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Archived discussions on CrazyEngineers

@Kaustubh Katdare • 25 Jun, 2013
After the Indian Government made it compulsory for everyone to install the DTH service at home, we opted for Tata Sky in order to make our lives 'Zingalala'. But it's the dreaded rainy season (for DTH services) and the set top box remains useless for extended periods of times. As soon as the rains get a bit heavier, the signal disruption starts and the DTH box starts showing a message to wait until the weather clears before the signal can be captured again.

I checked online and found out that the problem is common with all the DTH operators and not just Tata Sky. The signal disruption due to rain is actually called 'Rain Fade' and it depends on the transponder voltage, signal strength and can be countered by the size of the dish antenna.

That leads me to several questions below and I'll be happy if someone can throw some light-

1. What's the frequency of the DTH signal and why does it get affected because of the rain?

2. What are the other factors that can affect the DTH signal?

3. What are the ways a constant link between the satellite and the dish can be maintained (if at all possible) which will remain unaffected by weather conditions?

4. Are there any 'home remedies' to tackle the situation?

Update: With the new Tata Sky boxes and satellite; I'm hearing the news that this problem has been addressed. Can someone add more informative details?
@Anand Tamariya • 25 Jun, 2013 All satellite services have this problem. I bumped on the issue when I used worldspace in 2006. And it irks me that there is no solution in 2013 yet!!
@Kaustubh Katdare • 25 Jun, 2013
Anand Tamariya
All satellite services have this problem. I bumped on the issue when I used worldspace in 2006. And it irks me that there is no solution in 2013 yet!!
Yeah - it's indeed very interesting. I created a thread in this section to see what's actually wrong with the DTH signals and whether there's any solution to the problem. I'm more interested in an easy fix we can implement at home, all by ourselves.
@Jeffrey Arulraj • 25 Jun, 2013 Heard in TCL

Every six months there is a position where the Sun's heat is received maximum by the satellites governing the local dishes

At this point the temperature of the satellite shoots up momentarily above the critical temperature there by causing distortion in the o/p of the satellite

There is no solution to this unless we invent technology to mirror sun's radiation back to the inter stellar space and that to cost effectively
@Anoop Kumar • 25 Jun, 2013 Looks like CDMA type technique can solve this problem.
Instead of direct link, there will be asynchronous transfer of data packets 😀
@Jeffrey Arulraj • 25 Jun, 2013 That is true but upload efficiency is not as high in CDMA as satellite uplinking and downlinking becomes more lossy and also pricy

So it is not implemented for satellite communication
@Anand Tamariya • 27 Jun, 2013
Conqueror
Heard in TCL

Every six months there is a position where the Sun's heat is received maximum by the satellites governing the local dishes

At this point the temperature of the satellite shoots up momentarily above the critical temperature there by causing distortion in the o/p of the satellite

