long frame
Transport stream
Single input stream
RF-Level: -46 dBm
Signal/Noise: 6.7 dB
Carrier width: 2.999 Mhz
BitRate: 4.951 Mbit/s
----------------------------------------
TP N: 7
Frequency: 3865.982 Mhz
Symbol rate: 4289 KS
Polarization: Horizontal
Spectrum: Normal
Standard/Modulation: DVB-S/QPSK
FEC: 3/4
RollOff: 0.35
RF-Level: -44 dBm
Signal/Noise: 9.3 dB
Carrier width: 5.791 Mhz
BitRate: 5.930 Mbit/s
----------------------------------------
TP N: 8
Frequency: 3872.992 Mhz
Symbol rate: 6666 KS
Polarization: Horizontal
Spectrum: Normal
Standard/Modulation: DVB-S/QPSK
FEC: 3/4
RollOff: 0.35
RF-Level: -43 dBm
Signal/Noise: 7.9 dB
Carrier width: 9.000 Mhz
BitRate: 9.216 Mbit/s
----------------------------------------
TP N: 9
Frequency: 3888.977 Mhz
Symbol rate: 1850 KS
Polarization: Horizontal
Spectrum: Inverted
Standard/Modulation: DVB-S/QPSK
FEC: 3/4
RollOff: 0.35
RF-Level: -45 dBm
Signal/Noise: 7.5 dB
Carrier width: 2.497 Mhz
BitRate: 2.558 Mbit/s
----------------------------------------
TP N: 10
Frequency: 3895.914 Mhz
Symbol rate: 4809 KS
Polarization: Horizontal
Spectrum: Normal
Standard/Modulation: DVB-S/QPSK
FEC: 3/4
RollOff: 0.35
RF-Level: -45 dBm
Signal/Noise: 6.0 dB
Carrier width: 6.493 Mhz
BitRate: 6.649 Mbit/s
----------------------------------------
TP N: 11
Frequency: 3934.941 Mhz
Symbol rate: 3000 KS
Polarization: Vertical
Spectrum: Normal
Standard/Modulation: DVB-S/QPSK
FEC: 3/4
RollOff: 0.35
RF-Level: -43 dBm
Signal/Noise: 8.1 dB
Carrier width: 4.050 Mhz
BitRate: 4.147 Mbit/s
----------------------------------------
TP N: 12
Frequency: 3947.963 Mhz
Symbol rate: 17599 KS
Polarization: Vertical
Spectrum: Normal
Standard/Modulation: DVB-S2/8PSK
FEC: 3/4
RollOff: 0.25
Pilot: off
Coding mode: CCM
Long frame
Transport stream
Single input stream
RF-Level: -39 dBm
Signal/Noise: 6.4 dB
Carrier width: 21.999 Mhz
BitRate: 39.228 Mbit/s
----------------------------------------
TP N: 13
Frequency: 3970.977 Mhz
Symbol rate: 12499 KS
Polarization: Horizontal
Spectrum: Normal
Standard/Modulation: DVB-S2/QPSK
FEC: 1/2
RollOff: 0.20
Pilot: off
Coding mode: ACM/VCM
Long frame
Transport stream
Single input stream
RF-Level: -38 dBm
Signal/Noise: 6.9 dB
Carrier width: 14.999 Mhz
BitRate: 12.362 Mbit/s
----------------------------------------
TP N: 14
Frequency: 4151.341 Mhz
Symbol rate: 900 KS
Polarization: Horizontal
Spectrum: Normal
Standard/Modulation: DVB-S/QPSK
FEC: 3/4
RollOff: 0.35
RF-Level: -44 dBm
Signal/Noise: 8.2 dB
Carrier width: 1.215 Mhz
BitRate: 1.244 Mbit/s
----------------------------------------
TP N: 15
Frequency: 4154.726 Mhz
Symbol rate: 1600 KS
Polarization: Horizontal
Spectrum: Inverted
Standard/Modulation: DVB-S2/QPSK
FEC: 3/4
RollOff: 0.25
Pilot: off
Coding mode: CCM
Long frame
Transport stream
Single input stream
RF-Level: -44 dBm
Signal/Noise: 11.9 dB
Carrier width: 2.000 Mhz
BitRate: 2.381 Mbit/s
----------------------------------------
Total Scan Time = 2913.865s

The BLscan report shows a moderate number of DVB-type carriers to explore.

