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DRM Transmissions by AIR Delhi

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DRM Transmissions by AIR Delhi

Postby desai_amogh » Thu Feb 08, 2007 1:46 am

HEY Guys,
At last the !!!! DRM !!!! is INDIA !!!

did any one in this forum tried decoding the DRM transmissions ??
i heard the r transmitting it daily at 6100KHz at 3:30 pm..
if any one owns a digitally tuned receivers then its easy to decode these signals.
Im thinking use DEGEN DE 1103 (a chinese Digital Reciever) for this ..
any one knows the modifications required for this reciever for receiving DRM transmissions ???
Amogh
+91 9823144405

Degen DE1103,Homebrewed 7 Mhz SSB rx,15m longwire.
Join me to spread this hobby at: http://www.electronicsforum.in
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Postby mvs sarma » Thu Feb 08, 2007 2:35 pm

Hi, Amogh,

It is news and intersting. i am really interested to see wether i can use any project of elektor magazine --they published articles on DRM

regards

Sarma
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RE: DRM Transmissions by AIR Delhi

Postby desai_amogh » Fri Feb 09, 2007 1:49 am

hello SWLs!!

here is the deal

if u have a digitally tuned receiver with good sensitivity. and the receiver
shud have a 12 khz IF output or if it doesnt the ull need to add a frequency
downconverter to convert the IF 445khz to 12 khz as we need to connect this
signal to the computers soundcards LINEIN port ( & the soundcard wont take
any frequency more than 20KHz)

Then there is software called DREAM which decodes this DRM digital signals
to AAC format audio & u can listen to it from the speaker !!
u can download this software from here http://drm.sourceforge.net/

there r lots of websites which help u how to modify ur receivers like :
http://www.drm.org/receiversequip/receiversequip.php


so y wait ????????
put ur Recievers in use !!
its gonna be fun !!

Amogh
Amogh
+91 9823144405

Degen DE1103,Homebrewed 7 Mhz SSB rx,15m longwire.
Join me to spread this hobby at: http://www.electronicsforum.in
desai_amogh
 
Posts: 33
Joined: Fri Oct 20, 2006 6:12 am
Location: Pune/Goa

Postby mvs sarma » Tue Feb 13, 2007 12:16 pm

Hi, Amogh,

Your concepts are also amogh. Thanks for the lead

we have to make a simple mod so that normal domestic radios wirth analog tuning can also be optimised for receiving the DRM. i feel, if the L.O cabe modified as crystal oscillator with minute fine tuning and with a IF converter additionally switched IN , whtehre we can manage to tune in 6100KHz-- of course i understand limitation ( the Rx must be resonable vey of high sensitivity and the IF amp section of suitable bandwidth.)pehpas you might have gone thro elektor dec2k7 article SHORTWAVE RECEIVER WITH DDS and with DRM FACILITY
i hope our .Org could come forward with their FIRST DRM RX for common man even


Regards

Sarma
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Postby vu3wjm » Thu Feb 15, 2007 1:57 pm

Hi!

This is very interesting. With regular receivers we will need a 12khz convertor as rightly pointed by one of our friend and Dream software.
Aquadrature type downconvertor and many SDR softwares can also be used.
In normal receiver common type, this amounts to tapping the IF 455khz and pobably mix it with 468khz resonator available in mkt. I will see what can be done. However I find it very interesting if we pull a 6.144khz xtal sufficiently in super VXO we can still have a DC type RX. Some thing like this:

2SC2570A negative feedback or norton noiseless Rf preamp+2 diode mixer+2 transistor common base type audio preamp. 1 transistor BC547 6.144mhz pulled xtal LO.

Will give it a try in couple of days.

73
Rahul VU3WJM
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Postby mvs sarma » Thu Feb 15, 2007 11:11 pm

Hi,

It should actually be free from PC-- if we have again use PC sound card, it is preferable that AIR can put it on ther website itself and we can listen. Once, they broadcast, we sould have a portable rdio to be capable of receiving the sameonpotable radios and run off batteries. If only digital radios can receive it, the analog radios could also receive witha local osc modding only for DRM part.

Perhpas a sort of low power child card add on to radio with a minor improvisation is needed. i do understand, that local oscillator (VFO) must be stable. but expecting DDS for this is rahter threeee costl- an exaggeration of too costly--

Regards

Sarma
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Postby desai_amogh » Fri Feb 16, 2007 2:21 am

Hey !! gr8 to see u guys workinh !!
im not so good in creating circuits so wud wait till some one creates one downconverte ..

right now its more than enough for me to start receiving the DRM transmissions..than i can think of making it mobile !!
any one here has any idea when AIR gonna start the transmissions again ??
i did try to mail the AIR Delhi-Khampur stations to ask when is the next transmissons..but no teply yet..
its been more than 5 days...
Amogh
+91 9823144405

Degen DE1103,Homebrewed 7 Mhz SSB rx,15m longwire.
Join me to spread this hobby at: http://www.electronicsforum.in
desai_amogh
 
Posts: 33
Joined: Fri Oct 20, 2006 6:12 am
Location: Pune/Goa

Postby vu3wjm » Fri Feb 16, 2007 11:14 am

Hi!

Sharma Ji! Making a dedicated rx free from PC would require a an asic decoder chip apart from rest of the ckt. This becomes viable only once the volume of production goes up. Till then I will stay with PC.

In past I have made many downconvertors believe me for less than Rs75 you can have a very good Rx once a use of PC is made for processing.

