如何在brightscript中获得网速

sub GetNetworkSpeed()
    startTime = CreateObject("roDateTime")
    urlTransfer = CreateObject("roUrlTransfer")
    urlTransfer.SetUrl("http://www.example.com/smallfile.txt")
    
    urlTransfer.SetCertificatesFile("common:/certs/ca-bundle.crt")
    urlTransfer.EnableEncodings(true)
    
    urlTransfer.AsyncGetToString()
    
    while urlTransfer.GetStatus() = "in progress"
        wait(1, true)
    end while
    
    if urlTransfer.GetStatus() = "succeeded"
        endTime = CreateObject("roDateTime")
        elapsedTime = endTime.Diff(startTime)
        speed = 8 * urlTransfer.GetBytesTotal() / elapsedTime.TotalSeconds()
        print "网速：" + speed + " Mbps"
    else
        print "请求失败"
    end if
end sub