Posts by strannik

I liked everything except the man-made jump from 11131 to 11135 MHz, which throws IQmonitor to the last place due to the lack of a lock for the "fat" transponder at 11132 MHz V

Antenna 1.05m, Kyiv

Max SNR = 20.4 dB !!!

Quote from qwer

Just a look -via manual scan- on the radio services, using small SR... (from Türksat 3A West beam, according LyngSat))

Antenna 1.05m, Kyiv

Quote from femi

C-Band on Turksat?

Turksat does not have a C-band, but the program, unlike us, does not know this... It works with RF signals, the frequency of which is indicated on the lower, gray scale of the spectrum. When the LNB heterodyne frequency is higher than the upper frequency of the range, the RF frequency values will decrease from left to right, while the C-band frequencies increase in this direction (upper, main frequency scale).
I do not have a C-band RF signal, so I feed the program, which is configured to receive the C-band, RF signals of the Ku-band and get a test spectrum, which is a mirror image of the real Ku-band spectrum. Compare the central RF frequencies of typical transponders with the Ku-band spectrum in the messages above on the feed and you will see that the program works correctly in the C-band dynamic spectrum mode

Quote from femi

With this function you can optimize your dish. But remember, other bands, like C- or K-band may not be the same!

It's a very rare case when you are wrong...

Today I reconnected the antennas:
- the 90°E antenna, which was connected via the "blue" notch filter to the A input of the TBS 6983, was connected via the "silver" notch filter to the B input of the TBS 6983;
- the 42°E antenna, which was connected via the "silver" notch filter to the B input of the TBS 6983, was connected via the "blue" notch filter to the A input of the TBS 6983
I loaded the spectrum of 42°E registered yesterday from the database and displayed it on the tablet in gray, as a basis for comparing the spectra. I registered the spectrum of 90°E in blue on it, and then registered the spectrum of the vertical polarization of the 42°E satellite in purple:

From the comparison of the spectra it clearly follows that the interference waves in the RF frequency range of 970 - 1010 MHz are interference on the cable from the antenna and they are completely suppressed by the "blue" rejection filter. "Blind" scanning of the satellite position 42°E was carried out, which confirmed the high efficiency of the filter, especially when receiving on the 3rd and 5th subharmonics of the internal heterodyne, as well as on horizontal polarization:

Today I reverse engineered the "silver" notch filter to show its design and, at the same time, to increase the notch frequency. First, I unscrewed the quarter-wave section of the filter (1) from the tee:

Then I removed the protective cap from the ballpoint pen as shown in photo (2) :

The open end of the coaxial cable (I used a Finmark 690 cable, in which the insulator is foamed polyethylene, with a shortening factor of 0.86) is wrapped with black electrical tape to prevent the central core from shorting to the cable braid, and it to the outer screen.
In the figure (3) the insulation is unwound, and two marks with a black felt-tip pen are visible on the cable:
- the first is at the calculated distance from the bare end of the central core and along it the cable was cut after winding the F connector;
- the second is applied exactly according to the size of the cable, which is hidden under the blue cap of the first copy of the rejection filter, the rejection frequency of which is higher and is at the bottom of the Ku range.
Finally, you can see in the figure (4) how the cable was cut with metal scissors. The cable deformation was eliminated by finger-crimping, and before insulating with electrical tape, the absence of a short circuit of the foil or wire braid hairs on the central core of the cable, which should be strictly on its axis, was checked.
Having insulated the end of the cable and inserted it into the handle body, I screwed the quarter-wave section of the rejection filter onto the tee.
Having registered the spectrum, I made sure that the rejection maximum had shifted up in frequency, remaining below the beginning of the Ku range.

In general, the spectrum has changed for the better and has become noticeably cleaner, and the SNR of many transponders has increased, especially in the area of the 3rd and 5th subharmonics:

The strongest effect was observed for horizontal polarization:

A pleasant surprise for me was the 11069 H transponder, which I had not seen before in the shadow of its powerful neighbors...

