Yale Premium Alarm Hsa6400 Wirefree Alarm Kit

[JohnD]

just catching up with some unanswered questions here

... agree that your expensive pro system will also not protect people who are stupid or careless, and as I accurately and truthfully pointed out, the effects can be even worse?

...estimate the probability that an interfering signal will block a sensor at the same fraction of a second that a burglar breaks into your house, ...

Let's assume, for the purpose of the exercise, that the house is an ordinary domestic house, built in an ordinary street full of other domestic houses, and is not built under the aerial of a BBC transmitter, neither is it built next to an electricity power station.

Alternatively, tell me, how often, in the last year, did you plip the wireless unlocker of your car, when it was parked outside your house, and find that the car did not unlock?

 

[mdf290]

No spurious false alarms have occured due to channel occupancy.

You have proof of that from the system's log of events ?

We are also into the area of signal strength are we not in other words the nearest sensors ie the ones in the local system are more likely to block an external system than an external signal is likely to block a local signal... Is that not true?

Good, you are starting to realise that reliable wireless communication requires more than just sticking off the shelf components in place.

You say the sensors in Mr A's system are more likely to block an external system. How does that affect Mr B whose system is external to Mr A's system.

Signal strength at the receiver is affected by distance to which the inverse square law, (twice the distance means the signal strength is one quarter ) but that is only one of the many factors that affect signal strength. The next thing to consider is the polar diagram of the receiver's aerial and how this affects the field strength required for the receiver to respond. Is the aerial omni-directional or is it more receptive to signals from one particular direction. Bits of metal close to the receiving aerial will alter the polar diagram,

Is the receiver AM or FM or PM ( phase modulation ) ?

AM receivers mix all incoming signals that are in the receiver's pass band while FM and PM tend to lock onto the modulation on the strongest signal. On AM broadacst radio you can hear two stations that on on the same frequency at the same time. The sound your hear is a mixture of both programs often with a whistle or whining sound that is the difference between the two carrier frequencies. On FM you normally hear only one or the other though the receiver may switch from one to the other as the relative signal strengths vary.

So lets make a little scenario here...

Based on the inverse square law you have described..

There are two Yale alarms in two Park Homes Mr A's and Mr B's seperated by approximately 15 metres.

This is a typical configuration.

If Mr A and Mr B BOTH arrive home and open their doors activating their door contacts at EXACTLY the same time.

What will be the net result at the control panel in the Home of Mr A

1/ It will not register a signal recieved as both signals cancel each other out

2/ It will pick up and register the signal from Mr A's own contact and will not 'see' the weaker signal from Mr B's contact

3/ It will pick up the weaker signal from Mr B's contact and will not register it's own stronger signal.


I know from driving my car that when you get poor reception in a car and you lose a radio station and pick up another station you get either one or the other. I have never had a scenario where I can hear TWO radio stations playing at the same time...

The answer to the scenario posed above explains in simple detail why despite installing 20 adjacent wireless alarms there has never been any problems.

It also puts your whole suggestion of two adjacent alarms stopping one from operatinginto a different light.

It would seem now that further circumstances other than simple location have to be considered as pure distance between the systems favours NO problems with disruption due to the inverse square law and in fact the polarity of the control panels placement and the positioning of the sensors has more impact.

In fact what you have also said by reference is that it would actually be possible if installing two systems in adjacent homes if they were installed at the same time by monitoring signals you could actually place them so each system could not intefere with its neighbours in any circumstance by carefully using the sensors polarity and positioning making in effect two totally independent systems with no possibility of crosstalk. Perhaps by sheilding sensors with foil to direct the transmissions so signals only went towards their own control panel.

 

[bernardgreen]

[I know from driving my car that when you get poor reception in a car and you lose a radio station and pick up another station you get either one or the other. I have never had a scenario where I can hear TWO radio stations playing at the same time...

Because it was almost certainly an FM radio, try it on medium wave which is AM

favours NO problems with disruption due to the inverse square law and in fact the polarity of the control panels placement and the positioning of the sensors has more impact.

Polarity ? The inverse square is only one factor, wall construction and many other parameters affect the signal strength, even human bodies reduce signal strength.

Perhaps by sheilding sensors with foil to direct the transmissions so signals only went towards their own control panel.

If you are unlucky about the size and distance of the foil from the sensor's transmitter then you could end up with the tin foil acting as a director which instead of screening the signals it acts as a "lens" ( more correctly a director ) which sends most of the radiated energy in the wrong direction. ( look up the theory of the Yagi aerial )

 

[bernardgreen]

What will be the net result at the control panel in the Home of Mr A

With FM the receiver will most probably lock onto the stronger of the two and present that message to the processor.

With AM it will mix the two and present a confused mix of two messages to the processor.

That is why I asked the question, AM or FM

 

[JohnD]

If Mr A's sensor and panel are inside his house, and Mr B's sensor and panel are inside his, we can have an expectation of which is likely to have the stronger signal.