73

Rahul VU3WJM
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Posts: 52
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Postby desai_amogh » Wed Feb 21, 2007 1:05 am

Hey !!
hello vu3wjm cud u gimmme a a working circuit of a downconverter.
im using a digital receiver(chinese) named Degen DE1103 u can find the info abt this rx here

i read some forums & they say tht this rx is very good for ssb & swl ..but not so good for DRM receptions...
this is the forum

& thr r some forums which say they have succesfully tested & used this rx for DRM reception this is the link

so im kinda confussed abt this.
lemme know if u want the circuit diagram of this rx to check wher we can connect the downconvertor i have it in my mailbox..
waiting for ur respnce !!
regards
Amogh
Amogh
+91 9823144405

Degen DE1103,Homebrewed 7 Mhz SSB rx,15m longwire.
Join me to spread this hobby at: http://www.electronicsforum.in
desai_amogh
 
Posts: 33
Joined: Fri Oct 20, 2006 6:12 am
Location: Pune/Goa

Postby mvs sarma » Wed Feb 21, 2007 7:18 pm

Hi, Amogh,

there is no need to confusion. i feel these are reports of one's own observations and these commnets are not ultimate.
In my opinion,

1. if the drm is local station almost any Rx should work-- only limitation try a individual crystal osc with fine tune at 6100. and if possible Frequency locl loop -- like huff puff method .this can be incorporated by just an add-on child card.
2. the same child card can have another L O with470KHz resonator type and pulled to 455+/-12KHz and a mixer and a L-C LPF with cut off at 12.5 or so, . the whole thing should not be costing 150 to 200/- and few Ma of current.

3. the circuit can be interposed to be switched only when DRM is required.

4. Not to expect wonders of DRM on DX, i fear-- the effort maynot be worthwhil-- this is a limited comment.-many Hams with great experience of DXing may perhaps achieve good results. i am yet to try waiting for a nearby station insead of Delhi.

we may use recovered IFTs and other compo's of reputed makes. =

incidentally do you know of price and availability of AD9851BRS-- the DDS chip from Analog Devices sir,
Regards
Sarma
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Postby desai_amogh » Thu Feb 22, 2007 3:25 am

hello sarmaji !!
thanks for reply !!
cud u tell me where u r located ??
im not so good at creating the circuits.. but good at constructing it if u cud help me with a circuit diagram .. the worst thing is tht i dont have any equipments for frequency measurment ...

im really not sure as to what that huff-puff method means.. neither ill be able to create tht LO myself.. plz lemme know if u have any circuit diagram on the websites which i can construct

Regards
Amogh
Amogh
+91 9823144405

Degen DE1103,Homebrewed 7 Mhz SSB rx,15m longwire.
Join me to spread this hobby at: http://www.electronicsforum.in
desai_amogh
 
Posts: 33
Joined: Fri Oct 20, 2006 6:12 am
Location: Pune/Goa

Postby desai_amogh » Thu Feb 22, 2007 3:45 am

i found one downconvertor !!
its here http://www.sat-schneider.de/download/Mixerflyer.pdf
Amogh
+91 9823144405

Degen DE1103,Homebrewed 7 Mhz SSB rx,15m longwire.
Join me to spread this hobby at: http://www.electronicsforum.in
desai_amogh
 
Posts: 33
Joined: Fri Oct 20, 2006 6:12 am
Location: Pune/Goa

Postby mvs sarma » Thu Feb 22, 2007 11:18 am

Hi Amogh,
you got a really nice download. perhpas ne612 smd version-- difficult to procure. you don't underplay yourself-- most of us are not circuit designers. we adopt best possible circuiots and improvise them with our limited component resources.

the crystal mentioned(around 438 to 470 KHz, -i haven't seen inindian catalogs. in germany, every thing could be possible and prices are nothing to them perhaps.

finally , it is a very good URL sir. let us do something- PCBs could be expected from me. assy also i can try hereitself, with my experience in telecom.

how about Dx coverage and signal strength -- my interest is mod a general pointer type Rxto receive drm.

let us work. in the mean time we have also to watch for modules availability in india and they may ne initially costly, i fear.


HUFF_PUFF i am contructing a project from issue 2/98 of Elektor UK, VFO stabilizer with display using 16F84A at 4MHz-- it is a vfo tunable from 8 to around 80 MHz and a type of Frequency lock loop.- download the 98 issue and read the article.it is availble in general section of our site, as you know

regards
Sarma
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Postby vu3wjm » Tue Feb 27, 2007 11:53 pm

Hi!

Dear Sarma Ji & Amogh,

Regarding Degen query it is simple the set cannot decode DRM however given the technology and DRM transmitted power of 250KW it is more than adequate on sensitivity department.

On next topic of tapping the IF and processing it can be done easily in digital domain. There are softwares for 12khz IF solution where I feel a 468KHZ ceramic resonator is ideal. For QSD X4 multiplidrfrequency would be required to generate the 90deg phase shifted osc's.

612s are not absolutely necessary you can even make 2 mixers with 4X2 nos 1N4148 diode. I simply do not understand why people crib for 602/612 when a passive 4 diode mixer with 1N4148 is a better performer upto 50MHz and beyond.

Just my suggestions

73

Rahul VU3WJM
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Posts: 52
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Postby mvs sarma » Sun Mar 04, 2007 3:29 pm

Hi Rahul,

It is Nice we can make ring modulators using IN4148, but need two transformers and an Osc block.

let us see as to how to get the 6100 frequency tuned by normal Rx by only substtuting L.O by a more stable one and as we are interested in DRM while on DXing-- see my case. i have to receive delhi station at Hyderabd and still enthuse for DRM- just for that sake we can't spend a moon for a digital RX ( i have SONY ICL-SW11)

modding will be easy with small components, as little space in the portable. - i am even looking for smd version of NE or SE612 if available.

All the best for DRM soon.

regards
Sarma
Regards
Sarma
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