Quote from satesco

You overwhelm me, dear strannik, with your generosity, in the not-at-all peaceful conditions in which you live.

Я ценю Вашу иронию по поводу небывалой "щедрости" в условиях военного времени, ведь Вы наверняка читали

Quote from strannik

My costs for making the notch filter were only $0.57

57 центов - это копейки в нашем понимании.

Гораздо хуже, что Вы не понимаете, что я от Вас хочу - СПЕКТРЫ полезных волн и волны-помехи как функцию мощности сигнала от радиочастоты на входе Вашего приёмника. Знаю, что у Вас есть программа IQmonitor, с помощью которой это делается за пять минут, и Вы нею умеете пользоваться. Не хотите пользоваться - насильно мил не будешь - сделайте спектры на любом другом программном продукте или спектро анализаторе. Вам для расчёта заградительного фильтра нужны именно RF частоты. И выберите, пожалуйста, один объект для наших показательных расчётов режекторного фильтра

Quote from satesco

I was wondering if it would be possible to make one for me, for a fee, including shipment.
What do you say?

I offered to make a filter together and for free. To begin with, I asked to make a spectrum of the range of interest to you, on which the interference would be visible:

Quote from strannik

First, please make a spectrum of the working frequency range with the spectrum of the intense interference that you want to suppress in IQmonitor. And publish it here, in the topic.

In IQmonitor, unlike other similar programs, there is a gray scale at the bottom of the spectrum, which is not striking, but which displays RF frequencies regardless of the range of received waves, the frequency of the first heterodyne and the method of conversion (up or down) of useful signals.
These frequencies (the beginning and end of the operating range), as well as the frequency of intense interference at the Z receiver input, are the basis for calculating the length of coaxial lines in the rejection filter.
If for some reason you change your mind - let me know - we will wait until someone is really interested in this (no longer mine) problem.
femi
Many thanks for the link to the pdf file. Unfortunately, it is copy-protected and cannot be translated into Russian... And I do not know German, although I had two graduate students from Germany on an internship (Frank Volkersdorfer and Catherine Schöne, with whom we communicated in English).
I was pleased to look through the articles that are my peers and which I see for the first time. I looked through the drawings, graphs and formulas - they fully correspond to the classical theory of wave propagation in lines.

. . . Notch filter of frequency 10724 MHz . . .
======================================
filatov_yuri
March 14th, 14:59

14 March 2025 - Филатов Юрий ака СТРАННИК

14 March 2025. Спутниковое телевидение

filatov-yuri.livejournal.com

Vertical polarization spectrum with intense (-35 dBm) interference at frequency 10724 MHz

Intense interference at frequency 10724 MHz (intermediate frequency 974 MHz) creates a strong background of intermodulation interference, which degrades the reception of satellite signals in the entire Ku range.

To combat this interference, a filter was designed and tested from two sections of coaxial cable, an RF tee and three F-type connectors.

A rejection filter is connected between the satellite antenna drop cable and the PCI-exp card input. The spectrum obtained with this setup with the results of a blind search is shown below.

Vertical polarization spectrum with a rejection filter, which suppressed intense interference by 17 (-24) dB

Interference suppression at a frequency of 10724 MHz was 17 dB, which had a very favorable effect on the SNR of useful signals. It increased by 0.2-1.9 dB. In addition, a signal from two more transponders was additionally received, one of which with SNR = 9.7 dB!

Below you can compare the spectra WITHOUT a notch filter (on the right) and the same frequency ranges recorded WITH a notch filter (on the left):

Beginning of the Ku band — spectrum with a notch filter on the left, spectrum without filtering on the right

SNR gains (from left to right) were 0.2, 0.3, 0, 9.7 and 0.9 dB

Middle part of the Ku band — spectrum with a notch filter on the left, spectrum without filtering on the right

Here the gains are 0.4, 1.0, 1.9, 0.7, 0, 0.5, 0.3, 0.7, 0.1, 1.0, 1.5, 0.5, 0.3, 0.5, 0.6, 0.9, 0.9, 1.0, 0.9, 1.1 dB

End of the Ku band — spectrum with notch filter, on the right is the spectrum without filtering

At the end of the range, the gains are 0.5, 0.3, 0.5, 0.6, 0.9, 0.9, 1.0, 0.9. 1.1, 1.2, 0.8, 0.6 and 0.7 dB.

