NPR-VSAT : IP access over QO-100 WB

  • I have developed the protocol /solution : NPR-VSAT.

    It allows low datarate IPv4 access over the QO-100 WB transponder.

    It could be used for low-datarate Hamnet access.

    Documentation, source code, binary:

    (sorry for the quick-and-dirty website, I will do better soon).

    You should read the "user guide" first if you are interested.

    Current status:

    The current version is usable for beta-tests.

    In parallel, I am under discussion with AMSAT-DL.

    At short term, we are allowed to make short duration tests (~30 min maxi).

    It is currently too early to say if we could have one day a permanent 24h/day unattended NPR-VSAT Hub station. I dream of it, it would be the ultimate achievement.

    It depends also on the interest and acceptance of the "community".

    If you are interested by the project, if you want to test it at short term, you can contact me. E-mail : f4hdk at free dot fr

    Do not hesitate to share with us the "usages" that you imagine if you had such an IP access.

    Some characteristics of NPR-VSAT:

    - Inherited from my previous project "NPR-70" New Packet Radio

    - Runs on PC, either Windows or Linux

    - runs with full duplex SDR, preferably Adalm-Pluto

    - MF-TDMA (multi-frequencies Time-Division-Multiplexing-Access)

    - Multi users, probably one or several dozens of simultaneous users

    - low data-rate, 20kb/s to 100kb/s for users

    - dynamic resource allocation

    - up to 4 or 5 channels, each 50kS/s or 100kS/s or 200kS/s

    - modulation BPSK or QPSK

    - coordination via a central station, the VSAT-Hub

    - full-mesh : client stations communicate directly with each others

  • F4HDK

    Changed the title of the thread from “NPR-VSAT : IP access over QO-100 Wide-Band” to “NPR-VSAT : IP access over QO-100 WB”.
  • Hi,

    In DVB-RCS location of the client station is taking into account in order to estimate the variable distance from the satellite that is affecting the accuracy of the time slot. As I see the user is not giving grid locator. This is not affecting the slotting mechanism ?

    Congratulations for you work !!!

  • Hello Georges, thank you very much for your message.

    With NPR-VSAT, you don't have to set manually the precise location or distance to satellite.

    A client station estimates the round-trip time (= Timing Advance), at each new connection, and it also measures and maintains this value constantly afterwards.

    How? The client just reads its own signals.

    The initial connection occurs in a dedicated "discovery time-slot". A very-large time-slot, in which unconnected clients send very-short radio frames for "connection request".

    The unconnected client station sends almost in the middle of this discovery time-slot, in order to compensate the big Timing-Advance uncertainty.

    A client station also saves automatically this Timing-Advance value locally (on the PC), for the next startup.

    If you want to test this solution, you can contact me, preferably in private (e-mail f4hdk at free dot fr, or via private forum message).

    I only provide the binary/executable and the source code for the "client" part. I would host the VSAT-Hub, for these tests.

  • Hi,

    this is a great innovation, i will follow this discussion carefully. I am already connected to the HAMNET via a 5Ghz link, a new way via QO-100 would be great. I installed the SW and everything seems to work fine. Waiting for the HUB to come up ;)



  • Hello Guillaume,

    I have read about your project and I find it very interesting and very well documented.

    This weekend we have an EA-CT microwave meeting and I have no doubt that it will be the subject of discussion.

    I have installed the SW and indoor tests seem fine.

    Later I will try the loop on the QO-100 and then waiting for you to start the HUB.

    Congratulations for your work!!!

    73 Aitor

    • Official Post

    Dear All,

    As Guillaume F4HDK pointed out, we are currently in deep discussion with him regarding his NPR-VSAT solution for QO-100.

    To get a broader agreement and acceptance we will establish an “expert team” to review and investigate the following areas:

    • Technical Feasibility
      • performance (modulation, FEC, bandwidth, required power).
      • non-interference (mainly due to pulsed uplinks) with DATV.
      • look at the major strengths and weaknesses.
      • other technical aspects.
      • setting-up a HUB at AMSAT-DL in Bochum.
    • Coordination and band planning
      • interoperability and compatibility with other modes.
      • proposal for a new WB-Transponder bandplan.

    The “expert team” will prepare a proposal to AMSAT-DL for a final decision and implementing.

    Everyone might understand that there is a complex “management/political” decision to be made at the end. While it will be difficult to make everyone happy, we have to make sure that the solution that is deployed is technically sound and accepted by most users. Also, we want to treat everyone fair and not favour or disfavour one mode of operation.

    On the other hand, Guillaume invested a lot of time in this very exciting project and we want to value the efforts and contribution he makes to the community. Indeed, there is always potential for improvement.

    As he says, the ultimate goal could be a permanent HUB, ideally located in Bochum with access to the HamNet. But to be clear: this would be for direct User / Client access only. Gateways or traffic between Gateways will not be permitted and this is not planned by design either.

    Until then, please make sure to follow the WB bandplan and general guidelines before starting any experimental transmissions (which is required for anyone on the WB-transponder anyway):

    • All transmitting stations shall monitor the wideband spectrum monitor.
    • All transmitting stations shall monitor the co-ordination chat window.
    • All experimental transmissions shall only be inside the reserved 1 MHz section for “experimental modes” just beside the DATV-Beacon.
    • All transmissions will be limited to short duration tests (~30min).

    If we see during the evaluation that there are no problems, we may gradually extended those periods. For example, for those times of the days where there is not much other activity.

    Watch this space!

    Best 73 de Peter, DB2OS

    President AMSAT-DL and QO-100 Project Leader

  • It would be interesting to know who still uses Hamnet as an end user when everyone has internet. And the Internet is also better suited for networking the virtual kingdoms of some sysops. The focus of the QO100 should be human-to-human communication ( QSO ).

  • Hello Frank,

    I for instance use Hamnet and know quite some people who do. It is also used as a backbone for packet radio links and for access to terrestrial DATV repeaters which are out of range for a direct access.

    As Peter pointed out: "... this would be for direct User / Client access only. Gateways or traffic between Gateways will not be permitted and this is not planned by design either."

    As Guillaume explained above his concept supports "Multi users: probably one or several dozens of simultaneous users. " and "Full-mesh : client stations communicate directly with each others".

    Let us wait for the evaluation and conclusion of the expert team.

    I am very excited to see such an additional use of the wideband transponder.

    Kind regards