TV remote IR receiver module

[pawihte]

Are TV IR remote control receiver modules frequency selective? I
know that remote control systems use PWM and the pulses are
decoded by a microprocessor. What I would like to know is whether
the module that functions as the IR photosensor, amplifier and
pulse shaper is usually tuned to a particular carrier frequency
so that they are not all interchangeable (aside from things like
pin-out, pulse polarity, etc.).

If this is so, how sharply are they tuned? Is it likely that a
receiver tuned to, say 38 kHz, will respond well to 36 or 40 kHz
emissions?

 

[Rich Webb]

On Thu, 26 Nov 2009 13:00:33 +0530, "pawihte" <pawihte@invalid.com>
wrote:

Are TV IR remote control receiver modules frequency selective? I
know that remote control systems use PWM and the pulses are
decoded by a microprocessor. What I would like to know is whether
the module that functions as the IR photosensor, amplifier and
pulse shaper is usually tuned to a particular carrier frequency
so that they are not all interchangeable (aside from things like
pin-out, pulse polarity, etc.).

If this is so, how sharply are they tuned? Is it likely that a
receiver tuned to, say 38 kHz, will respond well to 36 or 40 kHz
emissions?

Generally, the 3 dB down points of these are at about +/- 2 KHz so yes,
you'll get a response with a 36 KHz signal using a 38 KHz module.

--
Rich Webb Norfolk, VA

 

[Hammy]

On Thu, 26 Nov 2009 13:00:33 +0530, "pawihte" <pawihte@invalid.com>
wrote:

Are TV IR remote control receiver modules frequency selective? I
know that remote control systems use PWM and the pulses are
decoded by a microprocessor. What I would like to know is whether
the module that functions as the IR photosensor, amplifier and
pulse shaper is usually tuned to a particular carrier frequency
so that they are not all interchangeable (aside from things like
pin-out, pulse polarity, etc.).

If this is so, how sharply are they tuned? Is it likely that a
receiver tuned to, say 38 kHz, will respond well to 36 or 40 kHz
emissions?

They have an integrated band pass filter with a narrow passband. Here

is a picture of a Panasonic detectors sensitivity versus fc.

http://i50.tinypic.com/zn4u4h.png

It may work but at a minimum you will have a reduced range.
Sensitivity for the 38kHz Panasonic is reduced to about 54% typical at
36kHz.

Other things to consider is they are also matched to specific
wavelengths which is what the other graph shows. They also have
specific data formats here's some from the TSOP348XX series.


The data signal should fulfill the following conditions:
o Carrier frequency should be close to center frequency
of the bandpass (e.g. 38 kHz).
o Burst length should be 10 cycles/burst or longer.
o After each burst which is between 10 cycles and 70
cycles a gap time of at least 14 cycles is necessary.
o For each burst which is longer than 1.8 ms a corresponding
gap time is necessary at some time in the
data stream. This gap time should be at least 4 times
longer than the burst.
o Up to 800 short bursts per second can be received
continuously.

It doesnt hurt to try if your just scavenging detectors and emitters.

 

[pawihte]

Hammy wrote:

On Thu, 26 Nov 2009 13:00:33 +0530, "pawihte"
pawihte@invalid.com
wrote:

Are TV IR remote control receiver modules frequency selective?
I
know that remote control systems use PWM and the pulses are
decoded by a microprocessor. What I would like to know is
whether
the module that functions as the IR photosensor, amplifier and
pulse shaper is usually tuned to a particular carrier
frequency
so that they are not all interchangeable (aside from things
like
pin-out, pulse polarity, etc.).

If this is so, how sharply are they tuned? Is it likely that a
receiver tuned to, say 38 kHz, will respond well to 36 or 40
kHz
emissions?

They have an integrated band pass filter with a narrow
passband. Here
is a picture of a Panasonic detectors sensitivity versus fc.

http://i50.tinypic.com/zn4u4h.png

It may work but at a minimum you will have a reduced range.
Sensitivity for the 38kHz Panasonic is reduced to about 54%
typical at
36kHz.

Other things to consider is they are also matched to specific
wavelengths which is what the other graph shows.

Thanks. This one appears to be intended for 940nm LEDs, with
practically zero response to 850nm radiation. Are remote controls
more or less standardised for 940nm?

They also have
specific data formats here's some from the TSOP348XX series.


The data signal should fulfill the following conditions:
o Carrier frequency should be close to center frequency
of the bandpass (e.g. 38 kHz).
o Burst length should be 10 cycles/burst or longer.
o After each burst which is between 10 cycles and 70
cycles a gap time of at least 14 cycles is necessary.
o For each burst which is longer than 1.8 ms a corresponding
gap time is necessary at some time in the
data stream. This gap time should be at least 4 times
longer than the burst.
o Up to 800 short bursts per second can be received
continuously.

This seems to imply that it's not suitable for detection of a

continuous emission with infrequent interruptions for
applications like an intrusion detector or an event counter. Is
that correct?

It doesnt hurt to try if your just scavenging detectors and
emitters.

 

[pawihte]

Rich Webb wrote:

On Thu, 26 Nov 2009 13:00:33 +0530, "pawihte"
pawihte@invalid.com
wrote:

Are TV IR remote control receiver modules frequency selective?
I
know that remote control systems use PWM and the pulses are
decoded by a microprocessor. What I would like to know is
whether
the module that functions as the IR photosensor, amplifier and
pulse shaper is usually tuned to a particular carrier
frequency
so that they are not all interchangeable (aside from things
like
pin-out, pulse polarity, etc.).

If this is so, how sharply are they tuned? Is it likely that a
receiver tuned to, say 38 kHz, will respond well to 36 or 40
kHz
emissions?