My costs for making the notch filter were only $0.57

Quote from satesco

What do you say?

What can I say?
Taking money from old friends and colleagues is not in my rules...
As one wise fisherman said when he was asked for a fish:
"I will give you a fish, but you will be full for one day.
I will give you a fishing rod, and you will be full for life"
I will describe the design of the rejection filter and help calculate and adjust it, and you yourself will cut two pieces of coaxial cable with a known coefficient of electrical shortening, screw on three F connectors and close the appendix with a metal cap from a ballpoint pen.
First, please make a spectrum of the working frequency range with the spectrum of the intense interference that you want to suppress in IQmonitor. And publish it here, in the topic.

Quote from SaTom

A few years ago I read a Hungarian Satellite DX-r book or magazine published in the 1990s, and which this very solution was proposed and described, for KU band applications.

You probably remember my post about the impossibility of reception in the C range due to powerful out-of-band interference in the "Small talk" section.
I thought a lot about how to suppress this interference or the interference that I have at 10730 MHz and interferes with reception at the beginning and throughout the Ku range.
I thought for a long time, and recently calculated and made a rejection filter in five minutes, which is shown in the figure

{ Rejection 10700 MHz -24 dB }

I was counting on a rejection frequency of 10700 MHz, so as not to completely cut off useful frequencies at the beginning of the Ku range. In fact, it turned out that the interference on the original spectrum, which is drawn by the blue curve at a frequency of 10730 MHz, after the inclusion of a rejection filter in the gap of the antenna cable is suppressed by 24 dB (see the black curve on the spectrum)

{ Rejection 10730 MHz -24 dB }

At the same time, the local minimum of the noise level is at frequencies of 10640 - 10740 MHz.
And C/N at a frequency of 10390 MHz increased by 5 dB!

Please compare the results of the blind search during registration after the inclusion of a rejection filter in the antenna cable and before (without a filter) in the figure:

{ Before_&_after_Rejection }

{ Without_Rejection }

{ Before_&_after_Rejection }

Pay attention to the 11263 MHz transponder, whose "legs" are exactly at the noise level along the black curve, and the transponder lock reserve has increased by 2.9 dB!
And the SNR of the 11881 MHz transponder has increased from 16.9 on the original (blue) spectrum to 18.4 dB with a rejection filter, i.e. by 1.5 dB.
The 11895 MHz transponder, which was not locked without a filter, after the inclusion of a rejection filter received a confident lock with SNR = 17.4 dB!

This post is based on my article Notch Filter on my blog

Quote from Notch Filter

https://filatov-yuri.livejournal.com/2025/02/15/

femi

Many thanks for the great, painstaking, and, most importantly, very productive work!

Due to the inadequacy of the translation, there is confusion between a unipolar LNB and an LNB with one polarization (as a rule, the vector of a linearly polarized signal is perpendicular to the wide side of a rectangular waveguide). But if H (horizontal) polarization is enabled in IQmonitor, the LNB is supplied with a supply voltage of 18V, and V (vertical) polarization corresponds to a supply of 13V, which leads to a decrease in the transmission coefficient and some deterioration in the frequency response.

Therefore, two similar, but not identical curves are observed on the dynamic spectra, which show changes in C/No.

In the upper left corner, the instantaneous C/No value for 18V supply is shown, and below, in gray numbers, the C/No strongly averaged over the ring stack is shown. This real-time statistical processing allows to increase the accuracy of C/No measurement to 0.01dB compared to 0.2 dB at the ADC output. The instantaneous C/No value for 13V power supply is shown in the upper right corner.

