Welcome to the NavList Message Boards.

NavList:

A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

Compose Your Message

Message:αβγ
Message:abc
Add Images & Files
    or...
       
    Reply
    Re: Navigation using satellite doppler shift
    From: Peter Monta
    Date: 2016 Jan 30, 22:25 -0800

    EPIRBs and COSPAS/SARSAT use this in reverse for the sat to find the EPERB.


    Yes---DORIS as well.
     

    I know this is not exactly celestial navigation but I was wondering how accuratly you could get a fix by observing the Doppler shift as a satellite goes by. Certainly with the amateur communication satellites one can observe a significant shif in the UHF or VHF frequency, and it should be easy to automate measuring this with a cheap software defined radio dongle (like a TV dongle). I wonder how accurate the frequency is on the oscillators and how accurately we know teh emphemeris data? My guess is provided the orbit is fairly well known it should be as accurate as an EPIRB (a couple of nautical miles). 


    I think it depends on the satellite.  For example, Iridium uses OCXOs (ovenized crystal oscillators), which are good but not in the same class as the rubidiums or PHMs on GNSS satellites.  There has been some discussion on NavList of doing optical navigation with satellite photography, as they did with PAGEOS in the 1960s, and it would be helpful to have better orbits than the TLE services provide (~few hundred meters for LEO).  This is identical to doing photographic lunars, just with moons that are a lot closer and dimmer and subject to perturbations---they have high-maintenance orbits, unlike the big guy.

    A network of inexpensive receivers camped out on various ad-hoc satellite signals, and using GPS as a reference, would be just the thing, if orbits are not otherwise available.  Do the commercial LEO constellations (Iridium, Globalstar, Orbcomm, etc.) publish meter-quality orbits as a public service?  Surely they all have GPS on board.  Anyway, once good orbits are available, what you propose is then similar to TRANSIT, as you mentioned (or perhaps "assisted TRANSIT", with ephemeris information from this external source).

    Cheers,
    Peter

       
    Reply
    Browse Files

    Drop Files

    NavList

    What is NavList?

    Join NavList

    Name:
    (please, no nicknames or handles)
    Email:
    Do you want to receive all group messages by email?
    Yes No

    You can also join by posting. Your first on-topic post automatically makes you a member.

    Posting Code

    Enter the email address associated with your NavList messages. Your posting code will be emailed to you immediately.
    Email:

    Email Settings

    Posting Code:

    Custom Index

    Subject:
    Author:
    Start date: (yyyymm dd)
    End date: (yyyymm dd)

    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site