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WANTED: small piece of source code !!!!

Hi,

I'm prety desperate trying to write some ******* piece of source.
I want to send a 14 bits binary word to my PC speaker.
This word needs to be modulated by some biphase system on a carrier with a
frequency of 36 kHz and a duty-cycle of 25 %. (I don't even know if this is done
by some driver of needs to be programmed.)
I think this kind of programming needs to be done in ASM.

Is there anybody out there, who can help me??????

Thanks,

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Re:WANTED: small piece of source code !!!!


Quote
SNIPER wrote:

> Hi,
> I'm prety desperate trying to write some ******* piece of source.
> I want to send a 14 bits binary word to my PC speaker.
> This word needs to be modulated by some biphase system on a carrier with a
> frequency of 36 kHz and a duty-cycle of 25 %. (I don't even know if this is done
> by some driver of needs to be programmed.)
> I think this kind of programming needs to be done in ASM.

> Is there anybody out there, who can help me??????

I'd like to see anyone get 36kHz out of their PC squawker.  (Anyone got a titanium
dome PC speaker?)

  -=Richard Goedeken

Re:WANTED: small piece of source code !!!!


Quote
In article <311B94AA....@iastate.edu> Richard Goedeken <p...@iastate.edu> writes:
>From: Richard Goedeken <p...@iastate.edu>
>Subject: Re: WANTED: small piece of source code !!!!
>Date: Fri, 09 Feb 1996 12:38:34 -0600
>SNIPER wrote:

>> Hi,
>> I'm prety desperate trying to write some ******* piece of source.
>> I want to send a 14 bits binary word to my PC speaker.
>> This word needs to be modulated by some biphase system on a carrier with a
>> frequency of 36 kHz and a duty-cycle of 25 %. (I don't even know if this is done
>> by some driver of needs to be programmed.)
>> I think this kind of programming needs to be done in ASM.

>> Is there anybody out there, who can help me??????
>I'd like to see anyone get 36kHz out of their PC squawker.  (Anyone got a titanium
>dome PC speaker?)
>  -=Richard Goedeken

   P.W.M !!!!

Re:WANTED: small piece of source code !!!!


Quote
Rocky (sueso...@iafrica.com) wrote:

* Richard Goedeken <p...@iastate.edu> writes:

Quote
* >SNIPER wrote:

* >> Hi,
* >> I'm prety desperate trying to write some ******* piece of source.
* >> I want to send a 14 bits binary word to my PC speaker.
* >> This word needs to be modulated by some biphase system on a carrier with a
* >> frequency of 36 kHz and a duty-cycle of 25 %

  [SNIP]

* >I'd like to see anyone get 36kHz out of their PC squawker.  (Anyone got
* >a titanium dome PC speaker?)

*
* P.W.M !!!!
*

  I've got Peavey SP2-Ti's and 118HC Subs (4 of them!) connected to
my sound blaster card and Roland JV-35 synth.  I can't even get 36kHz
out of those titanium domes!  They drop off -3db at 20khz.

======================================================================
Elminster                                     Computer Game Programmer
elmin...@access.digex.net   http://www.access.digex.net/~elminstr
======================================================================

Re:WANTED: small piece of source code !!!!


In article <4freop$...@hermes.louisville.edu>
           gclin...@starbase.spd.louisville.edu "George C. Lindauer" writes:

Quote
> It turns out the problem wasn't stated very well... what he really wanted
> to do is use the output pin prior to the lp amps to drive an IR led
> so that he could use his computer to control TVs and stuff.  I don't
> know enough about electronics to know if there were any reasons that
> taking the signal at that point wouldn't work; but I whipped him up a program
> so he could try it.  Anyone know any reasons why what he's really up
> to wouldn't work?

The European electronics magazine 'Elektor' did a project a few years ago
to connect an IR LED across the PC speaker and used it to transmit Philips
RC5 remote control codes.

I've just had a quick check, the article was in the July/August 1994 edition,
the software is available for 21.50 US Dollars or 10.75 UKP. The UK phone
number is 01305-250995, and the USA phone number is (603) 924-6371.

Nigel.

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          | Lower Pilsley   |                                        |
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Re:WANTED: small piece of source code !!!!


In article <4fvpnb$...@news4.digex.net>
           elmin...@access1.digex.net "Elminster" writes:

Quote
>   Good idea, but aren't the electromagnetic field waves (light, IR, UV)
> in the megahertz range?  I suppose you could use some kind of frequency
> multiplier circuit...

Assuming this wasn't intended as a joke, the 36KHz is used to modulate the
IR carrier signal - that is, it turns it on and off 36,000 times a second.
This modulation is then detected in the receiver, and de-modulated to
recover the original signal.

The signal is actually modulated twice, the IR is modulated at 36KHz, and
the 36KHz is gated by the actual data. I don't know why they use modulation
frequencies in the 36-40KHz region, but it seems a bit coincidental that
these were the frequencies used in the older ultrasonic remotes. If I was
a sceptic I might think they just bunged an IR LED in place of the original
ultrasonic transducer :-).

Nigel.

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Re:WANTED: small piece of source code !!!!


Quote
Nigel Goodwin (nig...@lpilsley.demon.co.uk) wrote:
> Assuming this wasn't intended as a joke, the 36KHz is used to modulate the
> IR carrier signal - that is, it turns it on and off 36,000 times a second.
> This modulation is then detected in the receiver, and de-modulated to
> recover the original signal.
> The signal is actually modulated twice, the IR is modulated at 36KHz, and
> the 36KHz is gated by the actual data. I don't know why they use modulation
> frequencies in the 36-40KHz region, but it seems a bit coincidental that
> these were the frequencies used in the older ultrasonic remotes. If I was
> a sceptic I might think they just bunged an IR LED in place of the original
> ultrasonic transducer :-).

