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Point to Point Wireless Communication

Discussion in 'Radio and Wireless' started by stoui333, May 14, 2019.

  1. stoui333

    stoui333

    6
    0
    May 14, 2019
    Hi,

    I have been searching for days now to find something suitable for my application but it seems that the RF transceivers are either too industrial or too hobbyist.

    I `m looking for a low frequency (400MHz) high power (500mw-1w) RF transceiver with USB interface not heavier than 1kg nor bigger than 100x100mm.

    The idea is to have a remote connection from my laptop (connected with the mating RF transceiver over USB) on the desired PC at 1km distance.

    The link speed should be at least 0.5Mbps.

    What ever i found in the market it meets all the requirements beside the link speed that the max i found was 14.4kbps.

    Any suggested vendors, manufactures, transceiver models?

    Thanks!
     
  2. Nanren888

    Nanren888

    67
    10
    Nov 8, 2015
    May I ask what drives your choice of frequency and power?
    It's just that these will limit your options.
    Remote connection, for what? peripherals, remote desktop? Custom protocol? Serial over USB?
    Urban or rural?
    Line of sight?
     
  3. Harald Kapp

    Harald Kapp Moderator Moderator

    9,003
    1,791
    Nov 17, 2011
    0.5 W to 1 W at 400 MHz is usually not one of the unregulated (free) frequencies and power ranges.
    433 MHz is more likely to give results. A quick Google search for turnes up a bunch of modules claiming to bridge 1 km or more but most (if not all) with only uart interfaces at up to 115 kBps.

    For higher data rates a higher frequency is employed. I found a "NRF24L01+ 2.4GHz PA+LNA SMA 1Km Wireless RF Transceiver für Arduino Raspberry Pi" module claiming max. 2 MBps, alas with an SPI interface, not USB. Althouhg one could add a USB/SPI interface on both ends for PC communication.
     
  4. stoui333

    stoui333

    6
    0
    May 14, 2019
    Frequency: I would like to avoid the cellular network frequencies + Wi-Fi ones. Also, lower frequencies tent to travel more distance than the higher ones but have lower data rates.
    Power: I suppose that 500mw-1w (27-30dbm) output power would be sufficient for 1km distance.
    Purpose: Remote desktop
    Area: Rural LoS

    I know that market has 5GHz point to point communications over Lan but the devices are huge
     
  5. Nanren888

    Nanren888

    67
    10
    Nov 8, 2015
    I wholeheartedly agree that you probably should stay off the cellular bands.
    Interference with licensed spectrum will be frowned upon with consequences. That will go for many bands.
    .
    All bands will have power limits, often as EIRP.
    Check out the bands available. Others here likely know this area well.
    .
    If size is a factor, antennas tend to shrink with increasing frequency. From memory, LOS path loss will increase with frequency.
    By the time you have workable remote desktop over radio over 1km, I think you may have a not insignificant size.
    If you are communicating over ground, from antennas not mounted very high, you may have to watch multiple-path, particularly the two-path model.
    .
    People have claimed significant distances with WiFi and directive antennas, even pringles-based ones. Probably exceeds the WiFi EIRP.
    WiMax will get you higher rates further, but at a cost.
    .
    I understand: not what you asked for, but staying mostly within legal requirements is likely a good plan.
     
    davenn and Harald Kapp like this.
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