There is no solution to this unless we invent technology to mirror sun's radiation back to the inter stellar space and that to cost effectively
Why does this happen at times of rain? Or is this one more reason why signal might go bad?
@Jeffrey Arulraj • 27 Jun, 2013 Signals can be reflected and dispersed a little by the droplets of water. This dispersion of signal can lead to loosing focus of radio signals. This can produce noisy signal reception
@RON_04 • 28 Jun, 2013 after a thorough research i found out a simple solution......place ur dish just below a 1feet shade....the rain wont effect it not even the wind...
@Kaustubh Katdare • 28 Jun, 2013
RON_04
after a thorough research i found out a simple solution......place ur dish just below a 1feet shade....the rain wont effect it not even the wind...
Are you sure that works? Because if that's the right solution, simply covering the dish antenna with plastic should do the trick. I doubht that's the right way of fixing the problem though. Because in my opinion, it's the excess humidity and moisture in the air and as Conqueror said, droplets of water that affect the signal strength.
@Jeffrey Arulraj • 28 Jun, 2013 • 1 like
RON_04
after a thorough research i found out a simple solution......place ur dish just below a 1feet shade....the rain wont effect it not even the wind...
I wish that will be really that easy. But in reality this noise is due to the long distance between the transmitter (Satellite) and Receiver(dish). This noise can not be easily removed by placing in shaded region.
@Sindhu Chowdary • 28 Jun, 2013 • 3 likes all the DTH services are operating through satellite communication.these DTH signals generally operates around 4Ghz and mostly 11Ghz i.e., Ku band...the main advantage of using this band is that the antenna size can be very small and the receiving equipments are relatively cheaper..
as Conqueror said signals can be dispersed by rain droplets and hence cause distortion...due to this distortion the decoder at the receiver fails to acheive the proper signal strength and hence we get a blank screen..
not only these certain other factors like DTH dish alignment , position of the low noise amplifier at the dish also effects the signal strength..
as far as i know there is no perfect solution to this problem unless we switch to some other frequency band..
there is one way which is just to improve the condition is by using superhydrophobic ( which means highly resistant to water) surfaces for antennas..it only reduces the effect thats all...
@Ashraf HZ • 28 Jun, 2013 Put up a couple of satellite dishes (à la antenna diversity), combine signal, do some coding and voila! Reduced BER 😀
@RON_04 • 30 Jun, 2013 see when the technicians install the dish they use a device to check whether the dish is catching the satellite signal properly or not........now after that if you have a shade to prevent the rain drops hitting the dish then the problem is almost solved. but yes it is a cheap solution which will not prevent heavy storms
@Esha Raghute • 30 Jun, 2013 The only solution to 'SIGNAL LOST' problem due to weather conditions is to readjust the dish because strong winds n rains moves the dish and the angle is lost and hence the signal.so readjust the dish position is all I can suggest.it works when I've the same problem.😀
@Jeffrey Arulraj • 30 Jun, 2013
RON_04
see when the technicians install the dish they use a device to check whether the dish is catching the satellite signal properly or not........now after that if you have a shade to prevent the rain drops hitting the dish then the problem is almost solved. but yes it is a cheap solution which will not prevent heavy storms
Well you can't cover the entire distance between the satellite and the roof do understand that
@lal • 30 Jun, 2013 • 1 like C -band doesn't seem to be afftected by this problem much. I hope it is because of the lower frequency than Ku-band (clarify communication engineers please).
But then, this problem can be solved to a large extent if I use a bigger antenna/dish, right?
@Jeffrey Arulraj • 30 Jun, 2013 All bands are affected b solar impact, C band gets lesser affect due to rain. But solar interruption is yet to be conquered in any band
@Sindhu Chowdary • 30 Jun, 2013 • 1 like Ku band is more affected by rain because above 10GHz the dissipations due to rain increases and hence rain fade occurs...but solar impact isnt much serious problem i think
@Harshad Italiya • 30 Jun, 2013 • 1 like
Esha Raghute
The only solution to 'SIGNAL LOST' problem due to weather conditions is to readjust the dish because strong winds n rains moves the dish and the angle is lost and hence the signal.so readjust the dish position is all I can suggest.it works when I've the same problem.😀
No that's not the main reason because sometimes cloudy environment cause signal disturbance and sometimes because of heavy rain. So main problem is signal error due to all this.

We can overcome this change in angle issue if we can put some mechanism which rotates dish in some directions and based on feedback signal. I am not sure about it's feasibility.
@Sindhu Chowdary • 30 Jun, 2013
lal
C -band doesn't seem to be afftected by this problem much. I hope it is because of the lower frequency than Ku-band (clarify communication engineers please).
But then, this problem can be solved to a large extent if I use a bigger antenna/dish, right?


actually you are almost correct...but correctly speaking it is not because of lower frequencies but because of higher wavelengths...
the attenuation increases as the wavelength approaches the size of a rain drop..the size of typical rain drop is approximately 1.5mm...
you know that wavelength and frequency are related by c=wavelength*frequency...
now for C band frequency is 4GHz..and so its wavelength becomes 75mm quite larger than the size of rain drop...so signals passes through the rain with less attenuation..for Ku band frequency is 11GHz it means its wavelength is around 25mm..it is also larger than that of rain droplet but still it has attenuation which can be managed...but if you go further i.e.,Ka band and V band their frequencies are very high and so very low wavelenghts..
hence the higher the frequencies the higher the attenuation due to rain..
hope i cleared your doubt
@Sindhu Chowdary • 30 Jun, 2013
Harshad Italiya
No that's not the main reason because sometimes cloudy environment cause signal disturbance and sometimes because of heavy rain. So main problem is signal error due to all this.

