Garage Door Opener Range.

I'm with you, antenna is the solution. I'd try cutting a director and reflector to proper lengths and just hung then in place for a test. Two pieces of wire could solve his problem. Mikek

I'm not familiar with the Infiniti Q45 or the associated remote. Normally, I would look at the encoder chip in the Homelink and see if I can find a receiver that uses the matching receiver chip. However, Homelink works by cloning the codes from the remote, so all that may not be necessary. If the visor thing has a picture of a house above the buttons, it will do rolling code which covers most remotes. Here's the instructions for the Homelink: With luck, it might work with your unspecified model garage door opener.

Good find Jeff, looks exactly like on my visor... and the instructions are quite clear. All I had found so far were confusing and conflicting :-(

Door opener is Genie 2024. Not exactly my favorite brand, but it looks like they've cured the problems I reported about 10 years ago... _jerk_ starting the door. ...Jim Thompson

That will detune the front end since it wasn't designed for a complex, 50 ohm antenna. Some of the single board controllers have an etched trace for the antenna. Also, any physical modification voids the FCC acceptance. Some of these are super regen, and a better antenna will radiate crap that will cause interference.

If the instructions are unintelligible, they were either written by the design engineer, or translated from some Chinese. The conflicts are intentional, intended to keep tech support in business.

This looks like the full solution:

Thanks.

Any jerk can open a garage door. Are you looking for an IQ or attitude test before allowing the garage door to open? I haven't seen it done but I suspect some kind of challenge/response game can be built into the remote. Patent it?

Hint: The belt drive builds up tension in the belt before overcoming the door startup friction. If the startup friction is sufficiently high, that can result in a rather spectacular lurching start. The chain drive doesn't act like a spring but makes more noise and costs more money. The fix is not to swap the belt for a chain, but rather to deal with the friction problem by finding where it's binding. Unbalanced tension/torsion on the pair of springs supporting the door is the usual culprit. I've performed several miraculous cures by simply balancing the springs or if adjustable, the spring tension.

--- What I'd do would be to drill a hole through the garage wall next to the door but up high, then connect a length of 50 ohm coax to a weatherproof 900MHz rubber duckie antenna with a 90 degree mounting flange/bracket and pass the coax through the hole from the outside of the garage to the inside.

Next, I'd mount the rubber duckie to the outside wall with the whip oriented vertically, and weatherize the installation.

Finally, I'd mount another rubber duckie on the inside wall, with the whip oriented vertically, and connect the coax.

Voila! passive repeater, - probably with some gain - nice clean install, and your warranty stays intact since you haven't even touched the holy RX.

--- What I'd do would be to drill a hole through the garage wall next to the door but up high, then connect a length of 50 ohm coax to a weatherproof 900MHz rubber duckie antenna with a 90 degree mounting flange/bracket and pass the coax through the hole from the outside of the garage to the inside.

Next, I'd mount the rubber duckie to the outside wall with the whip oriented vertically, and weatherize the installation.

Finally, I'd mount another rubber duckie on the inside wall, with the whip oriented vertically, and connect the coax.

Voila! passive repeater, - probably with some gain - nice clean install, and your warranty stays intact since you haven't even touched the holy RX.

John Fields

Everyone seems very concerned about the warranty, does anyone leave a unit modified and then call for warranty service?

Let me answer that for you.

Of course not, you put it back to original and then ask for warranty service.

Unless your mod caused the problem. Mikek

Passive repeaters, with omni antennas don't work. The problems is that the small "illumination area" (my term) of the two antennas results in a huge overall loss. Let's play with the numbers. I'll use 0dB gain for all the antennas and for the inside to outside passive repeater losses to make the math easier.

Garage door opener receiver end. Sensitivity 1 uv/12dB SINAD = -107 dBm Antenna gain on receiver = 0 dB Distance to passive repeater antenna is 10 meter. Path loss at 433 Mhz = -45 dBm Inside Antenna gain passive repeater = 0 dB Loss between inside and outside antennas = 0 dB Outside antenna gain passive repeater = 0 dB Distance from outside passive repeater antenna to remote control is 10 meters. Path loss at 433 Mhz = -45 dB Antenna gain on remote control = 0 dB Transmit power (about 100 microwatts) = -10 dBm Remote control transmitter end.

So... if we start out with -10 dBm of signal and have -90 dB of total path loss through the passive repeater, the signal level arriving at the receiver will be -100 dbm, which 3 dB above the receiver sensitivity. For PWM modulation and a crude demodulator, my guess(tm) is that at least 6 dB SNR is required to demodulate the data. That puts the passive repeater scheme about 3 dB short of working.

However, had there been no passive repeater over the same 20 meter distance, the path loss would have been -51 dB, resulting in a -61 dBm signal level at the receiver, which is 46 dB above the receiver sensitivity and 40 dB above my guess(tm) as to the operating threshold. That should work just fine. More simply, the difference in overall path loss between this 2 hop passive repeater and a direct shot without the passive repeater is: 45 + 45 - 51 = 39 dB

There are a few situations where passive repeater do work and are useful, but extending the range of a garage door opener is not one of them. However, if you want to make it work, you'll need at least a directional antenna at the receiver, pointed to inside passive repeater antenna, which should also be directional. If the approach is along a fixed path, a direction antenna for the outside antenna will also help. The total gain of these three antennas should equal the 39 dB path loss difference in order to get the same performance as a direct shot without the passive repeater.

I've build passive repeaters like this for situations where any signal is better than none at all. The catch is that if there's any signal leakage from a direct path that bypasses the passive repeater, there will be cancellation, nulls, dead spots, and irate clients.

You really should do the math on that idea to find out why it won't work. Also, they do not use 900 MHz for this model.

Gain?

At 200 m (down the street, why he is doing this) the FSPL is 71 dB. The Tx antenna will have lots of loss buried in the car body. The Genie opener just has a short (15 inches) length of wire hanging down for its antenna. No real

It's not at 900 MHz.

Whoosh whoosh...

In a black helicopter ?>:-} ...Jim Thompson

Or even 1900 MHz. Do you even think before typing?

Whoosh whoosh...

Agreed. 0 dB losses and 0 dBm gains were mostly so I didn't have to reach across the desk for my calculator. I made no effort to be accurate or even realistic. I simply wanted to demonstrate the effect of putting a passive repeater in the middle of the RF path. I can change the numbers to more closely reflect reality, but the added losses due to the passive repeater will not change things very much.

A 200 meter outside path will make a passive repeater even less desirable. If I leave the inside path at 10 meters, which I think is realistic for across a large garage, and use 200 meters for the distance between the car and the garage the path loss will be:

Without passive repeater. 210 meter path at 433 MHz: the loss is 72 dB.

With 200 meters plus the passive repeater at 10 meters, the loss is:

-126 dBm, which is well below the receiver operating level.

That's a difference of 44 between using a passive repeater and a direct shot. Throwing in realistic antenna gains will make things even worse.

Quiz: Starting with a 1/4 wave whip antenna over a large ground, how short can this antenna be cut before the gain drops substantially? The numbers in the filenames are the antenna lengths in wavelengths. For example, monopole_0_125 is 0.125 wavelengths or 1/8th wavelength. I only ran 3 applicable lengths, but the gain figures should offer a clue that as long as the feed impedances are reasonably well matched, you can probably cut an antenna down to below 1/20th wavelength, and still have a fair amount of gain: wavelengths gain(dbm) 0.250 5.19 0.125 4.85 0.050 4.75 The VSWR is atrocious, but the gain is still mostly there.