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Real World Examples of range for Parallax 433 Mhz Transceiver? — Parallax Forums

Real World Examples of range for Parallax 433 Mhz Transceiver?

WBA ConsultingWBA Consulting Posts: 2,934
edited 2011-01-13 12:23 in Accessories
While visiting with friends from church today, I was reminded of Bigweld's motto "see a need, fill a need" and I think the Parallax 433 Mhz Transceiver would be a good fit as long as the range would suffice. I need to get a simple chunk of data to travel between two buildings about 80 feet apart. One unit would be about 30 feet into the first building behind a set of glass doors and behind a set of oak double doors and/or 6" sheetrock wall. The other unit would be just behind a standard insulated 4" sheetrock wall.

I only have one of them so I can't test myself yet, but does anyone else have some experience with the inter-building range with these devices? Web page says 250 feet line of sight, so I almost want to assume that going through a couple walls would still be okay at 110 feet.

Comments

  • kuismakuisma Posts: 134
    edited 2011-01-03 00:07
    There are many parameters determining the range. Baud rate, transmission encoding, how the receivers handles noise, noise in the environment, antennas, demands on reliability etc, making your question difficult to answer.
  • MoskogMoskog Posts: 554
    edited 2011-01-10 23:48
    With replacing the exisiting dummy load on top of the tranceivers with better, tuned antennas you could increase the range alot.
    There are a lot of examples of homebrew 433MHz or 70cm antennas found on internet, just google around.
    Remember you can also increase range by moving the RX/TX module to a place with better sight just by adding a cable in between the tranceiver and the Basic Stamp. 4-5 meters with CAT3 cable or similar should be no problem.
  • bsnutbsnut Posts: 521
    edited 2011-01-13 01:10
    I am in full agreement in what he stated about putting the module closest to other one and putting dummy load on the antenna. I would stick, the RF module outside in a plastic waterproof 6"x6"x4" junction box.

    Remember these RF modules are "Line of Sight" this means there is nothing else between the one module and other module like a building. In a nutshell you can see the other module location.
  • languerlanguer Posts: 6
    edited 2011-01-13 12:23
    As previously mentioned it is hard to answer since wave propagation is very environment-specific. Gut-feel says that for low baud rate; you're probably close.

    A few things that may help if you are a little short in range:
    > Lower baud rate (if possible).
    > The power of the transmit side on the TRM IC is adjustable through a resistor that goes between pin-12 and Vcc. I'm not sure what Parallax has in there (probably something close to 1k-ohm); but page 11 of the TRM datasheet (http://www.linxtechnologies.com/Documents/TRM-xxx-LT_Data_Guide.pdf) talks about this.
    > You could use a bigger antenna (in place of the short stubby).
    > You could connect the antenna to the module through a coaxial cable, allowing you to place the antenna just outside the building.
    > You could place the module outside the building and connect to the STAMP/PROPELLER/MCU through a cable interface.
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