The service summary confirms what we already knew – not many free DVB services to watch. I did manage to catch a narrow carrier (900kS/s or about 1.2Mhz wide) with the Prof 8000 which was slightly unexpected. It’s not the lowest SR out there, but any low-SR service (<1000kS/s) can be quite a challenge for some cards especially to blind-scan.

Interesting Signals

The spectrum in horizontal and vertical polarities, respectively, seem to show lots of narrow data carrier activity, especially in the horizontal. In fact, this satellite seems to be quite fascinating for data services as well.

This satellite carries a large number of thin narrow-bandwidth carriers, and it seems like having line-up carriers/beacons/pilot-tones is crucial to maintaining the frequency alignment of downstream devices. As a result, it’s common to see carriers next to narrow data services like the above at 4159.03252Mhz in the vertical. These should be extremely stable, so maybe it can be of use to look at relative drift of LNB local oscillators over time.

Look at the wider picture and there’s a lot of odd things going on. There’s wide data services with repetitive spectral patterns (as we saw earlier), there’s data services which have drifting “blocks” (more later), there’s transmission bursts that sweep across a bandwidth (probably a radar), narrow services, slotted services and moderately wide services all packed together.

The radar seems to tread into some data service as well. I wonder if it’s a local radar here or whether it’s some within the uplink footprint that got picked up and rebroadcasted.

By far the most artistic service on the satellite comes from the “moving block” data transmission service at 4163.71Mhz in the vertical it seems. I suspect some of the weak images seen are intermodulation effects, but it makes it reminiscient of early DOS graphics made using block characters. The data seems to take a “winding” route like a river down the left, with a nearly continuous stream on the right.

Changing the time-scale compresses the blocks somewhat, but the behaviour seems consistent. The signal is about 2-2.5Mhz wide in all.

But that was only the beginning, with another pair of systems at around 4061.09Mhz in the vertical. The left system seems to be under heavy loading, with the right system being under moderate loading and an unrelated system in the middle. This suggests maybe one of the paired systems is an uplink, with the other a downlink.

Too pretty, especially with the line-up carrier on the left, not to put up a pair of images at different widths … just for eye candy.

There was this data service in the horizontal at around 3881.39Mhz which always seemed to alternate left-right (send-ack? two services with similar transmit patterns but offset in time?).

This one with narrow-spiky carriers near 3942.58Mhz horizontal is quite familiar now, having been seen in the past.

Beacons

A confirmed beacon was found at 3630.986798Mhz in the vertical polarity, of the AM type with (possibly PSK/MSK) subcarriers at 48khz and 72khz. Shift is about 10khz. This matches with publicly available information.

But of course, I’d go looking all over the band to see what else I could find. Because of the number of services and the number of pilot-tones/uplinked carriers, it’s hard to distinguish which is an actual satellite beacon and which are uplinked. This pair were curious since they seem to sit within a wider data transmission which would probably degrade its performance.

This one was sitting inside the LTE interference in the low end of the extended C-band in the horizontal. It doesn’t seem like a proper beacon but it looked a bit odd.

This pair sitting at around 3851.498Mhz in the horizontal look quite clean, but are probably line-up carriers for satellite modems.

The same goes for this one at 3628.36Mhz in the horizontal …

… and this one at 4059.1Mhz in the horizontal. A bit arbitrary, I agree, but there aren’t usually more than about three satellite-originated beacons, and fewer in the case of a multi-band satellite.

