How does the clifford alarm system get such good range??!?!

Wireless & IoT
1

http://www.clifford.com/Products/Produc … ductID=714

They have little keyfobs that can communicate with your car from up to a MILE away.

I’ve personally seen it work for my coworker’s car. I work in a 5 story office building and she can communicate with her car from her desk.

I’ve played with 415MHz Linx LR radios, and the range isn’t as good

I’ve played with XBee 2.4GHz radios, and the range isn’t as good

It’s really impressive stuff. How do they do that?!??!

2

No one has any idea?

3

I can take some guesses. There are a number of factors to get good range from an RF link. These are:

Transmitter power in a Narrow bandwidth. higher peak ERP

Modulate frequency and method. Associated with bandwidth and immunity to noise.

A receiver with good sensitivity and selectivity, steep-skirted narrow bandwidth.

A robust de-modulation and error correction methods.

The Clifford link says “1 mile range with SST” but I don’t know what SST is. It could be the modulation method and/or a combination of above features.

4

On factor is the choice of frequency bands and the host nation’s power limitations for that band. In the US, the 315/433MHz band where most remotes and wireless thermometers are have very low power limits and low duty cycle rules.

In 902-928MHz, one can use a lot higher power. And frequency hop to avoid interference.

And have a larger battery size for this class of device.

Next is the issue of transmitted signal occupied channel bandwidth and bit rate. Smaller bandwidth and/or lower bit rate = less required signal to noise to receive at some error rate. And forward error correction codes (effectively reducing the useful bit rate) allow for weaker signals.

And so on. It’s really about cost.

5

I was thinking of using products by Linx Wireless. I bought the demo kit for the LR series radios @ 418MHz and had ‘alright success’ … not all that great IMO

Would moving to something like the ES series @ 916MHz help me get more range?

http://www.linxtechnologies.com/product … s-modules/

http://www.linxtechnologies.com/product … n-modules/

6

clifford describes sst as " Range is important, and Clifford is proud to offer the longest range remotes in our history - up to a full mile using Digital Spread Spectrum Technology (SST). SST uses digital frequency hopping and multiple frequency transmission to assure that, if a frequency is blocked, the signal still goes through.

  • One Mile Range based on line of sight, unobstructed testing in ideal conditions. Actual range will vary due to local conditions including but not limited to environment, terrain, physical obstructions, vehicle location and orientation, interference and other possible impediments. "

what’s it say on the back of your coworker’s remote for FCC info?