The first dynamic spectrum was recorded at 09-49-36 and, according to the agreement, should correspond to the LNB position before the adjustment. It shows 9.7dB H (on average 9.93dB) and 10.9dB V.

The last dynamic spectrum was recorded at 09-56-56 and, according to the agreement, should correspond to the LNB position after the adjustment. It shows 12.5dB H - 2.8dB more (on average 11.93dB - 2dB more) and 11.4dB V - 0.5dB more.

Now let's compare the SNR on the feed reports after and before the adjustment:

17.4 - 16.6 = 0.8dB (H)

11.9 - 8.6 = 3.3 dB (V) On average, the SNR increased by 2.1dB, which corresponds well with the improvement of the average C/No by 2dB.

PS For TBS 5927, 6903, 6908 and 6983 cards, you need to enable the TBS-6983 checkbox, but do not enable the S2X checkbox!

I confirm the symbolic speed, but the modulation is not QPSK+16APSK, but more complex... But the signal is definitely DVB-S2X:

Excellent result! I would say more good and kind words if I could see the registration parameters in the main program window, as I did in my previous post.

Now I can advise you to check and, if I have interpreted the horizontal and vertical spectra correctly, adjust the LNB rotation around the axis:

- set the current frequency F=13505000kHz, and polarization H;

- turn on the dynamic spectrum Dynamical and adjust the vertical scale so that there is a reserve of ~2dB at the top and bottom;

- stretch the spectrum window as much as possible vertically to ensure maximum adjustment accuracy;

- turn on the V checkbox on the dynamic spectrum, then stop and close the dynamic spectrum. Immediately click Dynamical again - its window will open again, but in addition to the H spectrum, there will be a more inertial auxiliary spectrum V;

- make and save the original spectra (before adjustment);

- proceed with the alignment. If the computer screen is not visible from the focal point of the antenna - two smartphones and a video stream will help you (to avoid interruptions, press Start 100 many times);

- now slowly rotate the LNB around the axis so that the SNR (H) is maximum with minimum SNR (V), and the spectral pattern is as different as possible. Save this spectrum;

- without changing the angle of rotation of the LNB, try to slowly move the LNB to the side and away from the antenna mirror. Having reached the optimum for H and V, take a picture of the dynamic spectra. Keep in mind that this setting is frequency-dependent (see the article);

- now try (without fanaticism) to move the converter holder with your hand to the left and right (checking the correctness of the antenna adjustment to the satellite by azimuth), and then up and down (checking the correctness of the antenna elevation angle). If necessary, adjust the antenna.

Good luck to you, we are waiting for pictures of the dynamic spectra of your antenna

Today's observations are not impressive, but rather simply confirm the previous experiment:

Congratulations!

It looks like you have registered a transponder with a center frequency of 13583765 kHz in a frequency band of 3.75 MHz, which corresponds to a symbol rate of 3131 kS/sec

My attempt to receive this transponder on the 3rd harmonic of the heterodyne with a 1.05 m antenna and an Inverto Black Ultra LNB was not so successful...

Here is what I managed to "catch" in manual mode:

The day before yesterday I tried to install the latest version of CrazyScan...

I'm ashamed to say that I didn't succeed. At first I tried to reduce the area occupied by the program on the screen as much as possible and was unpleasantly surprised that now the minimum size of CS was 1012x682 pixels, and the spectrum itself occupies 922x403 pixels (the efficiency of using the screen area is only 54%)

The spectrum is "clogged" with the axial lines of the transponders, despite the fact that I removed the parameter signatures that completely kill the spectrum, deciding to print them out later as tables...

Compare with the spectrum of 800x478 pixels with the signature of the transponder parameters from IQmonitor Lite:

Dear crazycat made an attempt to correct SR transponders and remove (only from tables) unlocked transponders and ASPK modulations. He succeeded in the latter, but the "correction" of SR transponders by replacing the last digit with "0" only INCREASED the SR detection error!!! Compare the digits on the last spectrum and in the CS tables:

But that's not the saddest thing... The usual BlindScan stops after the first (maximum second) transponder found, so scanning in this mode is impossible with either TBS cards or budget cards (like OMICOM, for example)!!!