We can overcome this change in angle issue if we can put some mechanism which rotates dish in some directions and based on feedback signal. I am not sure about it's feasibility.

regarding the dish alignment i came across a page..i dont know whether it is much of use or not..but just check it out..
https://www.findurlaptop.com/tech/2012/09/04/dth-dish-alignment/
@lal • 01 Jul, 2013 So, some un-attenuated signal sure reaches the antenna. Now, if we place a bigger dish there, it will be able to collect much more signals, right. Thus boosting the over all signal strength at the receiver beyond that critical value. Shouldn't that help to some extent?
@Sindhu Chowdary • 01 Jul, 2013
lal
So, some un-attenuated signal sure reaches the antenna. Now, if we place a bigger dish there, it will be able to collect much more signals, right. Thus boosting the over all signal strength at the receiver beyond that critical value. Shouldn't that help to some extent?

yes it would definitely seems to help..but how big the antenna should be to receive such signals...
also the main advantage of Ku band itself is the use of small antennas...
what you suggested is true but we have to keep in my mind not only the solution but also the expenses..they should be balanced and also if the answer to this problem is such simple one already it should be implemented by now...
it is my point of you..if anything wrong please correct me....👍
@Ashraf HZ • 01 Jul, 2013 • 1 like
lal
So, some un-attenuated signal sure reaches the antenna. Now, if we place a bigger dish there, it will be able to collect much more signals, right. Thus boosting the over all signal strength at the receiver beyond that critical value. Shouldn't that help to some extent?
1. Its more costly. Larger dish would cause larger focus of power to the receiving element, so need more tougher hardware as well as safety requirements.
2. Depending on the satellite system used, the size of the reflect does matter to get focus on the right Ku band signal (and rejecting other satellites).

I suppose its better to have a farm of satellites than a huge one. Better control of the receiving signal, and each dish can act as a separate adjustable array.
@Amit0808 • 19 Aug, 2013 • 1 like Interesting discussion. I've a simple question: According to friends and other sources, DTH transmission in London remains largely unaffected by rain. What solutions could Sky TV have come up with that we in India haven't?
@Jeffrey Arulraj • 19 Aug, 2013 https://en.wikipedia.org/wiki/BSkyB

Please read the technical information page that gives a little details about the query you have

Mate the sky receiver focuses on a constellation of a satellites using Ku band receivers that aptly helps you to get much clearer imagery throughout the day

In India https://dreamdth.com/Thread-All-KU-band-Satellites-recivable-in-INDIA-official-coverage tells us the various ku band satellite locations

But the main problem comes in due to the spacing of the Ku band transponder satellites. In other words the satellites are wide spread in India when compared to that in UK as given here https://www.uk-satellite-tv.co.uk/satellitefootprintsinstallation_103674.html

The net result is that many areas in India come under shadow region of satellites But this is not the case in U. This occurs only due to the larger size of the nation and the longitudinal stretch of the nation
@ABCD ABCD • 19 Aug, 2013 Kaustubh Katdare, Government did make it compulsory to have DTH at homes. It was compulsory only to have Digitized connection. So you can still go with Digital Cable, which will have no prob with rains.
@maheshwaran ramasamy • 21 Sep, 2013 • 1 like simple trick that is cut the thinnest water bottle like aquafuna at the middle. place the bottom half of the bottle in dth antenna signal receiver. it will prevents the losing during rainy session and moisture will not affect 😀
@Kaustubh Katdare • 21 Sep, 2013 @maheshwaran ramasamy - will definitely try that. Looks like a nice trick. I've observed that Tata Sky has shifted to MPEG 4.0 transmission. Wondering if that alters everything. If the receiver isn't covered, I doubt it'll have any effect on the type of transmission.
@Sarathkumar Chandrasekaran • 21 Sep, 2013 I agree to maheshwaran . I had seen many dth like that but dont know the real background of it. One doubt: Does high wind blow has any impact on dth transmission?
@Jeffrey Arulraj • 21 Sep, 2013 Wind is air media and so it does not affect

Only features like humidity temperature and others which have relative permeability and permittivity will have some effect on signal transmission
@Sarathkumar Chandrasekaran • 22 Sep, 2013
Jeffrey Samuel
Wind is air media and so it does not affect

Only features like humidity temperature and others which have relative permeability and permittivity will have some effect on signal transmission
Are you sure about this?
Does severe cyclonic wind have impact on transmission?
@Jeffrey Arulraj • 22 Sep, 2013 • 1 like
SarathKumar Chandrasekaran
Are you sure about this?
Does severe cyclonic wind have impact on transmission?
Cyclonic wind has higher humidity

That will affect the signal transmitted and received mate
@yogi.bharadwaj • 03 Oct, 2013 i think its only happened due to the flowing water droplets on the antenna because when the antenna of mine DTH is not fixed i placed it inside in door and when rains it don't disturbs the signal.there is no need to change frequency or any other thing just try to make a antenna on which water don't flow or fix the antenna beneth the roof so,it don't suffer by flowing water and i think its worked.if i am wrong till then it works about 50% if not pls correct me.thank you.
@Shikimaru • 08 Oct, 2014 I think our problem will be solved if we know how d airtel dth system works as there is no interruption in signals even during rain. I wonder why this problem is there only in tata sky?
@hemantborole • 21 Jul, 2015 • 2 likes Aha! Something I can answer.

