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Spirent KB Article
Doc ID: FAQ17013
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SimGEN: How can I turn off individual frequencies on or off whilst a scenario is running, for example keep L1 on but turn L2 off?
One way to do this is to use antenna switching on the receive antenna pattern.
define pattern 1 with both on
define pattern 2 with L1 on but L2 off
define switching file to switch between patterns as needed
The attached scenario "turn frequency off" demonstrates this principle as so:
at t=0 minutes L1 and L2 are both ON
at t=1 minutes L2 is turned OFF
at t=2 minutes L1 is turned OFF and L2 is turned on
Remember values in the antenna pattern represent attenuation in dB's so any negative values are gains!
The alternative way to achieve a similar effect is to use the Tx antenna patterns, this method allows you to configure different antenna patterns, one which can be considered normal levels and an alternative pattern which has the maximum attenuation applied. Switching the second antenna pattern in at a scheduled time gives the effect of turning of either L1 or L2 signals whilst continuing to transmit the wanted signal. The signal will still be produced by the configured channels but will be at a reduced level.
The attached scenario named "turn GPS L1 frequency off" uses this method to turn off the L1 off after an initial period of having both L1 and L2 signals.
Use of the " Antenna pattern selection file", which is a .aloc file is used to achieve the switching
The level pattern #1 L1 and Level pattern#L2 files have the same characteristics as those used in the receive level pattern files, method 1 above.
turn frequency off.zip
turn GPS L1 frequency off.zip
Initially L1 and L2 and then L2 only after 10 secs.
Product : SimGEN