Search Length (802.16 OFDM)

Default: 120 Symbol-times (See 802.16 OFDM Standard Setups/Presets Table.)

Search Length specifies the length of time to acquire the input signal (in seconds). This defines the length of time that the pulse search is performed.

The VSA searches within the specified Search Length and demodulates the first complete pulse found. The pulse can occur anywhere within the Search Length. Pulses beyond the first complete pulse are disregarded and are not demodulated. In order for the Pulse Search algorithm to detect a pulse edge, the pulse must be at least 15 dB above the noise floor. The resultant pulse is then demodulated.

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How Result Length and Pulse Search effects Search Length

Manual: If Result Length is set to Manual, then the start of the burst and at least the Result Length (in symbols) must be within the Search Length.

Automatic or From FCH: If Result Length is set to Automatic or From FCH, then either there must be a complete burst within the Search Length or the start of the burst and at least the Maximum Result Length (in symbols) must be within the Search Length.

Pulse Search: When Pulse Search is cleared, the VSA searches for a preamble within the Search Length but does not use the RF Radio Frequency: A generic term for radio-based technologies, operating between the Low Frequency range (30k Hz) and the Extra High Frequency range (300 GHz). power envelope to aid the preamble search.

Longer Pulse Lengths increase the measurement time but make it more likely that a pulse will be found. If a pulse is not found a PULSE NOT FOUND status message is displayed.