rangefinders....

I'm thinking of making a device to watch for cars coming up my driveway.
I know about the commercial monitors for this, but they have some
drawbacks I'm trying to work around. So... I'm asking if anyone knows
of a good sensor solution for this. The requirements are:

Range: 10-50 feet, narrow angle
Ambient: daylight
Senses: vehicle moving towards the sensor
Reports: distance or speed

My idea is to monitor the signal and try to discriminate against
non-vehicles (animals) as well as ignore vehicles moving *away* from the
sensor. Bonus if it's precise enough to detect humans walking towards
it (constant speed, specific size).

I'm thinking of making a device to watch for cars coming up my driveway.
I know about the commercial monitors for this, but they have some
drawbacks I'm trying to work around. So... I'm asking if anyone knows of
a good sensor solution for this. The requirements are:

Range: 10-50 feet, narrow angle
Ambient: daylight
Senses: vehicle moving towards the sensor
Reports: distance or speed

My idea is to monitor the signal and try to discriminate against
non-vehicles (animals) as well as ignore vehicles moving *away* from the
sensor. Bonus if it's precise enough to detect humans walking towards it
(constant speed, specific size).

DJ Delorie wrote:

I'm thinking of making a device to watch for cars coming up my driveway.
I know about the commercial monitors for this, but they have some
drawbacks I'm trying to work around. So... I'm asking if anyone knows
of a good sensor solution for this. The requirements are:

Range: 10-50 feet, narrow angle
Ambient: daylight
Senses: vehicle moving towards the sensor
Reports: distance or speed

My idea is to monitor the signal and try to discriminate against
non-vehicles (animals) as well as ignore vehicles moving *away* from the
sensor. Bonus if it's precise enough to detect humans walking towards
it (constant speed, specific size).

Would be difficult, particularly if said object is approaching at
walking pace, is about the same size, and weight of a car, makes the
same rumbling noises as a car, but is made entirely of organic material.

I mean, it would never be able to warn if the mother in law is approaching.

Ok, ok. I'll leave quietly.

John Tserkezis wrote:

DJ Delorie wrote:

I'm thinking of making a device to watch for cars coming up my driveway.
I know about the commercial monitors for this, but they have some
drawbacks I'm trying to work around. So... I'm asking if anyone knows
of a good sensor solution for this. The requirements are:

Range: 10-50 feet, narrow angle
Ambient: daylight
Senses: vehicle moving towards the sensor
Reports: distance or speed

My idea is to monitor the signal and try to discriminate against
non-vehicles (animals) as well as ignore vehicles moving *away* from the
sensor. Bonus if it's precise enough to detect humans walking towards
it (constant speed, specific size).

Would be difficult, particularly if said object is approaching at
walking pace, is about the same size, and weight of a car, makes the
same rumbling noises as a car, but is made entirely of organic material.


The early Gunn diode based microwave alarms could detect anything
that reflects a signal, including people. The direction can be sensed as
well, but requires more circuitry. The return signal is beat against
the CW microwave signal, giving an audio signal. Early solid state
police RADAR used them, along with the automatic door openers in retail
stores.


I mean, it would never be able to warn if the mother in law is approaching.

Ok, ok. I'll leave quietly.

Please do.