MAHESH AND ALL, MY REPLY IS IN CAPITAL:
On Fri, 2009-09-04 at 12:19 +0530, mahesh acharya wrote: > Hello Hemant and all, > > I am not an expert in radio transmission however I would like to share > some of my thoughts that may be useful. > > I am sure the team has taken care of other things, I am very curious > to have a look at the set up. Can you send some foto's. Especially the > transmission cable between transmitter and antenna. > There may be a possibility of signal leakages/signal loss from within > the equipment/cables or overheating. Example the transmission cable > should not be running along metallic surface (pipe), wall, or ground. IF THIS WAS THE CASE THAN THE SOUND SHOULD COME ON ALL FREQUENCIES IN THE BAND AND NOT ONLY ON 107.8 > > > I am curious to knw how did u measure the 50watts output. THERE ARE STANDARD RF WATT METERS AVAILABLE IN MARKETS. !! > > > I am afraid the crackling noise is not picked up from the air. It is > due to phenomena called as FM threshold effect. And to put it in > simple terms there is mismatch in carrier to noise ratio. Thus u guys > need to identify the source of noise which I am pretty sure is > originating from other sources from within the studio. I would not be > surprised if the source is tube light!!, or machines in physics lab. AGAIN ALL THESE COULD BE TRUE ONLY IF SOUND IS CONSTANT ACROSS THE BAND. THIS YEAR ALONE WE HAVE MADE 32 TRANSMITTERS AND HAVE INSTALLED SEVEN IN INDIA. MANGALORE IS THE ONLY PLACE AND 107.8 IS THE ONLY FREQUENCY WHERE WE HAVE SEEN THIS PROBLEM. WE DONT KNOW AS OF NOW WHERE THE PROBLEM IS BUT POSSIBLE CAUSES MAHESH MENTIONED ARE THE MOST COMMON ONES AND WERE CHECKED UP IN FIRST HALF AN HOUR OF DETECTING THE PROBLEM > > > For the benefit of other readers, voice and music from a radio > actually piggy backs (modulates) on a radio wave called a carrier > (wave) and thus called carrier. > > Hemant signals from 50w transmitter can reach further of the terrain > is flat. However it is the voice and music that should be audible. So > if the signals are reaching 15-20 km but not audiable...it is as good > as not audible in the technical audit. Please appreciate noise cannot > b ignored as it is 'present'. > > cheers! > mahesh > > > On Fri, Sep 4, 2009 at 9:48 AM, Hemant <[email protected]> wrote: > Message: 1 > Date: Wed, 2 Sep 2009 19:24:00 -0700 (PDT) > From: Vickram Crishna <[email protected]> > > > > Hello All, > > Since Nomad engineers have installed and re-analysed the > problem faced > by Dr Rego, I would like to share following observations: > > 1. The transmitter is generating exactly 50 watts of power as > stipulated > by the Government. > > 2. The antenna is giving the stipulated gain (approx 2.8 dBi) > while coax > length is less than 10 meters. > > 3. The SWR is less than 1.1 > > 4. System is not generating any noise or spurious. Some > crackling sound > is being picked up in air. > > 5. Signals are reaching as long as 15 to 20 km if you ignore > the noise > > 5. All problems are sorted out if we operate anywhere else in > the > frequency band > > Possible reasons: > > 1. Spurious and harmonic interference from other RF systems, > may not > necessarily radio stations. > > 2. Very high levels of moisture due to monsoon season. > > Possible solutions: > > 1. Change the Frequency to 90.4 as given to many other > community radio > stations. > > 2. As it has been discussed before CRF should request WPC to > avoid > alloting 107.8 to low powered radio stations. > > Hope this helps. > > in solidarity > > Hemant > > > > Subject: Re: [cr-india] on frequency > To: CR India <[email protected]> > Message-ID: <[email protected]> > Content-Type: text/plain; charset="utf-8" > > Dr Rego > > There are two possible problems. One is that your own > transmitter is not > generating sufficient EIRP, which could be due to an antenna > mismatch. > The second, and more likely, is that other stations nearby are > generating spurious signals at your allotted frequency band. > As you > report, they 'invade' your space. > > According to you, 'checking' for the cause only got you the > answer > 'frequency' - who gave you this answer? If it is anyone from > the > Ministry (telecom or broadcasting)/WPC, then perhaps you need > to file an > RTI asking them for copies of orders given to the other > stations to > repair their setup. > > It would also be useful to track the actual status of > transmission > during your broadcast timings, and also at other times, in > order to > establish whether your bandwidth is being cluttered by > spurious signals > from other nearby stations. Finally, is there a chance that > you are > located too close to the transmission towers of any other > stations? The > SACFA clearance was supposed to take care of this aspect, of > course. > > Vickram > http://communicall.wordpress.com > http://vvcrishna.wordpress.com > > > > > ________________________________ > From: Dr Richie Rego SJ <[email protected]> > To: CR Forum <[email protected]> > Sent: Wednesday, 2 September, 2009 22:57:35 > Subject: [cr-india] on frequency > > > > Hi everyone! > > I have a problem. Would like to know how you would deal with > this - we > have 107.8 MHz frequency assigned to us. But low power radio > sets and > mobiles cannot receive our radio signals even in nearby areas > - car > stereo do. That means, local communities are deprived of our > transmission. People keep pleading us "increase signals" - > they have > listened to our station sometime; they have read in > newspapers. hence > their demand. We are unable because of the frequency. We > checked why > this happens. The answer is 'frequency'. In addition - noise! > > Besides, private FMs and AIR keep invading