140°E Express AM5 (?)

Turning up past Telstar 18’s slot, I spotted what clearly looked to be some satellite signal.

The signals resided in the extended C-band segment, with the above spectrums depicting the horizontal and vertical components. Given their similar amplitudes, I concluded that the signals are very likely circularly polarized. Putting the dielectric plate in, the signals in left and right polarity were as follows:

Now there was a clear separation of carriers to polarities, but there are still some commonalities which suggest that it may well be a similar transmission on both polarities. Most satellites targeting our area tend to use linear polarity, whereas those serving the US and Russia often use circular polarity. This gave me a hint that it might be Express AM5. It’s consistent with the location, the band in use and the circular polarity. Unfortunately, no services could be locked, so a 100% confirmation couldn’t be made. From the footprint data, we are way out of the coverage footprint which points to the north, covering parts of Russia, so the fact it could even be detected at this magnitude would be considered unusual. Could it be another satellite then? If it is … I wouldn’t have any idea what it would be given these characteristics!

A look at the services carried on LHCP in the vicinity of 3644.31Mhz seems to show high number of narrow data services with reference carriers on the left. It’s almost artful to look at the spectrum with quasi-random burst timings/lengths/widths.

A closer look at the reference carriers on the left shows that they seemed to be spaced at 100khz steps from 3658.368846Mhz. Maybe they’re line-up carriers which will change to active data when ready – some of the weaker images to the right may be intermodulation?

A closer look at some of the data carrier systems seems to show not only narrow bursts which stay within a given channel bandwidth resulting in a clear guard band, but the presence of wider bursts that span multiple channels. This might be indicative that all of these carriers belong to the same satellite modem/data system, with some “higher tier” equipment capable of using multiple slots across multiple carriers together in a form of “carrier aggregation”. Just crudely judging from the spectrum, it seems to be 4x carrier aggregation. I suppose if we zoomed out on Wi-Fi, we might see the same thing comparing an 802.11ac ~80Mhz wide transmission to an 802.11n single-channel ~20Mhz wide transmission.

Switching to RHCP, we can see the left set is strongly attenuated, but the right set comes up bright and strong. This implies that one set is probably used for uplink, and the other for downlink. This provides some frequency separation, making single-cable operation a little simpler, but also is important as many VSAT terminals are designed with an ortho-mode transducer which separates the polarities and allows a receiver and transmitter to be mounted using opposite polarities. This is needed so the transmission doesn’t overload/desensitize/damage the LNB used for receiving signals which is very sensitive.

So, all the services spotted seem to be VSAT narrow-band slotted TDMA/FDMA data. Maybe it’s another satellite co-located with Express AM5? Maybe it’s a re-use of the steerable C-band beam deployed to a different area?

The only clue is a beacon I spotted in the LHCP polarity, at 3948.067607Mhz, which seems outside the Express AM5 expected transmission band. The signal seems to be AM beacon with subcarrier at 77khz of a wide sort, but showing a different spectral signature (maybe a form of MSK?). According to this source, Express AM5 is expected to have a beacon on both polarities at 3850Mhz … and this does not seem to concur. However, mine seems close to 3950Mhz … which makes a typo a possibility? As a result, this is another mystery, with an inconclusive identity.

Conclusion

The first two satellites were positively identified, so nothing particularly special there, except for some very lovely looking spectrograms (which I dare to call art). The third was a bit of a mystery. In terms of mysteries, we’re really only just getting started. While I suspect the last satellite was indeed Express AM5, to hear a signal so far out of footprint would be odd. I won’t be starting any conspiracy theories though … it’s probably just a less-publicly-known satellite or a leased transponder/beam operating with different parameters.

From this slot onward for about 26 degrees of arc (to 166°E Intelsat 19), there is a gap in terms of C-band satellites which directly broadcast to home in this area, so I’d expect not to hear anything. Except that … I did. More head-scratching to come in the next post …

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