Paradise P300 Fault Mode Setting, Default normal fault detection, Max Sequential decoder gain

FAULT MODE SETTING

0Default (normal) fault detection

1ISDN Backup (<V2.14) / ISDN backup AND OQPSK Compatibility (>=V2.14) Software <V2.14: Exactly as defined for Fault Mode 13 (but available in earlier versions). Software >=V2.14: A combination of Fault Mode 13 (ISDN backup) AND Fault Mode 12 (OQPSK Compatibility).

2Telenor (Receive fail Transmit Inhibit, RTI)

This additional feature allows the guaranteed shutdown of transmission from a remote unmanned site even in the event that all M&C is lost. When enabled this remote shutdown is accomplished by muting the signal to the remote destination, which will then mute its transmit carrier whenever the `receive input signal is lost` for more than 10 seconds continuously. Specifically:

The definition of `receive input signal is lost` includes demod unlocked, FEC sync lost, RS sync lost, frame sync lost (if applicable), and Multiframe sync lost (if applicable).

The remote transmit will unmute when all the above alarms have been clear for 5 seconds.

3Max Sequential decoder gain

In normal operation at data rates of 128kbps and below, to reduce the delay through the sequential decoder (if selected as the FEC in operation), the decoder processing memory is shortened at the cost of slightly reduced decoder gain. This option disables the shortening of the memory, and leaves the maximum memory in circuit maximising the Sequential decoder gain (at the cost of increased processing delay). In the normal mode (when this function is not active) the decoder memory is 4096 bits, but at receive rates of 128kbps and below this is reduced to 2048 bits, 64kbps and below 1024 bits, and 32kbps and below 512bits. This means the maximum delay is 32ms at 128.001kbps, and stays between 32ms and 16ms right down to 16kbps, (below which, with the minimum 512bits of processing memory the delay increases again above 32ms). The data rate used to determine the processing memory size is the receive rate including any framing and Reed-Solomon overheads (as this is the output rate of the sequential decoder). See the separate note in section 8.4 on page 144 regarding minimising the Reed-Solomon delay.

4Slow Sweep / Poor Eb/No Acquisition

Satellite modems are one large compromise, and part of this compromise is a trade off between poor Eb/No acquisition performance and normal Eb/No acquisition speed. The modem is optimised for reasonably fast acquisition down to an Eb/No of 5dB, and the sweep speed is set to match goal. This option reduces the sweep speed (and hence increases the acquisition time) by a factor of ten, but improves the low Eb/No acquisition by approx 0.5dB. It is advisable when using this setting to narrow the Rx sweep width (if you know the frequency of the Rx carrier to be fairly accurate) to help speed up the acquisition while sweeping at this very slow rate.

5Post Reed-Solomon V35 Scrambling Not available on the P300.

6Fast Eb/No monitoring

The raw Eb/No information the M&C reads varies significantly and so the Eb/No displayed by the equipment is a heavily averaged to provide a steady result to display. In some circumstances it is desirable to have a faster display of Eb/No (eg to track short duration interruptions such as a helicopter crossing the beam), and this option disables the Eb/No averaging providing a faster responding, but rather jittery Eb/No display.

7Severely Degraded Phase noise mode

In response to a customer request to provide operation with a severely degraded receive phase noise in QPSK, this mode can be enabled. It allows operation with up to 20dB worse phase noise than the INTELSAT mask (DC - 1kHz), although at the cost of a degraded BER in normal operating conditions (BER is degraded by up to 1dB compared to `Normal` mode).

P300H P300 Series Modem Installation and Operating Handbook Page 202