Microhard pmddl2450 long range testing

  • Hello,
    I ma using VOXL2 with system image 1.4.1 along with Microhard pmddl2450 Add-on board for UAV side and USB carrier board for GCS side. I followed setup instruction on this page and I was able to have stable connection between GCS and UAV. I configured my GCS side Microhard as master and UAV side Microhard as slave. I enabled 256 bit AES encryption, 8 MHz channgel was setup with 20 dbm of power.
    I want to have 2 kms of LOS range with my setup. But as aircraft moved around 750 meters I started to face disconnections with UAV from GCS. On my UAV I 2S Li-ion 3500 mah battery pack powering complete aircraft and VOXL2 and on GCS I am connecting microhard to get power from Power bank of 2 Amp source current and ethernet connection is initiated with Android tablet. Also I using same molex antenna which are coming with Microhard modem. Are those antenna meant for long range applications?

    I want to understand a proper setup need for acutally achieving 2 kms of stable LOS communication with microhard as modem. Any help from community or ModalAI developes would be highly appreciated.

  • Dev Team

    Range will be affected by:

    • Antenna choice and placement
    • Interference

    Disable Wifi (which operates in the same frequency range) on both the drone (VOXL) and the ground station.

    Additionally, you will only get good range if you are away from buildings that could have wifi routers.

    Make sure the antenna are mounted such that there is direct line of sight to the ground station antennas, which should also be mounted such that there is direct line of sight to the drone

  • @Chad-Sweet Thanks for quick response.

    Regarding antenna can we replace molex antenna with some other high gain antenna? I see to it as culprit over here. We pasted two molex antenna on two sides of the drone which wasn't facing towards GCS.
    Regarding interference, we were testing the setup on complete isolated country side open land without any wifi routers and also we havne't connected any wifi router on UAV. So interference shouldn't be a problem over here.

    Mounting antenna in fashion where they would be always in line of sight is difficult with molex antenna setup which we receive with Microhard Add-on kit.

    Any suggestion on antenna to be used for long range communication over current microhard would be highly appreciated.

  • Dev Team

    Hi @Aks
    Also make sure you have the lowest modulation order that you need, and do not over-specify bandwidth if you do not need it (i.e.: use 4MHz instead of 8MHz).
    The maximum distance with microhard will only be done with MIMO, 4MHz, BPSK since it has the best receive sensitivity at -102.5dBm.
    Here is a snippet of their public data brief (a year or so old however), showing the various receive sensitivities based on various settings. You want the lowest number you can sustain for your expected throughput so you can get the best (smallest) receive sensitivity.
    If you set for 8MHz and 64QAM, you will have very short range at only -78dBm!
    Hope this helps!

Log in to reply