The frequency range is more likely dependent on what the FCC
likes in a "non-computing device". Devices that use clocks
at 40khz or slower are not considered to be using radio
frequencies. Also watch oscillators are real cheap and
32768 Hz is quite possibly an acceptable modulation rate
for an IR transmitter.

I have no hard evidence for the above speculations.

Charles.

Re:WANTED: small piece of source code !!!!


Quote
In article <caderDMuHCt....@netcom.com> ca...@netcom.com "Charles Ader" writes:
> The frequency range is more likely dependent on what the FCC
> likes in a "non-computing device". Devices that use clocks
> at 40khz or slower are not considered to be using radio
> frequencies. Also watch oscillators are real cheap and
> 32768 Hz is quite possibly an acceptable modulation rate
> for an IR transmitter.

> I have no hard evidence for the above speculations.

Hi Charles,

I don't think the FCC would have anything to do with it, as there are no RF
transmissions involved. And of course they would only have authority over
items used in the USA. The actual oscillator frequencies used in remotes are
around 455-470KHz using a crystal resonator, I presume this is used as the
clock oscillator for a dedicated micro processor. A very common fault with
remotes is one end of the resonator breaking off, the remote will often emit
IR then - but at a much lower modulation frequency.

Nigel.

          /----------------------------------------------------------\
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          | Lower Pilsley   |                                        |
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Re:WANTED: small piece of source code !!!!


Hello George!

 GCL> From: gclin...@starbase.spd.louisville.edu (George C. Lindauer)

 >>* >> I want to send a 14 bits binary word to my PC speaker.
 >>* >> This word needs to be modulated by some biphase system on a
 >>* >> carrier with a frequency of 36 kHz and a duty-cycle of 25 %

Hmmm. Why not try the parallel port instead.

 GCL> I quickly figured out he didn't want to be able to hear the sounds...
 GCL> anyone in audio at all is going to know the ear can't hear those
 GCL> frequencies anyway.  So I asked him what he really wanted...

 GCL> It turns out the problem wasn't stated very well... what he really wanted
 GCL> to do is use the output pin prior to the lp amps to drive an IR led
 GCL> so that he could use his computer to control TVs and stuff.

My knowdledge of electronics is a bit on the dull side, but the power between
the terminals of the speakler would probably kill chips and stuff designed for,
let's say 5v. Instead he could try using the parallelport.
The only reason I can find to be using the speaker port is that it is
theoretically possible to get a signal modulated on a carrier, but the speed
and voltage does not in my eyes qualify for a neat job, also contrlling the
actual frequency calls for some pretty weird code.
I'd would choose to control LED by letting a parallel port datapin, eg 0, go to
the base of a transistor and there by control the power going to the IR LED and
not use any direct current from the computer. Also I can see that unless you
know what you're doing you could end up with too much highfrequency noise from
the computer so that decoding the 14 bit binary word becomes difficult.... I
would suggest the parallel port and not the speaker port. remember you can't
draw too much power from the parallelport pins. a conventional LED uses 0.02
Amps and that directly at the plugsocket. I do not want to know what the IR LED
sucks of power. Use the transitor and seperate power supply for the job.
usually 3 * 1.5 volt batteries are good enough for most electronics.
Regards
Mikkel Breiler Cosysop Renoz BBS, Vinyl/Intuition

Re:WANTED: small piece of source code !!!!


Quote
In article <caderDMuHCt....@netcom.com>, Charles Ader <ca...@netcom.com> wrote:
> The frequency range is more likely dependent on what the FCC likes in
> a "non-computing device". Devices that use clocks at 40khz or slower
> are not considered to be using radio frequencies.

Really?

There are actually radio transmitters using frequencies below 40 kHz.
These frequencies are often used in submarines, because they propagate
very well under water.

Last fall, a transmitter in Grimestone, England, which was put out
of service for many years, was briefly revived as a historical
anniversary.  It transmitted at 17.5 kHz !!!!  The transmission
consisted of some Morse code, and ham magazines described how to
build antennas and receivers to receive this historical transmission.

Finally, the electromagnetic spectrum have almost every part between
10 kHz and about 100 GHz allocated for various kinds of radio
transmissions.

--
----------------------------------------------------------------
Paul Schlyter,  Swedish Amateur Astronomer's Society (SAAF)
Grev Turegatan 40,  S-114 38 Stockholm,  SWEDEN
e-mail:  pau...@saaf.se        p...@home.ausys.se

Re:WANTED: small piece of source code !!!!


On 15 Feb 1996 17:15:23 GMT, elmin...@access1.digex.net (Elminster)
wrote:

Quote
>  Good idea, but aren't the electromagnetic field waves (light, IR, UV)
>in the megahertz range?  I suppose you could use some kind of frequency
>multiplier circuit...

Yowch!

Multiply 36 KHz to IR, which is in the many-thousands-of-megahertz
range?

Large multiplier.

No, actually, the IR LED generates the IR "signal".  You just have to
turn it on and off (continuous wave modulation) at 36 KHz.

--
Al

Re:WANTED: small piece of source code !!!!


On Fri, 16 Feb 1996 01:26:53 GMT, ca...@netcom.com (Charles Ader)
wrote:

Quote
>The frequency range is more likely dependent on what the FCC
>likes in a "non-computing device". Devices that use clocks
>at 40khz or slower are not considered to be using radio
>frequencies.

A small device like that?  It would barely be powerful enough to come
under Part 15 (incident radiation).

You can modulate IR at whatever frequency you like.

36-40 KHz range just has lots of off-the-shelf components and years of
design.

Why re-invent the wheel?

--
Al

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