In addition, during the process of switching the TBS-6983 card from A ---> B, the RFscan/FFTscan impossible board popped up. Although only the second part of the statement is true, that there is no reason to block the normal scan button...

SNR=12.6 >> SNR=6.5dB

SR 80kS/s < SR 84 kS/s

Rmax=68 > Rmax=57

FER=0.024<<FER=0.068

13156960kHz - true frequency of 8PSK signal of DVB-S2X standard ?

11452000kHz - frequency which is accepted on the third subharmonic of the heterodyne of the outer ring of the signal as QPSK of DVB-S2 standard.

For this "pseudosignal" the inner ring of symbols with MER commensurate with the outer ring is perceived as interference and reduces the effective SNR by two times, i.e. by 6dB ---> 12.6 - 6 = 6.6 ~ 6.5dB

Dear femi

Your problems with TBS 6903x worry me and I am determined to try to solve them.

We need to solve the problem of processing DVB-S2x signals with regular DVB-S2 cards based on IQ constellation analysis.

There are a number of problems there, which I will write a separate article about. Work on the IQmonitor Pro software series will continue, but today there is a significant defect, which I call a "memory leak". This is related, as I think, to my favorite "black box" - StreamReader. This is manifested by writing information to the current (displayed on the screen) spectrum during the cyclic execution of the blind search procedure.

I really hope for your help in solving this problem.

I partially solved another problem, which is related to saving the results, on a lightweight version of the program (IQmonitor Lite). I will transfer this solution to IQmonitor Pro.

On the other hand, extensive testing and improvement of the above-mentioned software solutions is possible and effective when involving a wide range of satellite reception enthusiasts. Therefore, I intend to develop a lightweight version of IQmonitor, which, with an electronic key, will provide access to advanced functions and new features of the program.

In addition, I do not want the program to die along with its author

The topic created by my best friend stephan94 from a "small program" has grown into one of the largest branches of the forum, which continues to arouse interest among true fans of satellite reception

As the IQmonitor program improved, its interface developed and became more complex, and a new series of IQmonitor Pro programs appeared. Unfortunately, the events of the last two years, frequent and sudden power outages and power outages up to 23 hours a day, my concussion from a nearby exploding rocket, deteriorating vision, memory, deprivation of my mailbox by the Internet provider and, as a result, the loss of my Microsoft account led to incorrect Win - 10 updates and a successive crash of four operating systems out of five...
In short, starting from Windows XP, I installed Windows 7 PE, made a sector-by-sector copy of the failed system disk, installed Windows 7 Ultimat on a "new" used HP Compaqu Ellite 8300 machine, installed "native" Intel drivers, XE-4, began to restore files and programs...
It was at this hard time that I decided to simplify the IQmonitor Pro program as much as possible, its complex interface, and abandon a number of unique and unclaimed functions. So I came up with the idea to create a lightweight version of the program - IQmonitor Lite. Moreover, it should work with all versions of StreamReader by the respected crazycat, but, unlike CrazyScan, on old computers with a screen resolution of 800x600.
The minimum size of the main window of this program is 840x680 pixels:

With this window size and useful spectrum area of 758x382 pixels, only 0.5 of the area is used

Let's compare the IQmonitor Lite window area of 800x504 with the useful spectrum area of 710x390.

That 0.69 of the entire area is used, that is, 19% more.

See how this affected the readability of the spectrum:

The minimum spectrum size of 585x461 with the spectrum area itself being 500x390 pixels gives

an area utilization factor of 0.72, which is 22% more than CS:

Compare scanning speed and quality:

Pay attention to the readability of the spectra and the accuracy of determining the parameters of the transponders -

IQmonitor Lite is more than 4 times faster than CS and gives accurate SR values.

But you simply cannot get such a spectrum in CS: