Troubleshooting

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8. Troubleshooting

  • Polarization incorrect

    Units RAy3-17 and RAy3-24 must be mounted with opposite polarization; one with TX horizontal polarization (horizontal arrow) and the second with TX vertical polarization (vertical arrow). See Cross polarization for more info.

    Install the unit with the correct horizontal or vertical polarization: The arrow mark indicates the unit TX polarization. When the arrows heading perpendicular to the earth, the unit transmits a signal in vertical polarization. When the arrow is heading parallel to the earth, the unit transmits a signal in horizontal polarization. The connectors must point downward at an angle.

  • The link cannot be established

    Double check the correct polarization (see above) of both units on the link.

    Start with the most “resilient” configuration. This configuration depends on the type of unit. We recommend using the narrowest available bandwidth (e.g. 3.5 MHz), the lowest modulation level (QPSK_S) and maximum available output power. TX and RX channels must be the same as the RX and TX channels in the remote unit. When the connection has been established and the antennas have been directed, proceed with operation parameters.

  • Access to the Local unit is blocked

    Access to the Local unit may be accidentally blocked, for instance by disabling HTTPS access. If you can access the Remote unit over HTTPS, type its address in your web browser’s address field. The link will transfer the packet over the Local unit with blocked service access all the way to the Remote unit, which will give you access to the control menus of both units. Warning, the Remote unit will report as Local.

  • Distinguishing Local-Remote

    A unit accessed via service access always reports as Local. If you connect through another (peer) unit and radio channel, a certain amount of caution is necessary. For example, do not reduce the transmission power so that the link interrupts accidentally. Errors of this type should be fixed by the rollback function within approx. 1 minute.

    Resolution can be done by comparing the length of ping on Local and Remote. Pinging the unit behind the radio channel is slower. The difference is more pronounced in the case of a long packet and the low speed of the radio channel.

  • Access security

    For better protection against unauthorised access to configuration you should only allow as few kinds of access as possible. The most secure type is SSH with key – leave only SSH active with “only key” choice.

  • RSS

    To configure the link and monitor its state, several menus display the RSS signal strength. Please keep in mind, that Ray is not a measuring instrument, hence the precision of the RSS reading is limited. Though, in most situations the RSS reading accuracy is better than ± 2dB, the absolute RSS value should not be used for accurate comparisons e.g. between two links.

  • Problem with https certificate

    See the Appendix C, Https certificate

  • Overexcited receiver

    A natural property of each radio receiver is to compress the signal in one of the functional blocks, when the signal level gets out of the AGC (automatic gain control) dynamic range. The result of this effect is non-linear distortion of the received signal which is observed as decrease in the signal to noise ratio, i.e. in case of digital modulations increase of the Mean Square Error (MSE).

    Limit for guaranteed functionality of RAy3 radio receiver is -15 dBm (measured on the waveguide input). This limit applies for all channel bandwidths and all modulations.

    Beyond this limit the distortion of linearity appears and signal quality is depreciated. In extreme cases, this can lead to the disintegration of the radio link due to reduced signal to noise ratio (as a result of signal distortion).