However, with the HSA6400, HSA3800 etc, we can also get real-life experience by observing how often, if at all, interference blocks the signal by counting how often the system fails to start Entry Count Down after opening the front door. In my experience it is zero. Your experience may differ.

BTW, and while on the subject of real-lfe experience, Bernard, are you prepared to answer my question yet, about how often in the last year your remote blipper failed to unlock your car?

 

[bernardgreen]

Bernard, are you prepared to answer my question yet, about how often in the last year your remote blipper failed to unlock your car?

I think I did mention that am aware of locations where car key fobs are un-reliable due to nearby sources of radio frequency energy that over load front end of the car's receiver. One site opperator does mention this on their visitor's information sheet. On another site the car park was relocated after a number of incident where cars could not be un-locked other than by manual unlocking. It is worth pointing out that car security systems are specifically designed to react in a safe way to interfering signals as the effect of an immobiliser / steering lock or other anti theft device being activated when the vehicle is being driven could result in an accident. The comparison of car key fobs to DIY wireless alarms is not comparing like for like as regards radio communication protocol and reliability.

In general I have probably had one or two occasions where the first attempt to unlock at the normal distance from the car did not suceed but the second attempt when closer to the car did un-lock the car. Definately there have been occasions when within the normal range the car did not unlock.

 

[JohnD]

so, over the last year, that's how many times, would you estimate?

 

[mdf290]

I think it will be all quiet on this thread now. Bernards admission that the inverse square law applies to distance and signal strength actually blows away his argument about two systems next door to each other causing problems.
If two signals were recieved simoulltaneously in the famous argument that was never answered . . The alarm signal within the house would get acknowledged as it would be a stronger signal than the one from the neighbouring house.

But again here we are talking about two signals recieved absolutely simoultaneously.

So we are back to the probability of that event occuring (absolutely simoultaneous signals ) AND the probability of your neighbours signal also being stronger...

As Harry Hill would say - - What are the chances of that happening..

 

[bernardgreen]

Remember I said

The inverse square is only one factor, wall construction and many other parameters affect the signal strength, even human bodies reduce signal strength.

Your neighbour's front room PIR sensor could be much closer to your siren than the sensors at the back of your house.

And there are other items which transmit on frequencies that are in the pass band of low cost receivers ,

You haven't answered whether it is AM or FM.

 

[JohnD]

since you mention questions that haven't been answered, Bernard:

just catching up with some unanswered questions here

... agree that your expensive pro system will also not protect people who are stupid or careless, and as I accurately and truthfully pointed out, the effects can be even worse?

...estimate the probability that an interfering signal will block a sensor at the same fraction of a second that a burglar breaks into your house, ...

Let's assume, for the purpose of the exercise, that the house is an ordinary domestic house, built in an ordinary street full of other domestic houses, and is not built under the aerial of a BBC transmitter, neither is it built next to an electricity power station.

Alternatively, tell me, how often, in the last year, did you plip the wireless unlocker of your car, when it was parked outside your house, and find that the car did not unlock?

 

[mdf290]

Remember I said

The inverse square is only one factor, wall construction and many other parameters affect the signal strength, even human bodies reduce signal strength.

Your neighbour's front room PIR sensor could be much closer to your siren than the sensors at the back of your house.

And there are other items which transmit on frequencies that are in the pass band of low cost receivers ,

You haven't answered whether it is AM or FM.

FM

Ok so when I install to a new home as I typically do around many new housing developments with a 6400 system with a panel typically in the hallway a signal from the back of the home has to travel through a stooth partition wall whereas signals from nextdoor have to go through brick with an insulated lining.

So realistically this proves why I haven't been advised of any problems to date.

 

[bernardgreen]

pdf1m minimumSmoke detector Radio 433.92MHz AM super heterodyne 433.92MHz AM transmitter
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Power supply 6V, 4 x D alkaline cells. 3 miniature "lighter" battery. 3 years
Radio system 433.92MHz APoMwer supply 6V4,343x.9D2MalkHazlinAeMcetlrlsa.n3smitter miniature "lighter" battery. 3 years
years typical service life typical domestic service life
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Integral transmitter and super heterodyne receiver with jamming detection
Power supply Plug top adaptor type, input 230VAC 50Hz, output
Power supply 6V, 4 x AAA alkaline
Keypad remote control Keypad remote control
cells. 3 years typical domestic service life
Radio Microprocessor controlled Radio Microprocessor controlled T4e3s3t.9e2dMtHozEANM54transmitter 433.92MHz AM transmitter
Keyfob remote control


Yale say AM. ?????

 

[JohnD]

What did you ask for then?

 

[bernardgreen]

To know for certain if it was AM or FM as the reliability and operation is dependant on which method of modulation is used.

It is bit worrying that an "experienced installer" is not aware of type of wireless system is used.

 

[JohnD]

To know for certain

No, that can't be true.