Most of the signals you receive for TV broadcasts are going to be in Ku band. This name, in long hand, is Kurz under. The Kurz (K-band) frequency range is that which is resonant with water. Due to this, the K-band is absorbed and dispersed readily by atmospheric water (Humidity and clouds) and especially bad in inclement weather. The Ku band allows transmission at high frequencies and data rates while being able to penetrate the atmosphere with sufficient power left over to give acceptable signal performance. Ku isn't infallible though. Due to its proximity to that magic K-band, it is still very susceptible to precipitation. In addition to the absorption, the increased mass between the dish and the satellite scatters and attenuates the down signal from the satellite.

The wonderful thing about satellite receivers is Forward Error Correction. Built into the broadcast are check bits. This can vary in rate depending on the provider, but it is always there due to the nature of Satellite communication. This is the reason you get stops and starts in your TV's picture. You're seeing sections of unrecoverable data being thrown out, leading to the skip and audio abnormalities.

tl;dr, TV Broadcasts are in Ku-Band, which is attenuated by rain due to its frequency range. Also, any signal in almost any band is going to be attenuated to some degree by any increase in mass between transmitter and receiver.
@hemantborole • 21 Jul, 2015 • 2 likes What happens to these Ku bands when it rains? Well to learn that we need to know what Ku band is. In simple terms, this band refers to broadcast signals that range between the frequencies of 10.95 GHz and 14.5 GHz. The wave length of waves in this band is quite short (about 2cm). When any wave passes through the atmosphere and encounter water droplets it will cause some attenuation. This attenuation is exaggerated when the droplet “hits” the wave when it reaches half the wavelength in its diameter. This problem is common to all waves however, in case of waves in the Ku band, the degree of attenuation is far greater than those observed in other frequencies with greater wave lengths. Therefore, the moment it starts raining, there is chance of the signal being interrupted. Well, unfortunately no. Even networks that use the slightly higher frequency Ka bands are susceptible to this issue. One way out is the use of superhydrophobic surfaces for antennas used for DTH reception. As the name suggests, surfaces with these coatings will be highly water resistant. This method doesn’t guarantee a fix – but only reduces the effects. In simpler terms, this is known as the lotus effect. If you have observed the leaves of the lotus plant, you will notice that its surface never gets wet. This happens because of a natural effect (which will be too complex to describe here). More on that here. So, using an antenna with a superhydrophobic coating could help improve things. Other than that it seems unless we switch to some other frequencies for DTH broadcasts, this issue is here to stay!
@PCC • 25 Aug, 2015 Does this problem exists in developed countries (USA, UK, Germany etc.) also? If no, what technology they are using and why cannot we use the same?
@suresh_sk • 09 Oct, 2015 • 1 like guys..when it rains..u should enjoy the rain..and go out for a drive...dont sit at home in front of the TV...waiting for the rains to clear....that's the best solution...
and when u rtn...all rains gone...signal back...tv works...u r happy...family is happy...
@suresh_sk • 09 Oct, 2015 arey guys...think out of the box...do this simple solution....
when it rains switch off the TV...pick up ur car keys ask ur wife and kid to hop on and drive and enjoy the rains...if u eat non-veg...try some tikkas and kababs...
come back after it's stopped to rain ....and viola...TV is back...all done deal...period..
@Jawahar Jayagopi • 11 Nov, 2015 I too faced the problem intially - then dth provider a solution he tied half cutted plastic bottle - in the receptor side - so now i come the problem
@Vittalanand • 12 Nov, 2015 I do not agree with the idea of providing a rain cover over dish. Signals not only get earthed without reflection at tehdish, but they get attenuated at their pathe with is damp due to rain dripplets and a part get earthed on their way to dish itself.
@Vittalanand • 12 Nov, 2015 I do not agree with the idea of shading the dish. The signals not only areget affected by the reduced convergence of signals at the LNB, but in the course of travel through rain dripplets, a part of the signals get earthed in my opinion and this attenuates the siganal strength. as they are electriclly charged . When the rains continue, the cloud/ rain particels get neutalised to some extent and reception with low signal strength is enabled.
@Vittalanand • 12 Nov, 2015
Jawahar Jayagopi
I too faced the problem intially - then dth provider a solution he tied half cutted plastic bottle - in the receptor side - so now i come the problem
@Vittalanand • 12 Nov, 2015 You mean the problem has been overcome with a plastic cover.? I have tried binding a plastic cover over thge LNB but there is no remedy. The signals get attenuated when they cross wet plastc cover as they are erathed.The LNB is it selve has a plastic cover. May be the coupling saved from damp cndition , but the striking of signals inside LNB's coil remains still reduced.
@shah rahul • 16 Nov, 2015 great knowledge...thnx for shearing
@Ankita Katdare • 18 Dec, 2015 I was just wondering if there was a way to minimise the effect of rains on DTH signals. A friend just called up to say she read this post and they have Videocon D2H at her place and when they called up the authorities they said they were helpless and she'll have to wait till the rain gets over.

