Posts by s-band

qwer  satesco

I think that there are big problems with the BWEI LNBs on Ext KU. They appear to have very poor image rejection which gives the effect you see. It is especially bad on 42E due to the strong signals below 12.75GHz. I don't think they have much RF filtering. There is also the problem of unwanted sampling modes in TBS and other cards.

One way to check if you are 'seeing' an image is to look at the Spectrum box on CS which usually shows 'Inverted' on most signals. If it shows as non-inverted, it's likely to be an image response.

My modified SMW is a 12.25-12.75GHz PLL which had an LO of 11.3GHz. I have changed the LO to 11.75GHz and tried to improve the performance on ext Ku. However although the NF is 2dB, the gain is 20dB down compared to its response at 12GHz. I use a 1.5GHz high pass filter followed by an 18dB gain amplifier in the IF. I still see an increase in noise when pointing at the strongest satellites and this is probably caused by front end overload.

1.8PF 2dB NF LNB

I don't remember seeing the approx 800kHz wide signals at 13625.5, 13627.5 and 13605.5H which are all much too low to get a lock. The peak at 13526H is from 42E and the signals at the low end of the band were described here. As before, the transponder noise can be seen.

strannik I wonder if you are getting a false positive from the pair of closely spaced carriers on 13584 H & V. If the polarisation is not set exactly, both are present at the same time.

Nothing visible here. 1.8m PF, 2dB NF LNB

13497H still there but in and out of lock as clouds pass by.

The mid-transponder beacon has the 2, closely spaced frequencies similar to 5A but the vertical one is at a much lower level in this case.

The transponder bandwidth can be clearly seen on V & H. However, I can find no evidence of any other signals, from near London, and the method used here is quite sensitive.

1.8m PF 2dB NF LNB

femi What is your ext Ku LNB model number and LO frequency?

Today's plot the horizontal signal I had seen is no longer present. I'm using the same 2dB SMW LNB but on a 1.8m PF

Quote from strannik

SRmin = 30 kS/s :

As you can see, the constellation has become very clear, and SNR = 12.3 dB! SR = 92 kS/s, and at the corresponding frequency of the first harmonic

11452 MHz such a powerful signal is not observed

I'm not sure what that can be. Is it a terrestrial link?

Today jaes (SatsUK) found colour bars on 13497H 13330ks/s. I can only just lock this on a 1.8m dish. There is also a carrier on 13526.00073MHz horizontal.

The confusion over the polarity of 13584 is caused by there being 2 carriers spaced by 900Hz. The lower one is vertical and the upper is horizontal. If you use a wide bandwidth, you'll see a small dip as the skew is swept through 45 deg offset. In an audio BW the 900Hz tone should be audible.

For the plots below I used a modified SMW 12.25-12.75GHz LNB with an LO of 11.75GHz (the system is locked to a Rb source). The NF is about 2dB and the dish a 1.8m PF. The actual frequencies are on the plots.

Quote from un_q_

But, with smw, CrazyScan found some more transponders.

The number of TPs varies a lot with feeds on and off and 10804 and 10845H give random values and sometimes aren't detected due to their mode.

I carried out some tests to compare a Bullseye LNBF with a SMW Q-PLL Type C on a 1.8m PF dish.

SMW Q-PLL Type C on IRTE C120 adapter
Bullseye LNBF with feed removed fitted to C120 flange from Invacon LNB

The plots here used Crazyscan's blind scan 1 with 2MHz steps. This gives more repeatable results than BS2 but doesn't catch all signals. There is more data than presented here but it needs processing. I would normally compare systems using Sun noise but the tracking dish is out of use at the moment. Notes:

• Cloud cover changes resulted in 0.5dB variations, maybe more.
• 7E chosen as it was of interest at the time
• 10804 and 10845H give random values sometimes
• Skew set by nulling beacons. SMW had >32dB X polar rejection and Bullseye <27dB
• 10720H varied by the most with varying cloud (to be expected)
• Number of feeds varied through day
• Might be better to do 7W as that has most low level signals
• High SNR signals give poor indication of differences as 1dB RF change results in <<1dB SNR change when > about 15dB SNR.
• BS1 used with 2 MHz steps, BS1 & BS2 scans saved as .ini

I can see the the beacons using a RHCP feed on a 1.8m dish but nothing lockable (RH only)

Quote from stephan94

what is it " BSOD" ?

Blue Screen Of Death (Black in W11)

Using a Milsat band feed this time on RHCP I think these are from Syracuse 3A. 1.8m PF dish.

9GHz LO, Plot centred on 7495MHz but spectrum inverted.

TS Reader outputs and a good picture capture from 7702MHz:

1.8m RHCP

The upper 100MHz TP appears to be TP noise with pulsed BPSK signals as below:

There are more satellites than I thought with RHCP. I have to get on the roof to change polarisation so I don't do it often.

1.8m PF Dish RHCP

I question if it's worth spending time on X milsat but can't help it! Originally, I did it as a stepping stone to DSN. There's a lot to be found in the Earth observation part 7.75-8.4GHz so it's worth getting an LNB that will cover it all if possible. I've never tried them but I think this company https://roks-tv.com/lnb-xpxx-v1 has much better pricing than SMW/Norsat etc. I believe that they will do custom versions as well.

1.5m is fine for milsat and Earth obs. I was using a 1.2m before this 1.8m.

These 2 were first found by dreamsat on SatsUK. There must be more on the streams but I can only see the 2 channels with 640 x 360 resolution. It took a while to get full pictures from 7702MHz and I did not manage to get any complete frames from 7649MHz. There were bursts of audio form each. I was using a 1.8m PF dish.

I put the electronics and scalar from this post on the C band mount on a Precision (Elite) 1.8m PF dish. I'm not sure what effect the C band scalar has on the X band performance. It worked best with the X scalar fully inside the C band scalar.

1.8m PF

A year since the last look. This time with a 1.8m PF dish (LHCP).