Generally, the 3 dB down points of these are at about +/- 2 KHz
so
yes, you'll get a response with a 36 KHz signal using a 38 KHz
module.

Thanks.

 

[Hammy]

On Thu, 26 Nov 2009 23:01:02 +0530, "pawihte" <pawihte@invalid.com>
wrote:

Hammy wrote:
On Thu, 26 Nov 2009 13:00:33 +0530, "pawihte"
pawihte@invalid.com
wrote:

Are TV IR remote control receiver modules frequency selective?
I
know that remote control systems use PWM and the pulses are
decoded by a microprocessor. What I would like to know is
whether
the module that functions as the IR photosensor, amplifier and
pulse shaper is usually tuned to a particular carrier
frequency
so that they are not all interchangeable (aside from things
like
pin-out, pulse polarity, etc.).

If this is so, how sharply are they tuned? Is it likely that a
receiver tuned to, say 38 kHz, will respond well to 36 or 40
kHz
emissions?

They have an integrated band pass filter with a narrow
passband. Here
is a picture of a Panasonic detectors sensitivity versus fc.

http://i50.tinypic.com/zn4u4h.png

It may work but at a minimum you will have a reduced range.
Sensitivity for the 38kHz Panasonic is reduced to about 54%
typical at
36kHz.

Other things to consider is they are also matched to specific
wavelengths which is what the other graph shows.

Thanks. This one appears to be intended for 940nm LEDs, with
practically zero response to 850nm radiation. Are remote controls
more or less standardised for 940nm?

Not sure but likely considering the availability of universal remotes.

They also have
specific data formats here's some from the TSOP348XX series.


The data signal should fulfill the following conditions:
o Carrier frequency should be close to center frequency
of the bandpass (e.g. 38 kHz).
o Burst length should be 10 cycles/burst or longer.
o After each burst which is between 10 cycles and 70
cycles a gap time of at least 14 cycles is necessary.
o For each burst which is longer than 1.8 ms a corresponding
gap time is necessary at some time in the
data stream. This gap time should be at least 4 times
longer than the burst.
o Up to 800 short bursts per second can be received
continuously.

This seems to imply that it's not suitable for detection of a
continuous emission with infrequent interruptions for
applications like an intrusion detector or an event counter. Is
that correct?

If the intruder is the "Flash" then it wouldn't be suitable for
intrusion detection. The carrier is usually modulated (On/off) at
about 1 kHz (1mS). They are indeed used for this application I've done
it and you will find lots of examples on Google.

here's a link showing the carrier and data waveforms etc.

http://www.rentron.com/Infrared_Communication.htm

For an intrusion detection application you usually would not trip your
alarm unless you had a loss of signal longer then 100ms no human being
can run through a detector at that speed. This helps to avoid nuisance
trips.

A dual or multiple beam is even more reliable and less prone to
nuisance trips i.e cat, dog or leaf etc. Alignment could be difficult
and flooding adjacent receivers could be problamatic witout optics to
narrow the beam.

It doesnt hurt to try if your just scavenging detectors and
emitters.

 

[pawihte]

Hammy wrote:

On Thu, 26 Nov 2009 23:01:02 +0530, "pawihte"
pawihte@invalid.com
wrote:

Hammy wrote:

They also have
specific data formats here's some from the TSOP348XX series.


The data signal should fulfill the following conditions:
o Carrier frequency should be close to center frequency
of the bandpass (e.g. 38 kHz).
o Burst length should be 10 cycles/burst or longer.
o After each burst which is between 10 cycles and 70
cycles a gap time of at least 14 cycles is necessary.
o For each burst which is longer than 1.8 ms a corresponding
gap time is necessary at some time in the
data stream. This gap time should be at least 4 times
longer than the burst.
o Up to 800 short bursts per second can be received
continuously.

This seems to imply that it's not suitable for detection of a
continuous emission with infrequent interruptions for
applications like an intrusion detector or an event counter.
Is
that correct?

If the intruder is the "Flash" then it wouldn't be suitable for
intrusion detection. The carrier is usually modulated (On/off)
at
about 1 kHz (1mS). They are indeed used for this application
I've done
it and you will find lots of examples on Google.

here's a link showing the carrier and data waveforms etc.

http://www.rentron.com/Infrared_Communication.htm

For an intrusion detection application you usually would not
trip your
alarm unless you had a loss of signal longer then 100ms no
human being
can run through a detector at that speed. This helps to avoid
nuisance
trips.

A dual or multiple beam is even more reliable and less prone to
nuisance trips i.e cat, dog or leaf etc. Alignment could be
difficult
and flooding adjacent receivers could be problamatic witout
optics to
narrow the beam.

I'm not really trying to build an intrusion alarm. I'm trying to
learn more about the practical espects of IR remote control
design. The inrusion alarm was just an example of a possible
application, but it seems the Vishay TSOP348XX receivers are
designed on purpose to reject CW signals. The Panasonic PNA4602M
datasheet doesn't say anything specific about this.

 

[pawihte]

pawihte wrote:

I'm not really trying to build an intrusion alarm. I'm trying
to
learn more about the practical espects of IR remote control
design. The inrusion alarm was just an example of a possible
application, but it seems the Vishay TSOP348XX receivers are
designed on purpose to reject CW signals. The Panasonic
PNA4602M
datasheet doesn't say anything specific about this.

A Silan SM0038 module is very common in my area, being available
at practically all parts shops, but I can't find a datasheet for
it. Silan is a Chinese company and the type number probably means
it's tuned to 38kHz. It works at 5V. What's unknown is the
spectral range and whether it has restrictions regarding burst
length and duty cycle as with the TSOP348xx. I've emailed the
company, but no reply yet. Can anyone help?