Is it possible for these companies to create a hydro-phobic surface for the DTH antennas that we install in our homes? If such a coating is made on the dish's surface, it could become water resistant.

I am sure this will not guarantee a fix, but could it at least reduce the effects? Waiting to hear your inputs on this.
@lal • 18 Dec, 2015 • 1 like
Ankita Katdare
I was just wondering if there was a way to minimise the effect of rains on DTH signals. A friend just called up to say she read this post and they have Videocon D2H at her place and when they called up the authorities they said they were helpless and she'll have to wait till the rain gets over.

Is it possible for these companies to create a hydro-phobic surface for the DTH antennas that we install in our homes? If such a coating is made on the dish's surface, it could become water resistant.

I am sure this will not guarantee a fix, but could it at least reduce the effects? Waiting to hear your inputs on this.
The reason is not in any way related to the dish or LNB. Those devices are manufactured to withstand rain, sun and snow. Rain alone is the culprit here.

The signals from satellite transponders will be hindered by clouds and droplets of water when heavy rains pour down. That is like a semitransparent or even opaque, at times, wall that limits line of sight communication with the satellite.

There is nothing much to do rather than wait for the rain to clear off in Ku-band communication (used in DTH services). Or install a 'BIG' dish to collimate enough signal.
@Ankita Katdare • 03 Feb, 2016
lal
Or install a 'BIG' dish to collimate enough signal.
Why don't the service providers employ this solution? Are there any obvious disadvantages to it?
@Vittalanand • 03 Feb, 2016 may be you run four dishes with LNB in each dish , all oriented to satellite of which two each will be connected in series and both the sets of so connected dishes will be connected in parallel so that the total impedance will be maintained as a single LNB but the signal collection may be doubled even when there is rain, and without altering the loading parameters.. But I say this is only a desk top thinking not yet tried by me due to space,and cost restraints.
@lal • 03 Feb, 2016
Ankita Katdare
Why don't the service providers employ this solution? Are there any obvious disadvantages to it?
Yes, the biggest advantage of using 'Ku' band is the ability to use a very small collimator to get decent signal quality on average. A bigger collimator is kind of a hack for 'Ku band' communication. It's like altering/hacking Wi-Fi antennas for better coverage which in normal case is not required.
@Charan V • 03 Feb, 2016 Does getting signal from repeaters/boosters at neighboring places without rain work ?
@Rahul Kamat • 10 Jul, 2017 Hello Guys,

The rain outage in moderate to heavy rains has still not be solved. As soon as the rain gets stronger signal vanishes. I have seen signal go even in thick clouds when there is no rain, however this is for few mins.

One of my friend has a TS HD Transfer + STB and he got a new LNB known as Super LNB. The technician came and replaced the old LNB with Super LNB and changed the LNB settings in STB, and done.

Now he doesnt face much signal outage, unless its raining very very heavily.
@Kaustubh Katdare • 10 Jul, 2017 Though slightly off-topic; I think the days of DTH are numbered. It's soon going to be replaced by Fiber connected Internet TVs.
@Rahul Kamat • 10 Jul, 2017 Are there any companies that provide the same ??? AFAIK, IPTV was a failure and AIrtel withdrew their services. Jio on the other hand is coming up with what they say is Cable TV via FTTH. But i dont think DTH will soon be old or days are out numbered. Even in UK/US DTH still is a major competitor
@Kaustubh Katdare • 10 Jul, 2017 @Rahul Kamat - not at this time; but that is where the future is. Already about 50% of the TV shows watched in my house are all available on the Internet via Live TV. If Tata Sky loses the signal; we simply start streaming the show to our TV and it works pretty well.

I'm guessing it'll be Jio's TV offering that will work with JiFibre. At least, I'm hoping that I'll not have to renew my subscription in December this year. I firmly believe that DTH will go; even if not from the world; but from my home; for sure.
@Kaustubh Katdare • 16 Aug, 2018

Update: 

Has Tata Sky fixed the issue of signal disruption in rain? The other day, we've had heavy rains and yet the DTH worked fine. Can someone confirm?

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