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Lectrosonics SRb Ratio Mode

Karl Wasserman

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Jeff Wexler posted a clear and informative reply to Prahlad Strickland's question about diversity reception. Read it here:


I posted my question there, but as it was off-topic I've re-posted here so as not to derail the thread.


Lectrosonics' SR manual reads: "...the two channels can be used together as a single receiver in "True Diversity" Ratio Mode for enhanced performance in some environments."


My understanding is that in Ratio Mode, the dual receiver SR "favors" the audio signal from the receiver with the stronger signal from the transmitter. If Ratio Mode on the SR is a combination of antenna diversity and receiver diversity, how is it better than receiver diversity? If I use a pair of receiver antennas (matched or not) in fixed positions for each integrated receiver front end in an SR, both receiver sections will have (presumably) identical range and reception from the transmitter.


How does Ratio Mode purport to give a more robust signal than plain ol' receiver diversity?

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Hi Karl,

In Ratio Mode, the audio signal from the two receivers is blended. This will give a 3 dB improvement in SNR if the RF signal at both receivers is equal or if the signal at both receivers is so high that the audio quality at both receivers is identical. If the SNR at the receivers deteriorates slightly, the signals are blended with more weight going to the better receiver. When one of the receivers has a SNR about 3 dB worse than the other, the blending can't make up for the poorer receiver so then the audio signal is taken only from the better receiver. In Ratio mode, the antenna diversity is frozen with one receiver getting an in phase RF signal and the other getting an out of phase RF signal. That way if the RF at the antennas is in or out of phase, one of the receivers is getting an in phase signal.

Best Regards,
Larry Fisher

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