our frequency > gloriously. All > Our efforts and people's desire doesn't seem to be bearing > fruit. > > How would be address this problem? > I will try uploading an audio piece recorded from our own > transmitter in > our own campus & in the vicinity of the College. You can feel > the noise > and difference. > > If I succeed, the piece should be available through my blog > www.richardrego.wordpress.com for you to get a taste. > TC > > ==================================== > Rev Dr Richard Rego SJ > Director, SARANG SAC 107.8FM Community Radio > Head & Asst Prof., MCMS > Dept of Mass Communication > St Aloysius College; P.B. 720 > Mangalore - 575003. > www.richardrego.wordpress.com > www.staloysiuscollege.wordpress.com > 0824-2449706. > +919448546425. > > > > > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: > > http://mail.sarai.net/pipermail/cr-india/attachments/20090902/4c2c2f98/attachment-0001.html > -------------- next part -------------- > A non-text attachment was scrubbed... > Name: not available > Type: image/jpeg > Size: 12322 bytes > Desc: not available > Url : > > http://mail.sarai.net/pipermail/cr-india/attachments/20090902/4c2c2f98/attachment-0001.jpe > > ------------------------------ > > Message: 2 > Date: Thu, 3 Sep 2009 14:17:14 +0530 > From: mahesh acharya <[email protected]> > Subject: Re: [cr-india] on frequency > To: Dr Richie Rego SJ <[email protected]> > Cc: CR Forum <[email protected]> > Message-ID: > > <[email protected]> > Content-Type: text/plain; charset="iso-8859-1" > > Dear Dr. Richie, > > What is the transmitter output? and where is the transmitter > located? CR > policy allows to use max 250watt transmitter. > > However this will not assure that everybody will be able to > hear the > broadcast (the receiver should be in broadcast zone) but will > improve > the > situation a bit. > > The other option is to put repeater(s) where the signal > reception is > poor. > You will have to seek permission from Wireless Planning Commsn > to do > this by > building a strong case. (audio recording etc) > > *Some antenna basics > * > Omnidirectional Antenna's radiate power uniformally in all > directions. > Other > types of transmissions are unidirectional radiating more power > in one > direction (usually the direction of antenna that is pointed). > In terms > of > range difference omni directional will have small range of > reception. > Uni's > range of rcption will b more. > > Music systems in cars cannot recve the broadcast for the fact > that they > do > not have telescopic antenna (the ones u have on stand alone > radio sets) > and > since output of sarang may is in watts compared to kilowatts > (kilo=1000) > mobile phones will not rcve the broadcast at all unless they > are very > very > close to transmitter. > > Solution: Listeners will have to use telescopic antenna for > the radio in > music system. Using headphones in mobile may improve the > situation a bit > as > headphones act as antenna. > > Radio sets that are not able to recve good quality audio can > be improved > if > they point the telescopic antenna in the direction of the > transmitter. > Keeping the set near window will also help in some cases. > > Regarding FM and AIR invading the freq, this may not be > possible in all > the > radio sets. Some poor quality radio sets will recve strongest > signals > even > though you have tuned to freq that you want to listen. > > There is some degree of separation between freq's assigned by > WPC and > thus > some sets rcvng only FM and AIR may be true but not all. FM > and AIR were > were already present b4 sarang was assigned the freq. > I could be wrong and in case all the radio sets are rcvng FM > and AIR, > then > the matter should be taken up with WPC and I am sure they will > look into > it. > > > Hope this helps. > > regards, > mahesh > vu3mbv > > * > > * > On Wed, Sep 2, 2009 at 10:57 PM, Dr Richie Rego SJ > <[email protected]>wrote: > > > Hi everyone! > > > > I have a problem. Would like to know how you would deal with > this - we > have > > 107.8 MHz frequency assigned to us. But low power radio sets > and > mobiles > > cannot receive our radio signals even in nearby areas - car > stereo do. > That > > means, local communities are deprived of our transmission. > People keep > > pleading us "increase signals" - they have listened to our > station > sometime; > > they have read in newspapers. hence their demand. We are > unable > because of > > the frequency. We checked why this happens. The answer is > 'frequency'. In > > addition - noise! > > > > Besides, private FMs and AIR keep invading our frequency > gloriously. > All > > Our efforts and people's desire doesn't seem to be bearing > fruit. > > > > How would be address this problem? > > I will try uploading an audio piece recorded from our own > transmitter > in > > our own campus & in the vicinity of the College. You can > feel the > noise and > > difference. > > > > If I succeed, the piece should be available through my blog > > www.richardrego.wordpress.com for you to get a taste. > > TC > > > > ==================================== > > Rev Dr Richard Rego SJ > > Director, SARANG SAC 107.8FM Community Radio > > Head & Asst Prof., MCMS > > Dept of Mass Communication > > St Aloysius College; P.B. 720 > > Mangalore - 575003. > > www.richardrego.wordpress.com > > www.staloysiuscollege.wordpress.com > > 0824-2449706. > > +919448546425. > > _______________________________________________ > cr-india mailing list > [email protected] > https://mail.sarai.net/mailman/listinfo/cr-india > _______________________________________________ cr-india mailing list [email protected] https://mail.sarai.net/mailman/listinfo/cr-india
