Hello -

I'm currently adding a bit of security to my house by buying some cheap
wireless PIR sensors and receivers from
http://www.screwfix.com/app/sfd/cat/cat.jsp?cId=101495 , interfacing a PC
to them, and switching on lights, sending email alerts, posting webcam
pictures to a website, etc. when activated. It's going well so far.

I'd be interested to know if anyone can see pitfalls in this approach, eg.
- PIR manufacturer going out of business and not being able to get
compatible receivers/transmitters
- burglars who carry radio jammers (does this happen outside of crime
novels?)
- What am I losing by not using sensors intended for alarm systems
- Are inconspicuous PIR sensors less of a deterent than a big bell-box?
- I'm thinking of installing one of these at a property that already has an
"Anglian" branded wireless alarm system - are they likely to clash?

Thanks

"Simon" wrote in message
...

I'm currently adding a bit of security to my house by buying some cheap
wireless PIR sensors and receivers from
http://www.screwfix.com/app/sfd/cat/cat.jsp?cId=101495 , interfacing a PC

What are you doing for the data logger?

--
Mike W

"Simon" wrote in message
...
"VisionSet" wrote in message
...

"Simon" wrote in message
...

I'm currently adding a bit of security to my house by buying some
cheap
wireless PIR sensors and receivers from
http://www.screwfix.com/app/sfd/cat/cat.jsp?cId=101495 , interfacing a
PC

What are you doing for the data logger?

--
Mike W

I use the PC's serial port to monitor the state of the wireless receivers,
Java to poll the port, send the alerts and control the webcams, and a
database to log the data. It's very DIY.


So you have your PC on all the time. I'd definitely want to avoid that if
possible.

--
Mike W

"VisionSet" wrote in message
...

"Simon" wrote in message
...

I'm currently adding a bit of security to my house by buying some cheap
wireless PIR sensors and receivers from
http://www.screwfix.com/app/sfd/cat/cat.jsp?cId=101495 , interfacing a
PC

What are you doing for the data logger?

--
Mike W

I use the PC's serial port to monitor the state of the wireless receivers,
Java to poll the port, send the alerts and control the webcams, and a
database to log the data. It's very DIY.

"VisionSet" wrote in message
...


What are you doing for the data logger?


I use the PC's serial port to monitor the state of the wireless
receivers,
Java to poll the port, send the alerts and control the webcams, and a
database to log the data. It's very DIY.


So you have your PC on all the time. I'd definitely want to avoid that if
possible.


If you are doing it in Java then why not buy a board with JVM on it. about
50 quid, (prob less now). It comes with a one wire port for your
interfacing.

--
Mike W

On 2006-09-29 19:37:25 +0100, Owain said:

Simon wrote:
I'm currently adding a bit of security to my house by buying some cheap
wireless PIR sensors and receivers from
http://www.screwfix.com/app/sfd/cat/cat.jsp?cId=101495 , interfacing a PC
to them, and switching on lights, sending email alerts, posting webcam
pictures to a website, etc. when activated. It's going well so far.

Microsoft or Linux based OS? ;-)

Microsoft doesn't make any OSes.....

- Are inconspicuous PIR sensors less of a deterent than a big bell-box?

Internal PIR sensors are no deterrent. By the time Mr Scrote The
Thieving Scumbag is close enough to see your PIRs he's in your property.

The standalone mains-powered PIR sensor has a row of Knight-rider style red
LEDS, which should attract the attention of anyone peering in through a
window. OTOH, they'd look silly and possibly reduce security if the PIR was
installed outside.

VisionSet wrote:
"Simon" wrote in message
...

I'm currently adding a bit of security to my house by buying some
cheap
wireless PIR sensors and receivers from
http://www.screwfix.com/app/sfd/cat/cat.jsp?cId=101495 , interfacing a
PC

So you have your PC on all the time. I'd definitely want to avoid that if
possible.


An old P1 laptop sounds like a good candidate, pref with a backup
spare.


NT

Simon explained :
Hello -

I'm currently adding a bit of security to my house by buying some cheap
wireless PIR sensors and receivers from
http://www.screwfix.com/app/sfd/cat/cat.jsp?cId=101495 , interfacing a PC
to them, and switching on lights, sending email alerts, posting webcam
pictures to a website, etc. when activated. It's going well so far.

I'd be interested to know if anyone can see pitfalls in this approach, eg.
- PIR manufacturer going out of business and not being able to get
compatible receivers/transmitters

Buy enough plus spares.

- burglars who carry radio jammers (does this happen outside of crime
novels?)

Extremely unlikely, even if they already knew about the special system.

I would suggest the biggest pitfall is likely to be the reliability of
the PC itself - the likelyhood of it crashing. For really critical
stuff which needs to be able to restart the system should it crash,
consider a 'watch dog' system. PC sends a regular pulse signal out to a
discrete 'watch dog' circuit, if the circuit fails to see a regular
pulse from the PC, it reboots the PC. The pulse is generated by the PC
from running software, sent out via a bit on one of the ports.

- What am I losing by not using sensors intended for alarm systems
- Are inconspicuous PIR sensors less of a deterent than a big bell-box?
- I'm thinking of installing one of these at a property that already has an
"Anglian" branded wireless alarm system - are they likely to clash?

Nothing to stop you adding a big bell box and flashing lights.

Clash, unlikely if the PIR uses the PC wireless network frequencies
2.4Ghz and the Anglian 432Mhz licence free - no.

--

Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk

It happens that Simon formulated :
The standalone mains-powered PIR sensor has a row of Knight-rider style red
LEDS, which should attract the attention of anyone peering in through a
window. OTOH, they'd look silly and possibly reduce security if the PIR was
installed outside.

What about mains failure? No mains, no working alarm system.

--

Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk

"Simon" wrote in message
...
Hello -

I'm currently adding a bit of security to my house by buying some cheap
wireless PIR sensors and receivers from
http://www.screwfix.com/app/sfd/cat/cat.jsp?cId=101495 , interfacing a PC
to them, and switching on lights, sending email alerts, posting webcam
pictures to a website, etc. when activated. It's going well so far.

I'd be interested to know if anyone can see pitfalls in this approach, eg.
- PIR manufacturer going out of business and not being able to get
compatible receivers/transmitters
- burglars who carry radio jammers (does this happen outside of crime
novels?)
- What am I losing by not using sensors intended for alarm systems
- Are inconspicuous PIR sensors less of a deterent than a big bell-box?
- I'm thinking of installing one of these at a property that already has
an
"Anglian" branded wireless alarm system - are they likely to clash?

Thanks



What's your address (for when you are finished) ?

Harry Bloomfield wrote:

Clash, unlikely if the PIR uses the PC wireless network frequencies
2.4Ghz and the Anglian 432Mhz licence free - no.

70 cms, nice and jammable!